| http://www.w3.org/ns/prov#value | - If the hollow particles are formed of a thermoplastic material, such as cellulose acetate, ethyl cellulose, polyvinyl chloride, polyamides, polyethylene and the like, they may be adhered together in any desired arrangement by slightly softening their surfaces at an elevated temperature, with application of moderate pressure insuflicient to fiatten the particles.
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