Physics – Condensed Matter – Soft Condensed Matter
Scientific paper
2000-05-12
Physics
Condensed Matter
Soft Condensed Matter
25 pages, 15 figures
Scientific paper
Governing equations are derived for the kinetics of physical aging in polymeric glasses. An amorphous polymer is treated as an ensemble of cooperatively rearranged regions (CRR). Any CRR is thought of as a string of elementary clusters (EC). Fragmentation of the string may occur at random time at any border between ECs. Two string can aggregate at random time to produce a new string. The processes of aggregation and fragmentation are treated as thermally activated, and the rate of fragmentation is assumed to grow with temperature more rapidly than that for coalescence. This implies that only elementary clusters are stable at the glass transition temperature, whereas below this temperature, CRRs containing several ECs remain stable as well. A nonlinear differential equation is developed for the distribution of CRRs with various numbers of ECs. Adjustable parameters of the model are found by fitting experimental data in calorimetric tests for polycarbonate, poly(methyl methacrylate), polystyrene and poly(vinyl acetate). For all materials, fair agreement is established between observations and results of numerical simulation. For PVAc, the relaxation spectrum found by matching data in a calorimetric test is successfully employed to predict experimental data in a shear relaxation test.
No associations
LandOfFree
Modelling structural relaxation in polymeric glasses using the aggregation-fragmentation concept does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Modelling structural relaxation in polymeric glasses using the aggregation-fragmentation concept, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modelling structural relaxation in polymeric glasses using the aggregation-fragmentation concept will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-436413