Ethylene-methyl acrylate-glycidyl methacrylate toughened poly(lactic acid) nanocomposites

Poly (lactic acid) (PLA) was melt blended in a twin screw extruder using an ethylene-methyl acrylate-glycidyl methacrylate rubber as a toughener. PLA/rubber blends were immiscible as observed by scanning electron microscopy. Impact strength and ductility of PLA were improved by the addition of the rubber at the expense of strength and stiffness. An organo-montmorillonite (OMMT) was used at 2 wt % to counteract the negative effect of the rubber on modulus, and balanced properties were observed at 10 wt % rubber content. X-ray diffraction and transmission electron microscopy revealed the formation of intercalated/exfoliated structure in the ternary nanocomposites. Thermal behavior analysis indicated that the degree of crystallinity is slightly affected by the clay and the rubber. Both the clay and the rubber decreased the crystallization temperature of PLA and acted as nucleating agents for PLA. The viscosity of the mixtures as measured by melt flow index was highly influenced by the rubber and the OMMT. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 201

Poly(lactic acid)-layered silicate nanocomposites: The effects of modifier and compatibilizer on the morphology and mechanical properties

Poly(lactic acid) (PLA) based nanocomposites were prepared to investigate the effects of types of nanoclays. Five different organically modified nanoclays (Cloisites((R))15A, 25A, and 30B, and Nanofils((R))5 and 8) were used. Two rubbery compatibilizers, ethylene-glycidyl methacrylate (E-GMA) and ethylene-butyl acrylate-maleic anhydride, were used in the nanocomposites as compatibilizer-impact modifier. The degree of clay dispersion, the chemical compatibility between the polymer matrix and the compatibilizers, and changes in the morphology and mechanical properties of the nanocomposites were investigated. The mechanical properties and the morphological studies showed that the interactions between the different compatibilizers and PLA resulted in different structures and properties; such that the dispersion of clay, droplet size of the compatibilizer, and tensile properties were distinctly dependent on the type of the compatibilizer. Compatibility between C25A, C30B, and E-GMA resulted in the best level of dispersion, leading to the highest tensile modulus and toughness among the compositions studied. In the mentioned nanocomposites, a network structure was formed owing to the high reactivity of the epoxide group of GMA towards the PLA end groups resulting in high impact toughness. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42553

Effects of Mixing Protocols on Impact Modified Poly(lactic acid) Layered Silicate Nanocomposites

Poly(lactic acid)/2 wt % organomodified montmorillonite (PLA/OMMT) was toughened by an ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) rubber. The ternary nanocomposites were prepared by melt compounding in a twin screw extruder using four different addition protocols of the components of the nanocomposite and varying the rubber content in the range of 5-20 wt %. It was found that both clay dispersion and morphology were influenced by the blending method as detected by X-ray diffraction (XRD) and observed by TEM and scanning electron microscopy (SEM). The XRD results, which were also confirmed by TEM observations, demonstrated that the OMMT dispersed better in PLA than in E-MA-GMA. All formulations exhibited intercalated/partially exfoliated structure with the best clay dispersion achieved when the clay was first mixed with PLA before the rubber was added. According to SEM, the blends were immiscible and exhibited fine dispersion of the rubber in the PLA with differences in the mean particle sizes that depended on the addition order. Balanced stiffness-toughness was observed at 10 wt % rubber content in the compounds without significant sacrifice of the strength. High impact toughness was attained when PLA was first mixed with the clay before the rubber was added, and the highest tensile toughness was obtained when PLA was first compounded with the rubber, and then clay was incorporated into the mixture. Thermal characterization by DSC confirmed the immiscibility of the blends, but in general, the thermal parameters and the degree of crystallinity of the PLA were not affected by the preparation procedure. Both the clay and the rubber decreased the crystallization temperature of the PLA by acting as nucleating agents. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41518

Investigating the diffusional behaviour of Irganox (R) 1076 antioxidant in HDPE/Cloisite (R) 15A nanocomposite-based food contact packaging films Effect of nanoclay loading

In this research work, the prediction of the diffusion coefficient (D-p) of Irganox (R) 1076 (Ir-76) antioxidant in HDPE-based food contact packaging films was carried out. The diffusion of this additive was studied both, in neat HDPE film and in HDPE nanocomposites films made of HDPE matrix filled with 1, 3, and 5wt% of a commercially available organoclay (Cloisite (R) 15A). The diffusion experiments were carried out by using the Roe's method on films consisting of a stack of several polymer films having a total nominal thickness of 120 +/- 01m. Diffusion coefficients were determined in the temperature range 80 degrees C to 100 degrees C according to the second Fick's law by measuring the evolution of the Ir-76 concentration in the films by means of Fourier transform infrared (FTIR) spectroscopy analysis. The results indicated that the diffusion coefficient of Ir-76 in HDPE films decreased with the addition of the organoclay, and a maximum reduction of 78% (at 23 degrees C) in the diffusion rate of the Ir-76 was observed at an optimum filler content of 3wt%, thus making these films attractive for the plastic packaging industry