Structure–property relationship in fibers spun from poly(ethylene terephthalate) and liquid crystalline polymer blends. I. The effect of composition and processing on fiber morphology and properties

Abstract

SYNOPSISPoly(ethy1ene terephthalate) (PET) matrix was modified by blending with a specially prepared thermotropic liquid crystalline polymer (TLCP), in the hope to make the in situ composite during fiber spinning. It has been found that the TLCP did not fibrillate in the P E T matrix at any concentration under given processing conditions, although it did in the polycarbonate matrix. This was explained by the low interaction parameter (low surface tension) and partial degree of mixing of P E T and TLCP. The TLCP was an excellent processing aid even a t very low concentrations, but it had an adverse effect on the strength of highly drawn fibers. The modulus of both undrawn and highly drawn fibers increases slightly with increasing TLCP concentration. 0 1995 John Wiley & Sons, Inc.

Control of High-order Structure of Poly(ethylene terephthalate) Fibers by Blending with Liquid Crystalline Polymer

“…The same properties are also being utilized to form in-situ composites by reinforcing thermoplastics with LCP. There have been numerous reports for various blend systems containing LCP, among them many concerned with poly(ethylene terephthalate) (PET) blend system [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The mechanical properties of blends are significantly affected by the mode of dispersion, the shape and orientation of LCP and the interfacial adhesion between the two phases.…”

“…In some cases, the strength and the modulus of PET/LCP blend system are found to follow a linear mixture rule, resulting in significant improvement in strength and stiffness. The effect of processing conditions on morphology and properties of the blends was predominantly investigated for injection molding, while more recently efforts were also put on making in-situ composite fibers via melt spinning [12][13][14][15][16][17]. The blending of two kinds of LCP with different rigidity has been found to yield as-spun fibers with different degree of orientation [16].…”

Blends of Thermoplastic Polyesters: Sections 6–8

“…Thus, an LCP system, such as X7G-containing PET moiety in the copolymer chain, may not form fibrils in a blend with PET because of its partial miscibility with PET. It is noteworthy that fibril formation in LCPs is more favored by some matrix polymers, such as PC [109]. Thus, PC/LCP blends form the largest single group of in situ composites.…”

“…Various investigators have cited different viscosity ratio ranges for fibril formation. Petrovic and Farris [109] found that fibril formation took place in a blend of a given LCP with polycarbonate matrix at a viscosity ratio between 0.01 and 0.001, but did not take place in a blend of the same LCP with PET matrix under identical conditions of viscosity ratio and processing. The low interaction parameter (that is, low surface tension) and the partial degree of mixing between PET and LCP used were believed to be responsible for this observation.…”

Molecular orientation of extruded PET/LCP blend films. II. X‐ray pole figures

“…12,13,18,[23][24][25][26][27][28][29][30][31][32][33][34][35][36] In general, these studies demonstrated that the mechanical properties of the blends are significantly affected by the mode of dispersion, shape, and orientation of the LCP and the interfacial interactions between the two phases. In some cases, significant improvement in strength and stiffness are found.…”