Rotational-Moulded Building Blocks for the Circular Economy

Throughout the combination of unique approaches on innovative polymer composites and rotational moulding plastics processing technique, we developed a building block using a mix of recycled and virgin plastic. This block was a technical case study from a multidisciplinary approach - comprising materials science, polymers processing and design - to reinsert recycled plastics in the Circular Economy. The aim was to produce a three-dimensional interlockable block, combining unique design and unconventional materials to create an emblematic building element. We investigated the composition and availability of local plastic waste, as well as other waste-stream materials – concrete waste, red mud, hemp fibre, sugarcane bagasse. We prepared a range of composites and blends to test their prospective aspect and processability. To simulate the end-result of a rotationally-moulded part, we prepared samples of the blends in an oven. The thermal analysis showed that all materials were thermally stable at the processing temperature of the virgin polymer in rotomoulding, around 200 °C. There were an evident LLDPE continuous-phase and a recyclate dispersed-phase. We also explored the aesthetic effect of scattering particles of colour in the mixes. The impact test showed better results for the polyethylene-based recyclates if compared to polypropylene and poly (ethylene terephthalate) ones. We concluded that waste materials could be revalued into something practical and reproducible, produced by rotational moulding plastics processing. And we developed a viable and innovative potential product for the Circular Economy, requiring minimal fixing and no further external finishing.

An Experimental Investigation on Short and Long Fiber Reinforcement in Tampico and Palymira Reinforced LLDPE Produced by Rotational Moulding Process.

Rotational moulding is a powder processing technology widely used to manufacture hollow plastic products. It is a well-known process used for the manufacturing of large containers, water tanks, fuel tanks, refrigerated containers etc. The present work aimed at the incorporation of Tampico and Palmyra fibers as reinforcement in Linear Low-Density Polyethylene (LLDPE) matrix. The effect of fiber length on various properties like mechanical, morphological and vibration damping characteristics of the composites were investigated. The fibers were initially treated with 5% NaOH solution for better reinforcing efficiency and to improve the degradation temperature. Thermo Gravimetry Analysis (TGA) reported that a sufficient increment in degradation temperature is achieved by NaOH treatment on fibers. The short fiber composites considered for the study has obtained better mechanical strength than long fiber reinforced LLDPE composites. The results proved that fiber length has less effect on the vibration damping characteristics of the composites, but the percentage of fiber content is a significant factor for improving the natural frequency of the composites.