Polymer molded part, manufacturing process and its use

Abstract

A doubly stimuli-responsive polymer molded part comprising at least two different polymers, wherein the first polymer has an orientation of the polymer chains in at least one orientation direction and a degree of crystallinity of less than 10% of its maximum degree of crystallinity and a glass transition temperature T G1 exhibits and wherein the first polymer can have a crystallization temperature depending on the cooling rate and wherein crystallization does not occur at a cooling rate of > XK / min and wherein cold crystallization of the first polymer occurs at a cooling rate between 0 and XK / min from a starting temperature T KS1 takes place and wherein the first polymer is above T G1 the orientation of the polymer chains is lost through relaxation and where T KS , is at least 40 K larger than T G1and wherein, in the first polymer, the relaxation of the orientation is a faster process than the cold crystallization, and wherein, in the first polymer, cold crystallization and relaxation of the orientation in the orientation direction are accompanied by a reduction in volume, and wherein the heat deflection temperature T HDT2 of the second polymer a maximum of 10 K below the starting temperature of cold crystallization T KS , of the first polymer and wherein the second polymer either has no cold crystallization start temperature or the cold crystallization start temperature T KS2 of the second polymer at least 20 K above T KS , and wherein the second polymer, having been previously cooled, does not experience a reduction in volume during the subsequent heating, and wherein X takes on values ​​between 500 and 4.

Description

[0001] The invention relates to a molded part comprising at least two different polymers, a method for additive manufacturing of the molded part, and the use of the molded part as an adaptable, assembly-free mechanism.

[0002] US patent 2015 / 158 244 A1 claims a 3D-printed component that can change its shape in response to a subsequent external stimulus and is therefore adaptable. This effect is based on the different swelling behavior of the polymers used, particularly when a polymer undergoes a change in state from glassy to plastically deformable during swelling.

[0003] German patent DE 10 2019 007 939 A1 describes a so-called 4D printing process for manufacturing polymer molded parts from thermoplastic polymers with shape memory properties. During printing, the polymer is not completely melted, so that hard and soft segments exist side by side. Rapid cooling below the glass transition temperature causes the soft segments to solidify. In a subsequent heat treatment step at the so-called "switching temperature," the soft segments revert to an amorphous state and no longer resist the restoring force generated by the hard segments, which act as lattice points. The molded part then returns to its "programmed" shape.

[0004] The conference paper “Additive Manufacturing of Precise Non-Assembly Mechanisms,” published at the IFToMM-DA-CH conference on February 22, 2022 (DOI: 10.17185 / duepuplico / 75421), describes 3D-printed non-assembly mechanisms made from two different polymers. These mechanisms can be adjusted by a single heat treatment to eliminate bearing play. However, the bearing play reappears with continued use and cannot be further corrected.

[0005] US patent 2021 / 0245423 A1 discloses an additive manufacturing system comprising: a substrate defining a primary surface, a filament dispensing device, and a computer device configured to control the filament dispensing device to deposit a first volume of polymer material onto or adjacent to the substrate at a first deposition rate and temperature. A bidirectional deformation structure based on 4D printing is known from patent CN 113232294 A.The bidirectional deformation structure is characterized in that it comprises an outer enclosing structure, a deformation plate and a water-absorbing resin, wherein the inner section of the outer enclosing structure is a fence-like structure, the gap is filled with water-absorbing resin, a through-hole is formed in the side surface deviation position and the deformation plate is arranged in the through-hole.

[0006] CN 111793175 A discloses an improved photocurable multistimulus 3D printing shape memory material, characterized by being mass-produced from the following raw materials: 20 to 70 parts epoxy resin acrylate, 2 to 2 parts methacrylic acid, 30 to 60 parts of a modified inorganic filler, 10 to 30 parts dipropylene glycol diacrylate, 1 to 5 parts of a photoinitiator, 0.05 to 3 parts of a modified inorganic filler, and 1 to 5 parts of a treated fish scale soft layer. The shape memory process is completed by various stimuli, and the speed of shape memory recovery is increased by improving the mechanical properties. The entire shape memory process can be completed in just ten seconds.

[0007] A disadvantage of the previously known mold components that can be adapted by a subsequent stimulus is that an adaptation can only be made between two states and thus only once in the desired direction to achieve the programmed shape.

[0008] Therefore, the object of the invention is to provide a polymer molded part that can undergo a further adjustment of its dimensions to obtain the programmed shape through a renewed, differing external stimulus.

[0009] The object of the invention is solved by a doubly stimuli-responsive polymer molded part comprising at least 2 different polymers, wherein the first polymer has an orientation of the polymer chains in at least one orientation direction and a degree of crystallinity of less than 10% of its maximum degree of crystallinity. (HKSHSchmelz≤0.9) and a glass transition temperature T G1exhibits and wherein the first polymer can have a crystallization temperature depending on the cooling rate and wherein crystallization does not occur at a cooling rate of ≥ XK / min and wherein cold crystallization of the first polymer occurs at a cooling rate between 0 and XK / min from a starting temperature T KS1 takes place and wherein the first polymer is above T G1 the orientation of the polymer chains is lost through relaxation and where T KS , is at least 40 K larger than T G1 and wherein, in the first polymer, the relaxation of the orientation is a faster process than the cold crystallization, and wherein, in the first polymer, cold crystallization and relaxation of the orientation in the orientation direction are accompanied by a reduction in volume, and wherein the heat deflection temperature T HDT2 of the second polymer a maximum of 10 K below the starting temperature of cold crystallization T KS, of the first polymer and wherein the second polymer either has no cold crystallization start temperature or the cold crystallization start temperature T KS2 of the second polymer at least 20 K above T KS , and wherein the second polymer, having been previously cooled, does not experience a reduction in volume during the subsequent heating, and wherein X takes on values ​​between 500 and 4.

[0010] In a preferred embodiment of the invention, the first polymer is polylactide (PLA) or a compound of this polymer, and the second polymer is selected from the group consisting of acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene copolymer (ABS), methyl methacrylate acrylonitrile butadiene styrene copolymer (MABS), styrene acrylonitrile copolymer (SAN), polystyrene (PS), high-density polyethylene (HDPE), polypropylene (PP), polyamides (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyoxymethylene (POM), and / or mixtures or compounds of these polymers.

[0011] In an alternative embodiment of the invention, the first polymer is polyethylene terephthalate (PET) or a compound of this polymer, and the second polymer is selected from the group consisting of polyamides (PA), polycarbonate (PC), polyethylene terephthalate (PBT), polyoxymethylene (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PESU) and / or mixtures or compounds of these polymers.

[0012] In an alternative embodiment of the invention, the first polymer is polycyclohexylenedimethylene terephthalate (PCT) and / or a copolyester and / or compounds of this polymer, and the second polymer is selected from the group consisting of polyamides (PA), polyoxymethylene (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PESU) and / or mixtures or compounds of these polymers.

[0013] In a preferred embodiment, the first polymer is a copolyester of hexylenedimethylene terephthalate and hexylenedimethylene isophthalate (PCTA) with the following formula: and / or compounds of this polymer, and the second polymer is selected from the group consisting of polyamides (PA), polyoxymethylene (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), polyamide-imide (PAI), polyethersulfone (PESU) and / or mixtures or compounds of these polymers.

[0014] In a further alternative embodiment of the invention, the first polymer is selected from the group consisting of polyaryletherketones (PAEK), polyetherketone (PEK), polyetheretherketone (PEEK), poly(etherketoneketone) (PEKK), poly(etheretherketoneketone) (PEEKK), and / or poly(etherketone-etherketoneketone) (PEKEKK), as well as mixtures or compounds of these polymers, and the second polymer is selected from the group consisting of polysulfone (PSU), polyetherimide (PEI), polyethersulfone (PESU), polyamideimide (PAI), and / or mixtures or compounds of these polymers.

[0015] Table 1 shows an overview of the embodiments of the invention and typical characteristic values ​​for the polymers. Table 1: Embodiments of the invention Polymer 1 Polymer 2 name T G [°C] T KS [°C] name T G [°C] T KS [°C] T HDT [°C] 0,45 MPa PLA 45 - 65 90 - 105 ABS 95 - 105 - 70 - 125 MABS 100-110 - 104 - 106 ASA 95 - 105 - 80 - 95 SAN 95-110 - 105-115 PE-HD -130--100 Unknown 60 - 90 PP -20 - 20 Unknown 75 - 120 PS 80 - 105 - 75 - 110 PA 40 - 90 Unknown 60 - 240 PET 70 - 85 135 - 150 75 - 115 PBT 40 - 60 Unknown 115-150 PC 140 - 150 - 120 - 130 POM -75 - -60 Unknown 145 - 170 PET 70 - 85 135 - 150 PA 40 - 90 Unknown 60 - 240 PC 140 - 150 - 120 - 130 PBT 40 - 60 Unknown 115-150 POM -75 - -60 Unknown 145 - 170 PPS 85 - 100 Unknown 140 - 160 PSU 185 - 190 - 175 - 185 PEI 215 - 230 - Unknown PAI 215 - 200 - Unknown PESU 225 - 230 - Unknown PCTA 90 - 100 160 PA 40 - 90 Unknown 60 - 240 POM -75 - -60 Unknown 145 - 170 PPS 85 - 100 Unknown 140 - 160 PSU 185 - 190 - 175 - 185 PEI 215 - 230 - Unknown PAI 215 - 200 - Unknown PESU 225 - 230 - Unknown PEAK family 145 - 175 165 - 190 PSU 185 - 190 - 175 - 185 PEI 215 - 230 - Unknown PESU 225 - 230 - Unknown PAI 215 - 200 - Unknown

[0016] The process for producing the polymer molded part according to the invention also comprises the following steps: i. Selection of two polymers based on the presence of the following criteria: a. The existence of a temperature range in which decomposition-free melting or plasticizing of the first polymer and melting or plasticizing of the second polymer is possible; b. Presence of a glass transition in the first polymer and in the second polymer with the glass transition temperatures T G1 and T G2 ; c. Partial crystallizability of the first polymer above T G1 ; d. Suppression of crystallization in the first polymer at a cooling rate of ≥ XK / min ; e. Start of cold crystallization of the first polymer at a cold crystallization start temperature T KS1 ; f. Orientability of the polymer chains of the first polymer in at least one direction during additive manufacturing; g. Relaxation of orientation in the orientation direction of the first polymer above T G1 ; h. Relaxation of the orientation in the orientation direction is faster than crystallization in the first polymer; i. Relaxation of the orientation in the orientation direction of the first polymer is at least partially prevented by cooling with a cooling rate of ≥XK / min; j. Cold crystallization start temperature T KS The temperature of the first polymer is at least 40 K higher than the glass transition temperature Tg. G1 ; k. Crystallization and relaxation of the orientation in the orientation direction of the first polymer are accompanied by a contraction in at least one direction; l. Heat deflection temperature of the second polymer T HDT2 lies at most 10 K below T KS1 ; m. For the second polymer, either cold crystallization is not possible or the starting temperature of the cold crystallization of the second polymer is T KS2 After prior cooling at a cooling rate of ≥XK / min, the temperature is at least 20 K above T. KS1 ; ii. Conveying the polymers selected in step i. to a heated nozzle; iii. Passing the nozzle at temperature T Ext This involves plasticizing and orienting the polymers selected in step i. by the temperature T. Ext and shearing during conveyance; iv. Layer-by-layer deposition and further orientation perpendicular to the direction of orientation of the polymers plasticized and oriented in step iii onto a substrate with a cooling rate ≥ XK / min, where T Ext > T G for amorphous thermoplastic polymers and wherein T Ext > T Schmelzfor semi-crystalline thermoplastic polymers and wherein the cooling rate XK / min is a cooling of T Ext1 on T G1 enables a process that is faster than the relaxation time of the polymer's orientation (1 t). Relax1 .

[0017] Fig. Figure 1 shows a schematic diagram of the shearing process during steps iii and iv. First, the polymer melt is sheared through the nozzle. Then, the side of the nozzle moves over the deposited strand, shearing the melt strand. Immediately behind the nozzle, the melt is cooled. Depending on the material and printing strategy, the polymer melt can be sheared sufficiently to orient the molecules during printing. Rapid cooling behind the nozzle can make the time to reach the glass transition temperature shorter than the relaxation time for some polymers. In this case, the molecular orientations are frozen into the printed parts.

[0018] In a preferred embodiment of the method, the information on whether the criteria according to ia, b., c., d., e., i., j., m. are met is obtained by means of dynamic differential scanning calorimetry (DSC).

[0019] In another preferred embodiment of the method, the information on whether the criteria if, g, h, k are met is determined by means of isothermal dilation measurements.

[0020] In another embodiment of the method, the information on whether the criterion i. I. is met is determined by heat deflection temperature measurements according to DIN EN ISO 75 at a sample stress of 0.45 MPa or according to ASTM D648 at a sample stress of 66 psi. Alternatively, this value can be taken from the polymer's data sheet.

[0021] The information according to step i a., b., c., d., e., j., m. can be obtained by a person skilled in the art, for example, by means of measurements using differential scanning calorimetry (DSC). Fig. shows an exemplary DSC curve from which the information i a., b., c., d., e., j., m. can be extracted. ia

[0022] The existence of a temperature range in which decomposition-free melting or plasticization of the first polymer and melting or plasticization of the second polymer is possible is indicated in the DSC curves by the presence of a baseline at the corresponding temperatures. If endothermic or exothermic decomposition occurs, the curve deviates from the baseline. ib

[0023] The glass transition temperature can be observed as a step in the baseline of the measurement curves. The mean value of the extrapolated line corresponds to the glass transition temperature. iC

[0024] The partial crystallizability of the first polymer above T G1 is indicated by an endothermic melting zone. id

[0025] The suppression of polymer crystallization at a cooling rate of ≥ XK / min is evident after prior cooling of the polymer at the corresponding cooling rate of ≥ XK / min by the presence of an exothermic cold crystallization region.

[0026] The start of cold crystallization of the first polymer at a cold crystallization start temperature T KS , can be determined after evaluating the onset of the cold crystallization zone after prior cooling at XK / min. Fig.The evaluation of the onset shows the intersection of the tangent of the baseline and the tangent of the crystallization peak at the inflection point.

[0027] Between glass transition temperature T G1 and beginning of cold crystallization at T KS The temperature window of the first polymer must be sufficiently large, at least 40 K, to distinguish between orientation relaxation and cold crystallization. This should be measured at the lowest possible heating rates (near equilibrium), since the onset of cold crystallization shifts to higher temperatures with increasing heating rate than the glass transition. However, the heating rate must remain high enough to allow the glass transition to be determined. ij

[0028] The DSC curve can also be used to determine whether the cold crystallization start temperature T KS , of the first polymer by at least 40 K higher than the glass transition temperature T G1 is. in the

[0029] By comparing the DSC curves of the first polymer with those of the second polymer, it is possible to determine whether the starting temperature of the cold crystallization of the second polymer T KS2 at least 20 K above T KS1 lies.

[0030] The criteria if, g, h, k can be tested using isothermal dilation measurements as follows. The isothermal process progress as a function of time can be used as a relevant comparative parameter. Fig. This shows the time dependence of isothermal dilation. The process progress P(t) of orientational relaxation can be determined by the dilation D(t) perpendicular to the orientation direction (here, the Z-direction). Since only orientational relaxation can cause irreversible expansion during heat treatment, the maximum of the dilation can be approximated as the end of the process D. maxThe process progress as a function of time t can be determined as follows: P(t) = D(t) Dmax if and ig

[0031] The orientability of the polymer chains of the first polymer in at least one direction during additive manufacturing and the relaxation of the orientation in the orientation direction of the first polymer above T G1 can be determined by evaluating the contraction of a sample prepared according to steps ii. to iv. in the orientation direction (here X & Y direction) during simultaneous expansion orthogonal to the orientation direction (here Z direction) at the desired temperature above T G This relationship can be determined. Fig. to be taken. ih

[0032] The determination of whether the relaxation of the orientation in the orientation direction occurs faster than the crystallization of the first polymer is carried out as follows: The duration of the contraction of an orientation-free sample cooled at XK / min at the desired temperature is determined (see Fig. ) as well as the measurement orthogonal to the orientation direction of a sample prepared according to steps ii. to iv. at the desired temperature (see Fig. ) measured. The rate of change of the effect over time is compared. The rate of change of cold crystallization P(t) KS The effect of orientation relaxation can be directly derived from the first measurement. The progress of the effect can be obtained by subtracting the first measurement from the second. P(t)KS=D(t)KSDmin P(t)Relax=D(t)−D(t)KSDmax,Relax

[0033] Alternatively, a two-stage isothermal dilatation measurement of a sample prepared according to steps ii to iv can be performed perpendicular to the orientation direction (here Z-direction). This relationship is described in Fig.shown. The first isothermal stage is performed at a temperature between T G1 and 25 K below T KS1 , preferably at the temperature of the first heat treatment T W1 , and the second stage above T KS1 - 25 K preferably at the temperature of the second heat treatment T W2The procedure is carried out. The first isothermal stage is maintained until maximum expansion is reached. Heating to the second isothermal stage then proceeds at a moderate rate (here 2 K / min). If contraction occurs during this second isothermal stage, there must still be cold crystallization potential present in the component, which leads to this contraction. To determine the progress of cold crystallization at the end of relaxation using this method, another sample must be measured near equilibrium using DSC after completion of the first isothermal stage. The enthalpy of cold crystallization H is then determined. KS and the magnitude of the enthalpy of fusion |H Schmelz | compared. The following applies: PKS=1−HKS|HSchmelz| ik

[0034] By evaluating the direction-dependent dilation behavior, it can be determined whether the crystallization and relaxation of the orientation in the orientation direction of the first polymer are accompanied by a contraction in at least one direction. ii

[0035] The information as to whether relaxation of the orientation in the orientation direction of the first polymer is at least partially prevented by cooling with a cooling rate of ≥XK / min and thus whether criterion ii is fulfilled is obtained by the person skilled in the art as follows: In a sheared melt, both macro-Brownian motion and orientation processes occur simultaneously. Over time, the Brownian motion leads to a relaxation of the introduced orientations. If the orientation process is faster than the relaxation process, the molecules in the polymer melt orient themselves. Once the shearing stops, orientation processes cease, but the Brownian motion persists as long as the temperature remains above the glass transition temperature. Therefore, the orientations in the polymer are gradually degraded over time. The time required for this process is called the relaxation time, which is highly temperature-dependent.

[0036] In order to freeze the orientations, the following must apply: tRelax>>(TEXT−TG) / vK with t Relax Relaxation time T Ext Extrusion temperature T GGlass transition temperature v K Cooling rate

[0037] An investigation to determine whether this is possible can be carried out in several ways: 1. A test specimen (e.g., a cube) is printed with corresponding parameters ii to iv, and the dilation is then measured as a function of time and temperature. If irreversible expansion perpendicular to the orientation direction (layer plane) is present, orientations existed in the component before the measurement, which relaxed during the measurement. (cf. Fig. -Direction) 2. In a rotational rheometer, the polymer melt can be measured at T Ext Heated and then sheared constantly according to the shear rates in the printing process. Subsequently, the shearing of the polymer is stopped and simultaneously with v K under T G cooled down. The reduction in torque corresponds to relaxation.

[0038] Should upon reaching TG Even if residual torque is still present, orientations within the component are still frozen. The relationship between temperature, relaxation, and orientation freezing is described in... Fig. to see.

[0039] The information corresponding to step i I. can be determined by heat deflection temperature measurements according to DIN EN ISO 75 at a sample stress of 0.45 MPa or according to ASTM D648 at a sample stress of 66 psi. Alternatively, this value can be taken from the polymer's data sheet.

[0040] In a material, the effects of orientational relaxation and cold crystallization must occur at different rates during heat treatment. This means there is a heat treatment temperature at which orientational relaxation has already begun, but cold crystallization is still inhibited. The relationship is explained in Fig.To ensure sufficient contraction potential through cold crystallization after complete orientation relaxation, the progress of cold crystallization at the time of orientation relaxation should not exceed 25%.

[0041] Through a subsequent first heat treatment (first external stimulus) at a temperature T W1 above T G1 and 25 K below T KS , the clearance of the polymer molded part manufactured using the inventive method can be adjusted to a precise bearing gap.

[0042] If the bearing gap increases again as a result of using the polymer molded part, the bearing gap can surprisingly be reduced once more by a further heat treatment (second external stimulus) at a temperature T. W2 in the area between T KS , -25 K (lower limit) and T HDT2(upper limit) will be set.

[0043] The polymer molded part according to the invention is also used as a kinematic pair in a multibody system.

[0044] Preferably, the polymer molded part according to the invention is used as a kinematic pair in a multibody system, wherein the multibody system is a no-assembly mechanism.

[0045] Non-assembly mechanisms are movable mechanisms that can be manufactured in a single production step without any assembly required. With conventional manufacturing technologies such as injection molding, non-assembly mechanisms are currently only possible in the form of solid-state joints. Additive manufacturing processes make it possible to produce non-assembly mechanisms with joints consisting of kinematic pairs.

[0046] Fig.shows a no-assembly mechanism with a joint consisting of a kinematic pair.

[0047] Since the two processes of orientation relaxation and cold crystallization can be separated in the first polymer, it is possible to use it twice in the life cycle of assembly-free mechanisms to compensate for the bearing play.

[0048] The game of the assembly-free mechanism can be started with a first external stimulus at temperature T W1 Initially, the patient should be stabilized through orientation relaxation.

[0049] After a certain amount of wear and tear on the mechanism, the remaining crystallization potential can be utilized by subjecting the mechanism to renewed heat treatment at temperature T. W2 (second external stimulus). The shrinkage induced by cold crystallization is then used to compensate for wear-related play.

[0050] This opens up entirely new possibilities to extend the lifespan of such a mechanism – equipped with a kind of “induced self-healing” – and thus make it more sustainable.

[0051] To investigate the performance of a non-assembly mechanism with joints made of kinematic pairs, these can be assembled into a Watt's linkage. An example of such a Watt's linkage can be found in Fig. A Watt mechanism was used, employing four of the previously mentioned joints made up of kinematic pairs.

[0052] Without limiting the generality of the teaching, the following describes the production and use of a polymer molded part according to the invention.

[0053] The following types of devices are used: Type DSC: Polyma 214 Netsch Gerätebau GmbH Type TMA: TMA 402 Netzsch Gerätebau GmbH First polymer: Polylactide (PLA) from DAS FILAMENT 1. The polymer is heated near equilibrium in DSC until it melts, and the enthalpy of cold crystallization H is determined. KS (exothermic process) and the enthalpy of fusion H Schmelz (Endothermic process) evaluated. Is |H KS | < |H Schmelz | Part of the polymer crystallized during the previous cooling process. This provides information about the degree of crystallization after the previous cooling. 2. The polymer melt is then cooled down at a defined cooling rate. Step 1 is repeated again. 4. Step 2 is repeated with a different cooling rate.

[0054] This routine is systematically repeated until the cooling rate at which the desired cooling rate is determined has been determined. HKSH melting ≤ 0.9 This applies. This temperature should be considered the threshold for the cooling rate (in the case of PLA, 6 K / min). This cooling rate must be achievable in the subsequent printing process (criterion id). Fig. The DSC curves of PLA heating at various prior cooling rates are shown. The baseline demonstrates that decomposition-free melting or plasticization of PLA is possible (criterion ia is fulfilled). The partial crystallizability of PLA above T G1 is indicated by an endothermic melting range (criterion ic is fulfilled).

[0055] A sufficiently large temperature window of at least 40 K (step ij) must exist between the glass transition temperature and the onset of cold crystallization to distinguish between orientation relaxation and cold crystallization. This should be measured at the lowest possible heating rates (near equilibrium), since the onset of cold crystallization shifts more sharply to higher temperatures than the glass transition with increasing heating rate. However, the heating rate must remain high enough to allow the glass transition to be determined. Fig. The DSC curve of PLA is shown; it can be the glass transition T. G (Center point) of the investigated PLA is found at 58 °C (criterion ib), followed by the onset of cold crystallization T KS at 101 °C (criterion ie). The enthalpy of cold crystallization H KS At approximately 23.5 J / g, minus minor inaccuracies in the evaluation, it is exactly the same magnitude as the enthalpy of fusion H. Schmelzwith approximately -23.8 J / g.

[0056] In Fig. The isothermal expansion measurements of PLA are shown. Test specimens in the form of cubes (dimensions 7 × 7 × 7 mm) are used. 3The sample was prepared according to steps ii to iv, and its isothermal dilation in one direction was measured using a TMA. For this purpose, the sample was heated at a moderate heating rate (here 2 K / min) to the isothermal temperature (here 70°C). This temperature was then maintained until a nearly constant dilation value was reached (here 4 hours). The sample was then cooled slowly (here 0.2 K / min) so that the entire cross-section of the sample could follow the cooling process. This measurement was repeated in all directions (here XY plane = pressure plane = orientation plane, Z-direction = layer structure). It can be observed that after the measurement was completed, irreversible contraction had occurred in the X and Y directions, as well as irreversible expansion in the Z direction (criteria if, ig, ik fulfilled).

[0057] In Fig.is a two-stage isothermal dilatation measurement of a sample prepared according to steps ii. to iv. (cube 7 × 7 × 7 mm) 3 ) made of PLA perpendicular to the orientation direction (here Z-direction). The first isothermal stage is produced at a temperature between T G1 and 25 K below T KS1 , preferably at the temperature of the first heat treatment T W1 , (here 70 °C) and the second stage above T KS1 - 25 K preferably at the temperature of the first heat treatment T W2 The process is carried out at 80 °C. The first isothermal stage is maintained until maximum expansion is reached. Heating to the second isothermal stage then begins at a moderate rate (2 K / min). It is clearly evident that contraction occurs in the second isothermal stage (criterion ih).

[0058] Fig.The DSC measurement of a PLA sample after the first stage of the multi-stage isothermal dilation measurement is shown. The progress of the cold crystallization process is determined by comparing the cold crystallization enthalpy H. KS and enthalpy of fusion |H Schmelz | received and amounts to approximately 22% (criterion ih).

[0059] Second polymer: Acrylonitrile styrene acrylate (ASA) from Fillamentum Manufacturing Czech sro

[0060] In Fig. The DSC curve of ASA is shown. It is evident at the baseline that decomposition-free melting or plasticization of ASA is possible (criterion ia is fulfilled). The glass transition T G The center of the investigated ASA was found at 102 °C (criterion ib fulfilled). Neither a melting range nor cold crystallization could be detected (criterion im fulfilled).

[0061] The heat deflection temperature of ASA was taken from the manufacturer's data sheet. It is 96 °C and is therefore no more than 10 K lower than Tc. KS1 (Criterion II)

[0062] The manufacture of the assembly-free mechanisms according to the invention with a joint made of kinematic pairs is carried out as follows: The previously identified polymers, first polymer (PLA) and second polymer (ASA), are available as filaments for the additive manufacturing process.

[0063] The geometry for the assembly-free mechanisms with joints made of kinematic pairs was a rotary joint with undercut according to Fig. selected as well as a Watt mechanism according to Fig. consisting of several swivel joints.

[0064] All parts are printed on an Ultimaker S3 from Ultimaker BV without any enclosure. Both extruders are equipped with a standard AA-type nozzle with a 0.4 mm diameter. A standard glass build plate is used and coated with DIMAFIX from Dima3D before each print.

[0065] The print files were generated using CURA 4.8.0 from Ultimaker BV. The printing parameters are defined for each material and kept constant for all printed copies. An excerpt of the most important printing parameters can be found in Table 2 below. Table 2 Printing parameters: parameter PLA ASA layer thickness 60 µm 60 µm Track widths 350 µm 350 µm Number of outer contours 3 4 Infill density 100 % 100 % Infill pattern ± 45° ± 45° Extrusion temperature 200 °C 260 °C Temperature of the building plate 40 °C 40 °C Print speed 20 mm / s 20 mm / s Part fan speed 100 % 100 %

[0066] A Memmert GmbH & Co. KG UFE 400 universal oven is used for the heat treatment of the polymer molded parts. The polymer molded parts were placed in the oven at room temperature and then heated to the appropriate heat treatment temperature T. W1 or T W2heated. A heating rate of approximately 2 K / min is selected. The temperatures T W1 and T W2 were assessed according to the above-mentioned criteria on T W1 = 70 °C and T W2 The temperature is set to 80 °C. This temperature is then maintained for 4 hours. Afterwards, the samples are slowly cooled to room temperature. To ensure a constant cooling rate throughout the entire cooling cycle, a cooling rate of 0.2 K / min is selected.

[0067] After the polymer molding is manufactured, it exhibits a large degree of play between the kinematic pairs. This is due to the first stimulus (heat treatment) at T W1This is reduced to a usable bearing fit. After the first heat treatment, the polymer molded part is put into service. Wear occurs during use, leading to an increase in the bearing gap. At some point, the tolerated limit for this increase in the bearing gap is exceeded. In this condition, the polymer molded part is initially no longer usable. Now, the polymer molded part is heat-treated a second time (second external stimulus) at T W2 This results in a further reduction of the bearing gap, thus restoring the polymer molded part to a usable condition.

[0068] Fig. Figure 1 shows a schematic representation of the functional principle of the polymer molded part according to the invention when the invention is used as a kinematic pair in a multibody system. A renewed, deviating external stimulus (T) W2) another adjustment of the dimension is achieved to obtain the programmed form. List of illustrations: Fig. Schematic sketch of shearing during the additive manufacturing process Fig. Exemplary DSC curve of PLA Fig. Determination T KS -Values ​​based on the onset of an exemplary DSC curve Fig. Time dependence of isothermal dilation in an oriented sample Fig. Time dependence of isothermal dilation in an orientation-free sample cooled at XK / min Fig. Two-stage isothermal dilation measurement Fig. Relationship between temperature, relaxation and freezing of orientations in the first polymer Fig. Course of orientation relaxation and cold crystallization in the first polymer Fig.Assembly-free mechanism with a joint made of kinematic pairs Fig. Watt mechanism with four joints consisting of kinematic pairs Fig. DSC curves of the first polymer, in this case PLA, at different heating rates Fig. Isothermal dilation measurements of PLA Fig. DSC curve of PLA Fig. DSC curve from ASA Fig. Schematic representation of the use of the invention as a kinematic pair in a multibody system Fig. Sketch of the relevant temperatures

Claims

[1] Dually stimuli-responsive polymer molding comprising at least 2 different polymers, wherein the first polymer has an orientation of the polymeric chains in at least one orientation direction and a degree of crystallization of less than 10% of its maximum degree of crystallization and a glass transition temperature T G1 and wherein the first polymer can have a crystallization temperature depending on the cooling rate and wherein the crystallization does not occur at a cooling rate of > XK / min and wherein a cold crystallization of the first polymer at a cooling rate between 0 and XK / min from a starting temperature T KS1 takes place and the first polymer is above T G1 the orientation of the polymer chains is lost by relaxation and where T KS , at least 40 K greater than T G1and wherein in the first polymer the relaxation of the orientation is a faster process than the cold crystallization and wherein cold crystallization and relaxation of the orientation in the orientation direction in the first polymer are accompanied by a reduction in volume and wherein the heat distortion temperature T HDT2 of the second polymer a maximum of 10 K below the starting temperature of cold crystallization T KS , of the first polymer and wherein the second polymer either has no cold crystallization start temperature or has the cold crystallization start temperature T KS2 of the second polymer at least 20 K above T KS , and wherein the second polymer, upon prior cooling, does not undergo any reduction in volume during the subsequent heating and wherein X assumes values ​​between 500 and 4. [2] Dually stimuli-responsive polymer molding according to claim 1, characterized bythat the first polymer is polylactide (PLA) or compounds of this polymer and the second polymer is selected from the group acrylonitrile-styrene-acrylate (ASA), acrylonitrile-butadiene-styrene copolymer (ABS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), styrene-acrylonitrile copolymer (SAN), polystyrene (PS), high-density polyethylene (PE-HD), polypropylene (PP), polystyrene (PS), polyamides (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyoxymethylene (POM) and / or mixtures or compounds of these polymers. [3] Dually stimuli-responsive polymer molding according to claim 1, characterized bythat the first polymer is polyethylene terephthalate (PET) or a compound of this polymer and the second polymer is selected from the group polyamides (PA), polycarbonate (PC), polyethylene terephthalate (PBT), polyoxymethylene (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PESU) and / or mixtures or compounds of these polymers. [4] Dually stimuli-responsive polymer molding according to claim 1, characterized by that the first polymer is polycyclohexylenedimethylene terephthalate (PCT) and / or a copolyester and / or compounds of this polymer and the second polymer is selected from the group polyamides (PA), polyoxymethylene (POM), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), polyamideimide (PAI), polyethersulfone (PESU) and / or mixtures or compounds of these polymers. [5] Dually stimuli-responsive polymer molding according to claim 4, characterized bythat the first polymer is a copolyester of hexylenedimethylene terephthalate and hexylenedimethylene isophthalate (PCTA) having the following formula:and / or compounds of this polymer. [6] Dually stimuli-responsive polymer molding according to claim 1, characterized by that the first polymer is selected from the group of polyaryletherketones (PAEK), polyetherketone (PEK), polyetheretherketone (PEEK), poly(etherketoneketone) (PEKK), poly(etheretherketoneketone) (PEEKK), and / or poly(etherketone-etherketoneketone) (PEKEKK) as well as mixtures or compounds of these polymers and the second polymer is selected from the group of polysulfone (PSU), polyetherimide (PEI), polyethersulfone (PESU), polyamideimide (PAI) and / or mixtures or compounds of these polymers. [7] A method for producing a dual-stimulus-responsive polymer molding according to any one of the preceding claims, comprising the following steps: i. Selection of two polymers based on the presence of the following criteria: a. existence of a temperature range in which decomposition-free melting or plasticising of the first polymer and melting or plasticising of the second polymer is possible; b. Presence of a glass transition in the first polymer and in the second polymer with the glass transition temperatures T G1 and T G2 ; c. Partial crystallizability of the first polymer above T G1 ; d. Suppression of crystallization in the first polymer at a cooling rate of ≥ XK / min; e. Start of cold crystallization of the first polymer at a cold crystallization start temperature T KS1 ; f. Orientability of the polymer chains of the first polymer in at least one direction during additive manufacturing; g. Relaxation of the orientation in the orientation direction for the first polymer above TG1 ; h. Relaxation of the orientation in the direction of orientation is faster than crystallization in the first polymer; i. Relaxation of the orientation in the orientation direction of the first polymer is at least partially prevented by cooling at a cooling rate of ≥XK / min; j. Cold crystallization start temperature T KS , of the first polymer is at least 40 K higher than the glass transition temperature T G1 ; k. crystallization and relaxation of the orientation in the orientation direction of the first polymer are accompanied by contraction in at least one direction; I. Heat deflection temperature of the second polymer T HDT2 is a maximum of 10K below T KS1 ; m. For the second polymer, either no cold crystallization is possible or the starting temperature of the cold crystallization of the second polymer T KS2after prior cooling with a cooling rate of ≥XK / min is at least 20 K above T KS1 ; ii. conveying the polymers selected in step i. to a heated nozzle; iii. Passing through the nozzle at temperature T Ext plasticizing and orienting the polymers selected in step i. by the temperature T Ext and shear during production; iv. Layer-by-layer deposition and further orientation perpendicular to the direction of orientation of the polymers plasticized and oriented in step iii onto a substrate at a cooling rate XK / min where T Ext > T G for amorphous thermoplastic polymers and where T Ext > T Schmelz for semi-crystalline thermoplastic polymers and where the cooling rate XK / min is a cooling of T Ext1 on T G1 which is faster than the relaxation time of the orientation of the polymer 1 t Relax1and where X takes values ​​between 500 and 4. [8] Method according to claim 7, characterized by that the information on whether the criteria according to ia, b., c., d., e., i., j., m. are met is obtained by means of differential scanning calorimetry (DSC). [9] Method according to claim 7 or 8, characterized by that the information about whether the criteria if, g., h., k. are met is determined by means of isothermal dilation measurements. [10] Method according to claim 7, 8 or 9, characterized by that the information on whether the criterion i. I. is met is determined by heat deflection temperature measurements according to DIN EN ISO 75 at a sample stress of 0.45 MPa or according to ASTM D648 at a sample stress of 66 psi. [11] Use of a dual-stimuli-responsive polymer molded part according to one of claims 1 to 6 as a kinematic pair in a multi-body system. [12] Use according to claim 11, characterized by that the multibody system is an assembly-free mechanism.

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