Thermal degradation of PVC/NBR and PVC/ENR50 binary blends and PVC/ENR50/NBR ternary blends studied by DMA and solid state NMR

The changes in the structure and the morphology of the binary blends PVC/NBR and PVC/ENR, and the PVC/ENR/NBR ternary blend during thermal aging were investigated by dynamic mechanical analysis and solid state NMR. Samples were prepared by mechanical blending at 150 degrees C. Thermal aging was carried out at 80 degrees C for 7 days and at 140 degrees C for 2 days. The effect of the change in the tan 6 peak position, the tan delta peak width and the tan delta(max) were used to understand the miscibility and damping properties. Solid state C-13 NMR measurements were carried out using high power decoupling, cross polarization and magic angle spinning. Observation of new peaks and changes in the peak widths were used to understand the possible degradation mechanism and changes of the dynamics due to these reactions. Proton relaxation times were interpreted based on the heterogeneity of the matrix. Results show that there is a change in the morphology during thermal aging at lower temperature. (C) 2000 Elsevier Science Ltd. All rights reserved.