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Flammability performance and the microstructure of chars from poly(vinyl alcohol) (PVA) with α-type zirconium phosphate (α-ZrP) and montmorillonite (MMT) hybrid composites and multilayer composite were elucidated with microscale combustion calorimetry (MCC) and scanning electron microscopy (SEM). MCC revealed that the combination of α-ZrP and MMT did not impart synergistic effect in improving flame retardancy to PVA/ZrP/MMT hybrid composites, while multilayer composite showed better flame-resistant properties than hybrid composite. SEM demonstrated that the minimal loading levels of MMT in PVA/ZrP/MMT composites obstructed the development of intumescent chars in hybrid composites, but on-site mechanically reinforced the intumescent char in multilayer composite.

The mechanical properties and flame retardancy of linear low-density polyethylene/ethylene-propylene-diene terpolymer thermoplastic elastomers (TPEs) containing magnesium hydroxide sulfate hydrate (MHSH) whiskers and their corresponding un-vulcanized blends (UVBs) were evaluated using static tensile measurements, cone calorimetry and limiting oxygen index (LOI) tests. TPEs exhibited better fire-resistant properties in reducing peak heat release rate and improving LOI values to UVBs. Scanning electron microscopy (SEM) images showed that TPE sample left a more compact char after cone test. Results from tensile tests confirmed that TPEs had superior mechanical properties to UVBs due to the better compatibility between MHSH whiskers and polymer matrix.