Polylactic acid environments

Yussuf, A.A., Massoumi, I., Hassan, A. Comparison of polylactic acid/kenaf and polylactic acid/rise husk composites The influence of the natural fibers on the mechanical, thermal and biodegradability properties. J. Polym. Environ. 18(3), 422-429 (2010)... 

The poly-L-lactic acid shows high melting points and good mechanical properties. Polylactic acid degrades by hydrolysis, which has been shown to be accelerated by many enzymes. Recently, it has been found to be biodegradable in a compost environment [43, 45]. The thermoplastic material can be made stereo specific or racemic to yield different properties. 

Ho KLG, Pometto AL, Hinz PN. Effects of temperature and relative humidity on polylactic acid plastic degradation. J Environ Polym Degrad 1999 7 83-92. 

Drzal LT, editors. Natural fibers, biopolymers, and biocomposites. London CRC Press 2005. p. 527—77. b. Hagen R. Polylactic acid. In Matyjaszewski K, MoUer M, editors. Polymer science a comprehensive refierence, vol. 10, Polymers for a sustainable environment and green energy, McGrath JE, Hickner MA, Hofer R, volume editors. Elsevier, Amsterdam, Oxford, Waltham 2012. p. 231-236. 

G.L. Siparsky, K.J. Voorhees, F. Miao, Hydrolysis of polylactic acid (PLA) and polycaprolactone (PCL) in aqueous acetonitrile solutions autocatalysis. J. Polym. Environ. 6(1), 31-41 (1998)... 

The degradation of polylactic acid (PLA) plastic films in Costa Rica soil and in a leaf composting environment was investigated [22]. The average soil temperature and moisture content in Costa Rica were 27°C and 80%, respectively. The average degradation rate of PLA plastic films in the soil of the banana field was 7657 A/ /week. PLA films required two weeks to disintegrate physically in leaf compost rows. 

Ho K.-L.G., Pometto III A.L., Gadea-Rivas A., Briceno, Rojas A. D radation of polylactic acid (PLA) plastic in Costa Rican soil and Iowa State University compost rows, J. Environ. Polym. Deg. 

Biodegradation indicates degradation of a polymer in natural environment. This implies loss of mechanical properties, changing in the chemical structure, and into other eco-friendly compounds (Jamshidian et al. 2010). Degradable polymers from natural sources (such as lignin, cellulose acetate, starch, polylactic acid (PLA), polyhydroxylaUcanoates, polyhydroxylbutyrate (PHB)), and some synthetic sources (polyvinyl alcohol, modified polyolefins, etc.) are classified as biopolymers (John and Thomas 2008). It is noticeable that the nanocomposite from nonrenewable synthetic sources is neither wholly degradable nor renewable. 

The test materials used are all commercially available plastics that are made from corn, namely, polylactic acid (PLA) and polyhydroxyalka-noate (PHA). PLA and PHA materials have passed the ASTM D6400 compostability standard and biodegraded in a simulated industrial compost environment in 180 days. ASTM standards are applicable for plastic molded products and not plastic pellets. The samples for the ASTM D6691 test included the following ... 

Dharmalingam, S., et al. (2015). Soil degradation of polylactic acid/polyhydroxyalkanoate-based nonwoven mulches. Journal of Polymers the Environment, 25(3), 302—315. 

Siparsky, G.L., Voorhees, K.J., Dorgan, J.R., Schilling, K., 1997. Water transport in polylactic acid (PLA), PLA/Polycaprolactone copolymers, and PLA/Polyethylene glycol blends. J. Environ. Polym. Degrad. 5, 125—136. 

Rudeekit, Y., Numnoi, J., Tajan, M., Chaiwutthinan, P., Leejarkpai, T., 2008. Determining biodegradability of polylactic acid under different environments. J. Met., Mater. Miner. 18, 83—87. 

Synthetic environment friendly polymers with precnrsors from natural resource such as polylactic acid have shown enormous potential to snbstitute a wide variety of conventional fossil based packaging plastics and have been demonstrated to be even commercially viable. In view of this, a detailed description about various aspects of PLA such as synthesis, properties, and processing have been discussed as below. 

The synthetic absorbable sutures are made from polymers capable of degradation in the biological environment without adverse effects. One overall advantage of absorbable sutures is the elimination of clinical visits for their removal. These sutures are either homopolymers or copolymers based on degradable polymeric units such as polyglycolic acid, polylactic acid, or poly-/ -dioxanone. 

Fujiura, T., Sakamoto, K., Tanaka, T., and Imaida, Y., A study on preparation and mechanical properties of long jute fiber reinforced polylactic acid by the injection molding process, WIT Trans. BuiU Environ., 97, 231 240 (2008). 

Masaki, K., Kamini, N.R., and Ikeda, H. (2005) Cutinase-like enzyme from the yeast Cryptococcus sp. strain S-2 hydrolyzes polylactic acid and other biodegradable plastics. Appi Environ. Microbiol, 71, 7548-7550. 

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