Much academic research and industrial development explores new ways to create greener and environmentally friendlier chemicals and materials for a variety of applications. A significant part of this work focuses on the development, processing and manufacturing, recycling and disposal of green plastics, adhesives, polymer composites, blends and many other industrial products from renewable resources. Natural fibres offer the potential to deliver greater added value, sustainability, renewability and lower costs especially in the automotive industry. Further research involves the fibre crop production. The everincreasing volume of scientific literature refers with enthusiasm to the potential of natural fibres in technological, economic and ecological terms. This enthusiasm tends to also expand to the areas of human life and socio-economic development for the fibre crop growers and their communities. However, there is very little debate or evidence to support statements about the assumed advantages for the affected population in rural areas. We argue that despite the predicted new boom in the demand of natural fibres, it is unlikely that this will represent a real improvement in the quality of life of crop fibre growers and their communities. This paper examines the experience of Mexico as a case study and argues that only through consistent political will and co-operation between governments, industry, scientists, consumer groups and local communities, as well as a suitable economic strategy such as local subsidies, a truly sustainable economic development, social equity and improved environmental quality will be achieved for tens of thousands of natural fibre growers.
The wetting and moisture up-take behaviour, as well as the electrokinetic properties of various lignocellulosic fibres were characterised. Knowledge of surface and water uptake properties of this kind of materials will help to tailor their potential use in different end user applications. The surface tension of the fibres was determined from wetting measurements using the capillary rise technique. The wetting data were used to determine the surface tension of the fibres. Our results show that the surface tension of the lignocellulosic fibres is a linear function of their cellulose content. Zeta-potential measurements were exploited to characterise the surface chemistry of the fibres. Measuring the zeta-potential as function of time enables the rapid assessment of the water up-take, i.e. the swelling behaviour of the fibres. The results obtained by the zeta potential measurements correlate, with the exception of flax, in a linear manner with the results obtained from conventional moisture uptake measurements. Even though all lignocellulosic fibres are very hydrophilic due to the presence of polar oxygen containing groups they have different grades of hydrophilicity, which is also reflected in the different water uptake capabilities measured.The wetting, moisture uptake and electrokinetic properties of the lignocellulosic fibres are determined by the availability of the surface functional groups present, which is usually consequence of the processes used to separate, and extract the fibres from the plant (retting), as well as any further processing used to improve the fibre quality.
New applications of lignocellulosic fibres have been driven by numerous factors, including pressure from environmental groups, stringent environmental laws, waste minimisation efforts, recycling and cost reduction initiatives and responsible social awareness. However, the exploitation of such fibres in, for instance, fibre-reinforced composites or in the textile industry is hindered by the presence of waxy layers on the surfaces of lignocellulosic fibres. Many surface treatments are traditionally used to optimise the surface properties of natural fibres. A potential and environmentally sound surface treatment regards the use of atmospheric air pressure plasma (AAPP). The surfaces of various lignocellulosic fibres were modified using AAPP. We investigated the effect of AAPP treatment duration (i.e. 1 min and 3 min) on the surface properties of the lignocellulosic fibres using wetting and electrokinetic measurements. The critical surface tension of the untreated and AAPP-treated fibres was determined from wetting measurements using the capillary rise technique, whereas the changes in the surface chemistry were characterised by means of zeta (f)-potential measurements. A slight increase in the critical surface tension of the lignocellulosic fibres was found with prolonged treatment time, with the exception of abaca fibres. The post-treated fibres show a larger degree of hydrophilicity measured from the difference, Df, in the decay of the f-potential measured as function of time, with the exception of hemp fibres. Finally, f-potential measurements as function of pH validated the performance of both AAPP treatments.
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