Effect of Mg(OH) ₂ nanoparticles on thermal, mechanical and morphological properties of millable polyurethane elastomer

Millable polyurethane (MPU) rubber nanocomposites were prepared on a two-roll mill and molded on a compression molding machine. The amount of loading of Mg(OH) 2 nanoparticles ( nMg(OH) 2 ) was from 0.5 to 2.5 wt% followed by the addition of dicumyl peroxide (as a curing agent). The compounded matter was subjected to compression molding so as to get a cure sheet (130 × 130 × 3 mm). Mechanical (tensile strength, elongation at break (%) and abrasion resistance index), physical (hardness and swelling index), and thermal properties (flammability retardency and degradation stability) were studied. The extent of dispersion of nMg(OH) 2 particles was studied using scanning electron microscope and atomic force microscope. nMg(OH) 2 was synthesized using continuous ultrasonic cavitation technique. The size and shape of nMg(OH) 2 was confirmed using X-ray diffraction and transmission electron microscopy, which was found to be ∼20–60 nm with quasi shape. MPU:nMg(OH) 2 nanocomposites show improved mechanical, physical, and thermal properties compared to pristine MPU. This improvement was due to very fine grain size of nMg(OH) 2, which facilitates uniform dispersion of nMg(OH) 2 within MPU rubber matrix. However, higher loading of nMg(OH) 2 shows marginal decrement in properties due to agglomeration, especially at 2.5 wt%.