Quality Evaluation of Fibers and Yarns

Scope and Objectives of testing of textile materials; concept of quality; Selection of samples for quality assessment – random and biased samples – squaring technique and zoning technique for fibre selection; yarn sampling - use of random numbers - sampling for various types of yarn tests- yarn strength, linear density, elongation, twist.

Moisture relation and testing: standard atmosphere condition, moisture regain and moisture content and measurement of atmospheric condition, Fiber testing: Fibre length and length uniformity measuring techniques; Fibre strength and its relation to yarn strength. Fiber bundle strength tests. HVI, AFIS

Fibre fineness – definition- comparison of various fibres – its importance in yarn manufacture; measurement techniques. Cotton fibre maturity, estimation by microscopic method - maturity ratio and index, estimation by other methods – optical, air flow, differential dyeing; its importance in spinning. Fibre trash – influence on quality; measurement – principle and estimation of micro-dust for rotor spinning. High volume instrument for total fiber quality measurement.

Yarn Appearance and grading, yarn mass evenness parameters – measurement –nature of irregularity: - index of irregularity; limit irregularity electronic mass evenness determination – Yarn fault classification –Yarn abrasion resistance – importance and measuring technique. Yarn hairiness – importance and assessment techniques. Twist in single and ply yarns –twist

Tensile characteristics – Tensile Strength Testing modes – CRT, CRE and CRL, study of strength, single yarn strength; Lea count strength product (CSP) and Corrected Count Strength Product (CCSP), elongation, work of rupture, initial modulus, work factor and yield point – determination of yield point. Stress-strain relations of natural and manmade fibres, influence of fibre structure, humidity and temperature on tensile characteristics. Time effects Study of creep phenomena. Elastic recovery and its relation to stress and strain of fibres; mechanical conditioning of fibres and its influence on elastic recovery. Load cycling and extension cycling-their effect on elastic recovery. Introduction about torsional and flexural rigidity of fibers.