Polyarylate Based Blends

PC yields lower crystallinity and reduced crystallization rate for PCL, as would be expected from the above discussion. A similar situation exists for miscible blends of poly(butylene terephthalate) (PBT) and the polyarylate based on Bisphenol A isophthalate (PARi) [126]. PBT with a much lower Tg than PARi exhibits decreased spherulitic growth rates with PARi addition. PARi, which is very difficult to melt crystaUize (imblended), showed increasing spherulitic growth rate with PBT addition. 

In the engineering polymer blends, a number of advances in the technology and the commercial areas have been realized in the past decade. New commercial polymers have been manufactured by various combinations of preexisting polymers. One of the major areas has been with polyesters and polycarbonates (polybutyleneterephthalate/ polycarbonate polyethyleneterephthalate/polycar-bonate polyarylate/polycarbonate cyclohexane dimethanol based polyesters/polycarbonate). 

Apart from these, CS membranes find applications in the field of hemodialysis. The excellent fitm-forming nature and high mechanical strength of CS membranes made it a suitable candidate for hemodialysis application. For example, chitosan-poly(ethylene oxide) blend membranes showed improved permeability and blood compatibility due to their hydrophilic and porous nature [28]. However, the cellulosic membranes and synthetic membranes (made up of polyaryle-thersulfone, polyamide, PVP, polycarbonate, and PAN) have a well-established hemodialysis field as compared to CS-based membranes. 

Another property recently reported in detail for polyarylate is in the polymer blend area. An early French patent [33] noted that Bisphenol A polyarylate and poly(ethylene terephthalate) yield interesting mixtures. Further studies by Kimura et al. [34] and Robeson [35] found that with modest ester-exchange polyarylate and poly(ethylene terephthalate) form miscible mixtures (thus transparent with Tg values between the constituent values). Polyarylate and poly(butylene terephthalate) were noted to be miscible without ester-exchange [36]. Miscibility of three different cyclohexane dimethanol based polyesters with polyarylate was observed under minimum time and temperature exposure conditions [35]. 

Blends of BPADA-based Pis are also miscible with polyaryl ether ketones such as polyetherether-ketone (PEEK). As injection molded, many PEEK-PEI blends are transparent. 

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