Thermoplastic composite beam structures from mixtures of recycled HDPE and rubber crumb for acoustic energy absorption

Abstract

The use of recycled rubber crumb in the design and production of thermoplastic-rubber composites as sound absorbers can provide solutions to noise pollution and for the recovery of post-consumer materials from both packaging and waste tyres. The work of this study is concerned with the effect of rubber crumb incorporation in high-density polyethylene (HDPE) and also in HDPE glass fibre composites on acoustic, mechanical and physical properties. Recycled HDPE compounds containing variable concentrations of cured rubber crumb particles were prepared by twin screw extrusion. Thermal analysis has revealed a significant increase in the level of crystallinity of the HDPE component by increasing the rubber content in the mixes. Standard three-point bending and notched impact test specimens were manufactured by injection moulding, and large-scale beam samples were produced by compression moulding using an ad hoc method that allows variation of the through-thickness elastomer content as a means of obtaining composition gradients. The flexural modulus and impact strength varied monotonically with rubber crumb concentration. A fast Fourier transform technique was used to determine the acoustic performance of the beams over a wide frequency range. The graded structures produced large improvements in acoustic absorption properties in the frequency range of 2–6 kHz, notably from composite beams containing 20% rubber and also in some multilayer beams with rubber concentration gradients.

The effect of lamina configuration on low-velocity impact behaviour for glass fiber/rubber curved composites

“…Experimental studies in the literature have indicated that rubber reinforcement improves the ballistic, mechanical and acoustic properties of composites. [2][3][4][5][6][7][8] When the usage areas of composite materials are considered, curved surfaces are more frequently encountered due to structural design when compared to flat surfaces. Curved composite structures that are exposed to impact load are observed in many fields such as aircraft fuselage, nose and wings in the aviation industry, helmets and armours in the defence industry, and vehicle body, roof and side frames in the automotive and transportation industry.…”

Effects of Lignocellulosic Fillers from Waste Thyme on Melt Flow Behavior and Processability of Wood Plastic Composites (WPC) with Biobased Poly(ethylene) by Injection Molding

“…[9] pointed. The processing conditions [10] and the material characteristics [11] are the key parameters in injection molding. The WPCs industry will have to face a key challenge in the following years, which is the use of conventional injection molding equipment to obtain high filler content WPCs with complex shapes.…”