Preparation and characterization of thermoplastic polyurethane elastomer and polyamide 6 blends by in situ anionic ring‐opening polymerization of ϵ‐caprolactam

Abstract

The blends of thermoplastic polyether-based urethane elastomer (TPEU) and monomer casting polyamide 6 (MCPA6) were prepared using -caprolactam (CL) as a reactive solvent, and CL sodium as a catalyst at various TPEU contents (2.5-15 phr by weight). In situ anionic ring-opening polymerization and in situ compatibilization of TPEU/MCPA6 blends were realized in one step. The dissociated TPEU chains acted as macroactivator to initiate MCPA6 chain growth from the TPEU chains. The formed block copolymers (TPEU-co-MCPA6), which have been confirmed by Fourier transform infrared spectroscopy and 1 H-NMR analysis, improved the compatibility between TPEU and MCPA6. In addition, both differential scanning calorimetry and dynamic mechanical analysis studies revealed that the crystallinity temperature, melting temperature, the degree of crystallization, and the glass-transition temperature of MCPA6 component remarkably shifted to a low temperature with increasing TPEU content. Mechanical properties demonstrated that the impact strength and the elongation-atbreak of the blends significantly increased with the content of TPEU, whereas a progressive decrease occurred in tensile strength, flexural strength, and flexural modulus. WAXD spectra showed that only ␣-form crystal of PA6 component existed in the TPEU/MCPA6 blends. Furthermore, scanning electron microscopes (SEM) of the cryo-fractured surfaces confirmed a substantially improved compatibility, and reflected a seemly single-phase morphology. POLYM. ENG. SCI., 46: 1196 -1203, 2006.

Synthesis and characteristics of thermoplastic elastomer based on polyamide‐6

“…The results that we obtained for the effects of reaction time, reaction pressure and catalyst on the properties of copolymer prepared via esterification were consistent with previously reported results 23–25, 28, 29. The only exception is that the effect of variation of the reaction temperature has not been reported previously.…”

“…Segmented TPUEs are well known as a class of high performance materials with very good elasticity and poor thermal stability. Some studies have focused on introducing chains of polyimides with remarkable heat resistance and superior mechanical properties into PU backbones to prepare TPEs;23–25 polyimides may contribute a balance of good elasticity and mechanical properties. A US patent15 also introduced TPAEs with hard segments prepared from diisocyanate and aliphatic diacid that have high elasticity, high plasticity and high strength.…”

Polymerization kinetics of styrene in isotactic polypropylene pellets and evolution of phase morphology during polymerization

“…As a type of nanomaterials, nanoblends have received continuing attention since they are expected to have superior properties than the conventional micro‐structured blends. A number of methodologies have been developed to make polymer nanoblends, including in situ polymerization and in situ compatibilization reactive extrusion, supercritical CO 2 ‐assisted infusion and subsequent polymerization, high‐shear processing, conventional melt blending with small amount of minor component, solid‐state shear pulverization, and so on . Each approach involves its characteristic mechanism for the formation of nanoscaled dispersed phase.…”

“…In the in situ polymerization and in situ compatibilization reactive extrusion process, a monomer (such as ε‐caprolactam) is polymerized in a molten polymer matrix (such as PP) in the presence of a macro‐activator (such as isocyanate‐bearing PP). Different from conventional melt blending, phase morphology is formed by polymerization‐induced phase separation rather than reducing the size of the dispersed phase, and nano‐dispersion is stabilized by the generation of a very high amount of graft copolymer acting as compatibilizer.…”

A super‐toughened nylon 12 blends via anionic ring‐opening polymerization of lauryllactam in a twin screw extruder. Preparation, morphology, and mechanical properties

“…The other is heterogeneous system in which additive cannot be dissolved in lactam. Additive of the former system include polyamide, polystyrene, polyurethane, polyphenylene oxide and so on [28][29][30]. An additive of the latter system include functionalized polypropylene, rubber and so on.…”