THE SYNTHESIS, CHARACTERIZATION, AND WEATHERING BEHAVIOR OF POLYCARBONATES DERIVED FROM BIS(P-HYDROXYPHENYL)DIMETHYLSILANE (BPSI)

Polycarbonates and copolycarbonates based on BPSi and BPA were easily made using the standard interfacial technique. Molecular weight and NM R data indicate that up to 4 mol % of the BPSi decomposes during polym erization via a base-catalyzed rearrangement of BPSi to arylsiloxanes. Oxygen index studies show an increased flame resistance with increasi ng BPSi monomer content. DSC measurements show a decrease in glass tra nsition with BPSi monomer concentration while TGA shows an increase in char residue with BPSi monomer content. In addition, TGA indicates no change in either thermal or thermooxidative stability with the relati ve BPSi/BPA concentrations. Outdoor weathering of BPSi PC and BPA PC f ilms indicates that BPSi PC is ca. 5 times more weathering resistant t han BPA PC. This latter result can be attributed to a combination of B PSi PC's lower UV absorptivity, higher water repellency, and lower lik elihood for side chain photooxidation.