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The search for alternatives to petroleum-based thermoplastic polyamide elastomers (TPAEs) has recently drawn great interest. In this study, a bio-massed TPAE, PA12,36, was synthesized using 1,12-dodecanediamine (DDA) and fatty dimer acid (FDA, PripolTM1009) precursors via catalyst and solvent-free melt polycondensation. The molecular structure and molecular weight of the PA12,36 were characterized by 1H NMR, FTIR, and GPC. PA12,36 displayed a low melting temperature of 85.8 °C, an initial degradation temperature of 425 °C, and a glass-transition temperature of 30.4 °C, whereas it sustained satisfactory tensile strength (10.0 MPa) and superior strain at break (1378%). Furthermore, PA12,36 was foamed by supercritical CO2, and the cell size, cell density, and porosity were determined. The entangled long-chained FDA component generated a physically crosslinked network, which promoted the melt viscosity of PA12,36 against elongations of foam cell growth and increased foamability significantly. As a result, uniform structured cellular foams with a cell diameter of 15–24 µm and high cell density (1011 cells/cm3–1012 cells/cm3) were successfully achieved. The foaming window was widened from 76 to 81 °C, and the expansion ratio was increased from 4.8 to 9.6. Additionally, PA12,36 foam with a physically crosslinked structure presented a better creep shape recovery percentage (92–97.9%) and sturdier dimensional stability. This bio-based PA12,36 foam is a promising candidate to replace petroleum-based thermoplastic elastomer foams for engineering applications, particularly shoe soles. [ABSTRACT FROM AUTHOR]

In this work, a novel crosslinked polyamide (cPA) system with hybrid polymer networks was developed. The hexamethylenediamine, acrylic acid (AA), and bis(6‐aminohexyl) dodecanediamide (BAHD) were utilized as the main building block in crosslinked polyamide (cPA) system by Michael addition reaction and polycondensation, wherein an amide diamine monomer, BAHD, was utilized as the building provider of hydrogen‐bonding networks. Simultaneously, the internal covalent bond networks were constructed by the Michael addition between AA and diamine, resulting in permanent covalent crosslinks. By adjusting the ratio of BAHD content, a series of copolyamides were successfully synthesized, and the thermal, mechanical, and viscoelastic behavior of cPAs were systematically discussed. Based on these results, the best mechanical properties in our cPAs were found in the composition of BH37, which exhibited microcrystalline behavior and outstanding tensile properties with melting temperature of 55°C, tensile strength above 45 MPa, and elongation at break above 1000%. It demonstrated that the adjusting of reversible hydrogen bonds and permanent covalent crosslinks in hybrid polymer networks could effectively endow the cPAs with excellent flexibility and strength. These studies provide useful information for designing novel cPA materials with controlled thermal and mechanical properties, which suggested the potential for use in advanced application fields. [ABSTRACT FROM AUTHOR]

Among the polyamide series polymer materials, PA612 has excellent mechanical properties and low moisture absorption characteristics. This work studied the effect of coupling agent addition on the crystallization behavior, adhesive wear, mechanical, thermal, and morphological attributes of glass fiber (GF) reinforced PA612 composites. Amino-silane was applied as a coupling agent to enhance the interfacial adhesion between glass fiber and the PA612 matrix. The loading level of the coupling agent was changed to 0.5, 1.0, and 2.0wt%, while the GF loading level in the composite material was 10, 15, 20, and 30wt%. The composite materials were analyzed via X-ray diffraction, tribological characterization, and adhesion wear test. The mechanical, rheological, and thermal properties were also investigated. In addition, scanning electron microscopy (SEM) analysis was used to study the analytical samples' wear and fracture surfaces. Test results unveiled that adding 1.0wt% amino-silane coupling agent upgraded the fiber-matrix adhesion, mechanical properties (tensile strength:136 MPa), and corresponding wear resistance of GF reinforced PA612-based composites. Furthermore, it is compatible with pure PA612 substrates and has similar processing rheological behavior. These results reveal that the compiled PA612 matrix is highly viable for tribological applications comprising automotive parts, bearings, and bearing materials for space applications. Graphical Abstract [ABSTRACT FROM AUTHOR]

Bis(6‐aminohexyl) terephthalamide/adipic acid (BAHT‐AA) was chosen to be used as a comonomer to develop a novel polyamide 6 (PA6) with the trace‐content aromatic structure. A series of polyamide 6 copolymers (coPA6) with trace BAHT‐AA loading were synthesized to yield the modified copolyamides with multiple interactions of hydrogen bonding and π‐π stacking on the PA6 backbone. It was proved that the thermal stability and mechanical properties of coPA6 were significantly enhanced because of the introduction of the trace BAHT‐AA segment. More importantly, adding a trace (1, 2, and 4 mole%) of BAHT‐AA could effectively increase the network structure and highly decrease the free volume fraction in the polymer system that is proved by the relaxation behavior and melt viscoelastic behavior. The results showed that the integrated performances of coPA6 were better than that of pure PA6, which was highly correlated with the aforementioned multiple interactions. For example, outstanding tensile strength (73.0 vs. 56.8 MPa), and modulus (1167 vs. 929 MPa), and so on. This work provided the traditional PA6 with the modification of outstanding mechanical and thermal performances, thus expanding its application for the plastics and textile industries. [ABSTRACT FROM AUTHOR]

A green approach for the synthesis of bio‐based polyamides (PAs) with a new macromolecular structure was developed. These bio‐based PAs were synthesized by solvent and catalyst‐free polycondensation combining fatty dimer acid Pripol™ 1009 with new difunctional aminoamides (DAAs). The later DAAs building blocks were synthesized by aminolysis of renewable dimethyl sebacate (DMS) and dimethyl adipate (DMA) with three different aliphatic diamines having diverse chain lengths, 2, 4, and 6 carbons. Bio‐based PAs showed Mw up to 30,581 g/mol, initial thermal degradation over 380°C, Tm from 168.3–202.4°C, Tg from 28.3–37.5°C, strain from 36.4 ± 4.0–313.5 ± 2.0%, and tensile strength up to 27.4 ± 0.1 MPa. Interestingly, all the PAs films had excellent optical transparency with cut‐off wavelengths of 276.0–283.0 nm, transmittance from 82.7%–90.7% at 600 nm. As a proof‐of‐concept of their usage, one of the PA was shown to be form microcellular foam by the green scCO2 method. The foams possessed uniform (cell size; 40 μm, foam density; 0.265 g/cm3, expansion rate; 7.2) and bimodal (cell size; 24/38 μm, foam density; 0.302 g/cm3, expansion rate; 6.5) cell textures depending on their foaming temperatures. This is the first report of bio‐based PA foams and transparent films manufacturing without toxic solvents. [ABSTRACT FROM AUTHOR]

The present paper describes the novel aliphatic polyamide 6 (PA6) copolyamides by the melt polymerization reaction of our newly synthesized aliphatic diamine monomer: N1,N6-Bis-(2-aminoethyl)adipamide (BAEA). The BAEA/CHDA (1,4-cyclohexanedicarboxylic acid) salt was prepared by pertinent long-chain polyamide with the cycloaliphatic ring and isolated as white solid, utterly characterized for the first time. The chemical structure of BAEA, BAEA/CHDA salt and copolyamides (PA6-BAEA/CHDA) was identified by 1H NMR and FT-IR spectroscopy. Depending on the chemical compositions, the viscosity and molecular weight of the copolyamides were in the range of 19,447–13,536 g mol−1 and 2.74–2.2 dL g−1. With increasing BAEA/CHDA salt molar ratio in the synthesized copolyamides, their melting temperatures (Tm) decreased from 212.7 to 170.4 °C, and the glass transition temperatures (Tg) increased from 60 to 89.4 °C. Besides, the as-synthesized all copolyamides possess nearly similar thermal stability (Td-50% = 439.59 − 443.38 °C) as neat PA6. Mechanical testing data revealed that with an increase in a proportion of BAEA/CHDA salt, Young's modulus of copolyamides is increased from 698.54 to 1093.89 MPa, while the tensile strength is increased by 8.1%. [ABSTRACT FROM AUTHOR]

Abstract Three novel aliphatic long-chain comonomer-containing PA6 copolyamides were prepared via melt polycondensation reaction of novel bio-based N1, N6-bis(4-aminobutyl) adipamide derived polyamide salt, and ε-caprolactam. The goal of this study was to investigate the synthesis and the resulting crystal morphology, thermal, rheological and mechanical properties of copolyamides as a function of their comonomer composition. The long-chain based polyamide salt disturb the crystallization of the final copolyamides and lower the onset of melting and glass transition temperatures, which is the result of less stable γ-phase crystalline structure formation. Intriguingly, the thermogravimetric analysis measurements prove that the thermal stability of copolyamides can satisfy the requirement of multiple-processing without decomposition. Most notable is the fact that the tensile testing results exhibit outstanding mechanical behavior, i.e. elongation at break and tensile strength. Graphical abstract Image 107835 Highlights • A series of PA6-BABA/AA copolyamides were successfully synthesized from CPL and novel bio-based linear monomer BABA/AA. • Thermal properties of PA6-BABA/AA dependent on composition. • Copolyamides with thermal stability until 350 °C. • The elongation at break of PA6-BABA/AA is higher than that native PA6. • The PA6-BABA/AA is a potential polymer for industrial scale applications. [ABSTRACT FROM AUTHOR]

Renewable polymers with self-healing ability, excellent elongation, hydrophobicity, and selective oil absorption attributes are of interest for an extensive range of applications, such as e-skin, soft robots, wearable devices, and cleaning up oil spills. Herein, two fully renewable eco-friendly polyamide (PA)-based self-healing elastomers (namely, PA36,IA, and PA36,36) were prepared by a facile and green one-pot melt polycondensation of itaconic acid (IA), PripolTM 1009, and PriamineTM 1075 monomers. The molecular structures of these PAs were analyzed by FITR, 1H NMR, and 13C NMR. The distinct structure of these PAs shows superior strain values (above 2300%) and high ambient temperature autonomous self-healing ability. Interestingly, the synthesized renewable PA36,36 showed zero water absorption values and hydrophobic properties with a contact angle of θ = 91° compared to the synthesized PA36,IA and other previously reported PAs. These excellent attributes are due to the low concentration of amide groups, the highly entangled main chains, the intermolecular diffusion, the manifold dangling chains, and the numerous reversible physical bonds within the renewable PAs. Furthermore, the hydrophobic properties may aid in the selective oil absorption of the PA36,36-based foam, for which PA36,36 foam is produced by the green supercritical carbon dioxide (scCO2) batch foaming process. The PA36,36 foam with a microporous cellular structure showed better absorption capacity and high stability in repeated use. Due to these advantages, these bio-based PAs have potential for the production of eco-friendly self-healing materials, superabsorbent foams, and other polymeric materials. [ABSTRACT FROM AUTHOR]

The crystallization behavior of novel polyamide 6 (PA6) copolyamides with different amounts of bis (2-aminoethyl) adipamide/adipic acid (BAEA/AA) segment was investigated. The wide-angle X-ray diffraction (WAXD) results showed that as the amount of BAEA/AA segment increased to 10 mole%, the crystalline forms of all PA6 copolyamide were transferred from the stable α-form to the unstable γ-form because of the complex polymer structure. According to studies of crystallization kinetics, the Avrami exponent (n) values for all copolyamide samples ranged from 1.43 to 3.67 under isothermal conditions, implying that the crystallization is involved in the two- to three-dimensional growth at a high temperature of isothermal condition. The copolyamides provided a slower crystallization rate and higher crystallization activation energy (ΔEa) than neat PA6. Polyamide containing 10 mole% of BEAE/AA content exhibited a unique crystallization behavior in the coexistence of the α and γ forms. These results deepen our understanding of the relationship between BAEA/AA content, crystal structure, and its crystallization behavior in low-melting PA6, and they make these types of copolyamides useful for their practical application. [ABSTRACT FROM AUTHOR]

N1, N6-bis (4-aminobutyl) adipamide (BABA) diamine and sebacic acid (SA), also called BABA/SA polyamide salt, were used in a typical melt polymerization processes of polyamide 6 (PA6) to form a series of PA6-BABA/SA copolyamides. The effects of BABA/SA on the isothermal crystallization kinetics of PA6-BABA/SA were studied for the first time. An isothermal crystallization analysis demonstrates that the PA6-BABA/SA matrix provided a higher crystallization rate and shorter half-crystallization time than virgin PA6 did. The degree of crystallization of the PA6-BABA/SA30 matrix was also the lowest among all of the samples considered herein. This result is attributed to the high nucleation efficacy of a small amount of BABA/SA in the crystallization of PA6. Values of the Avrami exponent (n) from 1.84 to 3.91 were observed for all of the polyamide samples, suggesting that the crystallization was involved via a two- to three-dimensional growth mechanism. These findings deepen our understanding of the structure–property relationship of PA6-BABA/SA copolyamides, favoring their practical application. [ABSTRACT FROM AUTHOR]

This work investigated the synthesis of a novel low melting temperature polyamide 6 (PA6) copolyamide (PA6-BABT/SA) with different aliphatic/aromatic units weight content using a melt poly-condensation process. The bio-based aromatic N1,N4-bis(4-aminobutyl) terephthalamide diamine (BABT) and long-chain aromatic polyamide salt (BABT/SA, salt of BABT, and sebacic acid), components used for the synthesis of copolyamides, were obtained from bio-based monomers. For the first time, the pertinent BABT/SA aromatic polyamide salt was isolated as a white solid and completely characterized. By varying the weight ratio of BABT/SA salt, a series of copolyamides with different molecular weights and physical properties were prepared. The aromatic BABT/SA salt disrupted crystallization of the final copolyamides and lowered the onset of melting. The Fourier transform infrared spectroscopy and X-ray diffraction results indicated a steady decrease in the degrees of crystallinity with increasing BABT/SA salt segment ratio. Furthermore, compared to neat PA6, the obtained PA6-BABT/SA copolymers possessed a similar thermal stability and high transparency, but lower glass transition temperature around human body temperature. The PA6-BABT/SA copolymers with number-average molecular weight ≥30,000 Da presented good mechanical properties, specifically showing excellent tensile strength and elongation at break up to 105.2 MPa and 218.3%, respectively. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) is a semicrystalline polymer with excellent wide application for filament and packing materials. However, the use in filament and packing materials of PA6 with high crystallinity and rich hydrogen bonds is limited because of its low optical properties and poor anti-water absorption. In this work, a series of partially sustainable PA6 copolymers with high value were synthesized by melt polycondensation from fatty dimer acid (FDA) and upcycled chemical bis(6-aminohexyl) terephthalamide (BAHT). The chemical structure of partially sustainable PA6 copolymers was characterized by 1H NMR, FT IR, relative viscosity, and amine value. The mechanical properties, optical properties, and anti-water absorption of high-value PA6 copolymers depended on the BAHT salt loading and the chain length of aliphatic dicarboxylic acids. The tensile strength of PA6 copolymers was decreased, but the tensile toughness, optical transmittance, and anti-water absorption of that were significantly improved. Overall, this easy method opens up new avenues for devising excellent optical transmittance and low water absorption of polyamide materials, whereas providing the new strategy for carbon-neutral through rPET upcycling and biomass use, and these PA6 copolymers have the potential and economy to be widely applied. [Display omitted] • Combining both upcycling and biomass segments in polycaprolactam copolymers (CoPAs). • Bis(6-aminohexyl) terephthalamide (BAHT) upcycled from rPET bottle to promote spherulite shrinkage of CoPAs. • Fatty dimer acid influenced the optical behavior of the polyamide (transparency level > 80% and haze level < 10%). • Fatty dimer acid increased the anti-water absorption of CoPAs. • CoPAs prepared transparent monofilaments and films by twin-screw extrusion and hot-pressing. [ABSTRACT FROM AUTHOR]

• We are critically reviewed the synthesis and characterization of biodegradable PEAs. • Various synthesis methods used to prepare PEAs have been covered. • The applications of biodegradable PEAs are intensively studied. • Specifics studies on biomedical applications of α-amino acids based PEAs are described. Poly(ester amide)s (PEAs) have developed in current years as a vital class of synthetic biodegradable materials with specialty applications in various fields. These PEAs provide both amide and ester groups in their chemical structure, and they combine the finest mechanical and thermal properties of polyamides with the most fabulous biodegradable properties of polyesters. PEAs can be manufactured via various monomers and adopting different synthesis procedures, leading to PEAs with ordered, blocky, and random structures. Mainly, PEAs comprising α-amino acids (α-AAs) have grown as essential biomaterials in the biomedical fields (e.g., drug delivery, tissue engineering, hydrogels, and smart materials). The existence of α -AAs offers to more reliable cell-polymer interactions, permits the establishment of carboxyl, hydroxyl, and amine pendant reaction groups, and improves the overall PEAs biodegradability. In this paper, a comprehensive review is bestowed on the current progress in the growth of α-AAs based PEAs and functionalized PEAs, the major polymerized routes utilized in their production along with their vital biomedical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new series of sustainable polyamide elastomers was synthesized using a bio-based dimer diamine monomer. • The branched-structured dimer diamine efficiently suppressed the crystallinity of the polyamide elastomer system and induced chain entanglement networks for enhancing melt strength. • The new system was successfully applied to the fabrication of microcellular foams with a high expansion ratio and robust dimensional stability, effectively overcoming the foaming difficulties of high crystallinity and insufficient melt strength in traditional polyamide 6. • The foamed products could be facilely recycled and reprocessed due to the advantages of non-crosslinking and additive-free. In this study, we developed a sustainable polyamide foam system. A new series of polyamide elastomers was synthesized using a bio-based dimer diamine monomer as a building block to copolymerize with aminocaproic acid and adipic acid through step-growth polymerization, followed by supercritical CO 2 foaming for the fabrication of microcellular foams. The introduction of the branched-structured dimer diamine monomer effectively restricted the molecular packing and hydrogen bonding density of the polyamide system, leading to numerous small crystals acting as nucleation sites for heterogeneous cell nucleation. Simultaneously, the branched long chains of the dimer diamine formed chain entanglement networks, which increased the material melt strength against the elongational stresses of cell growth. The synergistic effect provided by dimer diamine led to the successful manufacture of foamed samples with a high expansion ratio and robust dimensional stability, effectively overcoming the foaming difficulties of high crystallinity and insufficient melt strength in traditional polyamide 6 (PA6). In addition, this polyamide elastomer foam system could be recycled and reprocessed due to the advantages of non-crosslinking and additive-free. Therefore, the study's findings constitute a promising direction for the usage of renewable sources in the development of foamable polyamide materials for sustainable applications in the plastics industry. [ABSTRACT FROM AUTHOR]

A novel aliphatic PA6 copolyamide (PA6(BAEA/AA))-based hot melt adhesive was synthesized from ε-caprolactam with the organic salt of bis(2-aminoethyl) adipamide (BAEA) and adipic acid (AA), with BAEA/AA content ranges from 5 to 15 mol%. The chemical structures of BAEA diamine, BAEA/AA organic salt, PA6(BAEA/AA) copolyamides, and neat PA6 were obtained using FT-IR and 1H NMR. Determined by the comonomer compositions, the relative viscosity (η r) and molecular weight (M w) of the PA6(BAEA/AA) were from 2.29 to 2.74 and from 14,530 to 19,500 g mol−1, respectively. Adding the BAEA/AA structure strongly affected the crystallization behavior and thermal properties of the copolyamides. DSC results revealed that the melting temperature (T m) of the copolyamides declined as the mole% of BAEA/AA increased in the range 5–15 mol%, and a TGA test revealed that the thermal decomposition of the copolyamides was similar to that of neat PA6. The T m , glass transition temperature (T g), and thermal stability (T d5%) with a BAEA/AA salt content of 10 mol% had the lowest values of 162.2, 40.3, 354.6 °C, respectively, while the fusion enthalpy (ΔH m) was lowest at 15 mol% (21.2 J g−1). Most remarkably, PA6(BAEA/AA) exhibits much better mechanical properties such as tensile strength (33.6–52.6 MPa) and elongation at breakage (114.7–584.5%), than the PA6 homopolymer. The peel strength of PA6 reached a maximum value of 53.4 N cm−1 at 10 mol% of BAEA/AA salt, and this value is better than those of commercial hot melt adhesives. [ABSTRACT FROM AUTHOR]