Separation of glass transition and melting in polyethylene/poly(butyl-methacrylate-co-methyl-methacrylate) interpenetrating polymer networks in TMDSCand DSC curves

Temperature modulated DSC (TMDSC) was tested concerning the possibility to separate the glass transition of the copolymer (BMA-co-MMA) component from the melting effect of the polyethylene (PE) in PE/BMA-co-MMA interpenetrati ng polymer networks prepared by in situ polymerisation. It was shown that a direct separation of both effects using TMDSC is not possible. The influen ce of the (excess) specific heat capacity of PE on the measured curve in th e range of the glass transition of the copolymer is not negligible. With th e TMDSC results of pure cross-linked PE (and because of the high accuracy o f TMDSC) a procedure was found to estimate both the step height Delta(Cp)(T -g) and the temperature T-g of the glass transition of the copolymer phase. Additionally, an estimation of the degree of cross-linking of the PE phase is possible. The accuracy of standard DSC measurements is insufficient to apply successf ully the procedure of data analysis developed for analysis of TMDSC results . In this case, the method of inflection point gives the chance to estimate the glass transition temperature of the copolymer phase. (C) 1999 Elsevier Science B.V. All rights reserved.