writer：Zhengyu Feng, Jia Guo, Yongxin Yan, Jun Sun ,* Sheng Zhang *, Wenjia Wang
keywords：Polylactic acidMesoporous silicaPhosphotungstic acidCombustionDegradation
source：期刊
specific source：Polymer Degradation and Stability, 2018,160,24-34
Issue time：2018年

Highly ordered mesoporous silica (SiO2) modified with phosphotungstic acid (PWA), was successfully prepared by vacuum impregnation. The chemical structure of as-designed PWA-mesoporous silica (PWA-SiO2) was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectra and small-angle X-ray scattering. PWA-SiO2, in association with intumescent flame retardant (IFR), was introduced into polylactic acid (PLA) by melt blending to obtain flame resistant composites. The flammability evaluation indicated that the presence of 19.0?wt% IFR and 1.0?wt% PWA-SiO2 in PLA achieved the maximal LOI value of 47.2%, passed the UL-94 V-0 rating, and significantly decreased the peak heat release rate from 622.4?kW?m?2 of neat PLA to 182.3?kW?m?2. The introduction of PWA-SiO2 could also slightly improve the mechanical properties of PLA composites. It is proposed that PWA-SiO2, which exhibits excellent catalytic effect, can play roles together with IFR in both condensed phase through promoting the formation of continuous dense char layer and gas phase through releasing non-flammable gas.

Schematic of the preparation process of PWA-mesoporous silica