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Effects of shear rate, viscosity ratio and liquid crystalline polymer content on morphological and mechanical properties of polycarbonate and LCP blends
Author(s) -
Tan L P,
Yue C Y,
Tam K C,
Lam Y C,
Hu X
Publication year - 2002
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.889
Subject(s) - materials science , polycarbonate , thermotropic crystal , shear rate , viscosity , composite material , reduced viscosity , polymer blend , polymer , inherent viscosity , temperature dependence of liquid viscosity , relative viscosity , shear (geology) , intrinsic viscosity , liquid crystalline , copolymer
Studies were conducted on the effects of shear rate, viscosity ratio and liquid crystalline polymer (LCP) content on the morphological and mechanical properties of polycarbonate (PC) and LCP blends. The LCP (LC5000) used was a thermotropic liquid crystalline polymer consisting of 80/20 of parahydroxybenzoic acid and poly(ethylene terephthalate) (PHB/PET). The viscosity ratio (viscosity of LCP: viscosity of matrix) was varied by using two processing temperatures. Due to the different sensitivity of materials to temperature, variation in the processing temperature will lead to varying viscosity of the components in the blends. Based on this principle, the processing temperature could be manipulated to provide a favourable viscosity ratio of below unity for fibre formation. To study the effect of shear rate, the flow rate of the blend and the mould thickness were varied. The shear rate has a significant effect on the fibrillation of the LCP phase. The effect was more prominent when the viscosity ratio was low and the matrix viscosity was high. At 5 wt% LCP, fibrillation did not occur even at low viscosity ratios and high shear rates. It was also observed that the LCP content must be sufficiently high to allow coalescence of the dispersed phase for subsequent fibrillation to occur. © 2002 Society of Chemical Industry