Rheological Behaviors and Properties of Poly (Ether Ether Ketone) In-Situ Blends: Effect of Chemical Structure of Added Thermotropic Liquid Crystalline Polyarylates

Synthesis and Properties of Semicrystalline Poly(ether nitrile ketone) Copolymers

As a high-performance engineering plastic, polyarylene ether nitrile (PEN) is widely used in many fields. The presence of cyano groups of PEN ensures its good adhesion to other substrates, but the inherent low crystallinity of PEN limits its application. In this work, the poly(aryl ether ketone) segment was introduced into PEN via copolymerization using both 2,6-Dichlorobenzonitrile and 4,4'-Difluorobenzophenone as the starting reagents to prepare poly (ether nitrile ketone) (BP-PENK). The effect of composition and thermal treatment on the crystallization behavior and properties of poly (ether nitrile ketone) were systematically studied. It was found that when the content of DFBP is 30%, the copolymer BP-PENK30 had the best mechanical properties, with a tensile strength of 109.9 MPa and an elongation at a break value of 45.2%. After thermal treatment at 280 °C for 3 h, BP-PENK30 had the highest crystallinity with a melting point of 306.71 °C, a melting enthalpy of 5.02 J/g, and crystallinity of 11.83%. Moreover, with the increase in crystallinity, the dielectric constant and energy density increased after thermal treatment. Therefore, the introduction of poly(aryl ether ketone) chain segments and thermal treatment can effectively improve the crystallization and the comprehensive properties of PEN.

Effects of Poly(ethylene-co-glycidyl methacrylate) on the Microstructure, Thermal, Rheological, and Mechanical Properties of Thermotropic Liquid Crystalline Polyester Blends

In this study, a series of thermotropic liquid crystalline polyester (TLCP)-based blends containing 1-30 wt% poly(ethylene-co-glycidyl methacrylate) (PEGMA) were fabricated by masterbatch-assisted melt-compounding. The scanning electron microscopy (SEM) images showed a uniformly dispersed microfibrillar structure for the TLCP component in cryogenically-fractured blends, without any phase-separated domains. The FT-IR spectra showed that the carbonyl stretching bands of TLCP/PEGMA blends shifted to higher wavenumbers, suggesting the presence of specific interactions and/or grafting reactions between carboxyl/hydroxyl groups of TLCP and glycidyl methacrylate groups of PEGMA. Accordingly, the melting and crystallization temperatures of the PEGMA component in the blends were greatly lowered compared to the TLCP component. The thermal decomposition peak temperatures of the PEGMA and TLCP components in the blends were characterized as higher than those of neat PEGMA and neat TLCP, respectively. From the rheological data collected at 300 °C, the shear moduli and complex viscosities for the blend with 30 wt% PEGMA were found to be much higher than those of neat PEGMA, which supports the existence of PEGMA-g-TLCP formed during the melt-compounding. The dynamic mechanical thermal analysis (DMA) analyses demonstrated that the storage moduli of the blends decreased slightly with the PEGMA content up to 3 wt%, increased at the PEGMA content of 5 wt%, and decreased again at PEGMA contents above 7 wt%. The maximum storage moduli for the blend with 5 wt% PEGMA are interpreted to be due to the reinforcing effect of PEGMA-g-TLCP copolymers.

Synthesis and characterization of poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls

Meta-poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls (meta-PPBEKK) was synthesized with 4,4′-dihydroxybiphenyls (BP), 1,3-bis(4-fluorobenzoyl)benzene (meta-DFKK) and 4-(4-hydroxyphenyl)-2,3-diazaphthalene-1-one (DHPZ). The copolymers are high-temperature resistant and have good solubility in many solvents. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, the addition of BP improves number-average molecular masses, intrinsic viscosity, mechanical properties and fluidity of meta-PPBEKKs. When the molar ratio of BP to meta-DFKK is 0.2, the intrinsic viscosity reaches 1.14 dL g−1, the number-average molecular mass reaches 44700 g mol−1, the maximum thermal elongation ratio reaches 14 with strength of 127.1 MPa and Young’s modulus of 2.4 GPa. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, meta-PPBEKKs have improved comprehensive properties, and make sense in many fields.