How to improve mechanical properties of polylactic acid with bamboo fibers

Bamboo fibers (BF) were mixed in polylactic acid (PLA) to improve its mechanical properties: impact strength and heat resistance. Three different types of BF were extracted from raw bamboo by either sodium hydroxide (NaOH) treatment or steam explosion in conjunction with mechanical processing. They were designated as “short fiber bundle,” “alkali-treated filament” and “steam-exploded filament,” respectively. Composite samples were fabricated by injection molding using PLA/BF pellets prepared by a twin-screw extruding machine. Among them, the highest bending strength was obtained when steam-exploded filaments were put into PLA matrix. Impact strength of PLA was not greatly improved by addition of short fiber bundles as well as both filaments. In order to improve the impact strength of PLA/BF composites, PLA composite samples were alternatively fabricated by hot pressing using medium length bamboo fiber bundles (MFB) to avoid the decrease in fiber length at fabrication. Impact strength of PLA/MFB composite significantly increased, in which long fiber bundles were pulled out from the matrix. The addition of BF improves thermal properties and heat resistance of PLA/BF composites due to the constraint of deformation of PLA in conjunction with crystallinity promoted by anneal (at 110 °C for 5 h).

[1]  X. Sun,et al.  Mechanical properties and crystallization behavior of poly(lactic acid) blended with dendritic hyperbranched polymer , 2004 .

[2]  H. Tsuji,et al.  Alkaline and enzymatic degradation of L‐lactide copolymers. II. Crystallized films of poly(L‐lactide‐co‐D‐lactide) and poly(L‐lactide) with similar crystallinities , 2005 .

[3]  Y. Ono,et al.  Crystallization behavior of poly(l-lactic acid) , 2006 .

[4]  K. Arakawa,et al.  Effect of crystallinity and loading-rate on mode I fracture behavior of poly(lactic acid) , 2006 .

[5]  J. Mano,et al.  Influence of melting conditions on the thermal behaviour of poly(l-lactic acid) , 2005 .

[6]  Jiu-gao Yu,et al.  Compatibility characterization of poly(lactic acid)/poly(propylene carbonate) blends , 2005 .

[7]  H. Takagi,et al.  The Manufacture and Mechanical Properties of Composite Boards Made from Starch-Based Biodegradable Plastic and Bamboo Powder , 2003 .

[8]  K. Oksman,et al.  The Effect of Morphology and Chemical Characteristics of Cellulose Reinforcements on the Crystallinity of Polylactic Acid , 2006 .

[9]  M. Skrifvars,et al.  Natural fibres as reinforcement in polylactic acid (PLA) composites , 2003 .

[10]  C. Moon.  Effect of molecular weight and fiber diameter on the interfacial behavior in glass fiber/PP composites , 1998 .

[11]  Seung‐Hwan Lee,et al.  Eco-composite from poly(lactic acid) and bamboo fiber , 2004 .

[12]  Kazuhiko Inoue,et al.  Kenaf‐fiber‐reinforced poly(lactic acid) used for electronic products , 2006 .

[13]  Manjusri Misra,et al.  “Green” composites from recycled cellulose and poly(lactic acid): Physico-mechanical and morphological properties evaluation , 2005 .

[14]  Seung‐Hwan Lee,et al.  Biodegradable polymers/bamboo fiber biocomposite with bio-based coupling agent , 2006 .