| 摘要 |
In pre-expanding polymeric particles incorporating an expanding agent the particles are fed into a steam atmosphere by means of a flow of steam and heated to a temperature above that at which the expanding agent becomes active, the particles being mechanically agitated to prevent their agglomeration and being removed from the steam atmosphere while capable of further expansion. The particles may be of polyvinyl chloride, polyvinylidene chloride, polymers and copolymers of styrene, substituted styrenes and polyacrylic esters, copolymers of butadiene or other dienes or of acrylonitrile and styrene in compositions at least 50% styrene, whilst the expanding agent may comprise one or more volatile hydrocarbons.ALSO:In pre-expanding polymeric particles incorporating an expanding agent, the particles are fed into a steam atmosphere by means of a flow of steam and heated to a temperature above that at which the expanding agent becomes active, the particles being mechanically agitated to prevent their agglomeration and being removed from the steam atmosphere while capable of further expansion. The particles may be of polyvinyl chloride, polyvinylidene chloride, polymers and copolymers of styrene, substituted styrenes and polyacrylic esters, copolymers of butadiene or other dienes or acrylonitrile and styrene in compositions at least 50% styrene whilst the expanding agent may comprise one or more volatile aliphatic hydrocarbons.
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