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Abstract  

Poly(lactic acid)/organo-montmorillonite nanocomposites were prepared by melt intercalation technique. Maleic anhydride-grafted ethylene propylene rubber (EPMgMA) was added into the PLA/OMMT in order to improve the compatibility and toughness of the nanocomposites. The samples were prepared by single screw extrusion followed by compression molding. The effect of OMMT and EPMgMA on the thermal properties of PLA was studied. The thermal properties of the PLA/OMMT nanocomposites have been investigated by using differential scanning calorimeter (DSC) and thermo-gravimetry analyzer (TG). The melting temperature (T m), glass transition temperature (T g), crystallization temperature (T c), degree of crystallinity (χc), and thermal stability of the PLA/OMMT nanocomposites have been studied. It was found that the thermal properties of PLA were greatly influenced by the addition of OMMT and EPMgMA.

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Abstract  

A number of experimental techniques are employed to characterize physical and thermal properties of poly(lactic acid), PLA. To characterize PLA in terms of molecular mass and molecular mass distribution, size exclusion chromatography was used. The value of the specific refractive index increment was measured by differential refractometry. The thermal properties of semicrystalline PLA were measured by standard and temperature-modulated differential scanning calorimetry. The thermal stability of PLA was monitored by measuring the changes of mass using thermogravimetric analysis. The mechanical properties of amorphous PLA were measured by dynamic mechanical analysis and the results were discussed and compared with DSC in the glass transition region.

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Abstract  

The effect of the dyeing on the melting behavior of poly(lactic acid) fabrics was investigated by differential scanning calorimeter. The DSC melting peaks at 10C min-1 of the untreated poly(lactic acid) fabric were observed at a temperature higher than those of the dyed fabrics. The restricting force from the extended tie molecules along the fiber axis seems to decrease in the dyeing process. When the sample was rapidly heated, the crystallites melted at lower temperatures since recrystallization was restricted. It was estimated, based on the heating-rate dependency of melting behavior, that the original crystallites of the untreated sample melted at 146.1C and those of the dyed samples melted at higher temperatures, suggesting that their crystallites are grown to be more perfect in the dyeing process.

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Abstract  

Thermal decomposition of poly(lactic acid) (PLA) has been studied using thermogravimetry coupled to Fourier transform infrared spectroscopy (TGA-FTIR). FTIR analysis of the evolved decomposition products shows the release of lactide molecule, acetaldehyde, carbon monoxide and carbon dioxide. Acetaldehyde and carbon dioxide exist until the end of the experiments, whereas carbon monoxide gradually decreases above the peak temperature in that the higher temperature benefits from chain homolysis and the production of carbon dioxide. A kinetic study of thermal degradation of PLA in nitrogen has been studied by means of thermogravimetry. It is found that the thermal degradation kinetics of PLA can be interpreted in terms of multi-step degradation mechanisms. The activation energies obtained by Ozawa–Flynn–Wall method and Friedman’s method are in good agreement with that obtained by Kissinger’s method. The activation energies of PLA calculated by the three methods are 177.5 kJ mol−1, 183.6 kJ mol−1 and 181.1 kJ mol−1, respectively.

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) and a density of 1.26 g/cm 3 was prepared at Ire Chemical Ltd., South Korea. Poly(lactic acid) (PLA) with an MFI of 15 g/10 min (190 °C/2,160 g) and a density of 1.22 g/cm 3 was supplied by Natureworks LLC, USA. The natural flours used as reinforcing

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Abstract  

The thermogravimetric analysis (TG) of two series of tri-block copolymers based on poly(L,L-lactide) (PLLA) and poly(ethyleneglycol) (PEG) segments, having molar mass of 4000 or 600 g mol–1, respectively, is reported. The prepared block copolymers presented wide range of molecular masses (800 to 47500 g mol–1) and compositions (16 to 80 mass% PEG). The thermal stability increased with the PLLA and/or PEG segment size and the tri-block copolymers prepared from PEG 4000 started to decompose at higher temperatures compared to those copolymers from PEG 600. The copolymers compositions were determined by thermogravimetric analysis and the results were compared to other traditional quantitative spectroscopic methods, hydrogen nuclear magnetic resonance spectrometry (1HNMR) and Fourier transform infrared spectrometry (FTIR). The PEG 4000 copolymer compositions calculated by TG and by 1HNMR, presented differences of 1%, demonstrating feasibility of using thermogravimetric analysis for quantitative purposes.

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3D printing of Acrylonitrile Butadiene Styrene (ABS) and Poly Lactic Acid (PLA) were used to prepare specimens utilising fused deposition modelling (FDM) technology. Two colours of PLA filament were printed; white and grey, whereas ABS only in white colour. Determining the tribological properties of 3D printed samples have been carried out, through obtaining the frictional features of different 3D printable filaments. Alternating-motion system employed for measuring the tribological factors. Studying the difference between static and dynamic friction factors and the examination of wear values were included. A comparison among the tribological behaviour of the 3D printed polymers has been investigated. The printed white ABS and PLA specimens show insignificant differences in the results tendency. On the contrary, the grey PLA exhibits a considerable variation due to the incredible growth in the coefficient of friction and wear average as well.

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products from the organism. Furthermore, their mechanical properties as well as their decomposition rate can be controlled depending on the application. Such biodegradable polymers are poly(glycolic acid), poly(lactic acid), and their copolymers [ 1 , 2

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. Vega-Lugo , A.C. & Lim , L.T. ( 2009 ): Controlled release of allyl isothiocyanate using soy protein and poly (lactic acid) electrospun fibers . Food Res. Int. , 42 ( 8 ), 933 – 940

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. Petersson , L , Kvien , I , Oksman , K . Structure and thermal properties of poly(lactic acid)/cellulose whiskers nanocomposite materials . Compos Sci Technol . 2007 ; 67 : 2535 – 2544 . 10.1016/j.compscitech.2006

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