Title : Enhanced flame retardancy and mechanical properties of high-density polyethylene (HDPE) reinforced with organically modified sepiolite clay
Abstract:
High density polyethylene (HDPE) has been known for being lightweight and tunable functional polymer possessing strong intermolecular forces and reasonably good tensile strength, with a potential of transforming into composite materials having superior mechanical properties. For example, increase in tensile strength, hardness and fracture resistance was observed by incorporating micro stearic acid coated nano clay. Other properties include moldability, resistance to corrosion recyclability etc. However, its high risks of flammability for important industrial applications, needed to be addressed. In this research, HDPE was reinforced with modified sepiolite clay, using vinyl tri-ethoxy silane (VTES) as coupling agent and di-methacrylate (DMC) to facilitate the crosslinking process, using a solvent-free melt extrusion process.
Structural analysis of neat and lyophilized sepiolite clay, while neat HDPE and HDPE/ sepiolite nanocomposites were analyzed through FTIR, which confirmed the modification of sepiolite clay and its successful incorporation in HDPE due to silane coupling which appeared through Si-O-C peak. Morphologies of the samples as witnessed through SEM, showed better interfacial adhesions and uniform dispersion of filler. 28% increase in tensile strength was exhibited by the developed nanocomposite. Thermal stabilities were explored using TGA, where the amount of percent residue increased up to 23%. Phase transition behavior of neat HDPE and HDPE/ m-sepiolite nanocomposites were observed through DSC analysis, where an increase in glass transition temperature Tg was observed, depicting clay entanglement and nucleation due to hydrogen bonding that restricted the molecular motion. Flame retardancy was observed as per ASTM D4986-20 method, which revealed that the burning rate was decreased up to 35 %, by incorporating 4 wt.% of the m-sepiolite clay.
