Comfort is an important quality criterion, especially for sportswear. It influences well-being, performance and efficiency. The necessary dissipation of heat and air flow, at high metabolic rates, must be designed and planned in advance. The influence of structure, density, mass and thickness of fabric were considered as well as yarn material composition, yarn linear density, yarn evenness and yarn hairiness. The influence of the mentioned parameters on thermal properties and air permeability was calculated. From the correlation analysis, it can be concluded that yarn’s linear density, yarn short fibers hairiness, and mass per unit area of knitted fabric has the greatest impact on heat resistance. The yarn linear density, the yarn hairiness of the longer protruding fibers, and the thickness of the knitted fabric have the greatest impact on air permeability. A statistically significant model of multiple linear regression equations was offered to predict the thermal comfort of knitted fabric.

As part of the recent trend towards sustainability in modern society, in general, the knitting sector has done its part to emphasise social responsibility and the careful use of resources. Focus has been placed on reusing, recycling and upcycling raw materials and reducing or even eliminating knitting waste. Manufacturers and users have rethought processes, production and consumption volumes. Sustainable preparation and finishing processes have been developed. Knitting machines that offer environmentally friendly manufacturing techniques with less impact on people and the environment and production methods that significantly reduce the wasted or unproductive time between manufacturing phases have been favoured. Sustainability is not just a new approach or a trend that is fashionable right now, but a must, a compelling concept for the survival of businesses in the future. Knitting as a unique technology spans quite opposite poles: hand and machine production, hobby and money‐making, individual and mass production, assembled and seamless products, fashion and technical market, and so forth. As such, it can adapt, expand and evolve towards sustainability, circular economy and Industry 4.0. This paper provides an overview of the versatility and complexity of knitting today, as well as its sustainability potential, optimisation and merging within knitting and with other processes and opportunities for transition to the circular economy and Industry 4.0, covering digitalisation, the Internet of things and robotisation in knitting. It also analyses the market for knitting machines, knitted fabrics and knitted goods, and addresses the pitfalls of consumerism.

The development of knitted fabrics with incorporated elastane has increased in recent decades. Knitting with these elasticized yarns usually results in a very compact structure. Loop length is considered to be the primary parameter for knitted structures. Consequently, knowledge of all factors influencing loop length is vital for planning yarn consumption, comfort fit, quality, performance and aesthetic properties of knitted fabrics made from elasticized yarns. The objective of this research was to study the impact of material, knitted structure and relaxation process parameters on loop length. In addition, the objective was to examine the differences in loop length of single weft knitted fabrics, produced from different types of elasticized and non-elasticized yarns. For both groups of knitted fabrics, elasticized and non-elasticized, knitted fabric density and relaxation process influence the loop length most of all. Loop length decreases during the process of consolidation, but this decrease is not substantial. Addition of elastane does not significantly influence the loop length.

Flammability testing of undergarments is a topic that is often overlooked and rarely on the list of textiles to be tested for fire safety. However, it is particularly important for professionals exposed to fire risk to investigate the flammability of underwear as its direct contact with the skin can be critical to the extent and degree of skin burns. This research focuses on the suitability of affordable blends of 55 wt.% modacrylic, 15 wt.% polyacrylate, and 30 wt.% lyocell fibres that have the potential to be used for flame-resistant underwear. The influence of modacrylic fibre linear density (standard and microfibres), ring spinning processes (conventional, Sirospun, and compact), and knitted structure (plain, 2:1 rib, 2:1 tuck rib, single pique, and triple tuck) on their properties required for thermal comfort in high-temperature environments was investigated. Scanning electron and optical microscopy, FT-IR spectroscopy, mechanical testing, moisture regain, water sorption, wettability, absorption, DSC, TGA, and flammability were tested to assess the desired suitability. The wetting time (5–14.6 s) and water absorption time (4.6–21.4 s) of the knitted fabrics have shown excellent ability to transport and absorb water compared to the knitted fabrics created from a conventional blend of 65% modacrylic and 35% cotton fibres. The afterflame and afterglow times of less than 2 s met the criteria for non-flammability of the knitted fabrics according to the limited flame spread test method. The results show that the investigated blends have the potential to be used for affordable flame-retardant and thermally comfortable knitted fabrics for underwear.

Contemporary multifunctional textiles are based on hi-tech functionalization. Knitted structures can be relatively rapidly designed and produced in a variety of textures due to their composition of many interlacing loop elements and their combinations. Foldable weft-knitted structures exist in a wide range of forms from simple rolls, ribs, and pleats to more complex three-dimensional structures. They exhibit new kind of geometry and deformation mechanisms. Some of them exhibit auxetic potential. Foldable knitted structures are multifunctional and widely usable. They can be produced in a variety of structures, qualities, and dimensions: in panels, fully-fashioned, or seamless. Their possible application lies in different fields, such as fashionable and functional clothing, sportswear, medical care, packaging, interior design, sound and shock absorption, etc.