Weibo Kong

Preparation and thermal properties of crosslinked polyurethane/lauric acid composites as novel form stable phase change materials with a low degree of supercooling

In this article, a series of crosslinked polyurethane/lauric acid composites was prepared as form stable phase change materials (FSPCMs) through a brief and solvent-free method. In the FSPCMs, lauric acid functioned as a phase change substance, and crosslinked polyurethane simultaneously functioned as a supporting material and phase change substance. Compared with traditional supporting materials in FSPCMs, the crosslinked polyurethane here obviously reduces the loss of latent heat from the supporting material and reduces the degree of supercooling of the obtained FSPCMs. The obtained FSPCMs were extensively studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), polarizing microscopy (POM), differential scanning calorimetry (DSC), thermal cycling tests and thermogravimetric analysis (TGA). The FTIR confirmed the chemical structure of the obtained FSPCMs. The XRD and POM results indicated that the FSPCMs exhibit comprehensive crystalline properties of polyurethane and lauric acid. DSC data showed that the FSPCMs have superior phase change properties with the phase change temperature and latent heat in the range of 26–38 °C and 90–131 J g−1. Moreover, low or no supercooling of the obtained FSPCMs was detected by DSC. The phase change temperature is suitable in the fields of solar energy saving and building engineering. Thermal cycling tests and thermogravimetric analysis (TGA) proved the good thermal reliability and stability of the obtained FSPCMs.

Preparation and characterization of a water resistance flame retardant and its enhancement on charring–forming for polycarbonate

Hexakis(4-nitrophenoxy) cyclotriphosphazene (HNTP) was synthesized and was added into polycarbonate (PC) functioned as intumescent flame retardant and charring agent. The chemical structure of HNTP was confirmed by hydrogen and phosphorus nuclear magnetic resonance (1H-NMR, 31P-NMR), energy-dispersive spectroscopy and Fourier transform infrared (FTIR). Flame retardancy and charring–forming behaviors of HNTP- and PC-based composites were extensively investigated with the limiting oxygen index, UL-94 vertical burning test, microscale combustion calorimeter (MCC) and thermogravimetric analysis. The water resistance of PC-based composites was studied by stationary water contact angle measurements. Furthermore, TG/FTIR was used to research their gaseous products and their releasing intensity during the decomposition. The morphology and chemical structure of residual char were used to study scanning electron microscopy (SEM) analyses and FTIR spectroscopy. The mechanical properties of samples were compared by tensile and impact tests.

Preparation and investigation of solid polymer electrolyte based on novel polyamide elastomer/metal salt

Antistatic-polyamide elastomers composed of poly(urethane-urea-amide) (PUUA) and NaSCN was successfully synthesized through in-situ reactive processing in double-screw extruder. The obtained antistatic-polyamide elastomers can be employed as solid polymer electrolyte to improve the surface conductivity of polymers. The effect of PUUA composition, NaSCN content, temperature and relative humidity on the surface resistivity of antistatic-polyamide elastomer was extensively studied by surface resistivity. The results showed that the surface resistivity of antistatic-polyamide elastomer was slightly influenced by temperature and relative humidity, and can satisfy the application of antistatic materials requirement. Moreover, thermalgravity analysis (TGA), tensile test and scanning electron microscopy (SEM) were used to evaluate the thermal stability, mechanical properties and morphology of fracture face of antistatic-polyamide elastomers. TGA results demonstrated that antistatic-polyamide elastomers have a good thermal stability with the onset decomposition temperature exceed 280?. Tensile tests revealed that the prepared antistatic-polyamide elastomers possess good mechanical properties. SEM showed that the antistatic ability of antistatic-polyamide elastomer is relative to the ion-conductive channels or network formed by the PUUA and NaSCN particles.