The aim of this study is to develop and investigate mechanical properties of knitted unidirectional thermoplastic composite prepregs. Knitted prepregs were fabricated by using thermoplastic yarns (high density polyethylene and polypropylene) and high performance yarns (kevlar, basalt and carbon) in double jersey inlay structure. This is a new approach to combine the reinforcing fiber with resin forming thermoplastic fiber during the knitting operation. The structures were stacked further in three stacking sequences at different angles (0/0/0/0, 0/90/0/90, 0/90/90/0), and hot compression was used to convert them into composite prepregs by melting the thermoplastic component. Mechanical properties e.g. tensile strength and modulus, flexural strength, flexural modulus, impact energy absorbed etc. were investigated in detail. Full factorial experimental design was used in order to study the effect of main yarn, inlay yarn and direction of stacking/plying on mechanical properties of composites. Analysis of variance (ANOVA) was conducted by Minitab 17 software to estimate the significance of testing direction (T), type of inlay yarn (I), type of main yarn (M) and stacking sequence (S) on mechanical properties. Overall highest tensile and flexural strengths were observed for Carbon fiber based samples followed by Kevlar and Basalt respectively. Theoretical estimation of elastic modulus shows similar trend as the experimental results. The inter-laminar shear strength is maximum when the fiber orientation changes in each layer. Type of main yarn and inlay yarn have significant contribution on impact related properties. Depending upon type of material, these composites can be used in aerospace, automotive, civil and sports goods.

Socks, which are a necessary item of clothing, need to be comfortable, affordable, and retain their quality throughout their life. Dimensional stability is one of the basic requirements of socks. The purpose of this study is to investigate the contributing factors, that is, elastane percentage, main yarn material, and process type on dimensional stability of socks. Four different percentages of elastane in plaiting yarn (4%, 6%, 8%, and 10%), two main yarns materials (100% cotton and polyester/cotton 52/48), and two process types (wash and bleach) were taken as level of input variables to study the effect on dimensional stability of socks using full-factorial experimental design method. Statistical tool (analysis of variance) was used to check the significant effect of different factors. It was found that with the increase in elastane percentage, shrinkage was decreased. Cotton was found to have more shrinkage percentage as compared to polyester/cotton. In addition, it was observed that washing treatment produced significantly lesser shrinkage than bleaching. These data present a great interest to sock manufacturers who can make better choices to manufacture, dimensionally stable socks.

The research aims the development of knitted reinforcement structures for inducing self-diagnostic properties into knitted reinforced composites for structural health monitoring. Conductive carbon fiber was used in knitted inlaid structures as inlay yarns, and l × 1 Rib knitted base fabric of polyester filament yarn was used for knitting. The reinforcement’s conductive nature induced self-diagnostic properties into composites using correlation of mechanical damages and changes in electrical resistance values. Single and double stimuli layers and inlay patterns of 3 × 1, 6 × 1 and 9 × 1 was used to check their impact on self-diagnostic properties. Mechanical testing and real-time electrical resistance monitoring proved knitted structures as a solution to induce self-diagnostic properties into composite materials. Composites having double stimuli (conductive) layers exhibited better self-diagnostic properties than single stimuli layer composites, and the self-diagnostic properties also improved as the inlay pattern of reinforcement moved from 9 × 1 to 6 × 1 and 3 × 1 inlay. Such knitted reinforced self-diagnostic composites could be practically used in structural health monitoring applications, e.g., complicated structures of large buildings infrastructures and machinery which require record of each minor happening with structures to keep smooth and successful running of the system.

Knitted fleece fabrics with superior comfort characteristics are chiefly focused in winter wear. Thermal characteristics are an area of interest in selecting fleece clothing. However, environmental hazards also need to be focused. Fleece clothing is worn in cold areas having higher ultraviolet rays exposures. Hence the clothing should have the capability of combating environmental challenges. The study focuses on engineering variable fleece structures with different materials. Cotton, nylon, and polypropylene fleece patterns have been knitted using fleece 1:1, 3:1, and 2:2 patterns. The designs vary by tuck and miss stitch configurations in the fleece course. Comfort characteristics were determined through air permeability, moisture management, and thermal resistance tests. Performance criteria were evaluated in terms of pilling resistance and ultraviolet protection factor (UPF) investigation. Structures and materials owing better comfort characteristics with satisfactory UPF have been predicted as safe clothing in UV affected zones, that is, fleece 3:1 possessed the optimum comfort characteristics and UPF simultaneously; however, the mechanical performance was better for 2:1 and 1:1 fleece fabric due to less amount of miss stitch floating yarns.

Knitted fabrics are renowned for stretch properties which owe to their comfort properties such as formability, fitting to the human body and shape retention after wearing. Optimum stretch is basic requirement in knitted socks to support blood flow in legs and feet. This stretch is achieved with fabric structure type and material used in it. Different factors affect the stretch and recovery of sock, but most contributing factors are elastane percentage, main yarn material and finishing process type. Four different percentages of elastane in plaiting (4%, 6%, 8% and 10%), two main yarns materials (Cotton and Polyester/Cotton PC), and two finishing process types(Wash and bleach) were taken as level of input variables to study their effect on stretch and recovery. Stretch and recovery tests were performed on knitted sock tube. After testing, Minitab software was used for analysis of variance of obtained results using full factorial design. Significance of all factors and levels was analyzed. It was found that with the increase in elastane percentage stretch was decreased and recovery was increased. Cotton was found to have less stretch and more recovery percentage as compared to PC. Additionally it was observed that washing treatment produced significantly higher stretch and lesser recovery than bleaching. Similar trend was also observed in interaction plot indicating that all variables were dependent on each other.