IRANIAN POLYMER JOURNAL
Year:2014 | Volume:23 | Issue:4|Papers Count:7

modification method, and then conjugated with toluene-2, 4-diisocyanate (TDI). The as-prepared TDI-PMMT sample was used as a blend polymer in poly (ethylene terephthalate) /TDI-PMMT composite (PET/TDI-PMMT). The chemical properties of original PMMT, TDI-PMMT and PET/TDI-PMMT composite were investigated by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). Results showed that chemical bonds which were formed between TDI and montmorillonite surface provided massive active isocyanate groups in in situ polymerization for the montmorillonite and matrix materials. This structure could have improved the compatibility between PMMT and PET effectively, and allow good distribution of the montmorillonite in polymer matrix. The spacing of montmorillonite layer decreased from 3.72 to 3.28 nm owing to the encapsulation of TDI groups. The physical morphology of nanocomposites was observed through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and XRD, and their thermal performance was evaluated by differential scanning calorimetry (DSC). XRD and SEM studies confirmed that compared to PMMT, the secondary-modified montmorillonite exhibited a better dispersion in PET matrix. TGA and DSC results showed that the thermal stability of PET/TDI-PMMT was superior to PET/PMMT. TEM images of PET/TDI-PMMT indicated that the TDI-PMMT exhibited good dispersion and the TDI-PMMT silicate layers were in better exfoliated state. The interface spacing of all samples was enlarged because of the heating reaction of oligomers. In the meanwhile, the mechanical properties such as tensile strength, flexural strength and flexural modulus of PET/TDI-PMMT were higher than those of PET/PMMT.

Conductive nanocomposites based on polyaniline/dextrin were synthesized by in situ polymerization of aniline in presence of dextrin. The nanocomposites were characterized by field emission scanning electron microcopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction and conductivity measurements. It was observed that the conductivity values increased with the increase of aniline content in nanocomposites. The obtained nanocomposites have been analyzed for the antioxidant activities using 2, 2-diphenyl-1-picrylhydrazyl assay. The results showed that the antioxidant activity of the nanocomposites was enhanced by increasing the aniline content. Polyaniline/dextrin nanocomposites were used as sorbent materials for the removal of heavy metals from aqueous solutions. The sorption data indicated that the novel polyaniline/dextrin nanocomposites have high tendency for the removal of heavy metal ions such as Cu (II), Cd (II) and Pb (II) from aqueous solutions. In addition, the in vitro biodegradability of polyaniline/dextrin nanocomposites with different weight ratios was studied by soil burial tests. The result demonstrated that the nanocomposites are biodegradable under soil environment by degradation range between 30.18 and 74.52%. The observed physical properties of the polyaniline/dextrin nanocomposites open interesting possibilities for novel applications of electrically conducting polysaccharide-based composites, particularly those that may exploit the antioxidant activity and heavy metal ions sorption of the polyaniline/dextrin nanocomposites.

Organic–inorganic hybrid nanocomposite coatings contain inorganic particles that are dispersed in organic phase in nanometric dimensions. Ceria and zirconia colloidal dispersions are uniformly distributed in the epoxy silica-based hybrid nanocomposite by sol–gel method and coated on 1050 aluminum alloy substrate with spin-coating technique. The hybrid sol is prepared by organic–inorganic precursors formed by hydrolysis and condensation of 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate (TEOS) in acidic solution using bisphenol A as networking agent and 1-methylimidazole as initiator in the presence of various ratios of ZrO2 and CeO2 colloidal nanoparticles. Particle size distribution, surface morphology and inorganic components distribution were determined by scanning electron microscopy (SEM) and EDXA techniques. SEM and Si, Zr, Ce mapping micrographs proved the uniform distribution of nanoparticles in the coatings. Transmission electron microscopy indicated that the nanoparticles dimension stay at the nanoscale level. The glass transition temperature (Tg) and loss properties (damping) of coatings were evaluated by dynamic mechanical thermal analysis. The corrosion protection of the coatings on the 1050 AA substrate was studied by potentiodynamic measurements. The results indicated that by introducing ceria nanoparticles in 1:1 molar ratio to TEOS in coating composition, corrosion protection was improved. However, the simultaneous presence of two nanoparticles (i.e., ceria and zirconia in 1:1 molar ratio) in the coating compositions increased the corrosion protection efficiency up to 99.8%. The multiple glass transitions and shifting to higher and wide range of temperatures by adding ceria and zirconia nanoparticles indicated a better network interaction between inorganic nanoparticles and organic molecular chains which also led to better corrosion protection of the coating in this composition.

Effects of different zinc borate (ZB) loadings on thermal, flammability and crystallinity properties of blends of 10 % rubber (9/1) natural rubber (NR)/epoxidised natural rubber (ENR)/metallocene linear low density polyethylene/N,N-m-phenylenebismaleimide/MgO were investigated. Fourier transform infrared spectroscopy revealed that –C=O and –OH groups appeared while C–O–C and C=C groups disappeared in all blend samples. ZB increased the activation of HVA-2 by changing the reaction mechanism and increasing the concentration of the –C=O groups in the blends due to the peak at 1,714–1,718 cm-1. The crystallinity of all blends was increased by ZB loading increase; therefore, it played the heterogeneous nucleation center and maximum crystallinity was observed at 6 phr ZB blend. The thermal stability of NR improved with increase of zinc borate loading and the highest thermal stability was determined for 8 phr ZB blend. Good compatibilization between the two rubbers (NR/ENR-50) was achieved in the presence of ZB, which was revealed by the presence of only one peak for their decomposition. The limiting oxygen index value of mLLDPE was decreased by two rubbers loading increase, while it was increased by ZB loading increase to provide fire barriers to protect flammable materials from thermal damage. It was concluded that ZB has a synergistic effect on the LOI values of flame retardant mLLDPE/rubber containing MgO.

Carboxylated nitrile butadiene rubber (XNBR)-based gloves are commonly used to protect users’ hands from the aggressive environment in various industrial applications. Permeation resistance and mechanical properties of gloves should be simultaneously considered to accomplish adequate protection. Accordingly, in this study, XNBR was reinforced with different amounts of nanoclay and the resulting dispersion was examined using X-ray diffraction and transmission electron microscope. The results showed that, nanoclay has been appropriately dispersed in XNBR lattice and therefore, considerable enhancements in mechanical properties, including tensile strength and modulus were gained. The permeation resistance of the synthesized nanocomposites was studied by two solvents, including perchlorethylene and aniline with low and high affinity to XNBR, respectively. Using permeation test cell, parameters of breakthrough time (BT) and steady-state permeation rate (SSPR) were determined. The BT and SSPR of aniline in nanocomposites with 3 phr nanoclay in comparison with neat polymer were increased 89% and decreased by 11%, respectively. Degradation resistance test of nanocomposite demonstrated acceptable integrity of its barrier properties after repeated exposure to selected chemicals. Analysis of mechanical properties and permeation indices of synthesized nanocomposites illustrated that the application of these materials for manufacturing protective gloves seems promising.

With the fast development of auto industry, more and more new functional materials are developed to satisfy our life. Auto interior materials are usually suffered from the attack of bacteria and therefore affect people. In this work, we reported on the fabrication of novel antimicrobial poly(vinyl chloride) plastic (PVCP-I, PVCP-II) with antimicrobial halloysite nanotubes and SiO2/ZnO/ZnS/Ag2S nano-composites as additives, respectively, and then these two kinds of novel antimicrobial poly(vinyl chloride) PVC materials were applied to automobile interior. FirebrakeÒ ZB was used as the fire retardant and the results showed that the prepared PVC materials have excellent non-flammability properties. The oxygen indexes of traditional PVCP, PVCP-I and PVCP-II were 30.1, 31.9 and 32.5 %, respectively. PVC antimicrobial materials were prepared by coating on the special paper. PVCP-I and PVCP-II could kill more than 99 % of Escherichia coli and Staphylococcus aureus with concentration of about 7×107 and 4×107 CFU mL-1, respectively. Mechanical properties and thermal stability were also investigated to study the physical characteristics of the prepared PVC plastic. The formation of nano-additives was confirmed by X-ray diffraction and transmission electron microscopy techniques. Antimicrobial capacity was used as a probe to evaluate the potential applications of prepared PVC-I and PVC-II materials in antimicrobial automobile interiors. Also, the material was characterized by thermo-gravimetric analysis; the result showed that PVCP-I and PVCP-II have excellent thermo-stability. What counts is the simple processing and outstanding characteristic of the PVCP material and great application potential may have in store for the obtained antimicrobial PVC-I and PVCP-II.

Chitin the second most abundant polysaccharide is synthesized by an enormous number of living organisms including fungi and insects. These biopolymers have found many applications in different areas such as: packaging material, membrane for removal of metal ions, dyes and pigments in waste water engineering; anti-cholesterol, fat binding, preservative and food additive in food industry; seed and fertilizer coating, controlled agrochemical release in agriculture; surface treatment, photographic paper in pulp and paper industry; moisturizer, body creams and lotions in cosmetics and toiletries. It has also found wide applications in biomedical such as tissue engineering, drug delivery, wound dressing, scaffolds, cancer diagnosis, etc. The majority of these versatile applications are coming of its non-toxicity, biocompatibility and biodegradability. Chitin is also easily processed as gel, membrane, and nanofiber. This review emphasizes an extensive bibliography of recent basic and applied research and investigations on the aspects of this interesting biopolymer including the recovery, preparation, modification and application of chitin and its derivatives and related compounds. A new class of biocompatible and biodegradable chitin-based polyurethane (PU) elastomer was also introduced and reviewed in this study and it was found that by incorporation of chitin into the PU elastomer backbone, biocompatibility and degradation rate of the final elastomer improved. PUs are one of the synthetic biocompatible polymers with excellent physical and mechanical properties. Combination of this polymer with chitin resulted to a new tailor-made biocompatible and biodegradable polymer with improved properties. These polymers have potential applications in various applications including biomedical.