Baljinder Kandola

Unsaturated polyester resin (UP), cured (crosslinked) with styrene, is probably the most widely used thermosetting resin in composites for marine, rail and construction sectors. However, a major drawback of cured UP is that it is highly flammable, largely owing to the copious amounts of flammable styrene evolved in a relatively low temperature depolymerization process, that burn with the production of a dense smoke. The chemical modification of the base resin or the crosslinker with halogenated elements, is the most common and effective method of rendering UP resin flame retardant. An alternative method of fire retarding is to blend UP with micro/nano particulate flame retardants (FR) or additional inherently flame retardant/char forming resins. This chapter discusses the effect of the FR blending component on the curing and morphology of the resin. The thermal stabilities and fire performances of the blends are also discussed.

Conventional flame retardant (FR) application processes for textiles involve aqueous processing, which for the creation of durability to laundering, often requires conventional functional group chemistry. Recently reported research using sol-gel and layer-by-layer chemistries, while claimed to be based on superior, more environmentally-sustainable chemistry, still require aqueous media with the continuing problem of water management and drying processes being required.
This paper outlines the initial work to confer durable flame retardant treatments to cellulosic textiles using a novel process utilizing high frequency high power electrical discharge atmospheric plasma and high powerUV laser facility for processing textiles with the formal name - Multiplexed Laser Surface Enhancement (MLSE) system. This patented system (MTIX Ltd., UK), offers the means of directly bonding flame retardant precursor species introduced into the fabric before plasma/UV exposure or into the plasma/UV reaction zone itself, thereby eliminating a number of wet processing cycles compared to conventional methods.
Exploratory work to date based entirely on trial and error processing has managed to achieve reasonable levels of durable flame retardant on cellulosic and wool textiles. Initial studies undertaken on upholstery quality, cellulosic blended fabrics (e.g. 80% viscose/20% linen) are described in this paper.

This work explores the possibility of reducing the flammability of unsaturated polyester (UP) resin, commonly used in marine composites, by co-blending with less combustible and char-forming resins such as phenol-formaldehyde, melamine-formaldehyde and furans. The compatibility and curing properties of UP, other resins and their blends in 50:50 wt-% ratios have been have been studied by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) techniques. Based on the successful establishment of curing conditions, plaques of resins have been cast and cured. Thermal stability has been studied by thermogravimetry (TGA), whereas the fire performance evaluation was carried out by limiting oxygen index (LOI) and cone calorimtery at 50kW/m2 heat flux. According to a fire risk assessment based on cone calorimetric data, the resole phenolic resins and their blends with UP achieved the highest fire safety rating.

This work presents the effect of a nanoclay and/or phosphorus/halogen based flame retardants on melt and burn dripping behavior of polypropylene. An experimental setup has been constructed to record the real-time melt-dripping behavior in a furnace. All experiments were repeated in a UL-94 set-up to replicate their melt dripping behavior in flaming conditions. A relationship between melt viscosity/rheology and melt dripping intensity of these polymers has been studied. The physical and chemical changes occurring during melt dripping have also been studied by conducting thermal analysis and rheology experiments on molten drops and comparing them with those of respective original polymer samples. The results have shown that during melt dripping a polymer degrades to a considerable extent and its viscosity is affected by the action of the flame retardant at that particular temperature range.

The effect of different flame retardant types on the thermal stability, flammability and char formation tendency of polypropylene (PP) nano/micro composite is studied. PP, compatabiliser, nanoclay, UV-stabiliser and different flame retardants have been compounded in a twin screw extruder to produce polymers with improved thermal and flame retardant properties. Thermal analysis has been used to study the thermal properties, and limiting oxygen index (LOI) and slightly modified UL-94 test for flammability of the samples. All flame retardants acting in the condensed phase (phosphorus- and nitrogen- containing) lowered the rate of decomposition, whereas halogenated flame retardants had a little effect. The addition of nanoclay with or without flame retardants increased the thermal stability of all samples and helped in char formation. All samples with flame retardants and no clay, burnt completely, which is not unexpected, given the low levels (5%) of flame retardants used here. However, the flame spread was low. On addition of clay to the compounded polymer, a change in burning behaviour was observed, flame spread was reduced and samples self-extinguished, except for the one containing melamine phosphate. A tube furnace was used for char formation at different temperatures and the charred structures have been examined with digital images, optical and scanning electron microscopy, and FTIR. This information has been used to understand the mechanisms of thermal degradation of different flame retarded PP - nano/micro composite samples.

Polypropylene fibres are widely used in manufacturing upholstery fabrics for domestic and office furniture, automotive and floor coverings. Flammability is becoming an increasing issue of priority for all sectors of the textile industry due to public safety awareness and stringent legislation controlling the use of products in different sectors There are several standard test methods developed in different countries across the world for testing their fire performance, each test having different criteria to meet .The behaviour of polypropylene -containing fabrics that are considered to be manufactured from the same raw material, construction and manufacturing process show variations in their burning behaviour especially when subjected to an external heat flux in addition to a small igniting flame.This paper attempts to correlate fibre, yarn and fabric variables including area density, air permeability, yarn/fabric colour, the effect of colouring pigment on fibre thermal degradation with final fabric flammability performance.

For the use of fibre-reinforced polymeric composites as structural materials for different applications, the associated fire risks and their assessment are crucial. For critical applications especially, most products have to conform to certain specified fire performance requirements and regulations. Another important issue is the mechanical performance of these composites during heat/fire exposure and the residual strength. This chapter reviews the key issues and performance requirements for load-bearing fibre reinforced polymer composites for various sectors of the industry. Several ways of improving their fire resistance are discussed and their effectiveness assessed by post-fire mechanical property evaluation.