Investigation of Segmental Dynamics in Polymer Glasses During Constant Strain Rate Deformation

Download or read book Investigation of Segmental Dynamics in Polymer Glasses During Constant Strain Rate Deformation written by and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have used optical measurements of dye reorientation to investigate the molecular dynamics of polymer glasses during deformation. In our work we have developed new instrumentation to perform constant strain rate deformations of polymer glasses while simultaneously measuring segmental mobility. By expanding our deformation protocols from creep and recovery to constant strain rate we have found that our molecular mobility measurement is more closely relevant to the theories, models, and simulations that the polymer glass deformation community is developing. We found that mobility was enhanced during deformation up to the yield point by a factor of 40 to 160 compared to the undeformed glass. In the postyield regime, this enhancement of mobility remained constant during the deformation. Finally, we found that high strain rates lead to higher postyield mobility, and that the mobility was correlated with the local strain rate as we have found previously with creep deformation experiments. The experimental features of the mobility enhancement, and its correlation with strain rate, are compared to computer simulations and theoretical models. This work significantly increases our understanding of molecular mobility during different types of deformations and shows the generalities of the measurement across many different systems. We have now found that the correlation of mobility and local strain rate is extremely robust across temperatures, types of deformations (postyield), and polymer glasses. We have also determined that a decrease in dynamic heterogeneity is a result of the deformation being applied to the polymer glass. By finding these generalities across different polymer glasses under different deformations, we can help provide the tools to create more accurate predictive models and simulations of polymer glass deformation.