Recycle of polyurethane:Application to phenolic resin

J-STAGE

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  • ポリウレタンのリサイクル:フェノール樹脂への応用

Description

Waste of polyurethane foam (PU) was utilized as a modifier to improve the toughness of phenolic resin. Novolac modified with PU was synthesized from phenol which dissolved various amount of PU and formalin under acid condition. Tg, average molecular weight, and melt viscosity of novolac modified with PU were increased with increasing PU. Molding compounds were prepared by hot roll-kneading from the modified novolac, hexamine, and wood flour. Test pieces of modified phenolic resins were prepared by transfer molding from the molding compounds. Thermal and mechanical properties of the modified phenolic resins were examined by deflection temperature under load and flexural properties. Fracture toughness was also examined using test pieces without containing wood flour. Heat resistance of the modified phenolic resin showed the maximum value at PU content of 10 phr. Flexural strength was improved with increasing PU, though flexural modulus was almost unchanged. Also the ultimate flexural strain value was improved. Fracture toghness of the modified phenolic resin showed 1.5 times as much as that of unmodified one at PU content of 10 phr. The mechanism of toughning for the modified resin system was investigated by dynamic thermomechanometry and scanning electron microscope. As a result, it is considered that toughning occurs based upon stress relaxation by plastic deformation in the vicinity of crack tips in a homogeneous and miscible structure.

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