No abstract

An unsaturated polyester bulk molding compound is made containing unsaturated polyester sheet molding compound-recyclate added as reinforcement. Grinding techniques are used to obtain the sheet molding compoundrecyclate. The flexural strength and modulus of bulk molding compounds containing 0 and 100% recyclate used as the reinforcing material are compared. In both cases the flexural strength and modulus are found to be reduced. Micrographs of the recyclate-reinforced bulk molding compound fracture area show cracks that initiate and propagate along the recyclate-new resin matrix interface. The poor interfacial bonding is the major reason for the loss in the strength and modulus values.

Recycling of thermoset molding compounds has been intermittently investigated for roughly the past 15 years. The use of sheet molding and bulk molding compounds has steadily increased over the same time period, but no closedloop recycling regime has been developed. First, a general discussion is made on the materials involved and some of their applications. The major recycling methodologies, energy recovery, chemical breakdown, thermal breakdown, and size reduction are all reviewed. Also, some of the new technologies being developed and areas where further work is needed are outlined.