Saowaroj Chuayjuljit

XSBR/NR Rubber Blends Filled with Polystyrene-Encapsulated Nanosilica Prepared by in situ Differential Microemulsion Polymerization

Rubber blends of caboxylated styrene butadiene rubber (XSBR) and natural rubber (NR) filled with polystyrene-encapsulated nanosilica (PS-nSiO 2) were prepared by latex compounding. The PS-nSiO2 synthesized by in situ differential microemulsion polymerization was used at 3 phr as the filler in three different XSBR/NR blend ratios (70/30, 50/50, and 30/70). The nanocomposite latex was cast into sheets on glass molds and cured in an oven. The specimens were examined for their tensile properties, dynamic mechanical properties, and thermal stability. The tensile strength and elongation at break were found to increase with increasing levels of NR in the rubber blends, but the modulus decreased. Moreover, the tensile properties, dynamic mechanical properties, and thermal stability were all improved by the addition of PS-nSiO2 within the blend systems.

Effects of Silica, Poly(methyl methacrylate) and Poly(methyl methacrylate)-Grafted-Silica Nanoparticles on the Physical Properties of Plasticized-Poly(vinyl chloride)

Nanocomposites of plasticized-poly(vinyl chloride) (PVC) filled with different contents (3-9 parts by weight per hundred of PVC resin) of nanosilica (nSiO2), nanosized poly(methyl methacrylate) (nPMMA) and PMMA-grafted-nanosilica (PMMA-nSiO2) were investigated in this study. nPMMA and PMMA-nSiO2 were synthesized via differential microemulsion polymerization. The addition of either an appropriate type or amount of nanofiller into the plasticized-PVC improved the tensile strength, Youngs modulus, tear strength, and thermal stability of the obtained nanocomposites, whereas the elongation at break decreased with increasing amounts of the nanofillers. Scanning electron micrographs of all the nanocomposites showed typical dimple fracture topologies similar to the neat plasticized-PVC.

Effects of ethylene octene copolymer and ultrafine wollastonite on the properties and morphology of polypropylene-based composites

The mechanical and thermal properties of polypropylene (PP)/ethylene octene copolymer (EOC)/wollastonite composites were investigated as a function of their composition in comparison to PP/EOC blends and native PP. PP was melt mixed with two loadings of EOC (20 and 30% (w/w)); and for the composites, each of these were mixed with three loadings of wollastonite (10, 20 and 30 parts by weight per hundred of the PP/EOC resin) on a twin-screw extruder and then injection molded. Both PP/EOC blends provided a higher elongation at break and impact strength but a lower tensile strength and modulus, storage modulus and flexural strength and modulus when compared with those of the neat PP. The addition of ultrafine wollastonite (particle size of 1200 mesh) into the blends increased the tensile modulus, storage modulus, flexural strength and modulus and impact strength in a dose-dependent manner. Thus, the combined use of EOC and wollastonite can provide balanced mechanical properties to PP. Moreover, thermogravimetric analysis showed that although the degradation temperatures of the composites were not improved, the char formation was remarkably increased with increasing wollastonite loadings.

Preparation of Natural Rubber/EVA/Montmorillonite Nanocomposites by Latex Compounding

Nanocomposite materials of natural rubber (NR)/poly(ethylene-co-vinyl acetate) (EVA)/montmorillonite (MMT) were prepared by latex compounding without modification of the MMT. EVA and MMT were well mixed at room temperature in the latex state and subsequently blended with NR latex at NR/EVA dry weight ratios of 100/0, 90/10, 80/20, 70/30, 60/40 and 50/50. Where used, MMT was added at 4 parts per hundred of dry rubber and EVA (phr). The homogeneous latex mixture was then cast into sheets on a glass mold, air dried for 2 days at room temperature and then in an oven at 70 °C for 6 h. It was subsequently cured at 110 °C for 2 h. After curing, samples were examined for their structure and morphology by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), whilst tensile properties were investigated using a Universal Testing Machine. The XRD patterns and TEM images of the nanocomposites showed an exfoliated structure. The 90NR/10EVA/4MMT exhibited the highest tensile strength, with incorporation of MMT offering a substantial improvement in tensile strength. SEM micrographs revealed that the MMT particles were well dispersed in the polymer matrix. However, increasing the EVA content to 50 wt.% reduced the compatibility between NR and EVA.

Poly(Lactic Acid)/Poly(Butylene Succinate) Blends Filled with Epoxy Functionalised Polymeric Chain Extender

In this work, biodegradable plastics were produced from different poly(lactic acid) (PLA)/ poly(butylene succinate) (PBS) blend ratios in the presence of a fix loading (1 phr) of a commercial epoxy functionalised polymeric chain extender (Joncryl ADR-4300-S). The effects of blend ratio and chain extender on the tensile properties, thermal stability and morphology were investigated by the tensile testing, thermogravimetric analysis (TGA) and scanning electron microscopy, respectively. The results show that the incorporation of PBS and Joncryl into PLA apparently reduced the tensile strength and tensile modulus, but increased the elongation at break of the blends in a dose-dependent manner. However, their blends provide interesting materials for industrial packaging applications, due to their enhanced ductility by decreasing the tensile modulus and increasing the elongation at break. TGA analysis showed that thermal stability of the blends was lower than that of the pure PLA and PBS. Moreover, the chain-extended products exhibit two stages of thermal decomposition, the first was due to the degradation of PBS, and the second was due to the degradation of PLA.

Nanocomposites of EVA/polystyrene nanoparticles/montmorillonite

Nanocomposites of ethylene vinyl acetate (EVA) copolymer, polystyrene (PS) nanoparticles, and montmorillonite (MMT) were prepared by latex compounding. The nanolatex of PS was synthesized by differential microemulsion polymerization and then blended with EVA at EVA/PS dry weight ratios of 90/10, 80/20, and 70/30, before mixing with MMT at 1, 3, or 5 parts per hundred rubbers. The latex composite mixtures were cast on a glass mold and compressed into thin sheets. The nanocomposites were characterized for their structures, mechanical properties, and thermal behaviors. The tensile strength, Young’s modulus, storage modulus, and thermal stability were all improved with the incorporation of MMT, although the extent of such depended upon and varied with the EVA/PS ratio of the nanocomposite.

Use of Carbon Nanotube and Nanosilica as Reinforcement Nanofillers in NR/SBR Blended Latex

The blended latex of natural rubber (NR) and styrene butadiene rubber (SBR) at dry weight ratio of 80/20 (NR/SBR) was reinforced with a very low loading level of either carbon nanotube (CNT) or nanosilica (nano-SiO2) (0.1-0.4 phr). The CNT and nano-SiO2 were compounded with NR/SBR rubber blend and other chemicals necessary for vulcanization in the latex state. The obtained nanocomposite latex was cast into thin sheet on a glass mold and then cured in an oven at 80°C for 3 h. The cured samples were subjected to the tensile, dynamic mechanical and thermal tests. The results revealed that the nanofillers have improved their tensile strength, modulus at 300% strain, dynamic mechanical properties and thermal stability but reduced the elongation at break. It was also observed that at similar nanofiller loadings the reinforcing effects of CNT are more noticeable than that of nano-SiO2.

Natural Rubber Blended with Polystyrene Nanoparticles Prepared by Differential Microemulsion Polymerization

Blends of natural rubber (NR) and polystyrene (PS) nanoparticles at 3—9 phr by latex compounding were investigated for their tensile properties, dynamic mechanical behaviors, and flammability. The nanolatex of PS was synthesized via differential microemulsion polymerization. The properties of NR were improved as a result of the incorporation of PS nanoparticles at 3 phr for tensile properties except the % elongation at break, and up to 9 phr for flammability. The results from dynamic mechanical analyzer showed that the elastic properties of NR near the glass transition temperature increased when the amount of PS nanoparticles was over 3 phr.

Mechanical properties, thermal behaviors and oil resistance of epoxidized natural rubber/multiwalled carbon nanotube nanocomposites prepared via in situ epoxidation

Epoxidized natural rubber (ENR)/multiwalled carbon nanotube (MWCNT) nanocomposites were prepared via in situ epoxidation of natural rubber (NR) using a molar ratio of formic acid/hydrogen peroxide to isoprene unit at 0.75/0.75 with five loadings of MWCNTs, ranging from 0.5–2.5 parts per hundred parts of rubber (phr), at 50°C for 4 h. Based on Fourier transform infrared spectra, the epoxide content of ENR in the nanocomposites was about 32.5–33.2 mole%. Accordingly, the products were referred to ENR30/MWCNT nanocomposites. The curing characteristics, mechanical properties (tensile properties, tear strength, and hardness), glass transition temperature (T g), thermal stability, and oil resistance of these in situ ENR30/MWCNT nanocomposites were investigated and compared with NR and neat ENR30. The results showed that the scorch and cure times of ENR30/MWCNT nanocomposites were the longest followed by NR and ENR30. The incorporation of an appropriate amount of MWCNTs into the in situ epoxidation apparently improved the properties of NR. Among them, the nanocomposites filled with 2 phr MWCNTs exhibited the highest mechanical properties, T g, thermal stability, and oil resistance. The mechanical properties of the in situ nanocomposites were also compared with those of the control nanocomposites prepared by adding MWCNTs directly in the prepared ENR30 latex. It was found that at similar MWCNT loadings, the in situ nanocomposites exhibited higher mechanical properties than the control nanocomposites.

Use of TBzTD as Noncarcinogenic Accelerator for ENR/SiO2 Nanocomposites: Cured Characteristics, Mechanical Properties, Thermal Behaviors, and Oil Resistance

This study reported the use of tetrabenzylthiuram disulphide (TBzTD) as a noncarcinogenic accelerator in a traditional sulfur curing system of epoxidized natural rubber (ENR)/nanosilica (nSiO2) composites. ENR used in this work was synthesized via in situ epoxidation of natural rubber (NR) in the presence of performic acid generated from the reaction of formic acid and hydrogen peroxide at 50°C for 8 h to acquire the epoxide content of about 40 mol%. Accordingly, the resulting ENR was referred to as ENR 40. The curing characteristics, mechanical properties, thermal behaviors, dynamic mechanical properties, and oil resistance of ENR 40/nSiO2 nanocomposites filled with three loadings of nSiO2 (1, 2, and 3 parts per hundred parts of rubber) were investigated and compared with NR and neat ENR 40. The results revealed that the scorch and cure times of ENR 40/nSiO2 nanocomposites were slightly longer than those of NR but slightly shorter than those of ENR 40. The tensile properties and tear strength for both before and after aging of all ENR 40/nSiO2 nanocomposites were higher than those of ENR 40, while the glass transition temperature, storage modulus at −65°C, thermal stability, and oil resistance of ENR 40/nSiO2 nanocomposites were higher than those of NR and ENR 40.