Question

project on effect of acids and bases on tensile strength of fibres

Answer 1

Besides their chemical composition and properties, most important property of these fibres is their tensile strength. Tensile strength mean the extent to which a fibre can be stretched without breaking and it is measured in terms of minimum weight required to break the fibre. To determine the tensile strength of any fibre, it is tied to a hook at one end and weighted are slowly added to the other end until the fibre break.

Since peptide bonds are more easily hydrolyzed by bases than acids therefore wool and silk are affected by basis not by acids. It is because of this reason that wool and silk threads breakup into fragments and ultimately dissolve in alkalines.

In other words alkalines decreases the tensile strength of animal fibres (wool & silk). Vegetable fibres (cotton & linen), on the other hand, consist of long polysaccharide chains in which the various glucose units are joined by ethers linkage. Since ethers are hydrolised by acids and not by bases therefore, vegetable fibres are affected by acids but not by bases. In other words acids decreases the tensile strength of vegetable fibres. In contrast, synthetics fibres such as nylon & polyester practically remains unaffected by both acids and bases.