/ Polysaccharides / Making materials
Making materials
Unlike synthetic polymers, natural polymers are characterized by a structural complexity that is very variable. For example, cellulose extracted from oaks grown in the north of France will not have exactly the same characteristics as the one extracted from eucalyptus grown in the south of Spain. Compared with synthetic polymers produced by men, whose properties are well-known, more parameters have to be taken into account regarding natural polymers.
Until now, research efforts on polymer materials have mainly involved synthetic polymers extracted from oil.
Among polysaccharides, cellulose and starch have been subjected to extensive research, particularly cellulose for paper and textile applications and starch for food uses.
Cellulose
Cellulose cannot be melted. It can, however, be processed from a solution to make materials. The best known products are based on the viscose process (fibres, films, sponges) and more recently on the lyocell method (fibres).
Cellulose can be derivatized to give several families of products like cellulose acetate, nitrocellulose, hydroxypropylcellulose, that are used either as additives in other materials or as such to produce films, fibres and bulk products.
Starch
Starch is mainly composed of two different polysaccharides, amylose and amylopectin. In certain conditions, they can be processed as synthetic polymers, i.e: by melting and processing them by well established methods (injection-moulding, blow-moulding, extrusion).
They are now used commercially to produce films for bags or chips for packaging. Polymers produced from starch like polylactic acid are now under development for uses thought to replace some of the oil-based polymers.
Cuttleries made from starch:
