Polycarbonates blowing agents

Phenyl-3,6-dihydro-l,3,4-oxadiazin-2-one (50) is a high temperature blowing agent used primarily for polycarbonates (qv). It is prepared by the reaction of a-hydroxyacetophenone and methyl carbazate (52), made from hydrazine and dimethyl carbonate (175) ... 

Comparatively little information is available concerning the use of additives in commercial grades of polycarbonate. Pigments, heat and ultraviolet stabilisers, blowing agents and fire retardants are used but the range of materials available... 

Dipicryl-l,3,4-oxadiazole has been described as an initiating explosive, 2,5-dimethyl-l,3,4-oxadiazole has been used to extract aromatic hydrocarbons from mixtures with alkanes. The use of 4,4 -carbonyl-bis(2-phenyl-5-oxo-l,3,4-oxadiazole) as a blowing agent for foaming thermoplastic compositions (e.g., polycarbonates) has been described < 1996CHEC-II(4)268>. 

Endothermic and inorganic chemical blowing agents have included materials that degrade into carbon dioxide when heated, such as sodium bicarbonate. Sodium bicarbonate s low decomposition temperature (100°C-140°C) suits its use with POs, though it can decompose rapidly, forming open-cell stmctures. Other endothermic agents include citric acid, sodium borohydride, and polycarbonic... 

A wide variety of polymers can be foamed, including the polymethanes, polyisocyanurates, PVC, polystyrene, ABS, polycarbonate, PET, PBT, polyamides, PPO, EVA and the polyolefins. Other additives required for the foaming process besides blowing agents may include foam nucleating agents, stabilisers, surfactants, plasticisers, colourants, flame retardants and particulate fillers. 

Azodicarbonamide, sulfonyl hydrazides, sulfonyl semicarbazides, and dinitro-pentamethylene tetramine are examples of exothermic blowing agents. Sodium borohydride, sodium bicarbonate, and polycarbonic acid are examples of endothermic blowing agents. 

PAA polyaryl amide PAI polyamide-imide PAN polyacrylonitrile PB polybutylene PBA physical blowing agent PBI polybenzimidazole PBNA phenyl- -naphthylamine PBT polybutylene terephthalate PC permeability coefficient PC personal computer PC plastic composite PC plastic compKJunding PC plastic-concrete PC polycarbonate PC printed circuit PC process control PC programmable circuit PC programmable controller PCB polychlorinated biphenyl PCB printed circuit board PCE perchloroethene PCR post-consumer resin pcf pounds per cubic foot... 

Axel Plastics Research Laboratories mentions INT 30 UDK as an internal lubricant and a mold-release agent for polycarbonates and polyolefins. It provides better transformability and improves rheological properties of the melt bulk polymer it prevents the formation of flow lines in the production of sheets by extrusion blowing. It is also an antistatic agent [30]. 

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