Elasticity and thermal transport of commodity plastics

Abstract

Applications of commodity polymers are often hindered by their low thermal conductivity. In these systems, going from the standard polymers dictated by weak van der Waals interactions to biocompatible hydrogen bonded smart polymers, the thermal transport coefficient κ varies between 0.1 − 0.4 Wm −1 K −1 . Combining all-atom molecular dynamics simulations with some experiments, we study thermal transport and its link to the elastic response of (standard and smart) commodity plastics. We find that there exists a maximum attainable stiffness (or sound wave velocity), thus providing an upper bound of κ for these solid polymers. The specific chemical structure and the glass transition temperature play no role in controlling κ, especially when the microscopic interactions are hydrogen bonding based. Our results are consistent with the minimum thermal conductivity model and existing experiments. The effect of polymer stretching on κ is also discussed.

Correlating thermodynamics, morphology, mechanics and thermal transport in PMMA-PLA blends

“…As expected from the blending of two materials, κ with x PLA shows a monotonic variation between the κ values of a pure PLA and a pure PMMA systems. While κ values are known for the pure phases on PMMA and PLA, which is also consistent with the earlier experiments [44,45] and simulations [32], we report κ data for PMMA-PLA blends here. This shows an internal correlation between the linear elasticity, mechanics, and thermal transport of commodity polymer blends.…”

“…1 atom OPLS force field is used to model PLA [30], while we have used a set of modified OPLS parameters for PMMA [31]. Earlier it has been shown that the PMMA force field parameters reasonably capture the properties of the solid, solvent-free PMMA, such as the specific volume, the macroscopic elastic moduli, and the thermal transport coefficient [32]. In this work, we have also validated that the PLA parameters give the correct estimates of specific volume at temperature of T = 300 K (i.e., 8.06×10 −4 m 3 /kg for experiments and 8.11×10 −4 m 3 /kg for simulations), elastic modulus, and thermal properties.…”

“…This will give N ℓ = 12ℓ p for PMMA and N ℓ = 15ℓ p for PLA. While N ℓ = 12 − 15ℓ p might look as too short to study the polymer properties, it is known to reasonably capture the conformational behavior of a single chain in solution [31] and in melt [32].…”

“…FIG.8:The main panel shows the thermal transport coefficient κ as a function of poly(lactic acid) (PLA) mole fraction xPLA. For comparison, we have also included experimental data for PMMA[45] and PLA[44] and also simulation data for PMMA from an earlier work using the Müller-Plathe method[32]. Inset shows the variation of κ with the elastic modulus E. Lines are drawn to guide the eye.…”

Enhancing the Thermo-Mechanical Property of Polymer by Weaving and Mixing High Length–Diameter Ratio Filler

“…They also developed a theoretical model related to bond energy, backbone rotation, in-plane bond ratio, and atomic amass to predict thermal conductivity of crystalline polymers [26]. Ruscher et al uncovered the link between elasticity and thermal conductivity of several polymers [27]. An et al investigated the effects of water content and cross-linking on the thermo-mechanical property of polyacrylamide hydrogels [28].…”