High molecular weight bio furan-based copolyesters have been synthesized by melt polycondensation and solid-state polymerization for packaging applications as bio based alternatives to PET.

An aliphatic/aromatic polyester blend has been dealt with in this study. As an aliphatic polyester, poly(butylene succinate) (PBS) was used, which is thought to possess biodegradability, but it is relatively expensive. It has been blended with poly(butylene terephthalate) (PBT) in order to obtain a biodegradable blend with better mechanical properties and lower cost. The miscibilities of PBS-PBT blends were examined not only from the changes of T g but also from log GЈ-log GЉ plots. Dynamic mechanical thermal analyzer (DMTA) was an appropriate, sensitive method to obtain the glass transitions properly. Thermal stabilities of PBS and PBT were also verified at the temperature of 240°C. A transesterification reaction between two polyesters at 240°C was hardly detectable so that it did not affect the miscibilities and properties of the blends.

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ABSTRACT:Copolyesters were prepared by melt-phase polycondensation of poly(ethylene terephthalate) (PET) prepolymer and a thermotropic liquid crystalline polymer (LCP), 60mol% p-hydroxybenzoic acid and 40 mo!% poly(ethylene terephthalate) (PHB60/PET40). The copolyesters were characterized using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), thermal analysis, and wide angle X-ray diffraction measurement. The molecular weights of final copolyesters decreased with the addition of LCP. GPC results indicate that chain scission reaction of LCP occurs accompanied by chain-growing reaction of PET. From NMR analysis, LCP added underwent transesterification resulting in statistical reorganization of chain sequence with producing ether type by-products responsible for limiting the chain growth of copolyesters. It was observed that the crystallization of PET was delayed and melting temperature decreased with increasing LCP content in copolyesters. The resulting thermal properties and structural regularities of copolyester can be modified by exchange reactions during preparation.KEY WORDS Liquid Crystalline Polymers / Poly(ethylene terephthalate) / Exchange Reaction / Molecular Weight / Ether / Crystallization / Melting Temperature Depression/ In the last two decades, the increasing demand for high modulus and high strength materials has drawn considerable interest to the field of liquid crystalline polymers (LCPs). A variety of thermotropic LCPs has been developed; one of the first known thermo tropic LCPs is the copolyester of p-hydroxybenzoic acid (PHB) and poly(ethylene terephthalate) (PET) disclosed by Jackson and Kuhfuss. 1 Blending PHB/PET copolyester with other various polyesters represents an interesting procedure for application and fundamental studies of the properties of LCP/polymer blends. 2 -5 Studies on the blends of this LCP with PET have been conducted in various research groups. The crystallization rates of PET in the blends were higher than that of pure PET, which was attributed to nucleation of PET by LCP. 6 -9 The phase behavior and miscibility of LCP/PET blends have also been reported by several workers. 10 -13 Phase separation via spinodal decomposition was observed for the blend prepared by solution blending. 10 Blending of polymers is thought to be an effective means for improving properties of one or more components. However, in general, when a rigid rod polymer and a flexible polymer are simply mixed together, one would expect them to be immiscible in the first place.Reactive blending may provide a useful way to improve physical properties during the preparation of new polymeric materials from already existing polymers. The potential utilization of reactions between components of