| 摘要 |
Expanded polymer granules are produced or sintered by heating respectively unexpanded polymer granules containing a foaming agent or expanded polymer granules using a high frequency alternating electric field. The granules may contain a compatible substance of higher power factor which may also be a plasticizer for the polymer, e.g. toluene sulphonamides, tetrachlorobiphenyl or dichloropentanes. Specified polymers are polystyrenes and chlorinated or brominated polystyrenes; polyvinyl chloride is also mentioned.ALSO:Expanded polymer granules are produced or sintered by heating respectively unexpanded polymer granules containing a foaming agent or expanded polymer granules using a high frequency alternating electric field. The granules may contain a compatible substance of higher power factor which may also be a plasticizer for the polymer, e.g. toluene sulphanamides, tetrachlorobiphenyl or dichloropentanes. Specified polymers are polystyrenes and chlorinated or brominated polystyrenes; polyvinyl chloride is also mentioned. In the examples, polystyrene beads containing petroleum ether are expanded and subsequently sintered into sheets by passing them on a conveyer belt between spaced electrodes, the potential difference between the electrodes being 103 volts for the expansion and 5 X 104 volts for the sintering and the frequency being 12 X 106 cycles per second; for the expansion stage the distance between the electrodes increases in the direction of travel of the conveyer belt. |
