Polyamide Elastomer Research Articles

Preparation and properties of polyamide elastomers by a new synthesis route of Michael addition reaction

At present, the mainstream industrial synthesis method of polyamide is still bulk fusion polymerization, which is not in line with the concept of green synthesis because of the high threshold of reaction conditions and large energy consumption. Based on this, a new synthesis route of polyamide elastomer was studied in this paper. By synthesizing the end-functionalized long carbon chain diacrylamide (DDA) containing amide bonds, the synthesis mechanism was made by the thiol double bond Michael addition reaction. A series of polyamide elastomers with different ratios of hard and soft segments were synthesized by using dimercaptan chain extenders with different molecular weights. The results showed that the new synthesis route successfully prepared DDA and polyamide elastomers. The mechanical properties of the products were excellent, and the strain rate could reach 383 %. Tensile strength up to 23.08 MPa. The synthesis route has the characteristics of simple reaction process, mild reaction conditions and high reaction conversion rate. It provides theoretical guidance for the new synthesis route of polyamide elastomer.

Effect of calcium silicate on foaming and anti‐shrinkage behavior of thermoplastic polyamide elastomers: Revelation of the open‐cell mechanism

AbstractThermoplastic polyamide elastomer (TPAE)/calcium silicate (CaSiO3) open‐cell foam with low shrinkage and high expansion ratio was prepared by using supercritical CO2 as a blowing agent. Adding CaSiO3 led to increased melt viscoelasticity and reduced crystallinity of TPAE. The primary mechanism of CaSiO3 promoting TPAE foam to form the open‐cell structure was discussed. The interaction between CaSiO3 and TPAE is fragile, making CaSiO3 easy to fall off the cell wall and form the open‐cell structure during foaming process. The increasing CaSiO3 content leads to increased cell density and thinned cell walls, thus increasing the tensile stress on cell wall. On the other hand, the agglomeration of CaSiO3 increases particle size, making it easier to fall off from the adhesion of TPAE matrix. The two aspects work together to improve the open‐cell content of TPAE foam up to 93.28%. The open‐cell structure is conducive to increasing the gas exchange rate and significantly decreasing foam shrinkage ratio. Finally, TPAE foam with a shrinkage ratio of only 2.68% and an expansion ratio of 18.77 times was obtained. In addition, open‐cell structure improves the adsorption performance of TPAE/CaSiO3 foam by 500%.

An atom economy polyamide elastomer derived from polyether amine‐based bis‐acrylamide and dithiol monomer and synthesized by thiol‐Michael addition click reaction

AbstractTraditional polyamide elastomer synthesis via polycondensation of diamines and dicarboxylic acids involves high energy use and by‐product mass loss. Here, we present a novel method using thiol‐Michael addition click chemistry to produce these elastomers under mild conditions, marking the first use of this strategy. The polymerization involves coupling bis‐acrylamide (BAA) with 3,6‐dioxa‐1,8‐octanedithiol (DODT), catalyzed by 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN). BAA is synthesized from polyetheramine and acryloyl chloride, creating a compound with amide groups and carbon double bonds at chain ends. These double bonds' electron‐withdrawing effect facilitates the click reaction efficiently, avoiding high energy and mass loss. The resulting polymers have a molecular weight of approximately 10,000 g/mol, verified by 1H NMR and FTIR spectroscopy, which show amide group presence. SAXS and AFM confirm nanophase separation of these groups. Tensile strength ranges from 0.235 to 0.542 MPa, decreasing with lower polyetheramine content but still showing notable elasticity. This method's low energy use, no mass loss, and good mechanical properties make it promising for developing high‐performance polyamide plastics and elastomers, appealing to researchers in both academia and industry.Highlights High elasticity, softness, and high tensile polyamide elastomer. Thiol‐Michael addition click reaction conforms to atomic economy. Long molecular chain contains extraordinary evolution of hydrogen bonding.

Effect of nucleating agent incorporation on the crystallization and mechanical properties of polylactide/polyamide elastomer blends

ABSTRACT The widespread application of polylactide (PLA) has been limited by its slow crystallization rate and poor toughness. In the present work, a low molecular weight nucleator, TMC 301, and polyamide elastomer (PAE) were incorporated into PLA through melt blending to mediate both the crystallization capability and impact toughness. It was found that the introduction of TMC 301 decreased the crystallization temperature of PLA during the cooling process, while enhancing its cold crystallization capacity of PLA in the heating scan. Accordingly, the presence of TMC 301 shortened the half-crystallization time of PLA at 95°C in the ternary blends with minimal influence on the Avrami index. Moreover, the dispersion size of PAE decreased when the concentration of TMC 301 increased to 0.3 wt%, leading to a substantial increase in the tensile toughness and the impact strength of the PLA/PAE/TMC 301 blend. It is suggested that the size of the elastomer particles is a critical factor influencing the toughening efficiency of TMC301 in PLA/PAE blends.

One-step facile pathway synthesis of PAPXD/1214-PEA thermoplastic elastomer: Structure and properties

In this study, a novel and facile one-step synthesis route was conducted to prepare semi-aromatic polyamide elastomer (PAPXD/1214-PEA) with p-phenylenediamine, dodecane diamine, dodecanedioic acid and polyether amine (PEA) as monomers. A systematic investigation has been conducted into the effect of hard segment content on the thermal, mechanical and solvent resistance of polymers when semi-aromatic polyamides are used as hard segments. It was found that the melting point of the copolymers gradually increased from 191.2 °C to 231.5 °C with the hard segment content increased from 39 % to 76 %, while the Vicat softening temperature (VST) enhanced from 103.2 °C to 192.2 °C. Compared with the commercial polyamide elastomer Pebax@ (produced by Arkema Inc) with similar hard segment contents, the VST of PAPXD14/1214-PEA were 17.4–66.2 °C higher. The mechanical performance of these elastomers was also largely improved with tensile strength increasing from 15.1 to 40.6 MPa, Young's modulus from 28.2 to 168.7 MPa, toughness from 91.1 to 170.7 MJ/m3. In addition, the solvent resistance properties of PAPXD14/1214-PEA was compared with the commercial polyamide elastomer Pebax@. After soaking in hydrochloric acid for 24 h, the tensile strength of PAPXD/1214-PEA with the hard segment content increased from 50 % to 63 % decreased down to 9.4 and 14.4 MPa, respectively. While the commercial polyamide elastomer Pebax@ (with similar hard segment content) decreased down to 1.5 and 4.3 MPa, indicating the commercial polyamide elastomer products were deteriorated. This suggests the corrosion resistance of the synthesized PAPXD/1214-PEA is much better than that of commercial product, and these semi-aromatic polyamide elastomers can be potentially applied in some harsh service environment especially for high temperature and corrosion sealing.

Enhancing mechanical and shape memory properties of polylactide/polyamide elastomer blends via reactive blending with a chain extender

AbstractThe structure and properties of incompatible polylactide (PLA)/polyamide elastomer (PAE) blends were tailored by a chain extender specifically the styrene–glycidyl acrylate copolymer Joncryl ADR4368 (ADR). Various PLA/PAE/ADR blends with different compositions were prepared by melt blending, and their morphology, crystallization behavior, and mechanical and the shape memory properties were systematically investigated. The results showed a uniform dispersion of PAE particles in the PLA matrix for the PLA blends with a reduction in particle size upon the addition of ADR. The crystallization of PLA was retarded, which was confirmed by a decrease in the melt crystallization temperature and an increase in cold crystallization temperature in the PLA/PAE/ADR blends. Rheological analysis showed an improvement in the melt elasticity of the PLA/PAE binary blend due to the presence of ADR, possibly attributed to the formation of long‐chain‐branched copolymers at the interface. Notably, the PLA/PAE/ADR blend exhibited superior toughness, featuring an elongation at break of 288% and a notched impact strength of 37 kJ·m−2, along with a high shape memory fixation rate and recovery rate when the ADR content was 1 wt%. Furthermore, the underlying toughening mechanism was elucidated. This work may offer an industrially scalable relevant model to fabricate high‐performance PLA materials.

Green preparation of lightweight and elastic thermoplastic polyamide/polyester elastomer composite foams using supercritical CO2

Green preparation of highly elastic foam is an effective strategy to reduce the cost of elastomers and broaden their application areas. In this work, thermoplastic polyamide elastomer (TPAE) was blended with thermoplastic polyester elastomer (TPEE) and chain extender ADR to improve the elasticity and overcome the weakness of easy tearing of TPAE foams. The results indicate that the melt strength of the blend was significantly improved with the use of chain extension. The foaming expansion ratio of the mixtures increased by 25 %, and the foaming recovery ratio reached 92 %. Mechanical properties showed that the maximum compressive stress of TPAE/TPEE foams was twice as high as that of TPAE, while the energy loss coefficient (11.38 %) was lower than that of TPAE at a high expansion ratio of 10. In addition, the resilience of TPAE/TPEE foams reached 73 % at an expansion ratio of 12.

A new method for studying the wear properties of novel wear‐resistant ethylene propylene diene monomers/polyamide elastomer material from the perspective of cross‐linked network structure

AbstractThe cross‐linked network and dynamic viscoelastic properties of ethylene propylene diene monomers (EPDMs)/polyamide elastomer (PAE) were systematically investigated by using equilibrium swelling test and rheological experiment. The filler network formed by single‐walled carbon nanotubes (SWCNTs) in the matrix of EPDM/PAE was studied and discussed in detail by virtue of scanning electron microscopy (SEM). The DIN abrasion test was conducted to derive the cross‐linked network dependence of the frictional wear performance of EPDM. The results indicated that the chemical cross‐linked network was contributed by EPDM and EPDM‐PAE macromolecular chains. In addition, the physical cross‐linked network consisted of the macromolecular entanglement of EPDM‐PAE and the interactions between EPDM/PAE and SWCNTs. Introducing PAE into EPDM matrix resulted in the change of the cross‐linked network, which was considered as the key factor to improve the abrasion resistance of EPDM. Furthermore, the physical cross‐linked network generated by PAE improved the strength of the EPDM matrix prominently. It is an innovative work in exploring the effect of microscopic structure on the macroscopic wear performance of EPDM vulcanizates.Highlights Preparation of EPDM/PAE elastomer using new wear‐resistant material. Analysis on the effect of solubility parameters using Hansen solubility parameter (HSP). Flory–Huggins interaction parameter on three‐dimensional crosslink networks. Microscopic discussion on crosslink‐filling network structure. A new perspective on the discussion of wear resistance mechanism.

Thermoplastic polyamide elastomer based flexible humidity sensor for breath monitoring

Nowadays, there are many researches on flexible humidity sensors based on different composites, such as polymer with graphene oxide, carbon nanotubes as conductive fillers. Herein, a flexible wearable device used for humidity detection and breath monitoring was fabricated based on the molecular designable thermoplastic polyamide elastomer (TPAE). TPAE is block copolymers consisting of the polyamide hard segments and the polyether soft segments. Among them, the hard segments (PA1212 or PA6) form the crosslinking network providing resilience, and the soft segments composed of PPO and PEO endow TPAE with flexibility and solvent-responsiveness. The resistance of TPAE-based humidity sensor decreases with the increase of relative humidity (RH), exhibiting negative humidity sensitivity. Besides, it has a wide humidity monitoring range (11 %RH ∼ 91 %RH) and good fitting degree of R2 > 0.99 which is hardly influenced by bending deformation. When the humidity sensor was exposed to organic vapor (e.g. ethanol), it exhibited a faster response of astonishing 4 s. This novel block copolymer not only shows good humidity sensing performance in many aspects, but also provides a novel strategy and approach for the preparation of the humidity sensing materials afterwards.

Organic vapor sensing behaviors of 4D printed thermoplastic polyamide elastomer by selective laser sintering

Thermoplastic polyamide elastomer (TPAE) films were prepared by selective laser sintering technology and their organic vapor sensing behaviors were investigated. The stable responsive electrical signal was attributed to the conductive pathways evolution formed by polyetheramine soft segments. And the response behaviors of the TPAE films were evaluated using organic vapors of different polarities. Unlike conventional materials that only respond to some specific organic vapors, TPAE showed a high negative vapor coefficient (NVC) effect for all tested vapors. Rapid response, high responsivity and good repeatability were observed in continuous immersion drying run (IDR) experiments at 20 °C. The sensing behaviors during the breathing tests showed a good discrimination for different ethanol vapor concentrations. This study not only provides a guidance for the preparation of organic vapor sensors with fast response, high responsivity and stable repeatability, but also provides a strategy to broaden the application of TPAE into 4D printing field.

4D printing light-driven actuator with lignin photothermal conversion module

Light-responsive shape memory polymers are attractive as they can be activated through remote and spatially-controlled light. In this work, 4D printing of poly(lactic acid) (PLA) composites with a near-infrared light-responsive was achieved by using the simple melt blending method and adding 3 wt% of lignin. Lignin with a conjugated structure was used as the photothermal conversion module. The composites exhibited significant photothermal effects under near-infrared (808 nm) laser irradiation, and the laser irradiation was also effective in initiating and controlling the shape memory. The structure of lignin can be improved by the action of dicumyl peroxide (DCP) to enhance the interfacial adhesion between polyamide elastomer (PAE) and polylactic acid (PLA), reduce the size of dispersed phases, and serve as an effective rheological modifier to exhibit the ideal melt viscosity required for 3D printing of composites. The good mechanical, thermal stability, and rheological properties provide assurance for the 4D printing of composites. This research provides an environmentally friendly and practical method for creating composites that have the potential to serve as ideal actuator components in a range of applications.

Dynamic sustainable polyamide elastomer toward ultratough and fully recyclable self-healing ionic conductors

The development of flexible ionic conductors with extreme elasticity, high ionic conductivity, desirable self-healing capacity and recyclability is a pressing need while challenging because the regulating of these performances is generally mutually exclusive. Herein, we report a dynamic double-crosslinking bio-based ionic conductive elastomer (DBICE), designed via the introduction of reversible covalent Diels-Alder motifs into a furan-functionalized biobased polyamide matrix, which realizes an ultratough, outstanding mechanical versatility (170.1 MJ m−3 toughness and 1342% elongation), unique self-healability (∼100% within 6 h), and capability to completely recycle and facilely reprocess. The specifically tailored ether-rich segments in the polyamide backbones with long-range ordering and selectively entrapped lithium-ion (Li+) provided high-efficient ion transport pathways, gaining remarkable room-temperature ionic conductivity of 1.66 × 10–3 S m−1. The resultant DBICE is assembled into a proof-of-concept flexible ionotronic sensor, exhibiting reliable resistivity sensing quality with high sensitivity and robust mechanosensation capability, and excellent recovery for the polymeric matrices and electronic components. This work provides a new molecular design principle for the sustainable development of advanced ionic conductors holding a great promise in wearable electronics or all-solid-state batteries.

Lightweight Antistatic Thermoplastic Elastomer Blend Foam: The Foaming Behavior and Mechanical Properties

A thermoplastic polyester elastomer (TPEE) has been widely used because of its excellent impact resistance and resilience, but its melt viscosity is too low to be used in the supercritical foaming. In addition, TPEE easily generates static electricity accumulation during processing, which has a risk of fire. Herein, a thermoplastic polyamide elastomer (PEBAX) with permanent antistatic properties was blended with TPEE, and triglycidyl isocyanurate (TGIC) was used as a chain extender to improve the compatibility and melt strength of the blends. Then, the TPEE/PEBAX blends were foamed by supercritical N2, and the cell structure and mechanical and antistatic properties of the blend foam were analyzed at a density of 0.1 ± 0.001 g/cm3. The results showed that when the blending ratio of TPEE/PEBAX was 70/30, the blend foam with a uniform cell structure had the most excellent mechanical properties. The resilience and elongation at break reached 83 and 850.3%, respectively. In addition, the surface resistivity and volume resistivity were 3.21 × 109 Ω and 7.35 × 109 Ω·cm, respectively, which were significantly lower than those of the IEC 61340 standard.

Developing sustainable and recyclable high-efficiency electromagnetic interference shielding nanocomposite foams from the upcycling of recycled poly(ethylene terephthalate)

The demand for high-performance electromagnetic interference (EMI) shielding composite foams with satisfactory environmental friendliness and high sustainability has increased considerably. However, considerable obstacles are frequently encountered in the practical development of incorporating upcycling of plastic wastes and environmentally friendly foaming technologies into the manufacture of such EMI shielding systems. In this research, we developed a lightweight sustainable nanocomposite foam system with outstanding EMI shielding performance from the integration of chemical upcycling of recycled poly(ethylene terephthalate) (PET) and supercritical carbon dioxide (sc-CO2) microcellular foaming. First, a green thermoplastic polyamide elastomer (TPAE) system was synthesized using a renewable bis(6-aminohexyl)terephthalamide (BAHT) monomer derived through the aminolysis of recycled PET, followed by adding single-walled carbon nanotubes (SWCNTs) into the TPAE system for the manufacture of TPAE/SWCNT nanocomposites. The π–π stacking of BAHT efficiently enhanced the melt strength of the material system, which was conducive for microcellular foaming process. After sc-CO2 foaming, a series of highly expanded nanocomposite foams with uniform microporous structure that could enable multiple reflections of electromagnetic waves were fabricated. Upon adding only 2 wt% SWCNTs, the foam system achieved a favorable conductivity of 0.15 S/cm and an extremely high specific shielding effectiveness (SSE) of 213.26 (dB cm3/g). Furthermore, the green nanocomposite foam possessed excellent durability. After being bent or twisted 1000 times, the foam maintained EMI shielding effectiveness of > 90% of the original value. Moreover, the foam could be easily recycled, reprocessed, and refoamed. For developing sustainable EMI shielding products, we believe that this study provides a promising direction with benefits of alleviating waste accumulation and reducing the use of virgin plastics in manufacture of foams, showing potential for advanced sustainable electronic applications.

Modification on crystallization behavior and mechanical properties of polylactide by the addition of polyamide elastomer

Modification on crystallization behavior and mechanical properties of polylactide by the addition of polyamide elastomer

Biobased Polyamide 4,36 Thermoplastic Elastomer and its Cellulose Nanocomposites

AbstractThe search for fossil fuel‐based polymer alternatives has attracted significant attention over the past few decades. A biobased polyamide elastomer, namely PA4,36, is synthesized through a facile polycondensation of fatty acid‐based monomer and 1,4‐butanediamine. The chemical structure and molecular weight distribution of the polymer are characterized by Fourier infrared spectroscopy and gel permeation chromatography. PA4,36 displays a medium hardness (Shore A/Shore D = 97/50), a high stretchability (1116%), ease of melt processing, and hydrophobicity. The introduction of cellulose nanocrystals (CNCs) to the elastomer reduces the melting temperature and crystallization temperature due to the disturbance of CNCs on polymer crystallization, and influences its thermal degradation. It improves the glass transition temperature by up to 5.1 °C because of the restriction of the molecular mobility of the polymer by CNCs. It increases the storage modulus significantly from 1.5 GPa at 25 °C for neat PA4,36, to up to 10.8 GPa for the nanocomposite with 10 wt.% CNCs. The biobased elastomer and its CNC nanocomposites can be promising alternatives to some fossil fuel‐based elastomers with medium hardness.

Effects of polyamide elastomer on the morphology, crosslink density, mechanical, and oil‐resistant properties of acrylonitrile‐butadiene rubber/polyamide elastomer vulcanizates

AbstractPolyamide elastomer (PAE) is a novel material which may improve the performances of acrylonitrile‐butadiene rubber (NBR). This work uses equilibrium swelling and rheological apparatus to study the effects of the PAE content on the overall crosslink densities of NBR/PAE vulcanizate. The presence of PAE significantly increased the overall crosslink density. During the aging stage, the overall crosslink density first increased and then decreased with increasing aging temperature from 25 to 150°C. There was a linear relationship between the tensile strength with the overall crosslink density of the NBR/PAE vulcanizate. Oil resistance of the NBR/PAE vulcanizate was improved with increasing PAE content.

4D printing of polyamide 1212 based shape memory thermoplastic polyamide elastomers by selective laser sintering

4D printing technology, also known as additive manufacturing technology for smart devices, offers a wide range of promising applications in aerospace, automobile, biomedical and soft robotics. However, there are only a limited number of commercialized elastomer materials for 3D printing which needs further development, especially smart elastomers. In this work, polyamide 1212 (PA1212) based thermoplastic polyamide elastomer (TPAE) was synthesized by one-pot melt polycondensation of 1,12-dodecanedioic acid (DA), 1,12-dodecanedioic amine (DN) and polyetheramine in a stainless steel reactor and then the TPAE powder for selective laser sintering (SLS) was obtained after freeze-crushing and sieving. Subsequently, the effects of sintering temperature, laser power, layer thickness, and scan spacing during SLS processing on the properties of the sintered parts were fully investigated. The tensile strength, elastic modulus and elongation at break of the sintered parts could reach 13.7 MPa, 124 MPa and 200 %, respectively, when the sintering temperature, laser power, layer thickness and scan spacing were set as 156 °C, 21 W, 0.10 mm and 0.10 mm, respectively. Moreover, PA1212-based TPAEs fabricated by SLS showed excellent and stable shape memory behavior. This work not only provides a designing strategy of 4D printable materials and referential SLS-processing parameters, but also broadens the application of polyamide-based elastomer materials into 4D printing fields.

Study on Chain Extension Blending Modification and Foaming Behavior of Thermoplastic Polyamide Elastomer.

In order to improve the melt foaming properties of thermoplastic polyamide elastomers and reduce the shrinkage rate of foamed materials, acid anhydride chain extenders SMA (styrene maleic anhydride copolymer) are used in this paper to in situ reactive blending thermoplastic polyamide elastomers (TPAE) and polyamide 6 (PA6). The rheological and crystalline properties of the modified samples were characterized by a rotational rheometer and differential scanning calorimeter, and the melt batch foaming experiment with CO2 as the foaming agent was carried out. The results showed that the melting enthalpy of modified TPAE reduced with the addition of content of PA6, which implied that the crystallinity of the hard phase of the system was depressed. Nevertheless, the reduction of crystallinity was beneficial to improve the penetration of gas and reduce the effect of the pressure difference inside and outside the cell on foam shrinkage. Additionally, the microcross-linked structure formed with the increase of PA6 content enhanced the storage modulus of modified TPAE, which could accelerate recovery of strain. The foaming temperature zone and recovery performance of all modified TPAE samples were significantly improved. The overall shrinkage rate was reduced to less than 10%, the maximum expansion ratio could reach 11-13 times with a more complete and uniform cell structure, and the resilience was improved by about 12%.

The novelty role of polyamide elastomer in the determination of crosslink density and the formation of crosslink network of EPDM vulcanizates

AbstractThe effect of polyamide elastomer (PAE) on the crosslink network of ethylene propylene diene monomer (EPDM) was systematically investigated by using equilibrium swelling method and rheological experiment. The swelling systems of the EPDM‐PAE vulcanizates were discussed by classification way. The results showed that PAE was involved in the construction of the crosslink network and decreases the chemical crosslink density and the total crosslink degree of EPDM vulcanizate. By linearly fitting the relationship between chemical crosslink density and total crosslink degree, the physical crosslink degrees of EPDM, EPDM‐PAE and PAE were estimated as 9.135, 2.934, and 0.820 dNm, respectively. The physical crosslink degree of EPDM vulcanizates was mainly contributed by the entanglement of rubber macromolecular chains. By contrast, the interaction of the inter‐macromolecular chains of EPDM‐PAE and the physical crosslink of PAE itself contributed less to the physical crosslink degree of EPDM vulcanizates. With the increase of aging time under 150°C, the roles of PAE in continuously promoting the crosslink reaction and leading to the degradation of crosslink network resulted in various changes in crosslink density and mechanical properties. It could be expected from this study that the construction of the crosslink network of EPDM‐PAE composite was unique, which provided a novel perspective on the microscopic crosslink structures and macroscopic properties of EPDM‐PAE based products.