| 摘要 |
From an environmental viewpoint, it is desireable to cause degradation of expanded EPS beads and foam cups and other products formed from expanded EPS beads, which are composed of polystyrene and a blowing agent such as pentane. For this purpose, the present invention utlizes the pre-expansion step as an opportunity to initiate foam product degradation by treating the expandable polymer beads during their pre-expansion. The objective of this degradation treatment is to initiate degradation of at least the surfaces of individual beads during their pre-expansion and before they are molded into the final foam articles. For this purpose, a number of degradation treatment options are disclosed for application during bead pre-expansion, including heating the beads by circulation with heated air, admixture of the beads with ozone, aromatic ketones such as acetophenone and benzophenone, and metallic salts, as well as irradiation of the expanding beads with uv radiation (e.g of a wavelength of about 260 nanometers). As a result of the interposed degradation treatment, the foam products degrade first into individual beads, and subsequently into polymeric dust, at a rate that depends upon the intensity of the degradation treatment that is selected.
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