知识与财富的链接
以三水乙酸钠-尿素共熔物、纳米蒙脱土为原料,采用熔融插层法制备低温水合盐复合相变储能材料,用XRD、SEM、FTIR和DSC测试了材料结构、结晶机理、成核性、过冷度、热性能及稳定性。研究结果表明,三水乙酸钠-尿素复合盐使纳米蒙脱土片层呈剥离形态,其片层相互搭建构成腔体包容复合盐;纳米蒙脱土作为成核剂使复合盐结晶温度提高18℃,晶粒尺寸减小;当纳米蒙脱土质量分数为33.3%时,所制备材料的过冷度比未加纳米蒙脱土时降低19℃,相变温度为32℃,熔融焓为132.0kJ/kg,纳米蒙脱土降低了复合盐的过冷度,避免了相变分层,赋予了复合盐成型性。
Nanocomposite phase change materials (PCM) at low temperature were prepared from sodium acetate trihydrate (SAT), urea and nano-montmorillonite (nano-MMT) by melt intercalation in a mixer. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR) and differential scanning calorimetry (DSC) were employed to study the composite constructure, crystal principle, nucleation mechanism, degree of undercooling, thermal property and stability of the mixed systems. The result indicated that nano-MMT formed exfoliated lamellas which could connect to each other in order to cover PCM. Nano-MMT,acting as an effective nucleating agent, increased the crystallization temperature by 18 ℃ and decreased the crystallite dimension. The novel composite material with 33.3 wt% nano-MMT kept excellent thermal energy storage performances as the latent was 132 kJ/kg and the melting point was 32 ℃. The composites’ degree of undercooling reduced by 19 ℃ compared to PCM without nano-MMT. The exfoliated nano-MMT lamellars could reduce degree of undercooling, avoide phase separation and keep the composites shaped.
