The classification, structure and physical and chemical properties of natural and manufactured fibres, and how those properties affect the performance and end use of a textile item

What this dot point is asking

You need to classify fibres, describe their structure, and link their physical and chemical properties to how a textile item performs in its end use. NESA does not want a list of fibres memorised in isolation. The marks come from reasoning: this fibre has this property because of its structure, therefore it suits this end use. The same reasoning underpins fabric choice in the Major Textiles Project, so understanding fibres well pays off twice.

Classifying fibres

Fibres split first into natural and manufactured. Natural fibres are either protein based, from animals (wool, silk, alpaca), or cellulose based, from plants (cotton, linen, hemp). Manufactured fibres divide into regenerated fibres, made by chemically reforming natural cellulose (viscose, modal, lyocell), and synthetic fibres, made entirely from chemicals derived from petroleum (polyester, nylon, acrylic, elastane). A second useful split is staple fibres (short lengths, like cotton or wool) versus filament fibres (long continuous strands, like silk and most synthetics), because length affects the texture and strength of the yarn that can be spun from them.

Structure and physical properties

A fibre's internal and external structure explains its behaviour. Wool fibres have natural crimp and overlapping scales, which trap air to give warmth and allow the felting that helps insulation but causes shrinkage. Cotton fibres are flat and twisted, giving softness and good absorbency but weak elasticity, so cotton creases. Silk is a smooth filament, producing lustre and strength. Synthetic filaments are smooth and uniform, giving strength, low absorbency and the ability to be heat set into permanent pleats.

Physical properties that matter for performance include absorbency (how much moisture the fibre takes up), strength or tenacity, elasticity and resilience (recovery from stretching and creasing), thermal properties (warmth and reaction to heat), and lustre and handle. Absorbency, for instance, makes cotton comfortable for warm-weather clothing but slow to dry, while polyester's low absorbency makes it quick drying and ideal for activewear.

Chemical properties

Chemical properties describe how a fibre reacts to substances and heat. These include reaction to acids and alkalis, resistance to bleaches, sunlight and biological attack, and flammability. Protein fibres are damaged by alkalis and chlorine bleach, which is why wool needs gentle detergents. Cellulose fibres tolerate alkalis but are weakened by acids. Synthetics generally resist chemicals and mildew but melt rather than burn and can be damaged by high ironing temperatures. Knowing these reactions explains care labels and informs safe finishing and laundering choices.

Linking properties to end use

The core skill is matching properties to the requirements of an end use. Upholstery fabric needs strong, abrasion resistant, fade resistant fibres, so a durable synthetic or a tightly constructed cotton blend suits it. A summer shirt needs absorbency and breathability, favouring cotton or linen. Activewear needs moisture management, stretch and quick drying, favouring polyester with elastane. Many products use blends to combine strengths, such as polyester and cotton to add easy care and strength to a comfortable, absorbent base. In every case the justification runs from structure to property to performance in the named end use.

Bringing it together

When the exam gives you a product, work backwards from its demands. Identify what the item must do, list the properties needed, then name a fibre or blend whose structure delivers those properties, and justify why competing fibres are less suitable. This structured reasoning, grounded in real fibre behaviour, is what separates a strong answer from a list of fibre facts.