LPA performance in low temperature SMC/BMC molding
- Ohio State Univ., Columbus, OH (United States). Dept. of Chemical Engineering
Unsaturated polyester (UP) resins with low profile additives (LPA) used in sheet molding compounds (SMC) and bulk molding compounds (BMC) are thickened for easy to handle and good fiber carrying characteristics. There are two basic thickening methods: alkaline earth oxides (e.g., MgO) to form ionic bonds of diisocyanate compounds to form covalent urethane linkages with UP and LPA molecules. Both of them have disadvantages--MgO has difficulty in thickening control that the compound viscosity keeps on increasing after maturation, while diisocyanate compounds form the covalent bonds which cannot break during molding and in turn reduce the shrinkage control ability of LPA. It would be desirable to develop new methods or materials without these disadvantages. The approach used in this study was to modify the LPA by grafting a thermo-breakable functional group to the LPA. The modified LPA was compared with the regular LPA by conducting a series of BMC molding experiments. Experimental conditions varied included different thickeners (MgO and MDI), initiators (TBP, PDO and Lupersol 256) and molding temperatures (80, 100, 120 and 150 C). Profilometer was used to measure the surface quality of each BMC panel. The shrinkage of the panel was obtained by measuring the dimension of the panels.
- OSTI ID:
- 392382
- Report Number(s):
- CONF-9602107--
- Country of Publication:
- United States
- Language:
- English
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