Aromatic polyesters flow properties

POLYARYLATES. These are clear, amorphous thermoplastics that combine clarity, high heat deflection temperatures, high impact strength, good surface hardness, and good electrical properties with inherent ultraviolet stability and flame retardance. No additives or stabilizers are required to provide these properties. Polyarylates are aromatic polyesters that are manufactured from various ratios of iso- and terephthalic acids with bisphenol A.1 The resultant products are free-flowing pellets which can be processed by a variety of thermoplastic techniques in transparent and... 

While the Tg of the various aromatic polyesters do not vary widely the actual flow properties are a function of the ratio of iso/terephthalate units in the polymer. 

Chlorinated paraffins are claimed to be one of the lowest cost FRs besides the hydrated metal oxides. They can be used with antimony oxide as FRs in unsaturated polyester resin systems. Special grades have been developed by Dover Chemical in its Hordaresin and Chlorez ranges for flame retarding high-impact polystyrene, offering an absence of polyhalogenated biphenyls or dioxins, low cost, improved melt flow, and better UV stability than aromatic brominated FRs. They are also used in rubber compounds, where they can also improve tensile and tear properties of neoprene, SBR, and nitrile, and in EPDM rubber for electrical or roofing products. 

Udipi [2] has discovered that polymer blends comprising a PC, amorphous polyester such as PETG, poly(ethylene terepthalate), and a nitrile rubber can form an alloy with superior balance of properties. Improved melt flow and spiral flow was demonstrated in injection molding applications. Udipi prepared a polymer alloy with 30% aromatic polycarbonate, 30% of PETG made of a condensation copolymer of terepthalic acid and a mixture of ethylene glycol and 1,4-cyclohexanedimethanol, and 3% nitrile rubber. This blend has a spiral flow of 27 cm, heat distortion temperature of 75°C, and Izod impact resistance of 130 J/m. 

White JL, Dong L, Han P, Laun HM (2004) Rheological properties and associated structural characteristics of some aromatic polycondensates including liquid-crystalline polyesters and cellulose derivatives. Int Union Pure Appl Chem 76(ll) 2027-2049 Wiberg G, Hillborg H, Gedde UW (1998) Assessment of development and relaxation of orientation in a sheared thermotropic liquid crystalline copolyester. Polym Eng Sci 38 1278-1285 Wilson TS, Baird DG (1992) Transient elongational flow behavior of thermotropic liquid crystalline polymers. J Non-Newt Fluid 44 85-112... 

---