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Revision as of 14:34, 18 December 2013 by 5.150.103.60 (talk)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)as a nucleating agent, thereby increasing the crystallization rate. Biodegradation of PDLA is slower than for PLA due to the higher crystallinity of PDLA.
There is also poly(L-lactide-co-D,L-lactide) (PLDLLA) – used as PLDLLA/TCP scaffolds for bone engineering.
Applications
Poly(lactic acid) can be processed by extrusion, injection molding, film & sheet casting, and spinning, providing access to a wide range of materials.
Being able to degrade into innocuous lactic acid, PLA is used as medical implants in the form of anchors, screws, plates, pins, rods, and as a mesh. Depending on the exact type used, it breaks down within the body within 6 months to 2 years. This gradual degradation is desirable for a support structure, because it gradually transfers the load to the body (e.g. the bone) as that area heals. The strength characteristics of PLA and PLLA implants is well documented.
PLA can also be used as a compostable packaging material, either cast, injection molded, or spun. Cups and bags have been made of this material. In the form of a film, it shrinks upon heating, allowing it to be used in shrink tunnels. It is useful for producing loose-fill packaging, compost bags, food packaging, and disposable tableware. In the form of fibers and non-woven textiles, PLA also has many potential uses, for example as upholstery, disposable garments, awnings, feminine hygiene products, and diapers.
Racemic and regular PLLA has a low glass transition temperature, which is undesirable. A stereocomplex of PDLA and PLLA has a higher glass transition temperatures lending it more mechanical strength. It has a wide range of applications, such as woven shirts (ironability), microwavable trays, hot-fill applications and even engineering plastics (in this case, the stereocomplex is blended with a rubber-like polymer such as ABS). Such blends also have good form-stability and visual transparency, making them useful for low-end packaging applications. Pure poly-L-lactic acid (PLLA), on the other hand, is the main ingredient in Sculptra, a long lasting facial volume enhancer, primarily used for lipoatrophy of cheeks. Progress in biotechnology has resulted in the development of commercial production of the D enantiomer form, something that was not possible until recently.
PLA is also used as a feedstock material in 3D printers such as Reprap,Makerbot, and Ultimaker.
Recycling
Currently, the SPI resin identification code 7 ("others") is applicable for PLA. In Belgium, Galactic started the first pilot unit to chemically recycle PLA (Loopla). Unlike mechanical recycling, waste material can hold various contaminants. Polylactic acid can be recycled to monomer by thermal depolymerization, or hydrolysis. When purified, the monomer can be used for the manufacture of virgin PLA with no loss of original properties (cradle-to-cradle recycling).
See also
- Cellophane
- Metallic glass
- Plastarch material
- Polycaprolactone
- Polyglycolide
- Poly-3-hydroxybutyrate
- Zein
- 3D Printing
- Acrylonitrile butadiene styrene
References
- Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1080/17452750802551298, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1080/17452750802551298instead. - Fiore, G (2010). "High Tg Aliphatic Polyestersby the Polymerization o f Spir olactide Derivatives". Polym. Chem. (1): 870–877.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Rafael Auras, Loong-Tak Lim, Susan E. M. Selke, Hideto Tsuji (ed.). Poly(Lactic Acid): Synthesis, Structures, Properties, Processing, and Applications. doi:10.1002/9780470649848. ISBN 9780470293669.
{{cite book}}: CS1 maint: multiple names: editors list (link) - J Paul Harvey and Robert F Games (ed.). ASTM STP 1217 Theoretical Strength Comparison of Bioasbsorable (PLLA) Plates and conventional stainless steel and Titanium Plates used in Internal Fracture Fixation.
- "Bioengineers succeed in producing plastic without the use of fossil fuels". Physorg.com. Retrieved 2011-04-11.
- "PLA". Reprap Wiki. 2011-04-04. Retrieved 2011-04-11.
- "PLA". MakerBot Industries. Retrieved 2011-04-11.
External links
- New polymerization technology for PLA developed
- White paper on the Science of Biodegradable Plastics, FP International
- Your plastic pal, The Economist article
- Comparisons and LCA cycle of PLA
