Abstract
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.
Highlights
Thermotropic liquid crystalline polyesters (TLCPs)—aromatic polyesters exhibiting liquid crystallinity in a molten state—are used in a variety of industrial sectors because of their excellent thermalPolymers 2020, 12, 2124; doi:10.3390/polym12092124 www.mdpi.com/journal/polymersPolymers 2020, 12, 2124 stability, dimensional stability, mechanical performance, and chemical resistance [1,2,3,4,5,6,7,8]
C–O, carboxyl ) at and TLCP-E30 blend, as the poly(ethylene-co-glycidyl methacrylate) (PEGMA) content increased in the blends
TLCP-based blends with 1–30 wt% PEGMA loadings were fabricated by facile and properties were investigated systematically by considering the chemical reaction and intermolecular efficient masterbatch-based melt-compounding, and their morphology, microstructures, and interaction between TLCP and PEGMA components
Summary
Thermotropic liquid crystalline polyesters (TLCPs)—aromatic polyesters exhibiting liquid crystallinity in a molten state—are used in a variety of industrial sectors because of their excellent thermal. The combination of excellent physical properties and facile melt-processability makes TLCPs an ideal engineering material for high-end applications in automobile, optical, and electronic devices Despite their outstanding thermal and mechanical performance, they are expensive in terms of the cost for expanding practical applications. To achieve a higher price-performance ratio without compromising the excellent thermal and mechanical properties of TLCPs, blending with conventional thermoplastic polymers is considered the most economical and effective method. It was found that the tensile mechanical properties of the as-spun fibers could be improved upon the addition of TLCPs. Che et al reported the influences of phosphorous-containing TLCP on the transesterification-controlled compatibility, microfibrillation, and rheological and mechanical properties of PC blends with acrylonitrile butadiene styrene (ABS) terpolymer [14]. The morphological features; microstructures; and rheological, thermal, and mechanical properties of TLCP/PEGMA blends were discussed in terms of the PEGMA content, intermolecular interaction, and reactivity between the PEGMA and TLCP in the blends
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