Preparation and Properties of Ethylene Vinyl Acetate (EVA)/Organoclay/Compatibilizer Nanocomposites: Effects of Organoclay Loading and Methyl Ethyl Ketone

Ethylene vinyl acetate (EVA)/organoclay/compatibilizer nanocomposites were produced using a melt compounding technique in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. Effects of organoclay loading (from 2 to 10 phr—parts per hundred of resin and methyl ethyl ketone (MEK), used as a compatibilizer, on the processing properties, tensile properties, morphology, thermal degradation, and water absorption behavior of EVA/organoclay nanocomposites were studied. Results indicate that the presence of organoclay increase the processing torque, tensile properties, thermal degradation, and resistance to water absorption. The optimum organoclay loading was achieved at 2 phr. This was caused by the dispersion state of individual silicate layers (intercalation/exfoliation) in EVA matrix. The intercalation/exfoliation structure affects the properties of EVA/organoclay nanocomposites as evidenced from the morphology studies such as x-ray diffraction (XRD) and transmission electron microscopy (TEM) evaluation. The addition of MEK has the ability to improve the tensile properties, thermal degradation, and slightly reduces the resistance of water permeation of EVA/organoclay nanocomposites. The enhanced properties were seen as a result of the better matrix and filler interaction. The EVA/organoclay/MEK nanocomposites shows better intercalation/exfoliation of individual silicate layers in the EVA matrix as indicated by TEM. Moreover, the XRD evaluation shows that intercalation/exfoliation of the organoclay was formed in the EVA matrix.     

Influence of Electron Beam Irradiation and Coupling Agents on the Thermal Stability of Sugar Cane Bagasse Fiber-Thermoplastics Scrape Composite

The influence of blending of sugar cane bagasse with thermoplastics scrape as well as incorporation of some coupling agents has been conducted using thermogravimetric analysis (TGA). In addition, the effect of electron beam preirradiation of low density polyethylene on the properties of the bagasse-LDPE composite was also studied. Simulation of TGA data reveals that the presence of bagasse fiber accelerates the volatilization of either polypropylene or polyvinylchloride. On the other hand, polyethylene and polystyrene were stable against the heat evolved during the pyrolysis of bagasse fibers. Also, it was found that incorporation of a mixture of pentaerithrol tetraacrylate (PETA) and dicumyl peroxide (DCP) as coupling agents improve the thermal stability of low density polyethylene whereas the role of irradiation was insignificant. Moreover, pronounced enhancement in the thermal stability was detected in polypropylene followed by polystyrene and polyvinylchloride on using PETA.     

Properties of Ferrite-Filled Natural Rubber Composites

Nickel zinc ferrite (Ni-ZnFe₂O₄)-filled natural rubber (NR) composite was prepared at various loading of ferrite. The tensile properties included in this study were tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break of the composites increased up to 40 parts per hundred rubber (phr) of ferrite and then decreased at higher loading whereas the tensile modulus was increased gradually with increasing of ferrite loading. Scanning electron microscopy (SEM) was used to determine the wettability of filler in rubber matrix. From the observation, the increase of filler loading reduced the wettability of the filler. Thermal stability of the composites was conducted by using a thermogravimetry analyser (TGA). The incorporation of ferrite in NR composites enhanced the thermal stability of NR composites. The swelling test results indicate that the swelling percentage of the composites decreased by increasing of ferrite loading. The initial permeability, μ_i and quality factor, Q of magnetic properties of NR composites achieved maximum value at 60 phr of ferrite loading for frequency range between 5000–40,000 kHz. The maximum impedance, Z _max of the NR composites was at the highest value at 80 phr ferrite loading for frequency range between 200–800 MHz.     

Preparation and Characterization of Ethylene Vinyl Acetate (EVA)/Natural Rubber (SMR L)/Organoclay Nanocomposites: Effect of Blending Sequences and Organoclay Loading

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay thermoplastic elastomer nanocomposites were melt compounded in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. In this paper, we demonstrate the effect of different blending sequences and organoclay loading from 2 to 10 phr (parts per hundred resins) on the tensile properties, morphology, thermal degradation, flammability, and water absorption behavior of EVA/SMR L/organoclay nanocomposites. EVA/SMR L/organoclay TPE nanocomposites were prepared by three different blending sequences, and each exhibited different tensile properties. Results indicated that the presence of organoclay increases the tensile properties, resistance toward thermal degradation, resistance to water permeation, and flame retardancy for all the nanocomposites prepared via different blending sequences. However, the optimum results for all the properties studied were achieved when EVA was blended with organoclay first and SMR L was incorporated later into the blend. The optimum organoclay loading was achieved at 2 phr. Results from scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies showed that at 2 phr organoclay loading, nanostructures of individual silicate layers were achieved, whereas at 8 phr organoclay loading, agglomeration was observed. Flammability of the nanocomposites decreased when the organoclay loading increased.     

Comparison of Properties of Polypropylene (PP)/Virgin Acrylonitrile Butadiene Rubber (NBRv) and Polypropylene (PP)/Recycled Acrylonitrile Butadiene Rubber (NBRr) Blends

The comparison properties of polypropylene (PP)/recycled acrylonitrile butadiene rubber (NBRr) blends and polypropylene/virgin acrylonitrile butadiene rubber (NBRv) blends were investigated. The tensile properties such as tensile strength, tensile modulus and elongation at break of PP/NBRv blends are higher than PP/NBRr blends. However, PP/NBRv blends exhibit lower stabilization torque and higher swelling percentage than PP/NBRr blends. Based on SEM, a finer morphology was observed in PP/NBRv blends in comparison with the PP/NBRr blends. The thermal stability of PP/NBRr is better than that of PP/NBRv blends.     

Curing Characteristics,Morphological, Tensile and Thermal Properties of Bentonite-Filled Ethylene-Propylene-Diene Monomer (EPDM) Composites

Bentonite (Bt) with irregular shape and surface morphology was used as a new type of filler in EPDM. EPDM/Bt composites were prepared using a laboratory size two-roll mill by adding 0 to 70 phr Bt. The effects of Bt loading on curing characteristics, morphology, tensile and thermal properties of EPDM/Bt composite were studied. Scorch and curing time were decreased with 0 to 30 phr loading and increased subsequently at 50 and 70 phr. Tensile strength and elongation at break (E_b) were increased with increasing Bt loading from 0 to 50 phr and decreased at 70 phr, whereas the tensile modulus (M100%) shows an increasing trend with increasing Bt loading. Thermogravimetric analysis shows the enhancements of thermal properties with increasing Bt loading. Morphological studies of tensile fracture surfaces of EPDM/Bt composite proves good interaction between Bt particles and EPDM at 50 phr and formation of Bt agglomerates at 70 phr.     

Effect of Multifunctional Additive on Filler Dispersion in Carbon-Black- and Silica-Filled Natural Rubber Compounds

The effect of multifunctional additive (MFA) on filler dispersion in carbon-black- (CB) and silica-filled natural rubber (NR) compounds has been studied. Silica dispersion, measured by computer-aided image analysis and scanning electron microscopy (SEM), showed a substantial improvement when MFA concentration is increased from 1 to 3 phr. After this level, there is a further but small improvement. However, for CB-filled NR compounds, CB dispersion showed a substantial improvement when the MFA used between 0 and 1 phr. As in silica-Filled NR compounds, there is only a small improvement in dispersion after 1 phr.     

Synthesis of polyvinylidene fluoride (PVDF) membranes for protein binding: Effect of casting thickness

Microporous polyvinylidene fluoride (PVDF) membranes were synthesized from PVDF/N‐methyl‐2‐pyrrolidinone (NMP) solutions using an immersion–precipitation method with a 2‐propanol/water mixture as a soft coagulant. The effects of membrane thickness on pore size distribution and surface/cross‐section morphology were studied using capillary flow porometry and scanning electron microscopy (SEM), respectively. All the synthesized membranes had a small range of pore size distribution, with the pore size decreasing with increasing casting thickness. The semicrystalline PVDF membranes demonstrated significant variations in morphology under SEM observation, with the existence of polymer agglomeration at a casting thickness of 500 μm and above. The protein binding capacity was observed to be highest at a casting thickness of 400 μm, where optimum pore morphology provided a large surface area for protein binding. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Analysis of MTHFR and MTRR Gene Polymorphisms in Iranian Ventricular Septal Defect Subjects

Ventricular septal defect (VSD) is one of the most common types of congenital heart defects (CHD). There are vivid multifactorial causes for VSD in which both genetic and environmental risk factors are consequential in the development of CHD. Methionine synthase reductase (MTRR) and methylenetetrahydrofolate reductase (MTHFR) are two of the key regulatory enzymes involved in the metabolic pathway of homocysteine. Genes involved in homocysteine/folate metabolism may play an important role in CHDs. In this study; we determined the association of A66G and C524T polymorphisms of the MTRR gene and C677T polymorphism of the MTHFR gene in Iranian VSD subjects. A total of 123 children with VSDs and 125 healthy children were included in this study. Genomic DNA was extracted from the buccal cells of all the subjects. The restriction fragment length polymorphism polymerase chain reaction (PCR-RFLP) method was carried out to amplify the A66G and C524T polymorphism of MTRR and C677T polymorphism of MTHFR genes digested with Hinf1, Xho1 and Nde1 enzymes, respectively. The genotype frequencies of CC, CT and TT of MTRR gene among the studied cases were 43.1%, 40.7% and 16.3%, respectively, compared to 52.8%, 43.2% and 4.0%, respectively among the controls. For the MTRR A66G gene polymorphism, the genotypes frequencies of AA, AG and GG among the cases were 33.3%, 43.9% and 22.8%, respectively, while the frequencies were 49.6%, 42.4% and 8.0%, respectively, among control subjects. The frequencies for CC and CT genotypes of the MTHFR gene were 51.2% and 48.8%, respectively, in VSD patients compared to 56.8% and 43.2% respectively, in control subjects. Apart from MTHFR C677T polymorphism, significant differences were noticed (p < 0.05) in C524T and A66G polymorphisms of the MTRR gene between cases and control subjects.     

Promising growth inhibitory potential of extracted natural silk sericin biopolymer against DEN-induced liver tumor in male mice

Silk sericin (SS), a protein biopolymer, is gaining an increasing attention in a variety of biomedical applications. Our objective was to identify the optimal extraction method yielding the highest silk protein content, to assess its chemical elemental composition, to characterize it, and to compare its conformation by X-ray diffraction and Fourier-transform infrared versus that of the commercial one. Herein, alkali and high temperature is the perfect approach. This study aimed further to test whether extracted SS could attenuate the adverse hepatotoxic effects induced by diethylnitrosamine (DEN) in mice. Animals were injected intraperitoneally once weekly for four consecutive weeks with physiological saline (0.9% NaCl), DEN (25 mg/kg), SS (1 g/kg) 90 min prior to DEN injection, melatonin (10 mg/kg) followed within 1 h with the administration of SS and 30 min later with DEN. The results confirmed the hepatotoxicity of DEN manifested by an increase in liver enzymes' activity, and pathological changes in the liver tissue. The combined use of SS and/or melatonin with DEN returned most of the parameters to values similar to the controls. Briefly, chemically characterized SS seems a valuable extract for further consideration as anti-carcinogenic agent. It has the potential to upgrade liver cancer chemotherapeutic agents.