Polylactic acid reinforcement

Polylactic acid (PLA) reinforced with kenaf fibres developed by NEC for personal computer housings. With a 20% level of kenaf fibres, the main properties compete with glass fibre reinforced ABS but the cost is 50% higher. The flexural modulus is more than 4.5 GPa and the HDT reaches 120°C. 

Another Japanese consumer electronics company, NEC, plans to adopt PLA biopolymers for its cellphones and personal computers in order to achieve product differentiation. Impact strength, heat deformation resistance and durability are required for cellphones and the company has developed a kenaf-reinforced polylactic acid that meets these requirements. Plans now call for the reinforced resin to be given non-phosphorous, non-halogen flame retardancy, and then applied to notebook personal computer housings starting in 2007. 

Mathew AP, Oksman K, Sain M (2006) The effect of morphology and chemical characteristics of cellulose reinforcements on the crystallinity of polylactic acid. J Appl Polym Sci 101 300-310... 

Oksman K, SkrifvarsM SJ-F (2003) Natural fibres as reinforcement in polylactic acid (PLA) composites. Compos Sci Technol 63 1317-1324... 

Iwatake, A., Nogi, M., Yano, H., Cellulose nanofiber-reinforced polylactic acid. Composites Science and Technology. 9, 2103-2106 (2008), DOI http //dx.doi.0rg/lO.lOl6/j.compscitech.2008.03.006. 

Daimler Chrysler has been increasing its research and development in flax-reinforced polyester composites for exterior applications for a number of years now [80]. Mercedes also used jute-based door panels in its E-class vehicles in 1996 [81]. Cotton fibres embedded in polyester matrix were used in the body of the East German Trabant car [82]. Some other applications are on Mercedes A and S class mamade from different bio-fibre-reinforced composites [83], Lotus manufactured Eco Elise bodyworks which contains hemp fibres, while sisal fibres are used for interior trimmings while the inner door panels for the BMW 7 Series contain 70% of sisal fibres. Plant fibre-reinforced polylactic acid composites with improved rigidity and reduced processing times have been applied in the Toyota Lexus HS250h hybrid vehicle recently. 

D. Gonzdlez, V. Santos, and J.C. Parajo, Silane-treated lignocellulosic fibers as reinforcement material in polylactic acid biocomposites. J. Jhermoplast. Compos. Mater. 25, 1005-1022 (2012). 

P.K. Bajpai, I. Singh, and J. Madaan, Joining of natural fiber reinforced composites using microwave energy Experimental and finite element study. Mater. Des. 35, 596-602 (2012). P. K. Bajpai, I. Singh, and J. Madaan, Comparative studies of mechanical and morphological properties of polylactic acid and polypropylene based natural fiber composites. Reinf. Plast. Compos. 31, 1712-1724 (2012). 

Cellulose nanofibers (CNFs) [87, 88] and nanowhiskers (CNWs) [89] derived from renewable biomass have attracted much interest as alternatives to microsized and glass-fiber reinforcements in composite materials. Jonoobi et al. [87] developed CNF-reinforced polylactic acid (PLA) by twin-screw exfrusion. Obtained PLA/CNF nanocomposites with 5 wt% CNF showed improved tensile modulus and strength. Ljungberg et al. [89] prepared nanocomposite films of isotactic-PP reinforced with cellulose whiskers, which were highly dispersed in the PP matrix with a surfactant. The surfactant-modified whiskers acted as nucleating agents for isotactic-PP and the obtained nanocomposite displayed an increased tensile strength and strain at break as compared to the neat isotactic-PP. 

Alimuzzaman, S., Gong, R.H., Akonda, M., 2013. Three-dimensional nonwoven flax fiber reinforced polylactic acid biocomposites. Polym. Compos. 35 (7), 1244—1252. http //dx.doi. org/10.1002/pc.22774. 

Reinforced matrix scaffold for tissue engineering Some biomaterials, like naturally derived materials (eg, type I collagen, alginate) or synthetic polymers (eg, poly-glycolic acid (PGA), polylactic acid (PLA)), are commonly used for tissue engineering as 3D scaffolds whose primary function is to control the geometry and the volume of... 

Jonoobi, M., Mathew, A. R, Abdi, M. M., Makinejad, M. D., Oksman, K. (2012). Aeomparison of modified and unmodified cellulose nanofiber reinforced polylactic acid (RLA) prepared by twin screw extrusion. (4), 991-997. 

The film stacking method is a technique where the fiber reinforcement is sandwiched between films of the same polymer, and then hot pressing is apphed to consolidate them together. Note that the melting of the matrix-giving film should start at lower temperature than the reinforcement. This technique has been apphed to a wide range of polymers, such as poly (ethylene terephthalate) (PET) [6-7], polypropylene (PP) [8-11], polyethylene (PE) [10,12] and polylactic acid (PLA) [13]. 

General discussions of the effect of reinforcing agents on the thermal properties of polymers include glass fiber-reinforced polyethylene terephthalate [28], multiwalled carbon nanotube-reinforced liquid crystalline polymer [29], polysesquioxane [30, 31], polynrethane [31], epoxy resins [32], polyethylene [33], montmorillonite clay-reinforced polypropylene [34], polyethylene [35], polylactic acid [36, 37], calcium carbonate-filled low-density polyethylene [38], and barium sulfate-filled polyethylene [39]. 

Y. Shimamura, A. Yamamoku, K. Tohgo, S. Tasaka, H. Araki, Mechanical properties of carbon nanofiber reinforced polylactic acid. Key Eng. Mater. 2007, 345-346, 1225-1228. 

Hu, R. and Lim, J. (2007). Fabrication and Mechanical Properties of Completely Biodegradable Hemp Fiber Reinforced Polylactic Acid Composites. Journal of Composite Materials 41(13), 1655-1668. 

Islam MS, Pickering KL, Foreman NJ. Influence of alkafi treatment on the interfacial and physico-mechanical properties of industrial hemp fibre reinforced polylactic acid composites. Compos Part A 2010 41 596-603. 

Extrusion and impregnation, electrospinning, and multilayer films are other processes applicable for reinforced nanocomposites. Thus, preparation of cellulose whiskers reinforced with polylactic acid nanocomposites (by melt extrusion carried out by pumping the suspension of nanocrystals into the polymer melt during the extrusion process), using polyvinyl alcohol as a compatibilizer for the dispersion of cellulose whiskers within the polylactic acid matrix, was reported (de Menezes et al. 2009) bacterial cellulose whiskers incorporated into poly(oxyethylene) nanofibers by electrospinn to enhance the mechanical properties of electrospun fibers (Peresin et al. 2010) or the use of the layer-by-layer assembly technique, which maximizes the interaction between cellulose whiskers and a polar polymeric matrix (Bruno et al. 2009 Aulin et al. 2010), are some examples of nanocomposites reinforced by the last three methods. 

Fama LM, Pettarin V, Goyanes S, Bernal CR (2011) Starch based nanocomposites with improved mechanical properties. Carbohydr Polym 83 1226-1231 Fama LM, Ganan P, Bernal CR, Goyanes S (2012) Biodegradable starch nanocomposites with low water vapor permeability and high storage modulus. Carbohydr Polym 87 1989-1993 Fama L, Kumar R (2014) Nanocomposites based on polylactic acid (PLA) reinforced by functionalized carbon nanotubes (CNT). In Kumar R (ed) Polymer-matrix composites t3fpes, applications and performance. Nova Science Publishers, Inc. USA (in press)... 

Nogi M, Yano H (2008) Transparent nanocomposites based on cellulose produced by bacteria offer potential innovation in the electronics device industry. Adv Mater 20 1849-1852 Oksman K, Skrifvars M, Selin JF (2003) Natural fibres as reinforcement in polylactic acid (PLA) composites. Compos Sci Technol 63 1317-1324 Pandey JK, Kumar AP, Misra M, Mohanty AK, Drzal LT, Singh RP (2005) Recent advances in biodegradable nanocomposites. J Nanosci Nanotechnol 5 497-526 Panshin AJ, de Zeeuw C (1980) Textbook of wood technology stracture, identification, uses, and properties of the commercial woods of the United States, 4th edn. McGraw Hill Inc., New York... 

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