Polyurethane foam rubber recycling

Densified polyurethane foam was used as a filler in rubber in an attempt to recycle this material. Small additions (up to 30%) did not much affect the cure rate but as the quantity was increased the rate of vulcanization slowed probably due to the effect of dilution and increasing viscosity. 

Polyurethane is a very common crosslinked polymer and many materials produced from it end up as waste. Given the quantity of material, recycling is a major problem. Cryogenic pulverization systems have been developed which can process PU foam to particles smaller than 1 mm (preferably <100 pm)/ " These particles are homogenized with polyol and then reacted with isocyanates to produce foam. This foam with 5% pulverized PU foam has a density equivalent to a similar foam produced without the recycled material. A further increase in filler content causes a density increase. Pulverized PU foam particles were also tried as a filler in natural rubber vulcanizates with good results. Figure 12.10 shows the effect of PU... 

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