A NiTi alloy weft knitted fabric for smart firefighting clothing

Abstract

A prototype of a new shape-memory nitinol knitted fabric intended for use as an active thermal insulating interlining in firefighting protective clothing was developed in the study presented in this paper. Weft knitted fabrics were made from commercially available cold-worked nickel titanium alloy monofils. Knits were made on a manual knitting machine from a monofil measuring 0.1 mm in diameter, while a hand-made knit was prepared from a monofil measuring 0.2 mm in diameter. Nitinol fabrics were annealed at 500 °C to achieve an austenite transition temperature of 75 °C. A special constructed mould made of a steel frame and aluminium domes measuring 30 and 20 mm in height was used to give the nitinol fabrics a new temporary shape. A two-way, shape-memory effect of the nitinol fabrics was achieved using a 15-cycle training process. The achieved shape-memory effect was tested in a heated chamber at 100 °C, where bulges measuring 12–25 mm in height occurred. NiTi knits made from finer monofil were the most successful shape-memory knits. They were machine knitted and achieved sufficiently high bulges, measuring 18 or 12 mm, that facilitated large enough air gaps for effective thermal protection. A smart textile system was prepared by inserting the trained nitinol fabric into a pocket made from two textile fabric layers sewn together. When it was exposed to environmental temperatures of 75 °C and higher, it instantly changed its form from a two-dimensional shape to a three-dimensional shape, while increasing the air gap in the pocket. A quilted fabric made from such a smart textile system could be used in firefighting protective clothing to locally improve thermal insulation and protect the human skin from overheating or burns.

Design and characterization of reversible thermodynamic SMPU-based fabrics with improved comfort properties

“…The results confirmed that the clothing designed offered a high degree of protection even in extreme thermal conditions. Lah et al 17 proposed inserting a layer of programmed SMA filament knitted fabric into the traditional protection textile system which, at 75°C, produces bulges that cause sufficient air space to create effective thermal protection. More recently, Wang et al 18 proposed an improvement of this textile system by reducing the number of layers to four (instead of the five in the traditional system), and integrating the SMA filaments per weft, in an aramid fabric.…”

Hump‐Inspired Hierarchical Fabric for Personal Thermal Protection and Thermal Comfort Management

“…In recent decades, the exploitation of firefighting materials, uniform structure designs, functional finishing, and processing technologies have gained tremendous attention for improved thermal protection of firefighter uniforms. [ 5–10 ] Among them, functional materials such as fireproof coatings, [ 11 ] fiber aerogels, [ 12–15 ] ceramic nanofibrous membranes, [ 16,17 ] phase‐change microcapsules, [ 18,19 ] shape memory materials [ 20,21 ] have shown their promising application potential in firefighter uniform. Although these functional materials do improve thermal protection of firefighter uniforms, poor moisture and sweat transport behavior of thermal protective fabrics can lead to fast increase of humidity level within firefighter uniforms, thus downgrading thermal protection performance, influencing the heat‐humidity comfort and reducing firefighter's working efficiency.…”

Design and fabrication of NiTi shape memory alloy/aramid composite fabric for thermal protective clothing

“…However, SMA springs have the drawbacks of high stiffness, which tend to bring discomfortable wearing experience for human body. To overcome this, Šalej Lah et al [12] utilized NiTi wires, which are thinner and softer than springs, to fabricate fabrics. Subsequently, a weft-knitted fabric fully made from NiTi wires was fabricated by Wang et al [13] to be applied in a pocket.…”