Natural fibres degradation

Surface Interaction and Degradation Natural Fibre Studies... 

As ToF-SIMS is a surface analytical technique, it is well suited to the study of surface interaction between a material and its environment or between a material and products applied to it. The surface modifications can then be studied, making it possible to establish links with degradation processes. Published papers on the study of natural fibres related to cultural heritage typically illustrate this aspect of ToF-SIMS analysis. 

Manfredi, L. B., Rodriguez, E. S., Wladyka-Przybylak, M., and Vazquez, A. Thermal degradation and fire resistance of unsaturated polyester, modified acrylic resins and their composites with natural fibres, Polym. Degrad. Stabil. 2006, 91, 255-261. 

In this chapter, we will describe the make-up of just three textile materials, all natural fibres, and will further present the mechanisms of degradation of their principal components. Our selection of two of them is somewhat indulgent as they are each the focus of current research projects. However, since all three compose the fabric of key historic textiles which were recently the subjects of commissions completed by Conservation Services at the Textile Conservation Centre, our choice was all the more easily made. Here we are keen to place the science in context, and so use these artefacts to introduce the fibres and their chemistry of ageing through a conservation science perspective. 

As for linen and other natural fibres, silk is sensitive to a variety of environmentally driven degradative processes, though in most cases the actual damage is caused by hydrolysis and/or oxidation. Attack on the polymer chains is generally initiated in the amorphous zones as a consequence of their more open structure and the incidence of reactive amino-acids (specifically histidine, lysine, phenylalanine, proline, threonine, tryptophan, tyrosine and valine). 

Torres, F.G., Arroyo, O.H., Grande, C., Esparza, E. Bio- and photo-degradation of natural fibre reinforced starch based biocomposite. Int. J. Polym. Mater. 55, 1115-1132 (2006)... 

Wu CS (2009) Renewable resource-based composites of recycled natural fibres and maleated polylactide bioplastic Characterization and biodegiadability. Polym Degrad Stab 94 1076-1084... 

Mukhopadhyay S, Srikanta R (2008) Thermal properties of high density polyethylene Composites with natural fibres coupling agent effect. Polym Degrad Stab 93 2048-2051... 

Z.N. Azwa, B.F. Yousif, A.C. Manalo, W. Karunasena, A review on the degradability of polymeric composites based on natural fibres. Materials and Design 47 (2013) 424—442. 

Regenerated fibroin fibres degrade faster than natural fibres. 

The lower thermal stability of natural fibres (up to 230 °C), limits the number of thermoplastics to be considered as matrix material for natural fibre thermoplastic composites. Only thermoplastics whose processing temperature does not exceed 230 °C are useable for natural fibre reinforced composites. These are, most of all, polyolefines, like PE and PP. Technical thermoplastics, like polyamides, polyesters and polycarbonates require processing temperatures >250 °C and are therefore not useable for such composite processing without fibre degradation. 

Biological stability Natural fibres are more prone to biological degradation than synthetic, but both suffer from accumulation of biological growths over their surfaces. Some synthetic materials limit the extent of the accumulation. 

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