Arthur Richard Horrocks

This chapter concentrates on research reported over the last 10-15 years which has some possibility of commercial exploitation with a view to replacing some of the currently used textile flame retardant finishing treatments and formulations, especially those with environmental concerns. In selecting research for this review, the major criterion has been the ability of a novel treatment or process to enable an ignited fabric to self-extinguish in a vertical strip test after being exposed to some durability treatment, ranging from a simple water soak to a number of cycles of a standard wash procedure.
Initially, strengths and weaknesses of currently used flame retardant treatments are discussed so that challenges posed in their replacement may be fully understood. This provides the basis for critically reviewing recent research into the replacement of formaldehyde-based finishes (particularly for cellulosics) and halogen-based textile back-coating formulations, for example. The more recent work into novel surface treatments, such as sol-gel, layer-by-layer and plasma-based research is also analysed in terms of the above criteria.
The chapter concludes by noting that most of these challenges still remain because much of the published academic research does not take into account the reasons for the effectiveness of current treatments, the need for them to be applicable by available processing technologies, their durability and their effects on textile aesthetics and properties as well as their potential costs

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.

The chapter considers the thermophysical and thermochemical factors that underpin the understanding of the heat resistance and flammability of the whole range of textile fibres and thus how the means of generating definable levels of flame retardancy and heat and fire resistance may be achieved. This in turn relates to the means of developing designed for specified levels of technical performance.
Fibres developed for fire and heat resistance may be divided into two groups principally those used in applications where ambient service temperatures are 100oC or less and those where temperatures may be in excess of this figure and often >150oC. Fibres in the first group are usually conventional fibres such as cotton and wool which have been flame retardant treated and man-made fibres like viscose, polyester, etc., which more often than not either contain flame retardant additives or copolymeric modifications.
Fibres in the second group are often referred to a heat and flame resistant fibres and comprise either highly cross-linked or aromatic chemical structures or are wholly inorganic, yielding ceramic fibres which may resist temperatures higher than 500oC for prolonged periods.
Within both these groups, current commercial examples are described and their respective applications identified together with national or international test protocols where relevant.

Survival textiles may be divided into two groups, the first being for short-term protection against extreme external conditions, such as occur during accidents, or against direct bodily injury, including ballistic or knife threats. The second group is where the protection must be provided for a longer period and so industrial and medical protective clothing assemblies as well as firefighters’ suits are examples here.
The underlying principles of fabric construction and garment design which have been found to optimize the level of protection on the one hand, coupled with the need to maximize comfort and minimize the often associated wearer stress, are outlined. Examples of currently available fabrics and personal protective clothing are presented together with related national and international standards which guarantee their desired levels of protection. Aftercare and cleansing requirements as well as future trends are also outlined.

Technical textiles feature throughout the transport sector where they are used in functional roles such as reinforcement in flexible composites, for example tyres, and rigid composites as structural elements. These latter function as metal replacements and so offer the main means of reducing overall vehicle mass to yield improvement in fuel efficiency. In parallel, increases in vehicle safety are driven by developments in technical textiles such as passenger seat belts and airbags. However, one essential feature that many vehicle components require, especially in passenger compartments, is a minimal level of fire resistance and as land, marine and air transport becomes more safety conscious, achieves higher velocities and capacities and increasingly uses composites within their structural components as a means of weight reduction, so the potential flammability of all materials used to construct them becomes of increasing importance.
This chapter is divided into three parts the first of which discusses technical textiles used as reinforcements of flexible and so-called mechanical rubber products which include tyres, hoses and drive beltings. Secondly, those products that increase passenger passive safety such as seat belts and airbags are outlined. Finally components and products which require certified levels of fire resistance, usually defined by international regulations and fire standards, are described for land, marine and air commercial transport. This section in particular, describes the major uses of technical textiles having both technical and aesthetic properties, especially within the passenger compartments, as well as composites for structural components, their respective fire risks, test regimes and favoured textile materials.

The principles of textiles requiring the properties of heat and fire protection are introduced within the context of the fundamental physical and chemical characteristics of component fibres and textile fabrics coupled with the underlying fire science requirements to understand the main textile design issues required. The large range of high performance fibres available for fire resistant end-uses is discussed in terms of generic chemical differences including the need for thermoset, totally aromatic or inorganic (ceramic) structures. The need for and types of fire resistant coatings and treatments are also introduced. Of especial relevance are the evolving technologies for conferring heat and fire resistance and these include the use of intumescent treatments and the potential usefulness of nanotechnologies, which has received much attention at the research level during the last 10 years. Typical applications of heat and fire resistant textiles are those where regulations usually demand their use and these include protective clothing, contract and domestic furnishing fabrics, fire barrier textiles (e.g. theatre fire curtains, insulative textiles) and military applications and, in particular, many textiles used in mass transport systems, such as commercial airlines, luxury cruise liners and the current generation of fast trains. The chapter concludes with a brief discussion of two projects undertaken in the author’s laboratories that illustrates two recent challenges posed by the needs of the commercial aerospace industry. The first outlines how decorative textiles comprising very expensive and aesthetically valued fabrics might be rendered fire resistant to the levels required by the regulations and yet preserve their exotic characteristics. The second shows how the development of textile composites for use as an acoustic and fire resistant barrier was successfully undertaken to meet the stringent and new international regulatory requirements for commercial airliner fuselage fire requirements.

In contrast to organic fibres, ceramic, i.e. inorganic, fibres, are not flammable and can maintain their physical strength and thus structure at very high temperatures. They find applications as materials used in very high temperature (> 1000o ) environments. This chapter provides an account of the range of these applications as well as the developments in ceramic fibre production techniques which enhance their high temperature properties.
Ceramic fibres are increasingly used as reinforcements in organic resin matrices for high performance structural ceramic matrix composites and metals required for aerospace and marine applications. Since organic resins are potentially flammable, it is important that the whole composite system be fire resistant. The current status of this topic is reviewed together with a discussion of the potential for future improvements.