applications | Wood-plastics composites The new material absorbs very little water: even


after being immersed in boiling water for five hours, it emerges intact. The only limiting factor is its inability to support high static loads – but even here its bending strength exceeds that of conventional particle board. Mexico-based Plastinova has devised a way to recycle


plastics and combine it with tequila agave bagasse – similar to wood fibre, but with greater resistance – to make products for the construction industry, or in the manufacture of benches, tables and chairs. The formulation comprises 10-35% agave fibre,


Above: Fraunhofer’s WPCs for bathrooms and kitchens absorb very little water


To define the design procedure, two flow rate


distributions were compared: that obtained when the complete extrusion die flow channel was modelled; and that of the reduced model, limited to the parallel zone. Extrusion results showed good correlation between


predicted and actual results. For each trial, the individual contribution of the ES allowed the most critical regions to be identified – which were adjusted for subsequent trials. “This process was shown to be effective, and should


be explored on future automatic design schemes,” said the researchers. The methodology also created WPC profiles of the correct dimensions, they added.


Bathroom boards Scientists at the Fraunhofer WKI Institute for Wood Research have helped to develop a suite of wood-plastic composites (WPCs) for use in bathrooms and kitchens. As part of the pan-European Limowood project, the


Right: Plastinova’s


new material uses waste from the


tequila industry


team has developed a WPC for internal use that also has low flammability. It has made a series of boards comprising 60% wood and 40% plastic – usually polyethylene (PE) or polyproplylene (PP). Both wood and plastic can be sourced from recycling streams. Fibres from plants like hemp or cotton, or the husks


of rice grains and sunflower seeds, can be used to replace the wood. The pressed WPC boards made by WKI are formaldehyde-free. “The question of formaldehyde emissions due to the binder used in conventional pressed wood products is not an issue in this case,” said WKI research scientist Arne Schirp. Choosing a combination of additives – such as red phosphorus and expanded graphite – the researchers enhanced the fire-retardant properties of the WPC boards, achieving a limiting oxygen index of 38%: this figure is around 27% for standard wood particle board and 19% for untreated WPC board.


70 COMPOUNDING WORLD | June 2016 www.compoundingworld.com


together with a recycled plastic matrix. The material can replace wood or aluminium in a number of structures according to Alberto Medina-Mora Urquiza, one of four founding partners of the company. Agave bagasse is often difficult to obtain because


companies use it as fuel for boilers. But Plastinova is based in Jalisco, in western Mexico, where tequila is produced, and reached an agreement with two local companies to harness the waste plant. To process 100kg of agave takes about 36 hours, and


it takes a further day to convert the fibre into a tonne of pellets or beads of recycled plastic, from which the boards are manufactured. They measure 1.20 x 1m, and are 10cm thick. First, the alcohol, sugar, bone and shell is removed


from the agave bagasse, leaving only the fibre for cleaning. After that it is dried, ground and pulverised, to obtain a flour-like powder. A compatibilising agent is also added to the fibre, altering the chemical composi- tion of the waste to make it more resistant and compat- ible with various types of plastics, such polypropylene and high density polyethylene (HDPE). One of Plastinova’s future plans is to replace agave fibres with ones from coconut, since according to their


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