Sustainable materials with high insulation capacity obtained from wastes from hemp industry processed by wet-laid

Abstract

This article reports on the revalorization of hemp waste from the textile industry, focusing on the development of new sustainable materials with high insulating properties. Wet-laid technology was used to manufacture nonwovens with different binding fibers, polylactic acid, and viscose fibers. The characterization of the acoustic insulating capacity was carried out using a Kundt tube, and the thermal insulating performance by measuring the heat transmission resistance ( R) and thermal conductivity ( λ). The results showed that the developed nonwovens have lower thermal conductivity values of about 0.027–0.034 W/(m K), were even lower than those of traditional thermal insulating materials, being the sample with 100 g/m2 of areal density and with a composition of 80% of hemp, 10% of polylactide and 10% of viscose the one with the lowest thermal conductivity (0.027 W/(mK). Their acoustic absorption capacity was around 0.76 at a frequency of 6 kHz, in samples containing high hemp waste (>80 wt%). However, the heterogeneous, discontinuous, and high void density structure that contributes to excellent insulating properties, lead to a decrease in their mechanical properties. This demonstrated that these materials are suitable for substituting traditional materials in insulating applications. Additionally, antifungal tests were carried out. However, hemp nonwovens proved to be inefficient against fungal proliferation.

Revolutionizing Sustainable Nonwoven Fabrics: The Potential Use of Agricultural Waste and Natural Fibres for Nonwoven Fabric

“…Liao et al (2020) investigated the use of hemp nonwoven fibre for the application of sound absorption [70]. In recent work, Gutierrez-Moscardo et al ( 2022) developed new sustainable nonwoven materials by utilizing waste material derived from processing hemp fibres in the textile industry using wet-laid technology and a thermal bonding process [25]. Nonwovens with different areal densities were manufactured with a high content of hemp waste (70-90 wt.%) and different binder fibres (polylactic acid and viscose fibres).…”

“…If properly managed, this can reduce their ecological footprint and be both technically and economically practicable [23]. Most lignocellulosic fibre waste produced from agricultural and forest waste is burned in fields, which releases a variety of pollution in the environment [23][24][25]. Interest in using these fibres as elements in manufacturing nonwoven fabrics is mainly related to their favourable structural properties and environmental/economic benefits.…”

Can the Hemp Industry Improve the Sustainability Performance of the Australian Construction Sector?

“…Currently, the paper, textile, food and construction sectors are the dominant markets for industrial hemp [58]. It is estimated that this versatile crop can be used for over 25,000 different products [81].…”

Structural Characteristics and Sound Absorption Properties of Waste Hemp Fiber

“…Hemp is a versatile crop used in a variety of products, including building materials, textile products, paper, foodstuffs, furniture, luxury markets, cosmetic products, and hygiene items, while the textile sector generally processes industrial hemp into fibers, fabrics, ropes, yarns, and home textiles [14][15][16]. The percentage of short fibers in hemp fiber is about 7.72%, and these short fibers are eliminated in the form of waste in the manufacture of hemp yarn and fabric, resulting in a waste of resources [17,18]. Given that hemp is a natural fiber, there are various uses for its textile waste, such as reinforcing materials and other matrix materials made of composite materials, to improve the utilization of hemp fiber and reduce resource waste, so as to achieve the development goals of peak carbon emission and carbon neutrality.…”