Synergistic effect of allophane with intumescent flame retardants on thermal behavior and fire retardancy of polypropylene

Polylactide (PLA) is one of the most widely used organic bio-degradable polymers. However, it has poor flame retardancy characteristics. To address this disadvantage, we performed melt-blending of PLA with intumescent flame retardants (IFRs; melamine phosphate and pentaerythritol) in the presence of organically modified montmorillonite (OMMT), which resulted in nanobiocomposites with excellent intumescent char formation and improved flame retardant characteristics. Triphenyl benzyl phosphonium (OMMT-1)- and tributyl hexadecyl phosphonium (OMMT-2)-modified MMTs were used in this study. Thermogravimetric analysis in combination with Fourier transform infrared spectroscopy showed that these nanocomposites release a smaller amount of toxic gases during thermal degradation than unmodified PLA. Melt-rheological behaviors supported the conclusions drawn from the cone calorimeter data and char structure of the various nanobiocomposites. Moreover, the characteristic of the surfactant used for the modification of MMT played a crucial role in controlling the fire properties of the composites. For example, the nanocomposite containing 5 wt.% OMMT-1 showed significantly improved fire properties with a 47% and 68% decrease in peak heat and total heat release rates, respectively, as compared with those of unmodified PLA. In summary, melt-blending of PLA, IFR, and OMMT has potential in the development of high-performance PLA-based sustainable materials.

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Effects of heterionic montmorillonites on flame resistances of polystyrene nanocomposites and the flame retardant mechanism

Journal of Composite Materials ◽

10.1177/0021998317724861 ◽

2017 ◽

Vol 52 (10) ◽

pp. 1295-1303 ◽

Cited By ~ 9

Author(s):

Yijiao Xue ◽

Mingxia Shen ◽

Fengling Lu ◽

Yongqin Han ◽

Shaohua Zeng ◽

...

Keyword(s):

Flame Retardant ◽

Flame Retardants ◽

Reducing Power ◽

Infrared Analysis ◽

X Ray Diffraction ◽

Flame Resistance ◽

Cone Calorimeter Test ◽

Intumescent Flame Retardants ◽

Thermal Stability Of ◽

Better Than

To improve the flame resistance of polystyrene, three kinds of organophilic heterionic montmorillonites (Na-montmorillonite, Ca-montmorillonite, and Fe-montmorillonite) reinforced polystyrene nanocomposites were prepared by melt dispersion method. The structure and composition of the organo montmorillonites were characterized by using X-ray diffraction and Fourier-transform infrared analysis. The adhesion between organo montmorillonites and polystyrene was investigated by scanning electron microscopy. The flame resistance and thermal stability of the polystyrene/organo montmorillonites were evaluated by cone calorimeter test and thermogravimetric analysis. The interlayer space of organo montmorillonites increased with the increase of the oxidation state of the cations. With the addition of organo montmorillonites, the peak values of all the flame resistance indexes of the polystyrene/organo montmorillonites nanocomposites decreased, among which the PHRR values have decreased the most, compared with those of polystyrene. Their corresponding test times have all been delayed following almost precisely the same trend. Therefore, their flame retardant ability come from their lamellated structures, their charring forming abilities, and the reducing power of Fe3+ in polystyrene/Fe-montmorillonite. Organo montmorillonites mainly act as a kind of intumescent flame retardants. The flame resistance of polystyrene/Na-montmorillonite nanocomposite was the best, and the polystyrene/Ca-montmorillonite came second, which is slightly better than that of polystyrene/Fe-montmorillonite.

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