Properties of PLA-Based Nanocomposites

Nanocomposites consisting of PLA and nanofillers frequently exhibit moderate improvement in mechanical and various other properties when compared to those of pure polymers. Improvements generally include a higher modulus both in the solid and the melt state, increased strength and thermal stability, decreased gas permeability, and an increased rate of degradability, of degradable polymers. 

The tensile modulus of a polymeric material has been shown to improve remarkably when nanocomposites are 

Sinha Ray et al. [27] reported the detailed measurement of flexural properties of neat PLA and various nanocomposites prepared with organoclay. They conducted flexural property measurements with injection molded samples according to the ASTM D-790 method. There was a significant increase in flexural modulus for nanocomposite prepared with 4 wt% of organoclay when compared to that of neat PLA, followed by a much slower increase with increasing organoclay content, and a maximum of a 50% increase for nanocomposite 

The degradation process of ahphatic polyesters is a complex process, which can proceed via hydrolysis (most often catalyzed by enzymes) and/or oxidation (UV- or thermo-induced). The stereoconliguration and possible ctystaUinity, relative hydrophobicity of the polymer matrix, and the presence of substituents can aU affect the biodegradabUity of synthetic polymers with hydrolyzable and/or oxidizable linkages in their main chain. 

The incorporation of OMLS fillers into the PLA matrix resulted in a small reduction in the molecular weight of the matrix. It is well known that PLA of relatively low molecular weight may show higher rates of enzymatic degradation because of the high concentration of accessible chain end groups [27]. However, in these cases, the rate of molecular 

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Petersson and Oksman (2006) compared the properties of PLA-based nanocomposites made of CNC and nonbiodegradable layered sihcate bentonite. At 5 wt % loading, there was more evidence of agglomeration in CNC/PLA composites than betonite/PLA composites, as shown in Fig. 7. The PLA/bentonite nanocomposite showed a 53 % increase in tensile modulus and a 47 % increase in the yield strength compared to neat PLA. The PLA/CNC system on the other hand showed no increase in tensile modulus and only a 12 % increase in yield strength compared to neat PLA. These results were lower than expected. Two factors were ascribed for... 

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