The field of biopolymers, while still in its early stages, is growing in
popularity everyday. Some biopolymers can directly replace synthetic plastics in
traditional applications, while others possess unique properties that may open new
applications. For most biopolymers, it's still too early to determine if they'll be
economically feasible on a large, industrial scale.
When you run into a spider's web, the last thing on your mind is,
"What a great a material!" But consider that the spider's silk has a
tensile strength 16 times greater than nylon! At the same time, silk maintains a
very high degree of elasticity. Attempts to manufacture gentically modified silk
have thusfar been disappointing due to low yields. If this can be improved, silk can
be applied to many applications.
Chitin, a polysaccharide found in the exoskeletons of insects and
shellfish, possesses many desirable characteristics. Chitin's most important
derivative, chitosan, is nearly a "model" biopolymer with it's useful physical
and chemical properties, high strength, biodegradability, and nontoxicity. In fact,
chitosan brings new meaning to the word "biodegradable" as the human body easily
breaks it down into simple carbohydrates, carbon dioxide, and water. This accounts
for the research that is trying to use chitosan in drug delivery systems.
Lactic acid is produced by the microbial fermentation of sugars
such as glucose or hexose. Feedstocks can include potato skins and corn. The
lactic acid monomers can be used to create low or high molecular weight polylactide
polymers. PLA commodity polymers are being developed for use as pulping additives in
paper manufacturing and as biodegradable packing materials. PLA's current price
level of $5.00/lb (US) will have to be significantly improved upon before it gains wide
acceptance. Currently, the medical community is the primary user of PLA.
Absorbable sutures such as Vicryl™ are made of 90% PLA and 10% polygylcolic acid
(PGA).
