CN107529848B

CN107529848B - Personalized shoe and manufacture thereof

Info

Publication number: CN107529848B
Application number: CN201680015087.7A
Authority: CN
Inventors: 黄为民; 王韬喜
Original assignee: Nanjing Licong New Materials Co ltd
Current assignee: Nanjing Licong New Materials Co ltd
Priority date: 2015-03-17
Filing date: 2016-03-17
Publication date: 2021-04-06
Anticipated expiration: 2036-03-17
Also published as: WO2016148654A1; CN107529848A

Abstract

A personalized moldable shoe, such as a shoe or shoe insert, wherein the shoe or shoe insert extends through the entire sole of the foot in use and is made of a stimuli responsive shape memory material, preferably a heat responsive shape memory material such as Ethylene Vinyl Acetate (EVA), Polyurethane (PU) or Thermoplastic Polyurethane (TPU). The invention also proposes a manufacturing method for forming said shoe, said method comprising heating said layer to a predetermined temperature; deforming the layer; and operating the layer using at least one fastener to form the shoe, wherein the deformation of the layer is performed by placing a foot structure on the layer.

Description

Personalized shoe and manufacture thereof

Technical Field

The present invention relates broadly to the design and function of footwear and to the particular materials used to manufacture the footwear.

Background

Consumers demand that their shoes be more comfortable and have more functionality, making these features important considerations in shoe design and evaluation. Both of these are the result of a complex interaction between the characteristics of the human body (particularly the legs and more particularly the feet) and the different elements of the shoe.

In terms of comfort, fit is a major determinant of purchasing shoes. The discomfort between the foot and the shoe can impair foot function and can result in excessive pressure from a tight fitting shoe or unnecessary friction from a loose fitting shoe. For example, crock, a american shoe company, is providing casual shoes with soft, comfortable, lightweight, and odor-resistant qualities around the world. However, this fit is limited to only the contact interface between the bottom of the foot (or sole) and the top of the sole.

Another custom fit shoe known as the Vibram five-finger shoe also provides a good wearing experience for the user. This is partly because the raw material of these shoes has a very high elasticity and can be elastically deformed to fit any shape (elastic fittings as socks). However, some users do experience discomfort because the elastic material may often exert undue pressure on the foot. In addition, the upper is typically so thin that it does not provide sufficient protection to prevent injury to the foot.

Because each consumer has a unique foot shape/configuration and has personal preferences for shoes, it is not always easy to find a pair of shoes from the market that comfortably fit an individual's foot, particularly for those consumers who need foot orthotics.

Therefore, personalization of shoes is an increasing demand. Currently, there are several ways to achieve this, such as additive manufacturing and the use of certain polymer materials inside the boot to make the sole portion adjustable.

However, these methods still suffer from a number of disadvantages.

For example, prior art memory foam-based insoles using slow recovery polymer foam (which is as soft as elastic sponge) do not provide sufficient mechanical support. For example, such memory foams are characterized by having low stiffness and rigidity. Furthermore, although custom shoes can be manufactured by 3D printing to better fit, this requires a cumbersome foot scanning process and an even more expensive printing manufacturing process.

There is a need to provide comfort, functionality, and protection of the entire foot to the wearer on an individual or personalized basis while maintaining a cost effective manufacturing process. The present invention seeks to improve upon the existing individualized footwear products.

Disclosure of Invention

The present invention is based on the following findings: the functionality of footwear, particularly the rigidity and flexibility (associated with 3D contouring), which is a personal preference, can be greatly improved by using certain Shape Memory Materials (SMMs), which are characterized by Shape Memory Effects (SMEs).

Accordingly, in one aspect, the present invention provides a moldable shoe or shoe insert that, in use, extends across the entire sole of the foot and is prepared from a stimulus responsive shape memory material.

In one embodiment, the stimulus responsive shape memory material is a thermally responsive shape memory material.

In one embodiment, the SMM is a Shape Memory Polymer (SMP). The inventors have found that: the use of SMP in shoe accessories is repeatable and immediate; can be restored to the original shape if necessary; providing a customizable combination of rigidity and flexibility; the local foot pressure is dispersed, and the manufacturing cost is low.

In another embodiment, the thermally responsive shape memory polymer retains two shapes.

In one embodiment, and during use, the moldable shoe or shoe insert is initially heated to between about 45 ° to equal to or below about 80 ℃, wherein the user then inserts his/her foot into the shoe or shoe insert to mold the shoe or shoe insert around the contours of the user's foot. The moldable shoe or shoe insert may be heated to an elevated temperature, such as about 80 ℃, but will typically be worn at a temperature of about 60 ℃ or less unless the sock or liner is worn on the bare foot.

The term "shoe" or "shoe insert" as used herein refers to the product that is the subject of the present invention, which extends to the entire sole of the foot, and may include a complete footwear product that requires or does not require any additional material, such as a hardened non-moldable polymer sole material. Thus, in certain embodiments, the invention provides the advantage of a complete footwear product that does not require any additional manufacturing steps, such as outer material stitching or outer sole adhesion. As an alternative, the term also includes shoe inserts, which may also extend over the entire sole of the foot, but also in, for example, prefabricated shoe shapes, such as hardened outer shoe shapes (e.g., for construction workers) or personalized shoe inserts for ski boots.

In some embodiments, a "shoe" or "shoe insert" may also be expressed as: the product that is the subject of the invention covers the entire foot and may also comprise a complete article of footwear with additional material or without any additional material, such as a hardened non-moldable polymer sole material. Thus, it should be understood that the term "entire sole" includes the forefoot, midfoot and heel. It should also be understood that "the entire foot" includes the forefoot, midfoot and heel. In order to provide the rigidity and flexibility required for comfort of the user, the invention contemplates that the surface of the shoe or shoe insert covers at least the beginning of the extension to cover the heel (or ankle), which may or may not cover the actual ankle. This is then compared to known shoe or shoe insert products that, for example, only cover the sole of the foot or partially cover the hindfoot and forefoot, but leave all or a portion of the upper midfoot exposed and/or unsupported.

A suitable combination of rigidity and flexibility can be achieved by varying the SMM composition, processing method/parameters and/or porosity following a number of standard polymer/polymer foam synthesis/processing methods. In one embodiment, the SMM is an SMP selected from Ethylene Vinyl Acetate (EVA), Polyurethane (PU), or Thermoplastic Polyurethane (TPU), or a combination thereof.

Based on the principle of Shape Memory Effect (SME) as a substrate for the present invention, Shape Memory Polymers (SMPs), including their composites/mixtures and constructed in solid or foam, comprise a number of (glass transition or melt/crystalline) polymeric materials with transition temperatures of about 45 ℃ to about 80 ℃ or below and their composites/can be applied in the present application, such as EVA or PU foams, PU, TPU or PU/TPU mixtures, etc. However, it should be understood that when the moldable shoe or shoe insert is initially heated up to about 80 ℃ (and above about 45 ℃), the temperature of the surface upon insertion of the bare foot will be about 60 ℃ or less, which is a temperature that is comfortable for the end user.

Drawings

Fig. 1-description of the first embodiment. (1) A human foot; (2) a shape memory polymer material; (3) a pair of common shoes.

Fig. 2-description of the second embodiment. (1) A human foot; (2) a shape memory polymer material; (3) a pair of common shoes.

Fig. 3-description of the third embodiment. (1) A human foot; (2) a shape memory polymeric material.

Fig. 4-description of the fourth embodiment, (1) a human foot; (2) a shape memory polymer material; (4) an outer sole.

Fig. 5-basic concept (I) of a comfort fit shoe according to an embodiment and proof of concept (II) of this embodiment.

FIG. 6-cross section (a) and magnified view under SEM of EVA foam sheet (b).

FIG. 7-DSC curve of EVA foam. Insertion diagram: magnified view of glass transition range upon heating.

FIG. 8-dimensions (units: mm) of uniaxial tensile test specimens.

Fig. 9-illustration of a complete SME cycle.

Figure 10-typical stress-strain relationship for uniaxial extension to 30% of maximum strain at three different temperatures, followed by cooling to room temperature and then unloading.

Figure 11-typical stress-strain relationship for uniaxial extension to 80% of maximum strain at three different temperatures, followed by cooling to room temperature and then unloading.

Figure 12-typical stress-strain relationship for samples with pre-stretch/samples without pre-stretch cycled at room temperature.

Figure 13-stress-strain relationship for the case of uniaxial compression to 30% of maximum strain at three different temperatures, followed by cooling to room temperature and then unloading.

Figure 14-stress-strain relationship for the case of uniaxial compression to 80% of maximum strain at three different temperatures, followed by cooling to room temperature and then unloading.

Figure 15-stress-strain relationship obtained by cyclic compression testing at room temperature with/without pre-compression.

Figure 16-shape fixation rate as a function of programming temperature.

Figure 17-shape recovery as a function of programming temperature.

Figure 18-shape recovery of EVA foam after clamping at different time periods at room temperature.

Figure 19-stress-strain relationship (a) for EVA foam compressed to 0.329MPa/0.1645MPa and then held at the applied compressive stress for 24 hours before unloading, and corresponding strain/stress versus time relationship (b).

Figure 20-evolution of recovery in samples with different compressive stresses of 0.329MPa and 0.1645MPa, respectively.

Fig. 21-illustration of an embodiment of the invention (fifth embodiment).

Fig. 22 is a diagram of an embodiment of the present invention (sixth embodiment).

Fig. 23 is a diagram of an embodiment of the present invention (seventh embodiment).

Fig. 24 is an illustration of an embodiment of the present invention (eighth embodiment).

Figure 25-illustration of a sole of an embodiment of the invention.

FIG. 26-illustration of a method embodiment of the invention.

Detailed Description

The basic principle of the invention is the use of Shape Memory Materials (SMM), which are characterized by a Shape Memory Effect (SME). Shape Memory Effects (SMEs) are generally described as shape switching phenomena whereby Shape Memory Materials (SMMs) can be restored to their original shape by the presence of a correct stimulus, such as heat (thermal response), light (optical response), chemistry (including water, chemical response), magnetic field (magnetic response), mechanical load (mechanical response), etc. This is in contrast to memory foam, which provides an instantaneous deformation, but slowly returns to its original shape, and thus has no ability to maintain a temporary shape, i.e., no SME. The polymers of the present invention that exhibit shape memory effects have both a visible current (temporary) form and a stored (original or permanent) form. Once the polymer is made by conventional methods, the material is brought into another temporary form by processes such as heating, deformation and finally cooling. The polymer retains this temporary shape until the activated shape becomes permanent under a predetermined external stimulus (in this example by heating). The material can be converted into its original (permanent) shape by reheating it, again ready for processing into another temporary form.

Based on this principle, the shape memory polymer material can be easily deformed into a temporary shape within a suitable temperature range (about 45 ℃ to about 80 ℃ or below about 80 ℃). Upon cooling, the temporary shape is largely retained while still being flexible enough and rigid enough to provide support.

In a preferred embodiment, the flexibility is such that the material will be easily deformed by stretching/bending of the hand or pressing with the fingers, and provide good resilience to return simultaneously. Measurement of young's modulus can be used to measure stiffness. The young's modulus for this application is preferably in the range 0.001GPa to 0.5GPa, such as 0.005GPa, 0.01GPa, 0.05GPa, 0.10GPa, 0.15GPa, 0.20GPa, 0.25GPa, 0.30GPa, 0.35GPa, 0.40GPa, 0.45GPa or a range between any two of these figures. When desired, such materials can only recover their original shape (permanent shape) when reheated for another round of finishing again. Shape memory polymeric materials, including composites and blends thereof, may be used in such comfortably fitting footwear because they may provide the desired combination of rigidity and flexibility.

For the purpose of achieving a comfortable fit footwear as described above, the basic requirements of the polymer foam are, among others: 1) flexible/elastic at both low and high temperatures. Elasticity can also be measured by young's modulus, preferably in the range of 0.001GPa to 0.5GPa, such as 0.005GPa, 0.01GPa, 0.05GPa, 0.10GPa, 0.15GPa, 0.0.20GPa, 0.25GPa, 0.30GPa, 0.35GPa, 0.40GPa or 0.45GPa or a range between any two of these figures; 2) capable of retaining a temporary shape (shape fixation rate > 40%, such as shape fixation rate > 42%, shape fixation rate > 44%, shape fixation rate > 46%, shape fixation rate > 48%, shape fixation rate > 50%, shape fixation rate > 52%, shape fixation rate > 54%, shape fixation rate > 56%, shape fixation rate > 58%, shape fixation rate > 60%, shape fixation rate > 62%, shape fixation rate > 64%, shape fixation rate > 66%, shape fixation rate > 68%, shape fixation rate > 70%, shape fixation rate > 72%, shape fixation rate > 74%, shape fixation rate > 76%, > 78%, or > 80%; 3) good shape recovery capability (shape recovery ≧ 40%, such as, shape recovery > 42%, shape recovery > 44%, shape recovery > 46%, shape recovery > 48%, shape recovery > 50%, shape recovery > 52%, shape recovery > 54%, shape recovery > 56%, shape recovery > 58%, shape recovery > 60%, shape recovery > 62%, shape recovery > 64%, shape recovery > 66%, shape recovery > 68%, shape recovery > 70%, shape recovery > 72%, shape recovery > 74%, shape recovery > 76%, shape recovery > 78%, or shape recovery > 80% and shape recovery can be used to quantify this capability (see fig. 16 and 17, equations 1-3); and 4) the heating temperature for activation should be only slightly above body temperature, especially during wear (programming). Temperatures not exceeding 60 c are still acceptable because the human body can tolerate the temperature for a short time, even barefeet for a few seconds. Furthermore, for the polymeric materials of the present invention, the activation temperature is typically in the range of Tg (glass transition) or Tm (melting). + -. 10 to 15 ℃.

The present invention contemplates eight possible embodiments of such a moldable shoe or shoe insert:

in a first embodiment (fig. 1), the shoe can be designed to be very thin (about 1mm to 3mm) and lightweight, and can be easily packaged and stored with minimal storage space. To obtain a perfect fit, the shoe is first heated to about 50 ℃ using warm water, an oven, a heater or a hot air blower (such as a blower) so that the shoe can be moulded (or have other types of irritation depending on the type of material used), and then the user inserts his/her foot (1) into the shoe or shoe insert (2), which will deform to conform to the shape of the user's foot. As shown in this figure, a shoe or shoe insert may be molded to cover the entire surface of the foot, all the way to the user's ankle, providing stability to the entire foot. After cooling, the deformed shape retains the appropriate stiffness and flexibility. The user obtains a comfortable fit shoe having an internal shape profile that is custom molded to the shape of his/her foot. For example, unlike Crocs shoes, there is no additional gap between the foot and the shoe, making it more comfortable, thereby reducing the risk of injury from sliding the foot. There is no additional internal space and incorrect pressure between the foot and the shoe, so the potential risk of injury can be minimized. Furthermore, the shoe can be made very thin and, if desired, for example, walking on rough ground, allows the user to further protect their foot lining by using the product as an insole to be inserted into a normal shoe (3) (i.e. a removable interior to eliminate possible discomfort caused by rough ground (e.g. thicker rocks)) or a hard/harder shoe. In this way, a comfortable fit is maintained even when the user is wearing ordinary shoes. Such a moldable shoe or shoe insert may deform back to its original shape when subjected to a second heating. With such materials, the mating process is repeatable and instantaneous, whereby a comfortable fit can be easily achieved.

In a second embodiment (fig. 2), the moldable shoe insert (2) is pre-fixed to the inner surface of a conventional shoe (3), functioning as a non-removable lining of a normal shoe.

This can be achieved by using known adhesive products used in shoe manufacturing processes. All the forming processes are the same as those mentioned in the first embodiment. Good fit performance can still be achieved in such an embodiment.

In a third embodiment (fig. 3), a moldable shoe made of a shape memory polymeric material is approximately 2 to 15mm thicker than the shoe of the first embodiment to provide better protection for the user.

In a fourth embodiment (fig. 4), a thick outsole (4) may be added to the underside of the moldable shoe (2). With this additional bottom layer, the shoe can cope with rougher ground conditions without affecting the comfort fit. The bottom layer or outsole material may be made of a harder and wear resistant material with/without shape memory effect. Multiple layers may also be incorporated in selected areas of the surface having impact absorbing material to accommodate athletic activities such as jogging. In another embodiment, Thermoplastic Polyurethane (TPU) dissolved in Tetrahydrofuran (THF) can be in the inner and outer layers to provide a degree of breathability and to prevent footwear (especially made from foam) from smelling odors due to perspiration. The vent/groove may also incorporate important points to further reduce fouling.

In a fifth embodiment (fig. 21), a shoe 100 manufactured by 3D molding is shown. The entire shoe is made of the same material, 104 represents a cut/hole or other weakening means (e.g. an indentation); 102 represent thicker sections to provide better support.

In a sixth embodiment (fig. 22), an insole 120 is shown, which includes a plurality of indentations 122. The plurality of indentations 122 may be through/non-through holes or even slots/grooves. The plurality of indentations 122 are configured to enable deformation of the insole 120 when the sock 124 is placed on the insole 120. It should be noted that insole 120 may also be made of a non-uniform foam layer to enhance fit and comfort. 124 may be pre-bonded to the insole 120. When the insole 120 is heated, it becomes soft, so that sock-shoes can be easily put on. After cooling, the insole becomes as stiff as a shoe.

In a seventh embodiment (fig. 23), a shoe 150 is shown folded to form a free-size shoe. The shoe 150 is formed by attaching, using at least one fastener 160 (such as,

) The first flap 152 is connected to the second flap 154 (or vice versa) to form the front of the shoe 150. Rear fasteningMembers 158 are also configured to couple to one another to form a heel counter for footwear 150. It should be noted that the foam layer 156 of the shoe 150 is not uniform for enhanced fit and comfort. The fastener 158 may be of the hook and loop type or any other form of secure temporary fastener. As with the other embodiments, heat is required to first soften the shoe.

In an eighth embodiment (fig. 24), another free-size shoe 180 is shown, folded into the form of a shoe. The shoe 180 is formed by connecting the third flap 182 to the fourth flap 188 (or vice versa) using at least one fastener 190 to form a front portion of the shoe 180. The shoe 180 does not include a heel counter, but rather a heal guard 186. It should be noted that the foam layer 184 of the shoe 180 is not uniform for enhanced fit and comfort and includes through/non-through holes or even slots/grooves.

As with the other embodiments, heat is required to first soften the shoe.

Referring to fig. 25, a sole portion 200 of the previous embodiment is shown. The sole portion 200 may be deformed whereby the deformation is substantially at the central portion 204, which includes through/non-through holes and even slots/grooves. In addition, the ball portion 202 and the heel portion 206 are made of different materials (with/without shape memory effect) for gripping and comfort.

In another aspect, referring to FIG. 26, a method 300 for forming a shoe is provided. The shoe is prepared from a stimulus responsive (thermal responsive) shape memory material layer by method 300, method 300 including heating the layer to a predetermined temperature (302). The predetermined temperature is between 45 ℃ and 80 ℃. Further, the method 300 includes deforming the layer (304), wherein the deforming of the layer is performed by placing a foot structure on the layer. The foot structure can be from a human body or a foot model. The deformation of the layer may comprise a deformation of a plurality of indentations within the layer, the plurality of indentations comprising through/non-through holes and even slots/grooves. Finally, method 300 includes manipulating the layer using at least one fastener to form the shoe (306). It should be understood that the manipulation of the layers is by folding.

Industrial applicability

Moldable shoes or shoe inserts according to the present invention have also proven to have great potential for athletic and medical applications. The following is a non-exhaustive list of various potential applications:

student shoes; fashion shoes; beach shoes; diabetic shoes; temporary shoes for fracture patients; an inner ski boot shell; fast personalized shoes are rented in the skating rink; a fin; the bicycle shoes are directly fixed on the bicycle pedals; and shoes for persons with abnormal foot shapes.

In addition to the foot, the concept of the invention can be extended for supporting elbows, knees and even the bottom, etc., to provide functions that are not only comfortable but also protective.

Examples of the invention

Fig. 5(I) shows an embodiment of a moldable shoe or shoe insert of the present invention. When heated to slightly above body temperature (e.g., 45℃.), the shoe becomes soft and highly elastic. Thus, the user can easily wear the shoe in the same way as if the elastic sock were perfectly fitted. After cooling back to body temperature, the material becomes somewhat stiff but still elastic enough to walk comfortably. Due to slight shape differences of e.g. the user's feet, e.g. between morning and afternoon, each re-installation requires re-heating, and the shoe can be re-heated to 45 ℃ for re-use/re-installation. Fig. 5(II) is also an embodiment of the above-described moldable shoe or shoe insert. In fig. 5(II) (a), the top sock is modified by coating it with a layer of low flow index thermoplastic polyurethane, while the bottom is the original sock used for comparison. Low flow indices, such as about 3g/10min to 20g/10min, ensure that the material will "flow" when stressed rather than when subjected to gravity. When a thin layer is applied to the sock, unlike a normal sock, the sock can maintain the shape of the foot after being deformed at the knitting temperature, rather than being shrunk to the original size. After heating to about 60 ℃, the thermoplastic polyurethane softens and the sock is altered. When the modified sock cools to slightly above body temperature, the thermoplastic polyurethane can still be molded. Thus, the modified sock may be conveniently worn as a moldable shoe or shoe insert. After a few minutes, the thermoplastic polyurethane becomes completely crystalline and therefore the sock becomes slightly stiffer and therefore less elastic than the original sock (the stiffness should range from about 0.001 to 0.5 GPa) but still flexible enough for the user to move around ((b) in fig. 5 (II)). The sock can maintain a new shape even after being removed ((c) in fig. 5 (II)). Only after heat softening of the thermoplastic polyurethane will the sock recover its original shape and can it be subsequently reused.

The present invention also contemplates the use of composite materials such as EVA/TPU blends, EVA/PCL (polycaprolactone) blends, silicone/TPU blends, silicone/PCL blends, silicone/melt gels. Glass/carbon fiber materials may be used for reinforcement. Although some shape memory materials according to some embodiments may be heated to 45 ℃ to 80 ℃, for some other materials such as PCL-based polymers, one may wear it even if cooled to room temperature, since such materials take a very long time to harden even at room temperature.

Materials such as PCL and TPU have a high melting temperature (over 60 ℃), but complete crystallization at or below body temperature takes up to 10 minutes. Thus, shape memory polymeric materials made from them can be heated to their melting temperature and then "donned" at room temperature.

Both foam and solid polymeric materials may be used.

From a manufacturing and logistics standpoint, capital investment and manufacturing and storage efforts can be greatly reduced since such moldable shoes or shoe inserts do not have a particular size and do not differentiate on either the right or left side. On the other hand, from the customer's perspective, instead of trying to find the proper shoe size, each shoe is now guaranteed to fit either foot.

In fig. 5(II), the sock is used as the elastic component and the thermoplastic polyurethane is used as the conversion component. The process of fixing the temporary shape is conventionally referred to as braiding, and the process of heating to return to the original shape is referred to as shape recovery.

Materials, thermal analysis and sample preparation

The material studied in this study was a commercial EVA foam with a thickness of about 5.6mm and a porosity of about 15%. Fig. 6 shows a cross section of the foam board and an enlarged view under a Scanning Electron Microscope (SEM). Samples for thermomechanical testing were cut from EVA sheets.

Differential Scanning Calorimeter (DSC) measurements were performed using a TA instrument (n.c., n.cassel, germany, usa) Q200 DSC at a heating/cooling rate of 5 ℃/min (under nitrogen) between 0 ℃ and 100 ℃. As shown in fig. 7, the EVA has two transitions. The glass transition occurs at about 55 ℃ and melting and crystallization are achieved by heating and cooling at 80 ℃ and 65 ℃, respectively. In applications such as comfortable moldable shoes or shoe inserts, a glass transition between about 50 ℃ and 60 ℃ (inset of fig. 7) is advantageous because such a temperature range between 50 ℃ and 60 ℃ is suitable for the human body. Any temperature above 60 c may cause the user to feel too hot to wear (and thus not last for a long time).

A dumbbell specimen (as shown in FIG. 8) and a small rectangular specimen (25X 20mm) were cut out of the EVA foam according to ASTM D638 standard (type IV) to perform uniaxial tensile test and compression test, respectively. Stress and strain as used in this study are used for engineering stress and engineering strain, respectively, unless otherwise indicated. Engineering strain/stress is related to the engineering application and not the basis (for theoretical studies and simulations, etc.).

Experiment and results

To determine whether a material can be used for a moldable shoe or shoe insert, uniaxial stretching and uniaxial compression are performed at different programming temperatures. In addition, room temperature cycling tests were performed to reveal whether the material still has excellent elasticity with high comfort in woven/unwoven conditions.

Uniaxial tensile test

Uniaxial tensile tests were performed using an Intron (Norwood, MA, USA)5565 test system with an integrated temperature controlled chamber. In all tests, 10 was used for loading and unloading^-3Constant strain rate in/s.

A typical thermally responsive SME cycle applied in this study includes two processes, namely programming and recovery, with four main steps (a-d), as shown in fig. 9.

In step (a), the glass transition temperature range under investigation is pulled to a specified maximum strain (. epsilon.) at a given test (programming) temperature_m) Thereafter, the sample was cooled to room temperature (about 22 ℃) to maintain maximum strain and then unloaded (step b). The resulting residual strain is represented by ∈₁And (4) showing. This is the first process of programming. In the next recovery process, after the applied constraint is removed, the sample may recover slightly at room temperature due to creep (c), so the residual strain drops to ε₂. Finally, the sample is heated to slightly above (less than 5 ℃) the previous programming temperature for 5 minutes (step d), the residual strain being expressed as ε₃. Note that significant creep in EVA foam was only observed in samples that were formed to high strain at room temperature. Thus, unless programming is performed at room temperature, for other programming temperatures,

i.e. step c can be omitted.

FIG. 10 shows three typical stress-strain relationships for EVA samples pre-stretched to 30% of the maximum braided strain at three different temperatures, i.e., 50 deg.C, 55 deg.C, and 60 deg.C. It can be seen that the residual strain of the pre-stretched sample is lowest (22.6%) at the lowest temperature (50 ℃, dashed line). The maximum residual strain was found to be about 27.4% in the pre-stretched sample (gray wire) with a maximum temperature of 60 ℃. Because the glass transition temperature of the material is between

This experiment thus demonstrates the shape fixation rate of this material in the above temperature range.

See fig. 9. Instantaneous shape fixation rate

And long-term shape fixation rate

Can be defined as:

and shape recovery rate (R)_r) It can be defined as the number of,

during the subsequent recovery, the samples were heated to a temperature more than 5 ℃ below their respective pre-stretching temperature for 5 minutes. All samples were found to be able to fully recover their original shape.

Fig. 11 shows three typical stress-strain curves when stretched to 80% maximum strain at 50 c, 55 c and 60 c, respectively. It was observed to show the same trend as in fig. 10, but the residual strain was much higher (about 70%). In addition to small deformations (30%), large deformations (80%) are also to be taken into account, since the user may also experience large deformations in the present application. Therefore, the shape fixation rate and the shape recovery rate after large deformation should also be studied.

After heating to more than 5 c below its respective pre-stretching temperature for more than 5 minutes, all samples were able to recover almost completely their original shape. The shape fixation and shape recovery of a single stretched and uniaxially compressed (mentioned below) sample in a single SME cycle is discussed in detail below.

Fig. 12 shows the stress-strain relationship in cyclic uniaxial stretching at room temperature in the samples with/without pretension. The pre-stretching was carried out at 60 ℃ to a maximum strain of 30% or a maximum strain of 80%. Note that for simplicity, the engineering strain calculation is based on gauge length in each individual test here. 5 cycles were performed with maximum programming strains of 10%, 20%, 30%, 40% and 50% (in increasing order). In the last cycle of all samples, there was a duration of 5 minutes before unloading.

The stress-strain curves for the samples with 30% and 80% pre-stretch show: the residual strain after unloading in each cycle was almost the same as for the samples without pretensioning. On the other hand, a small difference between the 30% pre-stretched sample and the original sample was observed. There was some significant residual strain after unloading in each cycle.

Furthermore, as the maximum strain under load increases, the corresponding residual strain increases. However, it was observed that 10 minutes after unloading, the residual strain could be largely removed.

Thus, it is understood that at room temperature, a foam with or without pretension can be considered to have greater elasticity with limited elastic viscosity. It should be noted that, as expected, the stress-strain curve of the sample with 30% pretension was only slightly higher than the stress-strain curve of the un-pretensioned sample, and the sample with 80% pretension appeared to be stiffer. Furthermore, a larger hysteresis in samples with higher pretension indicates a higher energy dissipation in the load/unload cycle. It appears that the influence of the pre-stretching strain (at least up to 30%) has no significant influence on the mechanical response of the foam.

Uniaxial compression test

Rectangular samples were used for a series of single and cyclic uniaxial compression tests. The same test machines and parameters as mentioned above for the uniaxial tensile test were used. Three samples were compressed 30% at three different temperatures (i.e., 50 ℃, 55 ℃ and 60 ℃), then kept cool to room temperature and finally unloaded. Fig. 13 shows the stress-strain relationship during the weaving process for these three samples. It can be seen that, as with uniaxial stretching, the sample tested at the maximum temperature of 60 ℃ has a maximum residual strain of about 30%, while the sample tested at the minimum temperature of 50 ℃ has a minimum residual strain of about 25%. Subsequently, the three samples were heated to slightly above their respective programming temperatures for 5 minutes for heat-induced shape recovery. All residual one-step strains were observed to be very small. An 80% precompression test was also performed. Their stress versus strain relationship is shown in fig. 14. Typically, the residual strain is around 75% and follows the same trend as described above, i.e. higher programming temperatures result in greater residual strain. After programming to 80% compression, the sample was heated to slightly above its rewritable programming temperature for 5 minutes as previously described. After that, the thickness of all samples was measured. The remaining strain in all samples was found to be about 40%.

Figure 15 shows the stress-strain relationship in three cyclic compression tests at room temperature for samples with/without pre-compression. As previously described, pre-compression with a maximum braid strain of 30% or 80% is produced at 60 ℃. Three maximum programs were applied to all samples in the cycle, 15%, 30% and 45% respectively (in increasing order). At the end of each cycle, no significant residual strain was observed in all samples, indicating excellent elastic response in both the pre-compressed and original samples.

Unlike the uniaxial stretching in fig. 12, fig. 15 shows: although the stress-strain curve for the 30% pre-compressed sample is very close to the sample without pre-compression (same as uniaxial tension), the 80% pre-compressed sample is significantly stiffer than the pre-compressed sample after being compressed to a strain above 20%.

Shape fixation rate and shape recovery rate

While shape fixation rate is a measure of how a comfortable fit shoe fits the contour of a particular foot, shape recovery rate shows the ability of a comfortable fit shoe to recover to its original dimensions during the next round of comfortable fit. The rate of shape fixation with programming temperature for both uniaxial tension and uniaxial compression at two different strains of 30% and 80% is plotted in fig. 16.

It can be seen that the shape fixation rate exceeded 75% in all tests. In general:

higher programming temperatures always lead to higher form-fixing rates, which are therefore ideal for shoes that maintain a temporary form to ensure greater comfort. The higher the shape fixation rate, the better the shoe can maintain the deformed shape, regardless of the elastic deformation. The perfect proportion is 100%, which means that the material can maintain exactly the same shape as the shape of the user's foot. In fact, any proportion above 75% may be considered suitable for this application.

However, high temperatures, for example, in excess of 60 ℃, may be intolerable to many people.

The rate of shape fixation in compression is generally higher than in tension;

higher maximum braiding strain is more effective in increasing the shape fixation rate, but this is not applicable at higher braiding temperatures.

Fig. 17 shows the shape recovery rate as a function of programming temperature for maximum programming strains of 30% and 80% for uniaxial extension and uniaxial compression. Clearly, while poor shape recovery (only between 40% and 55%) was observed in all the braided samples compressed to 80% of the maximum braiding strain, all the remaining samples had very high shape recovery. In particular, the shape recovery in all 30% stretched samples was 100%. Thus, it can be concluded that:

the shape recovery rate is more or less independent of the programming temperature;

higher shape recovery results in samples with lower braid strain;

shape recovery is only bad in the knitted sample by over-compression.

Effects of Long-term compression

Body weight is usually applied continuously for several hours during use. As shown in fig. 18(a), a piece of EVA foam was pressed at room temperature using two clamps (fig. 18 (b)). After 80 minutes, one clip was removed (fig. 18(c1)), and the other clip was applied for 115 hours (fig. 18(d 1)). The 80 hour clamped dimple recovered primarily after 40 hours (fig. 18(c2)), while the 115 hour clamped dimple remained visible after 23 days (fig. 18(d4)), which disappeared only after heating in boiling water (fig. 18 (e)). For accurate identification, we took a rather extreme investigation in which a small piece of EVA foam was first compressed to a maximum stress of 0.329MPa, which should be the maximum foot pressure of a normal young person, and then held for 24 hours and then removed.

Fig. 19(a) (black line) plots the stress-strain relationship of the samples throughout the test. We can see that when loaded to 0.329MPa, a compressive strain of about 64% is recorded. Over the next 24 hours, the compressive strain gradually increased to 80%. After unloading, the residual strain was 74%. For comparison, in another test, the maximum compressive stress applied was reduced by half to 0.1645 MPa. The resulting stress and strain curves are plotted in gray in fig. 19 (a). It can be seen that despite the halving of the applied stress, more creep induced strain is observed (above about 10%) while more strain recovery after unloading is found (about 4%). Fig. 19(b) plots the evolution of strain and stress over time during the entire loading/unloading process. It appears that the strain increase gradually becomes smaller during the load holding period. There was virtually no more increase in strain at about 15 hours (for 0.329MPa) or 18.5 hours (for 0.1645 MPa). As expected, higher applied stress requires less time to stabilize creep strain. In the next step, both samples were left to air at room temperature for 120 hours, recorded every 24 hours. Finally, the sample was heated to 60 ℃ for 10 minutes. The corresponding shape recovery is calculated and plotted in fig. 20. We can see that the shape recovery curves for both samples are about the same as the time. The shape recovery rate gradually decreases with the lapse of time. After 120 hours in air at room temperature, both had approximately 85% recovery. Further heating to 60 ℃ for 10 minutes gave complete shape recovery of 0.1645 MPa.

It should therefore be reasonably concluded that such EVA foam is suitable for reasonably long wear. Good heat-sensitive SMEs will not be present over extended wear at room temperature. According to fig. 10, 11 and 13, 14, at high temperatures, EVA foam is soft and can be stretched or compressed by 30% or more. Therefore, a shoe made of such foam should be easy to wear while ensuring a comfortable fit. As shown in fig. 16, the corresponding shape fixity in both uniaxial tension and compression is high, allowing the foam to largely maintain the programmed shape. Thus, the temporary shape of a shoe made of such foam is capable of largely retaining the personalized shape after "weaving". Even when programmed to 80% strain under uniaxial tension or uniaxial compression, the foam still has high elasticity at room temperature, as shown in fig. 12 and 15, which indicates that: such soft shoes still have elasticity, even being stretched to 50% or compressed by 45%. Thus, a prepared personalized shoe is not only easy to take off and put on, but also comfortable to wear. High elasticity at room temperature also means that even after knitting, the shoe is able to mostly maintain a personalized shape in the case of short to medium loading periods. This foam will creep for long periods of load (fig. 18 and 19), but most of the deformation due to creep will automatically recover, even without heating (fig. 20). It can be heated up to 60 ℃ to induce almost complete shape recovery.

Excellent heat-induced shape recovery was observed in fig. 17, except for 80% compressed foam. A possible reason behind the difficulty in shape recovery is excessive compression of the foam at high temperatures. One possible way to eliminate this problem is to reduce the deformation of the EVA foam. Theoretically, for the same compressive load, as the stiffness of the material increases, the corresponding deformation decreases accordingly. For such EVA foam, its stiffness can be easily increased by reducing its porosity.

According to fig. 16, the best results of the shape fixation rate in all tests were always obtained at a programming temperature of 60 c, which is 15 c higher than the comfort temperature. Therefore, the glass transition temperature of the EVA should be slightly lowered.

The results of a series of experiments with EVA foam show that: such foams are able to meet most of the requirements for a comfortable fit, particularly for moldable shoes. It has high elasticity at both high and low temperatures, and therefore can be easily woven for pleasant fitting and use.

The custom shape can be largely retained after weaving. Unless over-compressed at high temperatures, there is generally good SME shape recovery and subsequent reuse.

Claims

1. A moldable shoe comprising a complete shoe product, which in use extends across the entire sole of the foot, including the forefoot, midfoot and heel, and is prepared from a layer of stimulus responsive Shape Memory Material (SMM), the deformation of the layer comprising deformation of a plurality of indentations within the layer, the plurality of indentations comprising through/non-through holes and even slots/grooves; the sole portion is deformable, the deformation being at the central portion of the sole, the deformation comprising a through hole/groove; the stimulus-responsive shape memory material is a thermally-responsive Shape Memory Material (SMM) and the stimulus-responsive shape memory material is a Shape Memory Polymer (SMP); the stimulus response shape memory material is selected from ethylene-vinyl acetate copolymer (EVA), Polyurethane (PU) or Thermoplastic Polyurethane (TPU), or the combination of ethylene-vinyl acetate copolymer (EVA), Polyurethane (PU) and Thermoplastic Polyurethane (TPU); the stimulus responsive shape memory material is characterized by having a stiffness and/or elasticity based on a young's modulus of 0.001GPa to 0.5 GPa; the stimulus responsive shape memory material is characterized by being capable of retaining a temporary shape at a shape fixation rate of at least 40%; the stimulus-responsive shape memory material is characterized by a shape-recovery capability having a shape-recovery rate of at least 40%, and the moldable shoe is prepared from a layer formed of a stimulus-responsive Shape Memory Material (SMM).

2. A mouldable shoe according to claim 1, wherein the stimulus responsive shape memory material is initially heated to between 45 ℃ and 80 ℃.

3. A mouldable shoe according to claim 1, wherein the stimulus responsive shape memory material has a surface temperature in use of no more than 60 ℃.

4. A mouldable shoe according to claim 1, wherein the stimulus responsive shape memory material has a thickness of 1mm to 3 mm.

5. A mouldable shoe according to claim 1, wherein the stimulus responsive shape memory material has a thickness of 2mm to 15 mm.

6. A mouldable shoe according to claim 1, wherein the stimulus responsive shape memory material is coated on a fabric material.

7. A mouldable shoe according to claim 6, wherein the stimulus responsive shape memory material coated on the fabric material is characterised by a low flow index of 3g/10min to 20g/10 min.

8. A moldable shoe comprising a complete shoe product, said moldable shoe being prepared from a stimulus-responsive shape memory material layer, wherein said stimulus-responsive shape memory material layer is configured to be operated using at least one fastener to form said shoe, wherein said stimulus-responsive shape memory material layer comprises a plurality of indentations configured to enable deformation of said material layer, an opening perimeter of at least one of said plurality of indentations defining an opening in said stimulus-responsive shape memory material layer; the sole portion may be deformable, with the deformation comprising a through hole/recess at the central portion of the sole.

9. A mouldable shoe according to claim 8, wherein the stimulus responsive shape memory material layer is uniform.

10. A moldable shoe comprising a complete shoe product, said moldable shoe being prepared from a layer of material comprising a stimulus responsive shape memory material and a secondary material, wherein said layer of material is configured to be operated using at least one fastener to form said shoe; the material layer includes a plurality of indentations configured to deform the material layer; the sole portion may be deformable, with the deformation comprising a through hole/recess at the central portion of the sole.

11. The moldable shoe of claim 10, wherein an opening perimeter of at least one of the plurality of indentations defines an opening in the material layer.

12. A mouldable shoe according to claim 10, wherein the stimulus responsive shape memory material layer is uniform.

13. A method for forming a shoe, including an integrated article of footwear, from a layer of stimulus responsive shape memory material, the method comprising:

heating the stimulus responsive shape memory material layer to a predetermined temperature;

deforming the stimulus responsive shape memory material layer; and

operating the layers using at least one fastener to form the shoe,

wherein the deformation of the layer is performed by placing a foot structure on the layer; the deformation of the layer comprises deformation of a plurality of indentations within the layer; the sole portion may be deformable, with the deformation comprising a through hole/recess at the central portion of the sole.

14. The method of claim 13, wherein the predetermined temperature is between 45 ℃ and 80 ℃.

15. The method of claim 13, wherein manipulating the stimulus responsive shape memory material layer is by folding.