FOAMED SHEET | MATERIALS
Foamed sheet is finding use in a diversity of applications – including transport, construction and the food industry. Lou Reade reports
Taking the air: advances in plastic foamed sheet
Foamed products help to save weight if they can be used in place of their ‘solid’ equivalents – and so can find use in a diversity of applications. For instance, Sekisui Alveo says that the latest
application of its Alveolen NL LV polyolefin foam is an air duct made by automotive component supplier Linecross for the LEVC TX taxi – an electric version of the iconic ‘black cab’ of London. “This material is fine tuned to the needs of twin-sheet forming companies producing air ducts for automotive applications,” said Thomas Ross, business unit manager for Sekisui Alveo. “It offers the exceptional combination of fast heating and welding at low temperatures with high stiffness – which makes for fast and easy conversion.” Alveolen NL LV was developed specifically for use in an advanced vacuum twin-sheet thermoforming process in which two layers of foam are simultane- ously formed and welded into a lightweight, flexible air duct. Not only is the material optimised for vacuum forming, but it complies with the automo- tive industry’s standards for emissions, flammability,
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and chemical and temperature resistance. The ‘LV’ designation signifies low emissions. The material’s low thermal conductivity has been achieved through a combination of special resins and a high degree of material expansion. By varying the resins, thickness, and density, Sekisui Alveo can optimise its foams in terms of conversion (including cycle times, deep draw and welding) and application-related properties (such as weight, insulation value, stiffness and acoustics). Foam was chosen for key elements of the air duct system because it offers advantages over solid plastic: its high thermal insulation improves the response time of the climate control system, saves heating/cooling energy, and eliminates any problems with condensation, says Sekisui. At the same time, the lightweight material helps to reduce the car’s weight, improve vehicle efficiency, and allow more payload. Foams can be designed stiff enough to provide
reliable form stability of the ducts. Because they are more flexible than rigid materials, the ducts can be
December 2018 | FILM & SHEET EXTRUSION 13
Main image: Sekisui Alveo’s polyolefin
foam is used in an air duct in the LEVC TX electric taxi
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