Development of multi-layer fibrous composites for fire resistant and sound insulating doors

Abstract

This paper reports the development of new type of composite materials based on multilayer concept. The multilayer composites were mainly composed of waste fibre based nonwoven fabrics, woven glass fibres and wood layers. Each of these layers was designed to operate with different functionalities; but when these layers were combined into a single composite, these functionalities were expected to work together. This particular aspect allowed to develop a single structure for fire doors (fire resistance time of more than 90 min), as well as to get a better acoustic insulation behaviour (up to 47 dB). The multilayer structure was comprised of different layers such as MDF panels (2 mm), woven glass fibre layer (220 and 400 g/m2 ), wood materials (10 mm), woven glass fibre (220 and 400 g/m2 ) and waste fibre based no-woven fabrics (3 different types). Composite panels were produced using these combinations in a compression moulding machine using two types of thermosetting resin systems. Acoustic insulation behaviour of these composites was characterized using a method similar to the one applied in the EN ISO 140-3 standard. In this testing method, a white noise was applied in an insulated chamber and the noise level (in decibels, dB) for various frequencies was measured in the first and second compartments of the chamber. The difference between the noises measured in those two compartments, called the noise reduction coefficient (α), was used to assess the acoustic insulation behaviour. It was observed that a good noise reduction coefficient (up to 47 dB) was observed in case of developed composite materials at 500 Hz frequency. It was also observed that increasing the thickness of the panels was not found beneficial for sound reduction capacity and the use of non-woven fabrics in the panel increased the noise reduction coefficient significantly.