Mechanics of ABS Polymer under Low & Intermediate Strain Rates

Abstract

Thermoplastics polymers like Acrylonitrile Butadiene Styrene (ABS) are often reinforced with nano/micro reinforcements to enhance their mechanical, thermal and electrical properties. However, the viscoelastic nature of these polymers results in their strong dependence on the applied strain rate and temperature sensitivity, leading to their characterization complexity. Hence it is paramount to study the strain rate-dependent mechanics of neat ABS. In this study, the effect of strain rate and temperature on Young’s modulus of ABS polymer was characterized using a dynamic mechanical analyzer (DMA). Storage modulus curves at various temperatures and frequencies were transformed into a representative master curve at a specific temperature using the time-temperature superposition (TTS) principle. Based on this curve‘s storage modulus and frequency relation, an empirical fit function was developed and the strain rate values were extrapolated. Using integral relations of viscoelasticity, the results were further transformed to a time domain relaxation function to extract the strain rate-sensitive Young’s modulus at different loading rates. This method was validated by comparing the data with tensile tests conducted on ABS coupons as per ASTM D638-14. The results were acceptable over a wide range of strain rates and indicated a clear sensitivity of ABS to strain rate and temperature. The strategy used in this work can be employed to study the effect of reinforcement morphology in ABS thermoplastics using DMA.