NL2029164B1

NL2029164B1 - Modification of biopolymers using polyols and polyacids

Info

Publication number: NL2029164B1
Application number: NL2029164A
Authority: NL
Inventors: Aad George Binneveld Robbert; James Picken Stephen; ZLOPASA Jure; Otto Julius Böttger Willem
Original assignee: Univ Delft Tech
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2023-03-23
Also published as: WO2023038519A9; WO2023038519A1

Abstract

The present invention is in the ﬁeld of a method of modifying polymers produced by bi- ological species, in particular microorganisms, by reacting un-modiﬁed biopolymer, a modi- ﬁed biopolymer obtained by said method, an adhesive comprising said modiﬁed biopolymer, a ﬁbre reinforced composite comprising said modiﬁed biopolymer, and a ﬁbre reinforce panel comprising said ﬁbre reinforced composite.

Description

P100618NL00

Modification of biopolymers using polyols and polyacids

FIELD OF THE INVENTION

The present invention is in the field of a method of modifying polymers produced by bi- ological species, in particular microorganisms, by reacting un-modified biopolymer, a modi- fied biopolymer obtained by said method, an adhesive comprising said modified biopolymer, a fibre reinforced composite comprising said modified biopolymer, and a fibre reinforce panel comprising said fibre reinforced composite.

BACKGROUND OF THE INVENTION

A fibre-reinforced composite (FRC) is a building material that consists of three compo- nents, namely fibres (for strength and stiffness) as a discontinuous or dispersed phase, a ma- trix (binder) as a continuous phase, and the fine interphase region, also known as the inter- face. For fibres use can be made of natural fibres, synthetics fibres, or a combination thereof.

Examples thereof are flax, hemp, rice husk, rice hull, rice shell, cellulosic (waste streams), and plastic as ingredients. Fibres may need to be refined, blended, and compounded, such as in case of natural fibres from cellulosic waste streams. A high-strength fibre composite mate- rial in a polymer matrix can be formed thereby. The designated waste or base raw materials used in this instance are those of waste thermoplastics and various categories of cellulosic waste including straw, rice husk and saw dust.

In an alternative, e.g., to cellulosic waste streams, plant-based polymeric material, such as cellulose-based material thereof, may be used. Or a polyester may be formed directly from chemical products, such as by reacting an aliphatic polyalcohol and an aliphatic Poly carbox- ylic acid, such as is shown on WO2020/152082 A1, WO 2020/212427 Al, and WO 2021/023495 A1, which material may be used for manufacturing a laminate and the like.

Naturally occurring materials such as cotton, starch, and rubber were familiar materials for years before synthetic polymers such as polyethene and Perspex appeared on the market.

Many commercially important polymers are synthesized by chemical modification of natu- rally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulphur. Ways in which polymers can be modified include oxidation, cross-link- ing, and end-capping. Such polymers may find application as fiber reinforced composite ma- terials.

It is known that microorganisms are capable of producing biochemical compounds, such as lactic acid. Thereto typically a microbial culture is used. Therein microbial organisms reproduce in predetermined culture medium under controlled laboratory conditions. It is often essential to isolate a pure culture of microorganisms. A pure (or axenic) culture is a popula- tion of cells or multicellular organisms growing in the absence of other species or types. Re- markably also non-pure cultures are capable of producing chemical substances. Bacteria are capable of producing a wide variety of chemical substances, such as lactic acid, but also me- thane, and are therefore used in food industry, in waste treatment, and so on.

With the term “microbial process” here a microbiological conversion is meant.

Recently it has been found that biobased polymeric substances, such as extracellular polymeric substances (EPS), in particular polysaccharide comprising materials, obtainable from granular sludge can be produced in large quantities. These substances relate to biobased carboxylic acid-like chemicals, which may be present in an ionic form (e.g. cationic or ani- onic). Examples of such production methods can be found in WO2015/057067 A1, and

WO2015/050449 A1, whereas examples of extraction methods for obtaining said biobased polymers can be found in Dutch Patent application NL2016441 and in WO2015/190927 Al.

Specific examples of obtaining these substances, such as aerobic granular sludge and anam- mox granular sludge, and the processes used for obtaining them are known from Water Re- search, 2007, doi:10. 1016/j waters.2007.03.044 (anammox granular sludge) and Water Sci- ence and Technology, 2007, 55(8-9), 75-81 (aerobic granular sludge). Further, Li et al. in “Characterization of alginate-like exopolysaccharides isolated from aerobic granular sludge in pilot plant”, Water Research, Elsevier, Amsterdam, NL, Vol. 44, No. 11 (June 1 2010), pp. 3355-3364) recites specific alginate-like EPS in relatively raw form. Though initially the term “alginate-like”, or “alginate-like EPS” (ALE) was used, the biobased polymeric substances are found to be more complex in terms of chemical building blocks present therein. Therefore the term EPS is preferred. Details of the biopolymers can also be found in these documents, as well as in Dutch Patent applications NL2011609, NL2011542, NL2011852, NL2017470, and

NL2012089. Also reference can be made to the Nereda® process. These documents, and there contents, such as characteristics (e.g. molecular weights, dynamic viscosity, shear rate, tensile strength, and flexural strength) of the biobased polymers, are incorporated by reference.

Advantageously, in an initial step, granules of granular sludge can be readily removed from a reactor by e.g. physical separation, settling, centrifugation, cyclonic separation, de- cantation, filtration, or sieving to provide extracellular polymeric substances in a small vol- ume. Compared to separating material from a liquid phase of the reactor this means that nei- ther huge volumes of organic nor other solvents (for extraction), nor large amounts of energy (to evaporate the liquid) are required for isolation of the extracellular polymeric substances.

Extracellular polymeric substances obtainable from granular sludge (preferably obtained from granular sludge) do not require further purification or treatment to be used for some applications, hence can be applied directly. When the extracellular polymeric substances are obtained from granular sludge the extracellular polymeric substances are preferably iso- lated from bacteria (cells) and/or other non-extracellular polymeric substances. The granular sludge can be suitably produced by bacteria belonging to the order Pseudomonadaceae, such as pseudomonas and/or Acetobacter bacteria (aerobic granular sludge); or, by bacteria belong- ing to the order Planctomycetales (anammox granular sludge), such as Brocadia anammoxi- dans, Kuenenia stuttgartiensis or Brocadia fulgida; or by betaproteobacteria, such as Candida- tis Accumulibacter Phosphatis, or, by algae, such as brown algae.

Extraction of biopolymers from aerobic granular sludge is an emerging topic, and so far amongst others extraction with alkaline substances, such as Na,COj3, NaOH or NaOCl, and likewise with compounds having two amine groups, have been suggested and implemented.

The processes provide acceptable results for some further applications, but still produce a mixture of components present and need relatively harsh conditions. Na2CO: is found to pro- vide biopolymers with an number average molecular weight of 50-75 kDa, NaOH at a pH of 11-12 provides biopolymers with an number average molecular weight of 20-45 kDa, and

NaOCl provides biopolymers with an number average molecular weight of about 120 kDa(100-150 kDa)[as determined with GPC/SEC, Shimadzu Nexpera GPC].

In an alternative to biological products, algae alginate (e.g. from seaweed) has found ap- plication in various products, especially as gelling agents. Calcium alginate wound dressings are used worldwide in view of creating a moist wound environment that encourages more ef- fective healing. The alginate referred to here does not relate to a biopolymer of microbial origin.

In general it has been found difficult to further process products of biological origin, such as (these) microbial products, in particular biopolymers such as EPS, either in pure form as obtained from a reactor, or purified or extracted as indicated above.

So, practical application of biopolymers, such as alginate, has been limited. A problem with biopolymers is that upon further treatment water may need to be removed, which is diffi- cult.

The present invention relates to a product comprising a modified biopolymer, such as the above modified extracellular polymeric substance, a method of producing said modified biopolymer, and further aspects thereof, which overcomes one or more of the above disad- vantages, without jeopardizing functionality and advantages.

SUMMARY OF THE INVENTION

The present invention relates in a first aspect to a method of obtaining a modified biopolymer comprising providing an amount of at least one un-modified biopolymer pro- duced by at least one microbial species, such as an extra-polymeric substance, and (1) modify- ing the at least one un-modified biopolymer by reacting the unmodified biopolymer with at least one biodegradable and non-toxic ester-forming or ether-forming or anhydride-forming compound, wherein the ester-forming or ether-forming or anhydride-forming compound is ca- pable of forming at least two of esters and/or ethers, wherein the ester-forming or ether-form- ing or anhydride-forming compound is selected from polyols, polyacids, such as poly carbox- ylic acids, poly alcohols, poly aldehydes, molecules comprising at least one OH-group and one COOH group, and combinations thereof, at an elevated temperature, during a reaction time of at least 10 minutes, therewith forming a modified biopolymer-compound ester and op- tionally amide and optionally ether. The reaction may be inter-biopolymer molecule, intra- bi- opolymer molecule, or both. Surprisingly the water, being produced by the reaction, and/or being present, can be removed and therefore does not substantially hinder the present modifi- cation. The reactive compound is preferably a polyol, or a polyacid. It is important that in the reactive compound at least two ester-forming and/or ether-forming and/or anhydride-forming moieties are present, in order to modify the un-modified biopolymer. In an example, the extra- cellular polymeric substances comprise a major portion consisting of exopolysaccharides, and a minor portion, such as less than 30 % w/w, typically less than 10 %w/w, consisting of lipids and/or other components more hydrophobic than the exopolysaccharides, such as proteins.

So inventors found that it is beneficial to include e.g. polyols like glycerol, sorbitol and analogous, and/or polyacids, for instance citric acid, to modify microbial biopolymer formula- tions. In the case of Kaumera® (ALE) inventors established that 25% citric acid (CA) is about the stoichiometric amount to react with the available functional groups to form a Kaumera resin that can be cured at elevated temperature, such as at 140 C and higher, typically so as to yield a non-soluble ester/amide covalently crosslinked network. In conjunction to this base formulation additionally citric acid and e.g. glycerol (GLY) can be included into the biopoly- mer to modify the plasticity or flow of the resin obtained. This can be in a non-stoichiometric ratio, although possibly stoichiometric ratios are better to get a complete reaction after curing.

For CA/GLY this ratio may be about 3/1 in weight, based on the effective available acid groups (+2 in CA) and +3 OH in GLY. For the Kaumera polymer the level of acidity will in- fluence the number of effectively available carboxylic groups in the polymer (COOH 1n acid

ALE, for Na-ALE the carboxylic groups in the polymer do not participate). The Kaumera resin formulation of this generic type e.g. 75 Kaumera/25 CA + x%(3 CA/I GLY) are suitable asa binder for e.g. fibre reinforced panel manufacturing. Analogously, the aliphatic PHBV polyesters obtained from e.g. vegetable waste composting can be modified using CA/GLY and similar additions, to cleave the polymer chains, and decorate the ends with branched acid or OH functional end-groups of the PHBV chains. This may be useful to control the degree of crystallization, the melting point of the formulation, and the 'tackiness' of the final mixture, after some esterification/cleavage at elevated temperature, again typically above 140C. These

PHBYV based formulations are considered useful for optimizing the polymer performance as a matrix resin, or in adhesives (solvent based, hot melt, and pressure sensitive adhesives). It is worth noting that glycerol can be replaced by analogous polyols like sorbitol (6 OH groups) in case of evaporation of the GLY at elevated temperatures, etc.

In a second aspect the present invention relates to a modified, plasticized, or functional- ized biopolymer obtainable by a method according to the invention. It is considered an im- portant advantage of the present method of modifying, and the modified biopolymers ob- tained thereby, that characteristics of the un-modified biopolymers can be adapted largely as desired. In other words, the biopolymers can be plasticized, or functionalized, or modified in general, with a specific application thereof in mind, such as the use as an adhesive compound, or the use in a fibre reinforced composite. Said modified biopolymer may have a melting point of >150 °C, and/or a tackiness of > 200 J/m2, and/or a glass transition temperature of < °C (high temperature compostable), preferably < 40 °C, such as < 20 °C. For instance

PHBV is <0 C. A biopolymer PHBV based formulation that has a good hot melt and short-term tackiness properties is obtained.

In a further aspect the present invention relates to an adhesive comprising a biopol- ymer according to the invention, such as a solvent based adhesive, and a hot melt adhesive.

In yet a further aspect the present invention relates to a fibre reinforced composite com- 5 prising 1-70 wt.% of an adhesive according to the invention, and 30-99 wt.% fibres, in partic- ular cellulosic fibres, hemp fibres, flax fibres, and viscose fibres, preferably wherein the com- posite is 50-90% cured.

And the invention relates, in a further aspect, to a fibre reinforced panel comprising a fibre reinforced composite according to the invention.

Thereby the present invention provides a solution to one or more of the above men- tioned problems. Advantages of the present invention are detailed throughout the description.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates in a first aspect to a method according to claim 1.

In an exemplary embodiment the present method comprises (i) modifying the at least one un-modified biopolymer or providing at least one un-modified bio-polyester, (i1) plasti- cizing the at least one modified biopolymer or un-modified bio-polyester by reacting with an 0.1-35% stoichiometric amount of at least one biodegradable and non-toxic ester-forming or ether-forming or anhydride-forming compound, in particular 1-30 % stoichiometric amount, such as 5-25% stoichiometric amount, wherein the ester-forming or ether-forming or anhy- dride-forming compound is capable of forming at least two of esters and/or ethers, wherein the ester-forming or ether-forming or anhydride-forming compound is selected from polyols, polyacids, such as poly carboxylic acids, poly alcohols, molecules comprising at least one

OH-group and one COOH group, and combinations thereof, at an elevated temperature, dur- ing a reaction time of at least 10 minutes, therewith forming a plasticized biopolymer-com- pound ester and optionally amide and optionally ether, and/or (ii1) functionalizing the at least one modified biopolymer or un-modified bio-polyester by reacting with an 0.1-35% stoichio- metric amount of at least one biodegradable and non-toxic ester-forming or ether-forming or anhydride-forming compound, in particular 1-30 % stoichiometric amount, such as 5-25% stoichiometric amount, wherein the ester-forming or ether-forming or anhydride-forming compound is capable of forming at least two of esters and/or ethers, wherein the ester-form- ing or ether-forming or anhydride-forming compound is selected from polyols, polyacids, such as poly carboxylic acids, poly alcohols, molecules comprising at least one OH-group and one COOH group, and combinations thereof, at an elevated temperature, during a reaction time of at least 10 minutes, therewith forming a functionalized biopolymer-compound ester and optionally amide and optionally ether. In an alternative to reacting the un-modified bi- opolymer with the ester-, ether, or anhydride-forming compound one can also start with an un-modified biopolymer, in particular a bio-polyester. The bio-polyester is considered to be less reactive than an unmodified biopolymer having OH-groups available for reacting and op- tionally further groups for reacting. However, the bio-polyester can still be modified, such as plasticized, and/or functionalized, with at least one biodegradable and non-toxic ester-forming or ether-forming or anhydride-forming compound, typically under similar reaction conditions.

In step of plasticizing a small fraction of the available reactive moieties (or groups) is reacted, typically with an 0. 1-25% stoichiometric amount of such reactive groups being available, preferably with an 1-8% stoichiometric amount, such as with an 2-5% stoichiometric amount thereof. In an alternative, or in addition, the modified biopolymer or bio-polyester can be functionalized in a similar manner, by reacting a small fraction of the available reactive moie- ties (or groups), typically with an 0.1-25% stoichiometric amount of such reactive groups be- ing available, preferably with an 1-8% stoichiometric amount, such as with an 2-5% stoichio- metric amount thereof. Depending on he selection of the reactive compound (ester-forming or ether-forming or anhydride-forming compound) plasticity and/or function of the biopolymer or bio-polyester can be modified.

In an exemplary embodiment of the present method wherein the un-modified biopol- ymer has various moieties or groups available for reacting, such as comprises OH-groups available for reacting and optionally at least one of NH groups for reacting, carboxylic groups for reacting, RSO:H, groups for reacting, RPO:H, groups for reacting, ester-groups for reacting, ether-groups for reacting, O-acetyl groups for reacting, which typically are ke- tone group, sulfone groups for reacting, sulfonate groups for reacting, sulphonamide groups for reacting, and combinations thereof. It is noted that biopolymers produced by at least one microbial species may vary in terms of molecular weight, in terms of functional groups and amounts thereof being present in the biopolymer, in terms of sequence of monomers, dimers, etc. The un-modified biopolymer and the ester-forming or ether-forming or anhydride-form- ing compound are preferably provided in a stoichiometric ratio of biopolymer:compound of 0.7:1 to 2:1, more preferably 1:1 to 1.5:1. In an alternative during reacting the unmodified bi- opolymer and ester-forming or ether-forming or anhydride-forming an amount of 75-99.9 % of the stoichiometric ratio, which affectively is a too low ratio, preferably 80-95%, such as 85-90% of said stoichiometric ratio, of combined ester-forming and ether-forming and anhy- dride-forming compound is added. Such leads to “incomplete” reactions, or put different, par- tial modification of the un-modified biopolymer. Such partial modification may in fact be what is desired, having a specific application in mind.

In fact by selecting the amount of reactive compound, and/or a sequence of steps to be performed (such as plasticizing and functionalizing), the characteristics of the present un- modified microbial polymer can be modified as desired.

In an exemplary embodiment of the present method the polyol is selected from glyc- erol, trimethylolpropane, and pentaerythritol, from sugar alcohols ((CHOH),H2, where n = 4— 6), such as maltitol, sorbitol, xylitol, erythritol, and isomalt, and from polyvinyl alcohols (with formula (CH:CHOH),, wherein n<100, preferably wherein n<60, such as n<20),

In an exemplary embodiment of the present method the polyacid is selected from or-

ganic polyacids, such as dicarboxylic acids and tricarboxylic acids, such as citric acid, suc- cinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and malonic acid.

In an exemplary embodiment of the present method in the step of (1) modifying by reacting the unmodified biopolymer the ester-forming or ether-forming or anhydride-forming compound is provided in a weight ratio compound:biopolymer of 1:10 to 1:1, preferably 1:6 to 1:2, such as 1:5 to 1:4.

In an exemplary embodiment of the present method the modified biopolymer is ob- tained at a temperature of > 100 °C, preferably > 140 °C, such as > 160 °C, and preferably < 185 °C. Typically the temperature is increased significantly, in order to speed up the reaction.

In an exemplary embodiment of the present method the modified biopolymer is re- acted during 5-180 minutes, such as 10-60 minutes, such as 20-30 minutes, which is consid- ered to be relatively quickly.

In an exemplary embodiment of the present method the pressure is < 1000 kPa, such as <100 kPa, in particular < 50 kPa, more in particular < 10 kPa, that is, under a reduced pressure, in particular under a reduced water pressure. As such water being formed during the reaction is removed rather easily.

In an exemplary embodiment of the present method is performed under a nitrogen atmosphere.

In an exemplary embodiment of the present method the un-modified biopolymer is selected from polysaccharides, wherein the saccharide is preferably selected from trioses, tetroses, pentoses, hexoses, heptoses, octoses, dodecyloses, from amino sugars, such as galac- tosamine, glucosamine, sialic acid, N-acetylglucosamine, from sulfosugars, such as sulfoqui- novose, and carrageenan, from ascorbic acid, and mannitol, from polyuronic acids, such as comprising glucuronic acid, d-Galacturonic acid, and mannuronic acid, poly sugar acids, such as comprising aldonic acid, ulosonic acid, uronic acid, aldaric acid, Glyceric acid (3C), Xy- lonic acid (5C), Gluconic acid (6C), Ascorbic acid (6C), Neuraminic acid (5-amino-3,5-dide- oxy-D-glycero-D-galacto-non-2-ulosonic acid), Ketodeoxyoctulosonic acid (KDO or 3-de- oxy-D-manno-oct-2-ulosonic acid), Glucuronic acid (6C), Galacturonic acid (6C), Iduronic acid (6C), Tartaric acid (4C), meso-Galactaric acid (Mucic acid) (6C), and D-Glucaric acid (Saccharic acid) (6C), polymers comprising nonulosonic acid, such as sialic acid, such as al- ginate, inulin, starch, and celluloses, nitropolysaccharides, guar, and extracellular substances obtainable from granular sludge such as Kaumera, or wherein the bio-polyester is selected from polyhydroxy alkanoates (PHA), preferably wherein the PHA is formed from C;-C7 car- boxylic acids, such as Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB V), polylactic acid (PLA), and poly hydroxy butyrate (PHB), hybrid polymers thereof, and block- or co-polymers thereof , and combinations thereof. So a large variety of microbial polymers can be used in the present invention for modification.

In an exemplary embodiment of the present method the un-modified biopolymer is anionic or cationic. In view of solubility in water such may be an advantage.

In an exemplary embodiment of the present method the un-modified biopolymer is a non-linear biopolymer.

In an exemplary embodiment of the present method the un-modified biopolymer has an average molecular weight of >5kDa (size exclusion chromatography), preferably > 10 kDa, more preferably >20 kDa, such as > 100 kDa. Size exclusion chromatography, such as by us- ing a Shimadzu SEC, can be done using a suitable protocol, which are readily available. Such applies to other molecular weights as well.

In an exemplary embodiment of the present method the un-modified biopolymer has an average molecular weight of <1500kDa (size exclusion chromatography), preferably < 1000 kDa, more preferably <500 kDa.

In an exemplary embodiment of the present method the un-modified biopolymer has a multifunctionality, that is has different reactive groups, such as exemplified above. The mul- tifunctionality introduces some complexity at he one end, but also offers versatility at the other end.

In an exemplary embodiment of the present method the modified biopolymer-com- pound ester has an average molecular weight of >10 kDa.

In an exemplary embodiment of the present method the polyol and polyacid are pro- vided in a molar ratio of available OH-groups in polyol:available acid groups in polyacid of 1:10 to 1:2, preferably 1:5 to 1:3.

In an exemplary embodiment of the present method a partial reaction is performed, such as forming an anhydride, thereby removing a H:O molecule, and still remaining reactive functionality of the COOH, which may be used later. In view of the multifunctionality and polymeric character of the present biopolymer clearly more than one water molecule per bi- opolymer molecule can be removed.

In an exemplary embodiment of the present method the modified biopolymer-com- pound ester is post-cured at a temperature of > 150 °C, preferably > 160 °C, such as > 170 °C.

In an exemplary embodiment of the present method the modified biopolymer-com- pound ester is post-cured during 5-120 minutes, such as 10-60 minutes, such as 20-30 minutes.

In an exemplary embodiment of the present method the un-modified biopolymer comprises 30-200 % free OH-groups, in particular 50-150%, and/or comprises 5-30% free

COOH groups, in particular 10-25%, and/or comprises 1-10% free NH: groups, in particular 5-8%..

In an exemplary embodiment of the present method the unmodified biopolymers have an number average molecular weight of 50-75 kDa, such as after extraction with Na2CO: have an number average molecular weight of 20-45 kDa, such as after extraction with NaOH at a pH of 11-12, or have an number average molecular weight of 100-150 kDa, e.g. about 120 kDa , such as after extraction with NaOCl [as determined with GPC/SEC].

S

In an exemplary embodiment of the present method the modified biopolymer is non- soluble in water.

In an exemplary embodiment of the present method during (1) modifying, (i1) plasti- cizing, or (iii) functionalizing at least one further additive is provided, or a combination thereof.

In an exemplary embodiment of the present method during (i) modifying, (11) plasti- cizing, or (iii) functionalizing at least one mono-carboxylic acid is provided, or a combination thereof.

In an exemplary embodiment of the present method 30-99 wt.% fibres are added to the modified or un-modified biopolymer, in particular cellulosic fibres, such as fibres of 0.2-7 mm length, in particular 1-5 mm in length such as 2-4 mm.

In an exemplary embodiment of the present method a water content of the modi- fied or un-modified biopolymer is reduced, such as by hot-pressing at a temperature of 140-170 °C, in particular 145-160 °C, and/or under a pressure of 1-100 kN, in particu- lar 10-30 kN, such as 15-20 kN, and/or during a time of 10-60 minutes, in particular 15-45 minutes, such as 38-42 minutes.

In an exemplary embodiment of the present method a water content of the modi- fied or un-modified biopolymer is reduced by pre-drying of the modified or un-modi- fied biopolymer during a time of 10-240 minutes, in particular 60-180 minutes, at a temperature of 50-100 °C, in particular 70-80 °C.

In an exemplary embodiment the present fibre reinforce composite has a flexural modulus of 1-7 GPa (ASTM D790-17), and/or has a flexural strength of 5-30 MPa (ASTM

D790-17).

The invention is further detailed by the accompanying figures and examples, which are exemplary and explanatory of nature and are not limiting the scope of the in- vention. To the person skilled in the art it may be clear that many variants, being obvi- ous or not, may be conceivable falling within the scope of protection, defined by the present claims.

EXAMPLES/EXPERIMENTS

The invention although described in detailed explanatory context may be best un- derstood in conjunction with the accompanying examples.

For a PHBYV, treated wit citric acid, and glycerol (in the given weigh ratios) the follow- ing adhesive properties were obtained:

Maternal Adhesion energy (J/m?) after 10 minutes

Paper on glass of PHBV (90:7.5:2.5) 427 Jm?

Textile on glass of PHBV (90:7.5:2.5) 605 J/m?

Textile on glass of PHBV (95:3.75:1.25) 228 J/m?

Post-it on glass 12.1 J/m?

Sellotape on glass 245 J/m?

Table 1: adhesion energy measured on different materials.

In a further example a Tg of -6 to -10 °C, was obtained, depending on an amount on HV in the PHBV. A melting point of about 194 °C, aK of 1558°C/Da, and a t=0.4 in a Flory-Fox like Tm dependence was obtained. The melting temperature was > 150 °C for PHBV with small amounts of HV.

Kaumera (extracellular substances obtainable from granular sludge) films

Thin Kaumera/CA films were made at Chaincraft, by drying a solution of the two com- ponents. For DMTA testing, a film thickness of 100 to 200 um was desired. Therefore, before a first iteration at creating the films, the thickness that would result from the drying process was calculated by using the geometry of the cupcake trays the films were to be made in and estimating the eventual density of the film. The assumptions in this calculation, however, were plenty, which resulted in insufficiently coherent films. Several batches were made, of which the last one is described here.

First, about 20 g of 12 weight % Kaumera solution was weighed off and diluted to 4% with demineralised water. Next, different amounts of citric acid were added to the solution, to get specific ALE/CA ratios. These mixtures were stirred for about 10 minutes before specific amounts were poured into cupcake trays. These were then dried in the oven at 40 °C for at least 24h. The amount of solution poured into the cupcake tray was based on the earlier calcu- lations, but multiplied by 3 or 4, depending on the results of previous batches of films. Films were made with 0, 20, 22, 25, 29, 33, 40 and 50 weight % of citric acid.

After transporting them to Delft, the films were once again dried at 40 °C, this time in a vac- uum oven, to remove any moisture. Afterwards, they were placed in a desiccator. Before test- ing, the films were cut into 3mm wide strips to be able to fit in the DMTA machine.

DMTA testing

For DMTA testing, the strips were manually cut to a length of approximately 2 cm to fit in the machine. Temperature sweep measurements were done for different temperature ranges in be- tween -50 °C and 300 °C with a heating rate of 2 °C/min. The load was amplitude controlled, where the amplitude was set manually to be sure that the samples were in the linear regime.

The load was always applied at 1 Hz.

The machine used was a Perkin Elmer DMTA e7.

TGA testing

For TGA testing, small pieces of the films were used of around 8 mg. First, a temperature sweep test of 30 °C to 230 °C at 2 °C per minute was done on a pure Kaumera sample and a 25 weight % CA sample in order to identify temperatures at which different reactions would take place. Then, five more samples were subjected to a temperature sweep with isothermal steps at these temperatures so that the specific reactions would have the time to finish before others started. Doing so, individual reaction peaks could be deconvoluted in the time-weight graphs. The program had several heating steps at 2 °C per minute, and 30-minute isothermal steps at 90 °C, 115 °C, 160 °C and 220 °C. The full temperature range was 30 °C to 250 °C.

The device used was a Perkin Elmer TGA 8000.

In an example the glass transition temperature is obtained by reading the temperature at the point where the storage modulus becomes 1.25 GPa, which is around 20 °C. The glass transition point was determined derived to be about 40 °C. For TGA an initial 2 °C/min sweep for the pure Kaumera and 25% CA samples are taken. This showed water released per CA re- action. The amount of water released per citric acid molecule, on average, can be calculated from this data. The higher this number is, the higher the degree of cross-linking, because a molecule reacting with a Kaumera chain releases 1 water molecule, whereas a citric acid mol- ecule reacting with another releases only 0.5 water molecules per CA molecule. The upper limit will be 2, which is when each CA molecule reacts with a Kaumera chain on both sides.

In these tests, the numbers were around 0.5 for 24w% samples, and 0.3 for SOw% samples.

This indicates that the samples with a lower CA content, were more efficiently cross-linked than those with a higher content.

Testing of composites with Kaumera

The following composites were investigated:

A set of 20 samples consisting of 64 g of citric acid, 160 g of ALE and 56 g of shredded toilet paper.

A set of 10 samples consisting of 46 g of citric acid, 160 g of ALE and 56 g of shredded toilet paper.

A set of 18 samples consisting of 64 g of citric acid, 160 g of ALE and 56 g of ReCell R cellulose. The 3-point-bending test were performed at the mechanical lab in the faculty for maritime, mechanical and materials engineering at TU Delft. They were performed according to the standard ASTM D790-17, which was the most upto-date version of the

ASTM standard for testing "Flexural Properties of Unreinforced and Reinforced Plastics and

Electrical Insulating Materials" (ASTM International, 2017), the strain rate, which was given as 0:0lmm/mm/min by ASTM International (2017).. The tests were performed on a Zwick 7010 tensile tester, using a 10 kN load cell. The machine was operated using the Zwick/Roell

TestXpert 2.0 software. Furthermore, a Mituyoto micrometer was used to measure the dimen- sions of the samples, and a pair of digital calipers was used to measure the support span. ReCell is a recy- cled cellulose fibre form sewage water.

Mean flex. Flex. Modulus Mean Max. Max. strength

Modulus Ef [MPa] StDev (MPa) Strength Sm [MPa] StDev [MPa]

Toilet paper, much citric acid 3080 288 8.64 0.71

Toilet paper, little citric acid 4283 387 11.2 1.30

ReCell 3486 243 9.94 0.87

Table 2, Results of 3-point bend-testing

For an exemplary recipe, comprising 100 parts H-Ale, 30 parts citric acid, 6.6 parts glycerol, 5 parts bamboo powder and 25 parts of the above ReCell, the parts being on a weight basis, curing times and temperatures were investigated. Curing times were from >90 minutes for the lowest tested temperature of 140 °C to about 25 minutes for the highest tested temperature of 170 °C. A temperature of 160 °C with a curing time of 35-50 minutes was found optimal, e.g. in terms of almost no degradation of the product obtained.

In view of water content in the Kaumera/ALE, and in view of water formed by the reac- tion of e.g. citric acid with the Kaumera, such as due to esterification, extra care was taken to remove water before and during the reaction of Kaumera with he further ester-forming or ether-forming or anhydride-forming compound. Temperatures were varied from 140-170 °C, in particular 145-160 °C, and/or under a pressure of 1-30 KN, in particular 10-15 kN, and/or during a time of 10-60 minutes, in particular 15-45 minutes, such as 38-42 minutes. It was found that typically >90% of the sample was cured and in particular most (97%) to all of the sample was cured. Thereby uniform samples were obtained. Fibre reinforced composites formed by the present method typically had a flexural modulus Egex of 1-7 GPa, such as 2-5

GPa, and a flexural strength or of 5-30 MPa using the 3-point bending test, typically 10-20

MPa.

SUMMARY OF THE FIGURES

Figs. la-b, 2-3, and 4a-b show exemplary reactions.

DETAILED DESCRIPTION OF THE FIGURES

Fig. 1a shows a schematic reaction between two biopolymers, left and right, having re- active groups for reacting. Shown are OH-reactive groups, COOH-groups, NHz-reactive groups, whereas other groups, such as RSO4Hx groups, RPO4Hx groups, ester-groups, ether- groups, O-acetyl groups, sulfone groups, sulfonate groups, and sulphonamide groups, are not shown, but may be present. Citric acid is added, and reacts under forming of two esters in the example. Likewise, the citric acid may react with one or more of the other reactive groups. In fig. 1b a similar reaction as with the citric acid above is shown with glycerol.

Fig. 2 shows a schematic reaction between a modified biopolymer and a glycerol. The modified biopolymer is thereby functionalized. Likewise the modified biopolymer is plasti- cized. It is noted the terms “functionalize” and “plasticize” may at least partly overlap, de- pending e.g. on the type of biopolymer, reactant, reaction conditions, etc.

Fig. 3 shows a schematic “reaction” between a modified biopolymer and a glycerol. The glycerol is incorporated into the modified biopolymer. The modified biopolymer is thereby plasticized.

Fig. 4a shows a schematic reaction between an un-modified biopolymer, in this case polylactic acid, and citric acid. The citric acid reacts with an end-group of the polylactic acid.

Therewith the polylactic acid is thereby functionalized. Likewise the modified biopolymer is plasticized.

Fig. 4b shows a schematic reaction between an un-modified biopolymer, in this case polylactic acid, and citric acid. The citric acid reacts with an intermediate group of the pol- ylactic acid, effectively dividing the polylactic acid in two polymer chain parts, one with p monomers, and the other with q monomers, and the citric acid moiety in between. Therewith the polylactic acid is thereby functionalized.

For the purpose of searching the following section is added, which may be considered embodiments of the present invention, and of which the subsequent section represents a trans- lation into Dutch. 1. A method of obtaining a modified biopolymer comprising providing an amount of at least one un-modified biopolymer produced by at least one microbial species, and (1) modifying the at least one un-modified biopolymer by reacting the unmodified bi- opolymer with at least one biodegradable and non-toxic ester-forming or ether-forming or an- hydride-forming compound, wherein the ester-forming or ether-forming or anhydride-forming compound is capable of forming at least two of esters and/or ethers, wherein the ester-forming or ether-forming or anhydride-forming compound is selected from polyols, polyacids, such as poly carboxylic acids, poly alcohols, poly aldehydes, molecules comprising at least one OH- group and one COOH group, and combinations thereof, at an elevated temperature, during a reaction time of at least 10 minutes, therewith forming a modified biopolymer-compound es- ter and optionally amide and optionally ether. 2. Method according to claim 1, comprising (1) modifying the at least one un-modified biopolymer or providing at least one un-modified bio-polyester, (ii) plasticizing the at least one modified biopolymer or un-modified bio-polyester by reacting with an 0. 1-35% stoichiometric amount of at least one biodegradable and non-toxic ester- forming or ether-forming or anhydride-forming compound, wherein the ester-forming or ether-forming or anhydride-forming compound is capable of forming at least two of esters and/or ethers, wherein the ester-forming or ether-forming or anhydride-forming compound is selected from polyols, polyacids, such as poly carboxylic acids, poly alcohols, molecules comprising at least one OH-group and one COOH group, and combinations thereof, at an ele- vated temperature, during a reaction time of at least 10 minutes, therewith forming a plasti- cized biopolymer-compound ester and optionally amide and optionally ether, and/or (111) functionalizing the at least one modified biopolymer or un-modified bio-polyester by re- acting with an 0.1-35% stoichiometric amount of at least one biodegradable and non-toxic es- ter-forming or ether-forming or anhydride-forming compound, wherein the ester-forming or ether-forming or anhydride-forming compound is capable of forming at least two of esters and/or ethers, wherein the ester-forming or ether-forming or anhydride-forming compound is selected from polyols, polyacids, such as poly carboxylic acids, poly alcohols, molecules comprising at least one OH-group and one COOH group, and combinations thereof, at an ele- vated temperature, during a reaction time of at least 10 minutes, therewith forming a function- alized biopolymer-compound ester and optionally amide and optionally ether. 3. Method according to claim 1 or 2, wherein the un-modified biopolymer comprises OH-groups available for reacting and option- ally at least one of NH, groups for reacting, carboxylic groups for reacting, RSO:H, groups for reacting, RPO:H, groups for reacting, ester-groups for reacting, ether-groups for reacting,

O-acetyl groups for reacting, sulfone groups for reacting, sulfonate groups for reacting, sul- phonamide groups for reacting, and combinations thereof, and wherein the un-modified biopolymer and the ester-forming or ether-forming or anhydride- forming compound are preferably provided in a stoichiometric ratio of biopolymer:compound of 0.7:1to 2:1, or wherein during reacting the unmodified biopolymer and ester-forming or ether-forming or an- hydride-forming an amount of 75-99.9 % of the stoichiometric of combined ester-forming and ether-forming and anhydride-forming compound is added. 4. Method according to any of claims 1-3, wherein the polyol is selected from glycerol, tri- methylol propane, and pentaerythritol, from sugar alcohols ((CHOH),H:, where n = 4-6), such as maltitol, sorbitol, xylitol, erythritol, and isomalt, from polyvinyl alcohols with formula (CH,CHOH),, wherein n<100, and/or wherein the polyacid is selected from dicarboxylic acids and tricarboxylic acids, such as citric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and malonic acid. 5. Method according to any of claims 1-4, wherein in the step of (1) modifying by reacting the unmodified biopolymer the ester-forming or ether-forming or anhydride-forming compound is provided in a weight ratio compound:biopolymer of 1:10 to 1:1, preferably 1:6 to 1:2, such as 1:5to 1:4. 6. Method according to any of claims 1-5, wherein the modified biopolymer is obtained at a temperature of > 100 °C, preferably > 140 °C, such as > 160 °C, and preferably < 185 °C, and/or wherein the modified biopolymer is reacted during 5-180 minutes, such as 10-60 minutes, such as 20-30 minutes, and/or wherein the pressure is < 1000 kPa, such as <100 kPa, in particular under a reduced water pressure, and/or under a nitrogen atmosphere. 7. Method according to any of claims 1-6, wherein the un-modified biopolymer is selected from polysaccharides, wherein the saccharide is preferably selected from trioses, tetroses, pentoses, hexoses, heptoses, octoses, dodecyloses, from amino sugars, such as galactosamine,

glucosamine, sialic acid, N-acetylglucosamine, from sulfosugars, such as sulfoquinovose, and carrageenan, from ascorbic acid, and mannitol, from polyuronic acids, such as compris- ing glucuronic acid, d-Galacturonic acid, and mannuronic acid, poly sugar acids, such as com- prising aldonic acid, ulosonic acid, uronic acid, aldaric acid, Glyceric acid (3C), Xylonic acid (5C), Gluconic acid (6C), Ascorbic acid (6C), Neuraminic acid (5-amino-3,5-dideoxy-D-glyc- ero-D-galacto-non-2-ulosonic acid), Ketodeoxyoctulosonic acid (KDO or 3-deoxy-D-manno- oct-2-ulosonic acid), Glucuronic acid (6C), Galacturonic acid (6C), Iduronic acid (6C), Tar- taric acid (4C), meso-Galactaric acid (Mucic acid) (6C), and D-Glucaric acid (Saccharic acid) (6C), polymers comprising nonulosonic acid, such as sialic acid, from alginate, inulin, starch, and celluloses, from nitropolysaccharides, from guar, and from extracellular substances ob- tainable from granular sludge, such as Kaumera, or wherein the bio-polyester is selected from polyhydroxy alkanoates (PHA), preferably wherein the PHA is formed from C»-C7 carboxylic acids, such as Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polylactic acid (PLA), and poly hydroxy butyrate (PHB), hybrid polymers thereof, and block- or co-polymers thereof, and combinations thereof, and/or wherein the un-modified biopolymer is anionic or cationic, and/or wherein the un-modified biopolymer is a non-linear biopolymer, and/or wherein the un-modified biopolymer has an average molecular weight of >5kDa (size exclu- sion chromatography), preferably > 10 kDa, more preferably >20 kDa, such as > 100 kDa, and/or wherein the un-modified biopolymer has an average molecular weight of <1500kDa (size ex- clusion chromatography, preferably < 1000 kDa, more preferably <500 kDa, and/or wherein the un-modified biopolymer has a multifunctionality, and/or wherein the modified biopolymer-compound ester has an average molecular weight of >10 kDa. 8. Method according to any of claims 1-7, wherein the polyol and polyacid are provided in a molar ratio of available OH-groups in polyol:available acid groups in polyacid of 1:10 to 1:2, preferably 1:5 to 1:3. 9. Method according to any of claims 1-8, wherein a partial reaction is performed, such as forming an anhydride. 10. Method according to any of claims 1-9, wherein the modified biopolymer-compound ester is post-cured at a temperature of > 150 °C, preferably > 160 °C, such as > 170 °C, and/or post-cured during 5-120 minutes, such as 10-60 minutes, such as 20-30 minutes 11. Method according to any of claims 1-10, wherein the un-modified biopolymer comprises 30-200 % free OH-groups, in particular 50-150%, and/or comprises 5-30% free COOH groups, in particular 10-25%, and/or comprises 1-10% free NH» groups, in particular 5-8%, and/or wherein the unmodified biopolymers have an number average molecular weight of 50- 75 kDa, have an number average molecular weight of 20-45 kDa, or have an number average molecular weight of 100-150 kDa.

12. Method according to any of claims 1-11, wherein the modified biopolymer is non-soluble in water.

13. Method according to any of claims 1-12, wherein during (i) modifying, (ii) plasticizing, or

(111) functionalizing at least one further additive is provided, or a combination thereof, and/or wherein during (1) modifying, (ii) plasticizing, or (iii) functionalizing at least one mono-car-

boxylic acid is provided, or a combination thereof, and/or wherein 30-99 wt.% fibres are added to the modified or un-modified biopolymer, in particular cellulosic fibres, and/or wherein a water content of the modified or un-modified biopolymer is reduced, such as by hot-pressing at a temperature of 140-170 °C, in particular 145-160 °C, and/or under a pressure of 1-100 kN, in particular 10-30 kN, and/or during a time of 10-60 minutes, in particular 15- 45 minutes, such as 38-42 minutes, and/or by pre-drying of the modified or un-modified bi- opolymer during a time of 10-240 minutes, in particular 60-180 minutes, at a temperature of 50-100 °C, in particular 70-80 °C.

14 Modified, plasticized, or functionalized biopolymer obtainable by a method according to any of claims 1-13.

15. Biopolymer according to claim 14, wherein the biopolymer has a melting point of >150 °C, and/or a tackiness of > 200 J/m?, and/or a glass transition temperature of < 50 °C, preferably < 40 °C, such as < 20 °C (measured us- ing differential scanning calorimetry with Mettler Toledo TGA2 according to ISO 11357- 1:2016).

16. Adhesive comprising a biopolymer according to any of claims 14-15, such as a solvent based adhesive, and a hot melt adhesive.

17. Fibre reinforced composite comprising 1-70 wt.% of an adhesive according to claim 16, and 30-99 wt.% fibres, in particular cellulosic fibres, hemp fibres, flax fibres, viscose fibres, or a combination thereof.

18. Fibre reinforced composite according to claim 17, wherein the composite is 50-80% cured, and/or having a flexural modulus of 1-7 GPa (ASTM D790-17), and/or having a flexural strength of 5-30 MPa (ASTM D790-17).

19. Fibre reinforced panel comprising a fibre reinforced composite according to claim 17 or 18.

Claims

ConclusiesConclusions

1. Een werkwijze voor het verkrijgen van een gemodificeerd biopolymeer, omvattend het verschaffen van een hoeveelheid van ten minste één ongemodificeerd biopolymeer geproduceerd door ten minste één microbiéle soort, en 1) het modificeren van de ten minste één ongemodificeerd biopolymeer door reactie van het ongemodificeerde biopolymeer met ten minste één biologisch afbreekbare en niet- toxische ester-, ether-, of anhydridevormende verbinding, waarbij de ester-, ether-, of anhydri- devormende verbinding ten minste twee esters en/of ethers kan vormen, en waarbij de ester-, ether- of anhydridevormende verbinding wordt gekozen uit polyolen, polyzuren, zoals poly- carbonzuren, polyalcoholen, polyaldehyden, moleculen die ten minste één OH-groep en één COOH-groep omvatten, en combinaties daarvan, bij een verhoogde temperatuur gedurende een reactietijd van ten minste 10 minuten, waarbij een gemodificeerde biopolymeer-verbin- ding ester wordt gevormd, en eventueel amide en eventueel ether.A method for obtaining a modified biopolymer, comprising providing an amount of at least one unmodified biopolymer produced by at least one microbial species, and 1) modifying the at least one unmodified biopolymer by reaction of the unmodified biopolymer with at least one biodegradable and non-toxic ester, ether, or anhydride-forming compound, wherein the ester, ether, or anhydride-forming compound is capable of forming at least two esters and/or ethers, and wherein the ester, ether- or anhydride-forming compound is selected from polyols, polyacids, such as polycarboxylic acids, polyalcohols, polyaldehydes, molecules comprising at least one OH group and one COOH group, and combinations thereof, at an elevated temperature for a reaction time of at least 10 minutes, forming a modified biopolymer compound ester, and optionally amide and optionally ether.

2. Werkwijze volgens conclusie 1, omvattend (1) het modificeren de van ten minste één ongemodificeerd biopolymeer of het verstrekken van ten minste één ongemodificeerde biopolyester, 11) het plastificeren de van ten minste één gemodificeerd biopolymeer of ongemodificeerd bio- polyester door een reactie met 0,1-35% stoichiometrische hoeveelheid van ten minste één bio- logisch afbreekbare en niet-toxische ester-, ether-, of anhydridevormende verbinding, waarbij de ester-, ether-, of anhydridevormende verbinding ten minste twee esters en/of ethers kan vormen, waarbij de ester-, ether-, of anhydridevormende verbinding wordt gekozen uit polyo- len, polyzuren, zoals polycarbonzuren, polyalcoholen, moleculen die ten minste één OH- groep en één COOH-groep omvatten, en combinaties daarvan, bij een verhoogde temperatuur gedurende een reactietijd van ten minste 10 minuten, waarbij een geplastificeerde ester van de biopolymeerverbinding-ester vormend en eventueel een amide en eventueel een ether worden gevormd, en/of i11) het functionaliseren van de ten minste één gemodificeerd biopolymeer of ongemodificeerd biopolyester door een reactie met 0,1-35% stoichiometrische hoeveelheid van ten minste één biologisch afbreekbare en niet-toxische ester-, ether-, of anhydridevormende verbinding, waarbij de ester-, ether- of anhydridevormende verbinding ten minste twee esters en/of ethers kan vormen, en waarbij de ester-, ether-, of anhydridevormende verbinding wordt gekozen uit polyolen, polyzuren, zoals polycarbonzuren, polyalcoholen, moleculen die ten minste één OH-groep en één COOH-groep omvatten, en combinaties daarvan, bij een verhoogde tem- peratuur gedurende een reactietijd van ten minste 10 minuten, waarbij een ester van een ge- functionaliseerde biopolymeerverbinding en naar eventueel een amide en eventueel een ether worden gevormd.The method of claim 1, comprising (1) modifying at least one unmodified biopolymer or providing at least one unmodified biopolyester, 11) plasticizing at least one modified biopolymer or unmodified biopolyester by reaction with 0.1-35% stoichiometric amount of at least one biodegradable and non-toxic ester, ether, or anhydride-forming compound, where the ester, ether, or anhydride-forming compound can be at least two esters and/or ethers forms, wherein the ester, ether, or anhydride-forming compound is selected from polyols, polyacids, such as polycarboxylic acids, polyalcohols, molecules comprising at least one OH group and one COOH group, and combinations thereof, at an elevated temperature for a reaction time of at least 10 minutes, forming a plasticized ester of the biopolymer compound ester and optionally an amide and optionally an ether, and/or i11) functionalizing the at least one modified biopolymer or unmodified biopolyester by a reaction with 0.1-35% stoichiometric amount of at least one biodegradable and non-toxic ester, ether, or anhydride-forming compound, wherein the ester, ether, or anhydride-forming compound is capable of forming at least two esters and/or ethers, and wherein the ester, ether, or anhydride-forming compound is selected from polyols, polyacids, such as polycarboxylic acids, polyalcohols, molecules comprising at least one OH group and one COOH group, and combinations thereof, at an elevated temperature for a reaction time of at least 10 minutes, during which an ester of a functionalized biopolymer compound and optionally an amide and optionally an ether are formed.

3. Werkwijze volgens conclusie 1 of 2, waarin het ongemodificeerde biopolymeer OH-groepen omvat die beschikbaar zijn om te rea- geren en eventueel ten minste één van NHy-groepen om te reageren, carbonzuurgroepen om te reageren, RSO4Hx-groepen om te reageren, RPO:H,-groepen om te reageren, estergroepen om te reageren, ethergroepen om te reageren, O-acetylgroepen om te reageren, sulfongroepen om te reageren, sulfonaatgroepen om te reageren, sulfonamidegroepen om te reageren en combi- naties daarvan, en waarbij het ongemodificeerde biopolymeer en de ester- of ethervormende of anhydridevor- mende verbinding bij voorkeur worden verstrekt in een stoichiometrische verhouding van bio- polymeer:verbinding van 0,7:1 tot 2:1, of waarbij tijdens de reactie van het ongemodificeerde biopolymeer en de ester-, ether- of anhy- dridevormende verbinding een hoeveelheid van 75-99,9 % van de stoichiometrische verhou- ding van de gecombineerde ester-, ether- en anhydridevormende verbinding wordt toege- voegd.The method according to claim 1 or 2, wherein the unmodified biopolymer comprises OH groups available to react and optionally at least one of NHy groups to react, carboxylic acid groups to react, RSO4Hx groups to react, RPO:H, groups to react, ester groups to react, ether groups to react, O-acetyl groups to react, sulfone groups to react, sulfonate groups to react, sulfonamide groups to react and combinations thereof, and wherein the unmodified biopolymer and the ester or ether-forming or anhydride-forming compound are preferably provided in a stoichiometric biopolymer:compound ratio of 0.7:1 to 2:1, or where during the reaction of the unmodified biopolymer and the ester -, ether or anhydride-forming compound an amount of 75-99.9% of the stoichiometric ratio of the combined ester-, ether- and anhydride-forming compound is added.

4. Werkwijze volgens één van de conclusies 1-3, waarbij het polyol wordt gekozen uit glyce- rol, trimethylolpropaan, en pentaerytritol, uit suikeralcoholen ((CHOH)„H:, waarbij n = 4-6), zoals maltitol, sorbitol, xylitol, erytritol en isomalt, uit polyvinylalcoholen met formule (CH:CHOH),, waarbij n<100, en/of waarin het polyzuur is gekozen uit dicarbonzuren en tricarbonzuren, zoals citroenzuur, barn- steenzuur, glutaarzuur, adipinezuur, pimelzuur, suberinezuur, azelainezuur, sebacinezuur en malonzuur.The method according to any one of claims 1-3, wherein the polyol is selected from glycerol, trimethylol propane, and pentaerythritol, from sugar alcohols ((CHOH) x H , where n = 4-6), such as maltitol, sorbitol, xylitol, erythritol and isomalt, from polyvinyl alcohols of formula (CH:CHOH), where n<100, and/or wherein the polyacid is selected from dicarboxylic acids and tricarboxylic acids, such as citric acid, succinic acid, glutaric acid, adipic acid, pimic acid, suberic acid, azelaic acid, sebacic acid and malonic acid.

5. Werkwijze volgens een van de conclusies 1-4, waarbij in de stap van (i) modificeren door reactie van het ongemodificeerde biopolymeer de ester-, ether- of anhydridevormende verbin- ding wordt verstrekt in een gewichtsverhouding verbinding:biopolymeer van 1:10 tot 1:1, bij voorkeur 1:6 tot 1:2, zoals 1:5 tot 1:4.A method according to any one of claims 1 to 4, wherein in the step of (i) modifying by reaction of the unmodified biopolymer the ester-, ether- or anhydride-forming compound is provided in a compound:biopolymer weight ratio of 1:10 to 1:1, preferably 1:6 to 1:2, such as 1:5 to 1:4.

6. Werkwijze volgens een van de conclusies 1-5, waarbij het gemodificeerde biopolymeer wordt verkregen bij een temperatuur van > 100 °C, bij voorkeur > 140 °C, zoals > 160 °C, en bij voorkeur < 185 °C, en/of waarbij het gemodificeerde biopolymeer reageert gedurende 5-180 minuten, zoals 10-60 mi- nuten, zoals 20-30 minuten, en/of waarbij de druk < 1000 kPa is, zoals < 100 kPa, in het bijzonder onder een gereduceerde wa- terdruk, en/of onder een stikstofatmosfeer.The method according to any of claims 1-5, wherein the modified biopolymer is obtained at a temperature of > 100 °C, preferably > 140 °C, such as > 160 °C, and preferably < 185 °C, and/ or wherein the modified biopolymer reacts for 5-180 minutes, such as 10-60 minutes, such as 20-30 minutes, and/or wherein the pressure is < 1000 kPa, such as < 100 kPa, especially under reduced water pressure, and/or under a nitrogen atmosphere.

7. Werkwijze volgens een van de conclusies 1-6, waarbij het ongemodificeerde biopolymeer wordt gekozen uit polysachariden, waarbij de sacharide bij voorkeur wordt gekozen uit trio- sen, tetrossen, pentosen, hexosen, heptosen, octosen, dodecyosen, uit aminosuikers, zoals ga- lactosamine, glucosamine, siaalzuur, N-acetylglucosamine, uit sulfosuikers, zoals sulfo- quinovose, en carrageen, uit ascorbinezuur, en mannitol, uit polyuronzuren, zoals omvattend glucuronzuur, d-galacturonzuur, en mannuronzuur, polyuikerzuren, zoals omvattend aldon- zuur ulosonzuur, ureumzuur, aldaronzuur, glycerinezuur (3C), xylonzuur (5C), gluconzuur (6C), ascorbinezuur (6C), neuraminezuur (5-amino-3,5-dideoxy-D-glycero-D-galacto-non-2-A method according to any one of claims 1 to 6, wherein the unmodified biopolymer is selected from polysaccharides, wherein the saccharide is preferably selected from trioses, tetroses, pentoses, hexoses, heptoses, octoses, dodecyoses, from amino sugars, such as ga lactosamine, glucosamine, sialic acid, N-acetylglucosamine, from sulfosugars, such as sulfoquinovose, and carrageenan, from ascorbic acid, and mannitol, from polyuronic acids, such as including glucuronic acid, d-galacturonic acid, and mannuronic acid, polyic acids, such as aldonic acid including ulosonic acid , urea acid, aldaronic acid, glyceric acid (3C), xylonic acid (5C), gluconic acid (6C), ascorbic acid (6C), neuraminic acid (5-amino-3,5-dideoxy-D-glycero-D-galacto-non-2-

ulosonzuur), ketodeoxyoctulosonzuur (KDO of 3-deoxy-D-manno-oct-2-ulosonzuur), glucu- ronzuur (6C), galacturonzuur (6C), iduronzuur (6C), wijnsteenzuur (4C), meso-galactaarzuur (slijmzuur) (6C), en D-gluaarzuur (sacharinezuur) (6C), polymeren omvattend nonulosonzuur, zoals siaalzuur, uit alginaat, inuline, zetmeel, en cellulose, uit nitropolysacchariden, uit guar, en uit extracellulaire stoffen verkregen uit korrelslib, zoals Kaumera, of waarin de biopoly- meer wordt gekozen uit polyhydroxyalkanoaten (PHA), bij voorkeur waarin de PHA wordt gevormd uit C:-C7 carbonzuren zoals Poly(3-hydroxybutyraat-co-3-hydroxyvaleraat) (PHBV), polymelkzuur (PLA), en polyhydroxybutyraat (PHB), hybride polymeren daarvan, en blok- of co-polymeren daarvan, en combinaties daarvan, en/of waarin het ongemodificeerde biopolymeer anionisch of kationisch is, en/of waarin het ongemodificeerde biopolymeer een niet-lineair biopolymeer is, en/of waarin het ongemodificeerde biopolymeer een gemiddeld molecuulgewicht heeft van > 5 kDa (grootte-afwijkingschromatografie), bij voorkeur > 10 kDa, bij voorkeur > 20 kDa, zoals > 100 kDa, en/of waarbij het ongemodificeerde biopolymeer een gemiddeld molecuulgewicht heeft van <1500kDa (SEC), bij voorkeur < 1000 kDa, bij voorkeur <500 kDa, en/of waarbij het ongemodificeerde biopolymeer een multifunctioneel karakter heeft, en/of waarin de gemodificeerde biopolymeer-verbindingsester een gemiddeld molecuulgewicht heeft van >10 kDa. 8, Werkwijze volgens één van de conclusies 1-7, waarbij het polyol en het polyzuur worden geleverd in een molaire verhouding van beschikbare OH-groepen in het polyol:beschikbare zuurgroepen in het polyzuur van 1:10 tot 1:2, bij voorkeur 1:5 tot 1:3.ulosonic acid), ketodeoxyoctulosonic acid (KDO or 3-deoxy-D-manno-oct-2-ulosonic acid), glucuronic acid (6C), galacturonic acid (6C), iduronic acid (6C), tartaric acid (4C), meso-galactaric acid (mucilic acid) (6C), and D-gluaric acid (saccharic acid) (6C), polymers including nonulosonic acid, such as sialic acid, from alginate, inulin, starch, and cellulose, from nitropolysaccharides, from guar, and from extracellular substances obtained from granular sludge, such as Kaumera, or wherein the biopolymer is selected from polyhydroxyalkanoates (PHA), preferably wherein the PHA is formed from C:-C7 carboxylic acids such as Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), polylactic acid (PLA), and polyhydroxybutyrate (PHB), hybrid polymers thereof, and block or copolymers thereof, and combinations thereof, and/or wherein the unmodified biopolymer is anionic or cationic, and/or wherein the unmodified biopolymer is a non-linear biopolymer, and/or wherein the unmodified biopolymer has an average molecular weight of > 5 kDa (size error chromatography), preferably > 10 kDa, preferably > 20 kDa, such as > 100 kDa, and/or wherein the unmodified biopolymer has an average molecular weight of < 1500 kDa ( SEC), preferably < 1000 kDa, preferably < 500 kDa, and/or wherein the unmodified biopolymer has a multifunctional character, and/or wherein the modified biopolymer compound ester has an average molecular weight of >10 kDa. A method according to any one of claims 1-7, wherein the polyol and polyacid are provided in a molar ratio of available OH groups in the polyol:available acid groups in the polyacid of 1:10 to 1:2, preferably 1 :5 to 1:3.

9. Werkwijze volgens een van de conclusies 1-8, waarbij een gedeeltelijke reactie wordt uit- gevoerd, zoals onder vorming van een anhydride.A method according to any one of claims 1 to 8, wherein a partial reaction is carried out, such as to form an anhydride.

10. Werkwijze volgens een van de conclusies 1-9, waarbij de gemodificeerde ester van biopo- lymeerverbindingen wordt nagehard bij een temperatuur van > 150 °C, bij voorkeur > 160 °C, zoals > 170 °C, en/of wordt nagehard gedurende 5-120 minuten, zoals 10-60 minuten, zoals 20-30 minutenThe method according to any one of claims 1-9, wherein the modified ester of biopolymer compounds is post-cured at a temperature of > 150°C, preferably > 160°C, such as > 170°C, and/or is post-cured for 5-120 minutes, like 10-60 minutes, like 20-30 minutes

11. Werkwijze volgens een van de conclusies 1-10, waarbij het ongemodificeerde biopoly- meer 30-200% vrije OH-groepen omvat, in het bijzonder 50-150%, en/of 5-30% vrije COOH- groepen omvat, in het bijzonder 10-25%, en/of 1-10% vrije NH2-groepen omvat, in het bij- zonder 5-8%, en/of wanneer de ongemodificeerde biopolymeren een gemiddeld molecuulgewicht van 50-75 kDa, een gemiddeld molecuulgewicht van 20-45 kDa, of een gemiddeld molecuulgewicht van 100-150 kDa hebben [als bepaald met GPC/SEC].A method according to any one of claims 1-10, wherein the unmodified biopolymer comprises 30-200% free OH groups, in particular 50-150%, and/or comprises 5-30% free COOH groups, in in particular 10-25%, and/or 1-10% free NH2 groups, in particular 5-8%, and/or when the unmodified biopolymers have an average molecular weight of 50-75 kDa, an average molecular weight of 20-45 kDa, or have an average molecular weight of 100-150 kDa [as determined by GPC/SEC].

12. Werkwijze volgens één van de conclusies 1-11, waarbij het gemodificeerde biopolymeer niet oplosbaar is in water.A method according to any one of claims 1-11, wherein the modified biopolymer is not soluble in water.

13. Werkwijze volgens een van de conclusies 1-12, waarbij tijdens i) het modificeren, 11) het plastificeren, of 1ii) het functionaliseren ten minste één extra additief of een combinatie daar- van wordt toegevoegd, en/of waarin tijdens 1) het modificeren, ii) het plastificeren, of iii) het functionaliseren ten minste één monocarbonzuur wordt toegevoegd, of een combinatie daarvan, en/of waarin 30-99 wt.% vezels worden toegevoegd aan het gemodificeerde of ongemodificeerde biopolymeer, in het bijzonder cellulosevezels, en/of waarbij het watergehalte van het gemodificeerde of ongemodificeerde biopolymeer wordt ver- laagd, bijvoorbeeld door het warm persen bij een temperatuur van 140-170 °C, met name 145- 160 °C, en/of onder een druk van 1-100 kN, met name 10-30 kN, en/of gedurende 10-60 mi- nuten, met name 15-45 minuten, zoals 38-42 minuten, en/of door het voordrogen van het gemodificeerde of ongemodificeerde biopolymeer gedurende 10- 240 minuten, met name 60-180 minuten, bij een temperatuur van 50-100 °C, met name 70-80A method according to any one of claims 1-12, wherein during i) the modification, 11) the plasticization, or ii) the functionalization at least one additional additive or a combination thereof is added, and/or wherein during 1) modifying, ii) plasticizing, or iii) functionalizing at least one monocarboxylic acid is added, or a combination thereof, and/or in which 30-99 wt.% fibers are added to the modified or unmodified biopolymer, in particular cellulose fibres, and/or in which the water content of the modified or unmodified biopolymer is reduced, for example by hot pressing at a temperature of 140-170 °C, in particular 145-160 °C, and/or under a pressure of 1-100 kN, typically 10-30 kN, and/or for 10-60 minutes, typically 15-45 minutes, such as 38-42 minutes, and/or by pre-drying the modified or unmodified biopolymer for 10-240 minutes , typically 60-180 minutes, at a temperature of 50-100 °C, typically 70-80

°C.°C.

14. Gemodificeerd, geplastificeerd, of gefunctionaliseerd biopolymeer, te verkrijgen door middel van een werkwijze volgens een van de conclusies 1-13.14. Modified, plasticized or functionalized biopolymer obtainable by means of a method according to any one of claims 1-13.

15. Biopolymeer volgens conclusie 14, waarin het biopolymeer een smeltpunt heeft van > 150 °C, en/of een kleverigheid van > 200 J/m?, en/of een glasovergangstemperatuur van < 50 °C, bij voorkeur < 40 °C, zoals < 20 °C (gemeten met behulp van differentiële scanning calorimetrie met Mettler Toledo TGA2 volgens ISO 11357- 1:2016).15. Biopolymer according to claim 14, wherein the biopolymer has a melting point of > 150 °C, and/or a tack of > 200 J/m 2 , and/or a glass transition temperature of < 50 °C, preferably < 40 °C, such as < 20 °C (measured by differential scanning calorimetry with Mettler Toledo TGA2 according to ISO 11357-1:2016).

16. Lijm omvattend een biopolymeer volgens een van de conclusies 14-15, zoals een lijm op basis van oplosmiddelen, en een smeltlijm.An adhesive comprising a biopolymer according to any one of claims 14-15, such as a solvent-based adhesive, and a hot melt adhesive.

17. Vezelversterkte composiet omvattend 1-70 wt.% van een lijm volgens conclusie 16, en 30-99 wt.% vezels, in het bijzonder cellulosevezels, hennepvezels, vlasvezels, viscose vezels, of een combinatie daarvan.17. Fibre-reinforced composite comprising 1-70 wt.% of an adhesive according to claim 16, and 30-99 wt.% fibres, in particular cellulose fibres, hemp fibres, flax fibres, viscose fibres, or a combination thereof.

18. Vezelversterkte composiet volgens conclusie 17, waarbij de composiet voor 50-80% is uitgehard, en/of met een buigmodulus van 1-7 GPa (ASTM D790-17), en/of met een buigsterkte van 5-30 MPa (ASTM D790-17).18. Fibre-reinforced composite according to claim 17, wherein the composite is cured for 50-80%, and/or with a flexural modulus of 1-7 GPa (ASTM D790-17), and/or with a flexural strength of 5-30 MPa (ASTM D790-17).

19. Vezelversterkt paneel omvattend een vezelversterkte composiet volgens conclusie 17 of19. Fiber-reinforced panel comprising a fiber-reinforced composite according to claim 17 or

18.18.