Experimental investigation of cushioning characteristics of ldpepolymermicroballoon syntactic foam for packaging applications

Abstract

Syntactic foams which can be classified as closed cell foams are a specific class of foam where the air voids are deliberately introduced into the matrix using prefabricated hollow microspheres made of polymers, ceramics, carbon or glass. This thesis elucidates a successful attempt to fabricate and investigate the properties of a syntactic foam constituting low-density polyethylene (LDPE) as the matrix material and polymeric microballoon (PMB) as the filler material. Syntactic foams of different densities were prepared using LDPE as matrix and varying the PMB concentration at 1 wt.%, 2 wt.%,3 wt.%, 4 wt.% and 5 wt.% through the in-mould processing method. The prepared syntactic foams were analysed to assess the suitability for packaging applications specifically cushioning. A reduction of density by 65% has been achieved for the syntactic foam containing 5 wt.% of PMB as compared with that of the solid matrix material. The samples were tested for the compressive strength, tensile strength and flexural strength at various strain rates to study the strain rate dependent material behaviour. A new methodology to calculate the peak stress values from the compressive test data has been proposed. Using the calculated peak stress values of the prepared syntactic foam, the energy absorption characteristics were represented through the Energy Absorption Diagram and Rusch s curve . The variations in the tensile and flexural behaviour of the prepared syntactic foam were analysed with respect to strain rate and density of the syntactic foam. Foams, in general, are vibration dampeners. The vibration loss factor and the damping ratio of the prepared foams were analysed by subjecting the syntactic foams to free vibration as per the OBERST beam method. The syntactic foam samples were subjected to impact from various drop-heights using a drop-weight impact setup and theimpact and shock absorption characteristics were analysed with respect to varying impact energies. newline