Hydrogel a term on a substance formed developed reprocessed silkworm silk. It is a gel with aqueous solutions of the fibroin prepared as outlined earlier. The rate of sol-gel transition is directly dependent on temperature (higher the temperature the more rapid the gelation), pH (lower the pH the more rapid the gelation), and solids content (higher the solids higher the rates of gelation). Caution can also enhance rates of gelation, with the specific salts dependent on the type of silk; potassium plays a role with spider dragline silk and calcium with silkworm silk. The overall rate of gelation controlled via osmotic stress, with resulting mechanical, morphological, and structural details dependent on the standards and extent of water removal.
Demand for sustainable solutions
‘Environmental legislation and the need for continuous sustainability, including recyclability, in manufacturing, has increased interest in wood fibres and such bast fibres as flax, hemp, and kenaf fibre for use as fillers for polymer composites. In addition to these environmentally friendly composites, researchers have developed recyclable single component polymer composites for the automotive and construction industries.
EIN Engineering of Japan developed composites from waste wood and recycled plastics for outdoor applications, including crash barriers and sound-absorbing panels. Tech-Wood International’s Tech-Wood composite contains 70 per cent pinewood fibres and 30 per cent compatibilised polypropylene and has applications in the manufacture of the hurricane-resistant housing.
Daimler-Chrysler developed natural fiber-reinforced composites for underbody panels, engine and transmission covers, and sound insulation. Audi developed interior door trim panels made from polyurethane reinforced with flax and sisal nonwoven mats. Ford developed injection mouldable flax-polypropylene composites for radiator grills, front ends, and engine shields.’’