Aromatic Polycarbonate Based Blends

1 Aromatic Polycarbonate Blends with Aromatic Polyesters 

PET/PC blends are reported to be partially miscible, and the potential for transesterification has likewise been noted in various papers [410-413]. Melt blends of PC and PET were foimd to exhibit miscibility in blends of high PET content ( 70 wt% PET), but phase separated at lower PET level [410]. Increasing processing time during melt processing showed 

The SAN matrix of ABS was noted to be phase separated in PC blends at typical polymeric molecular weights. Miscibility was observed with component molecular weights 3000 [421]. The shear stress for interfacial failure of PC/SAN/PC laminates exhibited a strong maximum at 25 wt% AN in the SAN. Slight shifts in the Tg s of the components indicated a hmited amount of miscibility, and the shifts corresponded with the observed interfacial adhesion results and mechanical properties [422]. A study of SAN/PC blends showed SAN appeared at higher concentrations in the PC-rich phase than PC in the SAN-rich phase[423]. The Flory-Huggins interaction parameter was calculated to be 0.034. 

The mechanical properties of ABS/PC blends have been reported [424], with linearity reported for modulus and strength but elongation at break exhibiting a compositional minimum. The addition of PMMA to the ABS/PC blend was noted to have a compatibihzing influence on the mechanical properties as well as improved dispersion of the phases [425, 426]. Compatibilization of PC/SAN blends with a S-AN-MA (67/32/1) terpolymer reacted with 

The properties of SAN/PC and ABS/PC blends were compared with SMA (styrene-maleic anhydride copolymer)/PC and impact modified SMA/PC blends, with similarities in properties noted for the relevant comparisons [429]. PC/SMA blends were noted to be nearly transparent to slightly pearlescent. PC blends with a-methyl styrene-acrylonitrile copolymer (68/32 by wt) prepared by freeze drying showed single Tg behavior with lest observed upon thermal exposure [430]. This blend represents misdbihty achieved under non-equilibrium conditions. 

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Polycarbonates are prepared commercially by two processes Schotten-Baumaim reaction of phosgene (qv) and an aromatic diol in an amine-cataly2ed interfacial condensation reaction or via base-cataly2ed transesterification of a bisphenol with a monomeric carbonate. Important products are also based on polycarbonate in blends with other materials, copolymers, branched resins, flame-retardant compositions, foams (qv), and other materials (see Flame retardants). Polycarbonate is produced globally by several companies. Total manufacture is over 1 million tons aimuaHy. Polycarbonate is also the object of academic research studies, owing to its widespread utiUty and unusual properties. Interest in polycarbonates has steadily increased since 1984. Over 4500 pubflcations and over 9000 patents have appeared on polycarbonate. Japan has issued 5654 polycarbonate patents since 1984 Europe, 1348 United States, 777 Germany, 623 France, 30 and other countries, 231. 

The surface structure of melt-mixed blends of bisphenol A polycarbonate and PETP was investigated by FTIR attenuated total reflectance spectroscopy. Based on the peak intensity of the aromatic carbonate band for polycarbonate and the aliphatic ester band for PETP by using germanium and KRS-5 ATR crystals, the enrichment of the PETP component in the surface layer of the polycarbonate/PETP blend films was observed. 27 refs. 

Oligomeric aromatic phosphates have been patented and commercially used as flame-retardant additives mainly for impact-resistant polystyrene blends with polyphenylene oxide and polycarbonate blends with acrylonitrile-butadiene-styrene (ABS) copolymers (130,131). They have also been shown useful in thermoplastic polyesters (92). The principal commercial examples are based on phenol and resorcinol (Akzo-Nobel s Fyrolflex RDP) or phenol and bisphenol A (Akzo-Nobel s Fyrolflex BDP or Albemarle s Ncendx P-30). Although these have the diphosphate as their principal ingredient, they also contain higher oligomers. 

PC/PE blends exhibit less tendency to stress-cracking as well as higher chemical resistance than polycarbonate. PC/PE blends are resistant to mineral acids, many organic acids, oxidants, many fats, waxes, oils, saturated aliphatic hydrocarbons, alcohols, milk, and fruit juices. They are not resistant to alkaline lyes, hot water (100 °C), amines, concentrated acids and bases, methanol, aromatic and halogen-ated hydrocarbons [86]. 

The window of miscibility in this case is an ellipse contained within the boundaries of the copolymer composition map. Additional examples of the mean field approach to predict the miscibility window for cop olymer-copolymer blends include SAN/SMMA, SMMA/MMA-AN and SAN/MMA-AN [188], amSAN/SAN and amSAN/SMA [202], SMMA/SMMA (different compositions) [203 ], SMA/tetramethyl Bis A polycarbonate [204], chlorinated PVC (different compositions), chlorinated polyethylene (different compositions and MMA-EMA (different compositions) [177] and SAN/NBR [205]. This approach has also been applied to ternary blends of PPO/PS/poly(o-chlorostyrene-co-p-chlorostyrene) [206]. The mean field binary interaction model approach was also successfully applied to polyamides based on various combinations of aliphatic and aromatic units [207]. 

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