Effects of cellulose nanofibrils on the mechanical and thermal properties of phase change foams based on polyethylene glycol/cellulose nanofibrils/waterborne polyurethane.

Incorporating phase change materials (PCM) into three-dimensional porous network structures could effectively address the leakage problem. In this study, by investigating the effects of different cellulose nanofibrils (CNF) contents on the mechanical and thermal properties of polyethylene glycol (PEG)/CNF/waterborne polyurethane (WPU) phase change foams, a series of leak-proof, lightweight, and stable PEG/CNF/WPU phase change foams were synthesized. Utilizing CNFs as porous support materials could effectively mitigate the leakage of PCMs. Meanwhile, the incorporation of WPU dispersions leads to the formation of CNFs/WPU composite network structure, which enhances the mechanical strength of the phase change foams and further reduces the leakage of PEG. The morphological, crystallographic, chemical, mechanical, and thermal characteristics of PEG/CNF/WPU phase change foams with varying CNF concentrations were comprehensively assessed using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), mechanical testing, and differential Scanning calorimetry (DSC). The research results indicate that phase change latent heat of PEG/CNF/WPU phase change foam containing 0.8 wt% CNF reached 150.54 J·g-1 and demonstrated superior compressive strength, compressive yield stress, and compressive modulus with a remarkably low leakage rate of just 8.57 % after enduring a 30-day leakage test.