Zirconia-dispersed polyethylene glycol composites with a low temperature-degradation rate

The effect of tetragonal-zirconia nanoparticle inclusion on the temperature-dependent storage modulus, or the temperature-degradation rate, of polyethylene glycol (PEG)-based composites was investigated using shear-mode dynamic mechanical analysis (DMA) at temperatures ranging from room temperature up to 75°C. We carried out further investigations in the rubbery area in terms of the characteristic of the degradation rate with temperature and compared it with silica-quartz-filled PEG composites, which exhibited a potential as phase-change materials (PCMs). The investigation began by plotting the shear storage modulus (G′) of the composites and observing the slopes of the curves in the range of the rubbery area, which were assumed to follow a straight-line equation. Then, we completed the investigation by developing and introducing a temperature-dependent storage modulus model in the rubbery area for describing the storage modulus of such filler-dispersed PEG/inorganic composites, to yield the degradation rates of the composites. The new model includes parameters k₁ and C that are associated with the degradation rate and the amount of a filler, respectively. The model shows a satisfactory agreement with the experimental data of G′ in the rubbery area, being parameter k₁ is associated with a linear degradation rate.