| Summary: | The Underwriters Laboratories 94 Vertical Burning Test (or UL-94 V Test) is widely used to assess the fire performance of polymers and polymer composites. However, this test is largely based on visual observations of its ignition, burning rate and drip formation, if any, and a corresponding UL-94 V rating is assigned (V-0, V-1 or V-2), otherwise non-rated (NR). However, this test does not provide further scientific information on the flammability properties of materials. While there have been many mechanistic studies on the methods to achieve UL-94 V-0 rating, the reasoning behind why this is achieved is not well-established. This project aims to establish the critical parameters affecting the burning behaviour of polyamide 6 (PA6) and its composite in UL-94 V Tests and to understand their burning behaviour in UL-94 V Tests.
Various flame-retardant polymers are formulated by extruding the flame retardants with neat PA6 and flame-retardant carbon fibre-reinforced composites (CF/PA6) are also developed. The burning behaviour of both polymers and composites, both neat and flame-retardant, are then studied. The material and thickness dependency of the burning behaviour of polymers and composites had been established and the peak core temperature is found to be associated with the UL-94 V rating. Cone calorimetry also shows the difference between the burning behaviour of polymers and composites and the correlation of cone calorimetric parameters with the UL-94 V rating is also established.
Due to the difference in burning behaviour in polymers and composites, a clearer association between these parameters and UL-94 V Ratings is observed when composites are considered separately from polymers. The result of this project provides insight into the burning behaviour in both UL-94 V and Cone Calorimetric Tests. However, this understanding can be further enhanced by performing similar tests on more formulations, to obtain a generalised approach to achieve UL-94 V-0 rating for polyamide 6 and its composite systems.
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