Polymer blends for energy-efficient construction materials: simulation studies

Descripción

Phase change materials (PCM) represent a smart solution for improving energy efficiency in construction materials. PCM can store or release heat through a solid-liquid transition. When the transition temperature is in the human comfort zone (22ºC-27ºC), PCM help to reduce energy consumption and dampen indoor temperature fluctuations. Pure PCM can leak from construction materials while they are in molten state. To avoid this, they can be macro and microencapsulated or dispersed in a medium that remains solid during the phase transition. The latter are termed shape-stabilized phase change materials (SSPCM). In the present work, we used molecular dynamics simulations to study the structure and compatibility of polyethylene (PE)/octadecane blends as models for SSPCM. Octadecane acts like PCM and PE prevents octadecane loss from construction materials. We studied blend miscibility as a function of PE concentration at two different temperatures, below and above the melting points of PE and octadecane. We applied Flory−Huggins theory to analyze the results, which showed a strong dependence on temperature. We also calculated mechanical properties of both concrete and gypsum containing PE/octadecane blends. We found that the incorporation of SSPM into these construction materials resulted in the degradation of their mechanical properties