Effects of chemical reactions on the properties of polycarbonate/liquid crystalline polymer blends

Abstract

Effects of chemical reactions on the properties of the polycarbonate (PC)/ liquid crystalline polymer (LCP) blends are considered here. Not only thermal and rheological behaviors, but also morphology and molecular weight change are investigated. Reactive blends were prepared in a cylindrical flask at 300°C with varying processing time in the presence of a catalyst by the melt-phase reactions. For comparison, physical blends, in which chemical reactions were minimized, were also prepared at 300°C in a twin-screw extruder. It seems that transesterification and repolymerization did not occur, but depolymerization reaction took place slightly in PC/LCP physical blends. In reactive blends, however, transesterification and repolymerization as well as depolymerization reaction took place simultaneously. The depolymerization reaction occurred mainly at an early stage of processing; whereas, repolymerization reaction becomes especially dominant after some time (more than 30 min) in the presence of the catalyst, which had a great impact on its molecular weight. Also, chemical reactions changed the glass transition temperature and morphology as well as rheological behavior, which resulted in the enhanced miscibility in reactive blends.

Effect of silicone oil on the morphology and properties of polycarbonate

“…A clear phase separation was observed, even at 1 wt % of PDMS. A similar separated domain was observed in the PC/liquid crystal polymer; the uniformly dispersed phase indicated good dispersion 19. The T g s from the differential scanning calorimetry (DSC) and the sharp decrease of impact strength are related to the phase separation of the silicone oil.…”

“…A similar separated domain was observed in the PC/liquid crystal polymer; the uniformly dispersed phase indicated good dispersion. 19 The T g s from the differential scanning calorimetry (DSC) and the sharp decrease of impact strength are related to the phase separation of the silicone oil. The chain mobility of silicone oil at low temperatures and the rough fracture surfaces are the main reasons for the increase in impact strength and tensile strength.…”

Preparation and characterization of syndiotactic polystyrene/ethylene‐propylene copolymer blends

“…The reactive compatibilization method has been proved to be effective for controlling morphology in a variety of blend systems. However, research promoting a detailed understanding of the enhancement of interfacial properties resulting from reactive compatibilization is very limited 5, 6…”

“…However, research promoting a detailed understanding of the enhancement of interfacial properties resulting from reactive compatibilization is very limited. 5,6 Numerous papers of polymer blend systems for toughening have been reported using maleic anhydride (MA)-grafted polymers as a reactive modifier with various copolymers. 7 One of the wellknown examples is DuPont's super tough nylon, where MA is first grafted onto poly(ethylene-copropylene-co-diene) (EPDM) rubbers and then reacted with the terminal amine groups of nylons.…”

In memoriam

“…The two main drawbacks of these blends are probably the usually low interfacial adhesion and the small number of commercial LCPs available, which reduce the range of possible blends. Many attempts have been made to overcome the low adhesion, such as reactive processing,4, 5 chemical modification of the LCP6, 7 or the addition of a third component 8, 9. The limited range of available LCPs can be increased through blending, which provides, as for many materials, a unique opportunity for developing new materials.…”