Commercial Poly Lactic Acid Research Articles

Control of thermal degradation of poly(lactic acid) using functional polysilsesquioxane microspheres as chain extenders

ABSTRACTTwo functional polysilsesquioxane microspheres, poly(epoxypropoxy)silsesquioxane (PESQ) and poly(epoxypropoxy/amino)silsesquioxane (PEASQ), were grafted onto commercial polylactic acid (PLA) via functional group reactions through melt processing and directly used as novel chain extenders to improve the thermal stability of PLA. During the whole reaction time of 35 min, the torques of P‐2PESQ and P‐1PEASQ were 60% higher than that of processed PLA. Thermal gravimetric analysis (TGA) revealed that the addition of PESQ or PEASQ into PLA increased the onset temperature for thermal degradation. PEASQ was found to be a potential chain extender for PLA. Compared with the processed PLA, the thermal decomposition temperatures of PEASQ modified PLA increased from 318 to 334°C at 5% weight loss. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41977.

Characterization of polylactic acid films for food packaging as affected by dielectric barrier discharge atmospheric plasma

Dielectric barrier discharge (DBD) air plasma is a novel technique for in-package decontamination of food, but it has not been yet applied to the packaging material. Characterization of commercial polylactic acid (PLA) films was done after in-package DBD plasma treatment at different voltages and treatment times to evaluate its suitability as food packaging material. DBD plasma increased the roughness of PLA film mainly at the site in contact with high voltage electrode at both the voltage levels of 70 and 80 kV. DBD plasma treatments did not induce any change in the glass transition temperature, but significant increase in the initial degradation temperature and maximum degradation temperature was observed. DBD plasma treatment did not adversely affect the oxygen and water vapor permeability of PLA. A very limited overall migration was observed in different food simulants and was much below the regulatory limits. In-package DBD plasma is a novel and innovative approach for the decontamination of foods with potential industrial application. This paper assesses the suitability of PLA as food packaging material for cold plasma treatment. It characterizes the effect of DBD plasma on the packaging material when used for in-package decontamination of food. The work described in this research offers a promising alternative to classical methods used in fruit and vegetable industries where in-package DBD plasma can serve as an effective decontamination process and avoids any post-process recontamination or hazards from the package itself.

Degradation Behaviors of Different Blends of Polylactic Acid Buried in Soil

Polylactic acid (PLA), as the biodegradable polymer becomes more attention as a green material for industrial applications. Lipase-catalysed polymerization with Lecitase Ultra and Lipozyme TL IM were applied to synthesize PLA to decrease the chemical-catalysts utilization which having toxicity interferes in products. PLA products were characterized by end group/HPLC analyses for Mn/Mw determination. The results indicated that low molecular weight PLA could be successfully produced from commercial lactic acid by using the commercial lipases. With using Lipozyme TL IM as biocatalyst, obtainable Mn and Mw of PLA were 7,933Da and 194Da, respectively. For Lecitase Ultra used as biocatalyst obtainable Mn and Mw of PLA were 8,330Da and 216Da, respectively. Subsequently, the resulting PLA products from this method were prepared as PLA films blended with commercial PLA beads varying the blending ratios by casting on glass plate. Their degradable behaviors were studied under controlled soil burial laboratory conditions. The characteristics of PLA blend films were analyzed using visual observations, measuring weight loss, DSC and FTIR analysis. The results observed that the different blends ratios of PLA films showed more flexible than pure PLA film. Besides, the different blends of PLA films were disintegrated in soil within the short burial time.

The Influence of Mercerised Kenaf Fibres Reinforced Polylactic Acid Composites on Dynamic Mechanical Analysis

The potential of using cellulose to reinforce the thermal stability of kenaf derived cellulose (KDC)/polylactic acid (PLA) composite was investigated in this study. The cellulose was derived from kenaf bast fibre which was chemically treated via chlorination and mercerisation processes. The composites with various loadings of cellulose (dry weight basis) ranging from 0% to 60% were produced by melt mixing and compression moulding. Dynamic mechanical properties namely storage modulus (E’), loss modulus (E”) and tan δ of the KDC/PLA composites and the commercial PLA were analysed and compared as a function of temperature. ESEM micrographs demonstrated that the mercerisation of kenaf fibres have successfully removed the lignin and hemicellulose, thus producing cellulose which can be observed by its rougher surface and greater size reduction than the raw fibre. The DMA results demonstrated that the storage modulus of 60% KDC/PLA composite is twice higher than the commercial PLA and the rest of the composites within a high temperature range (above 80°C). The glass transition temperatures (Tg) generated from the loss modulus curves exhibit that the peak of the loss modulus was shifted to higher temperature as the percentage of the cellulose loading was increased. These results show a better thermal stability of the composites when incorporated with the cellulose.

Assessment on the effects of the operational conditions on the manufacture of PLA-based composites using an integrated compounding–injection moulding machine

Cellulose fibres were employed as reinforcement agent for biodegradable composites using polylactic acid (PLA) as a polymer matrix. PLA can be obtained from renewable resources, and it is attracting much interest owing to its favourable physico-mechanical properties and biodegradability. Prior to composite compounding, two commercial PLA from different suppliers were characterized for apparent density, flow index, crystallinity, thermal properties, melt flow rheology and intrinsic viscosity for comparison. In experiments performed with an integrated compounding–injection moulding machine (ICIM), the effects of the processing conditions on the mechanical properties of composites (tensile strength, stiffness and strain at break) were analyzed using a Taguchi experimental design. Other properties of the composites, such as surface morphology and fibre length distribution, were also considered. ICIM technology provided composites with better mechanical properties and lower fibre degradation than the conventional sequential extrusion and injection moulding (SEIM) technology.

Racemic tack yields stereoregular polylactic acid

Using racemic starting materials rather than single-isomer ones and employing a racemic catalyst, chemists at Michigan State University, East Lansing, have polymerized cyclic dimers of lactic acid to stereoregular polymer chains [ J. Am. Chem. Soc. , 122 , 1552 (2000)]. Their achievement produces a crystalline polylactic acid resin with physical properties that are superior to those of polymers with unordered configurations. The result is one more step forward in efforts to develop green biodegradable plastics from renewable resources as alternatives to polymers derived from petrochemicals. Potential uses for polylactic acid include cast, oriented, and blown films; fibers and nonwoven fabrics; coatings for paper and cardboard; and thermoformed, injection-molded, or blow-molded containers. The MSU publication comes hot on the heels of the introduction of commercial polylactic acid resin by Cargill Dow Polymers, Minnetonka, Minn. (C&EN, Jan. 17, page 13). Cargill Dow is a joint venture of Dow Chemical and...