Flammability and thermal properties of modified carbon nanotubes in poly(lactic acid)

Abstract

The multi-walled carbon nanotubes (CNTs) were modified using phosphaphenanthrene compounds (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)) and vinyl triethoxy silane (VTES) by covalent bond. The DOPO- and VTES-treated CNTs were named DVCNT, and the structure was characterized by Fourier transform infrared, thermogravimetric analysis, and transmission electron microscopy. Nanocomposites were prepared by adding CNTs or DVCNT to poly(lactic acid) (PLA), and the flame retardancy was examined by determination of limiting oxygen index (LOI), vertical burning (UL94), and cone calorimetry. Results reveal that the LOI of PLA/DVCNT_4% composites was increased to 26.6 and prevents dripping of PLA in some level, and DVCNT can significantly reduce heat release rate and mass loss rate during combustion, which indicate that DVCNT can improve the dispersibility of the CNTs in the polymer composites and hence enhance the flame retardancy simultaneously.

Rigid Polyurethane Foams Containing Modified Ammonium Polyphosphate Having Outstanding Charring Ability and Increased Flame Retardancy

“…The formation of the intumescent char layer was due to uniform dispersion of APP after coating on the one hand and the surface treatment agent PCOC acting as the carbon source on the other hand; so the carbon layer presented a typical morphology of the intumescent char layer. It is well known that the char layer can block the transfer of oxygen and heat, which decreased the combustion intensity of materials (Chen et al, 2016;Chen et al, 2017c;Li et al, 2018;Guo et al, 2019;Xu et al, 2019). From Table 4, the char yield of RPUF/MAPP-1000 reached 36.5% at 400 s. The results indicated that MAPP-1000 with a high degree of polymerization was more conducive to promoting the formation of the intumescent char layer with higher thermal stability.…”

A review on the processing–morphology–property relationship in biodegradable polymer composites containing carbon nanotubes and nanofibers

“…Biopolymers show low LOI values because they are highly flammable and ignitable. For instance, the LOI reported for PLA was 19% [156] and 19.5%, [155] and 21% for PBS. [164] However, other reported LOI values are greater than 21% for neat biopolymers, for example, the reported LOI values of PBAT were 22.8% [165] and 24.5% for PBS.…”

“…This has been mostly carried through the incorporation of flame-retardant materials such as intumescent flame retardants, nitrogen and phosphorus-based compounds, inorganic and organic materials, and halogencontaining compounds. [153][154][155] Nevertheless, halogenbased flame retardants have the disadvantage of releasing toxic gases and increases smoke release; hence, they are no longer favorable. [154] Although flame retardants are efficient in improving the flame resistance of polymers, large amounts are required, which occurs at the expense of other properties.…”

“…Similar behavior was also reported in DOPO-vinyltriethoxysilane (VTES)-modified CNT, which showed an increase in LOI of PLA to 26.6%. [155] Functionalized CNTs have better dispersion, which explains large improvements compared with unmodified CNTs.…”

Recent Advances in Characterization Techniques for the Interface in Carbon Nanotube-Reinforced Polymer Nanocomposites

“…Covalent functionalization can significantly improve the overall thermal performance for carbon nanotube-reinforced polymer nanocomposites due to a great increase in the thermal conductance of the interface [229,231]. However, excessive chemical functionalization will damage the intrinsic thermal properties of carbon nanotubes [244][245][246][247].…”