Effect of trimethylolpropane triacrylate cross-linkages on the thermal stability and char yield of poly (methyl methacrylate) nanocomposites

Publication date: January 2017
Source:Fire Safety Journal, Volume 87
Author(s): Logan C. Hatanaka, Qingsheng Wang, Zhengdong Cheng, M. Sam Mannan
Using an in-situ polymerization method, poly (methyl methacrylate) (PMMA) cross-linked by trimethylolpropane triacrylate (TMPTA) was embedded with nanosilica, aluminum oxide, or modified montmorillonite to produce various cross-linked nanocomposites. The same three nanofillers were also embedded into PMMA without TMPTA cross-linkages to quantify the effect of TMPTA cross-linkages on the thermal stability and char yield of nanocomposites. Data from Thermogravimetric Analysis (TGA) and Derivative Thermogravimetric Analysis (DTG) were used to show that cross-linking and nanofiller content act synergistically to improve the thermal stability of PMMA, increasing the on-set of degradation by nearly 100°C. The increase in thermal stability was attributed to the elimination of low temperature end initiated polymer unzipping by TMPTA cross-linkages and simultaneous stabilization of remaining degradation reactions due to nanofiller content. Char formed during a fire accumulates on the surface of the nanocomposite, forming a barrier that protects any unburned material below the surface. The DTG data showed nanocomposites containing 1wt% silica in PMMA cross-linked by TMPTA produced 14.1% char residues, while nanocomposites without TMPTA cross-linkages required five times the mass of nanofiller to achieve similar yields.

Graphical abstract

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