Correlation between in vitro Elastomeric Force Degradation and Glass Transition Temperature determined by Dynamic Mechanical Analysis

Abstract

Objective: To determine the relation between force degradation of elastomeric chains and its glass transition temperature (Tg) by dynamic mechanical analysis (DMA). Materials and methods: Elastomeric products from two different manufacturers (Groups A and B) were compared for their force decay in an in vitro experiment for 4 weeks. Force values (F) were measured at 0 hour, 1 hour, 24 hours, 1, 2, 3 and 4 weeks. Samples were subjected to DMA for its corresponding Tg. Mean force and Tg were compared with one-way analysis of variance (ANOVA) and post-hoc Duncan multiple range test. Two-way ANOVA was used to assess the effects between Groups and different time periods. Relationship between force and Tg were studied with regression analysis. Results: Force values decreased by 48% within 1 hour and then showed a continuous decrease to cease with only 24.5 and 20.2% for Groups A and B respectively. Tg also paralleled a decrease (Group A: –19.21 ± 1.73 to –26.10 ± 1.72 and Group B: –21.09 ± 2.14 to –27.30 ± 1.82). Beta and gamma subtransitions other than main alpha transitions (Tg) were noted. Loss of rigidity and deformation of samples were thus attributed to the structural changes in polymer. A strong relationship was noticed for force values and Tg (r = 0.89 for Group A and 0.86 for Group B). Conclusion: Tg can be considered as a dependable parameter in envisaging the force properties of an elastomeric chain. Clinically, it suggested