Edson Noriyuki Ito

Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC) of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts) and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

Rheological and mechanical characterization of poly (methyl methacrylate)/silica (PMMA/SiO2) composites

The search for new materials with properties suitable for specific applications has increased the number of research studies to fill the market demands. The development of polymer composites by the addition of inorganic fillers to the poly(methyl methacrylate) (PMMA) increases the potential use of this polymer in various application fields. The main objective of this work was to study the rheological and mechanical behavior of composites obtained from the addition of silica in two different types of PMMA matrix: a common (PMMAc) and an elastomeric copolymer (PMMAel). The results showed that the addition of silica particles to the PMMA matrix promoted an increase in torque, a decrease in the melt flow index of composites and an increase in hardness compared to pure polymers. The composites also showed a reduction of the maximum tensile strength for composites with PMMAc matrix and maintenance of tensile strength for composites with PMMAel matrix. The average width of scratch decreased due to a change in wear mechanism, attributed to the increase of hardness in the composites obtained.

Rheological, mechanical and morphological properties of poly(methyl methacrylate)/poly(ethylene terephthalate) blend with dual reactive interfacial compatibilization

In this work, the rheological, mechanical and morphological behavior of immiscible blend poly (methyl methacrylate) with elastomeric particles (PMMAelast) and post-consumer poly (ethylene terephthalate) (PET) with and without the use of the interfacial compatibilizer poly (methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate) (MGE) was studied. The significant increase in torque presented in rheological analyses has shown a indication of chemical reactions between the epoxy group of MGE with end groups of PET chains and also with the elastomeric phase of PMMAelast. The increased concentration of PET yielded an increase in maximum strength and elasticity modulus and a decrease in elongation at break. The PMMAelast/PET binary blend (50/50 wt%) and PMMAelast/PET/MGE compatibilized blend (65/30/5 wt%) showed pronounced results in elongation at break compared to PMMAelast, whereas, in the first results were due to the evidence of a co-continuous morphological structure and in the second, due to the efficiency of the dual reactive interfacial compatibilization of PMMAelast/PET blends. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses showed that PMMAelast/PET/MGE blends exhibit complex phase morphology due to the presence of elastomeric particles in the PMMAelast copolymer and in the use of MGE terpolymer.

XRD as an analytical tool for analyses of tommy atkins mango KERNEL polysAcharide

The aim of this work was to use X-Ray Diffraction (XRD) as an analytical tool for characterization of Tommy Atkins mango kernel starch and fibres. The experiments were performed in a Rigaku diffractometer DMAXB with CuKα (λ = 1.5406 Å) at 40 kV and 40 mA, analysis speed of 1o (2θ).min-1, with step scan of 0.05o, ranging between 2θ angle from 5o to 40o at 25 oC to calculate Sega Crystallinity Index (CI). Mango starch presented diffraction peaks at 2θ = 11.62o, 15.12o, 17.14o, and 23.1o, which represents a typical type A starch pattern. In this structure, amylopectin molecules are fitted to a monoclinic unit cell. Raw fibres presented peaks at 2θ = 12o and 22o, typical for a cellulose I pattern. Mercerized and bleached fibres, and nanowhiskers presented peaks at 2θ = 15o, 22o, and 34o, typical for cellulose II pattern. Cellulose I has two unit cell structures: Ia (triclinic) and Ib (monoclinic). Cellulose II occurs just as a monoclinic unit cell. The diffraction peaks of Cellulose II around 2θ = 22o are narrower and higher than in Cellulose I. Moreover, the chemical treatment washes off amorphous components of the fibre, remaining crystalline structures. It was possible calculate the CI for raw fibres (29.4%), mercerized fibres (50.3%), bleached fibres (69.8%), and nanowhiskers (58.0%). Thus, the XRD technique is an important analytical tool for identifies the crystalline pattern of the mango kernel polysaccharides, as well as to quantify the Segal Crystallinity Index. XRD as an analytical tool for analyses of tommy atkins mango KERNEL polysAcharide

Use of Brazilian Clay in Nylon 6 with Different Molecular Weight Nanocomposites

The effect of nylon 6 (Ny6) molecular weight on the development of polymer/layered silicates nanocomposites prepared by the melt intercalation technique was studied in this work. The nylon6/organoclay nanocomposites were prepared in the counter-rotational twin screw extruder. The results of torque rheometry showed that the presence of organoclay in the nylon 6 increased the torque. The results of X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed exfoliated and/or partially exfoliated structures.