Maleated Natural Rubber as a Coupling Agent for Recycled High Density Polyethylene/Natural Rubber/Kenaf Powder Biocomposites

Kenaf powder (KP) was incorporated into recycled high density polyethylene (rHDPE)/natural rubber (NR) blend using an internal mixer at 165°C and rotor speed of 50 rpm. The tensile strength and elongation at break of the composites decreased, while the tensile modulus increased with increasing filler loading. The water absorption was found to increase as the filler content increased. The maleic anhydride grafted natural rubber was prepared and used to enhance the composites performance. The addition of MANR as a coupling agent improved the tensile properties of rHDPE/NR/KP biocomposites. The water absorption was also reduced with the addition of MANR.     

Zero-current Switching Series Resonant High-voltage DC-DC Converter with Series-connected Primary Windings of Center-tapped Transformer

Abstract—This article proposes a novel zero-current switching series resonant inverter-fed voltage multiplier based high-voltage DC-DC converter. The series resonant inverter in the proposed topology has two power switches (insulated-gate bipolar transistors), two resonant capacitors, and only one high-voltage transformer with center-tapped primary windings. The power switches are connected in the form of a half-bridge network. The leakage inductances of the transformer's primary windings together with resonant capacitors form two series resonant circuits. The series resonant circuits are fed alternately by operating power switches with an interleaved half-switching cycle. The secondary winding of the high-voltage transformer is connected to a voltage multiplier circuit to rectify and boost the voltage. The converter operates in discontinuous conduction mode, and its output voltage is regulated by pulse-frequency modulation. Therefore, all the power switches turn ON and OFF at the zero-current switching condition. The main features of the proposed converter are lower power loss, less cost, and smaller size compared to previously proposed series resonant high-voltage DC-DC converters. The experimental results of a 130-W prototype of the proposed converter are presented both for dynamic and steady-state operation. The results confirm the excellent operation and performance of the converter.     

Effects of partial replacement of commercial fillers by recycled poly(ethylene terephthalate) powder on the properties of natural rubber composites

Commercial fillers, including carbon black (N550), halloysite nanotubes (HNTs), and precipitated silica, were replaced by recycled poly(ethylene terephthalate) powder (R‐PET) in natural rubber (NR) composites. Five different compositions of NR/N550/R‐PET, NR/HNTs/R‐PET, and NR/silica/R‐PET compounds, i.e., 100/20/0, 100/15/5, 100/10/10, 100/5/15, and 100/0/20 parts per hundred rubber (phr), were prepared on a two‐roll mill. The curing behavior, tensile properties, and morphological characteristics of the natural rubber composites were investigated. The results indicated that the replacement of carbon black, HNTs, and silica by R‐PET decreased the tensile strength and tensile modulus, such that NR/silica/R‐PET composites showed the lowest effect, followed by NR/HNTs/R‐PET and NR/N550/R‐PET composites. The negative effect on these properties can be explained by the decrease of crosslink density. The curing results revealed that with the replacement of carbon black by R‐PET, the scorch time and cure time decreased, but that the NR/HNTs/R‐PET and NR/silica/R‐PET composites exhibited the opposite trend. Scanning electron microscopy investigation of tensile fracture surfaces confirmed that the co‐incorporation of N550/R‐PET improved the dispersion of R‐PET and enhanced the interaction between the fillers and NR matrix more than R‐PET and silica/R‐PET hybrid fillers. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

Effect of filler surface treatment on the properties of recycled high‐density polyethylene/(natural rubber)/(Kenaf powder) biocomposites

Biocomposites were prepared from a kenaf core powder and recycled high‐density polyethylene/(natural rubber) blend by using an internal mixer at 165^oC and 50 rpm. The effect of the filler content and the filler surface treatment was studied. Chemical modification of kenaf filler was performed with alkali pretreatment followed by treatment with silane. Scanning electron microscopy and infrared spectroscopy studies confirmed changes in the chemical compositions and structural characteristics induced through the modification. It was found that treated biocomposites offered higher tensile strength and tensile modulus, but lower elongation at break compared with untreated biocomposites. Lower water absorption and higher thermal stability of the resultant biocomposites were also obtained when treated fillers were used. J. VINYL ADDIT. TECHNOL., 20:218–224, 2014. © 2014 Society of Plastics Engineers     

An intelligent based-model role to simulate the factor of safe slope by support vector regression

An infrastructure development in landscape and clearing of more vegetated areas have provided huge changes in Malaysia gradually leading to slope instabilities accompanied by enormous environmental effects such as properties and destructions. Thus, prudent practices through vegetation incorporating to use slope stability is an option to the general stabilized technique. Few researches have investigated the effectiveness of vegetative coverings related to slope and soil parameters. The main goal of this study is to provide an intelligent soft computing model to predict the safety factor (FOS) of a slope using support vector regression (SVR). In the other words, SVR has investigated the surface eco-protection techniques for cohesive soil slopes in Guthrie Corridor Expressway stretch through the probabilistic models analysis to highlight the main parameters. The aforementioned analysis has been performed to predict the FOS of a slope, also the estimator’s function has been confirmed by the simulative outcome compared to artificial neural network and genetic programing resulting in a drastic accurate estimation by SVR. Using new analyzing methods like SVR are more purposeful than achieving a starting point by trial and error embedding multiple factors into one in ordinary low-technique software.

     

Characteristics of microcapsule of red ginger (Zingiber officinale var. Rubrum) essential oil produced from different Arabic gum ratios on antimicrobial activity toward Escherichia coli and Staphylococcus aureus

Essential oil has antimicrobial activity. Encapsulation of essential oil might affect its antimicrobial activity. The present study was aimed to study the characteristic of red ginger essential oil microcapsule obtained from varying Arabic gum ratios on the growth inhibition of E. coli dan S. aureus. Red ginger essential oil from steam distillation was coated using Arabic gum with ratio 1:3, 1:4, 1:5 (w/b). The 1:3 (v/w) ratio of red ginger essential oil and Arabic gum showed the best microcapsule characteristics with average inhibition diameter zones 5.67 mm for E. coli and 6.67 mm for S. aureus, and reduction of bacterial count for E. coli 1.8 log CFU/g and S. aureus 2.3 log CFU/g, yield of microcapsule 51.54%, water activity 0.207, water content 3.57%, solubility 97.46%, surface oil 0.08%, and particle size 258.2 µm. The major component of red ginger essential oil was ar-curcumene, zingiberen, β-bisabolene, β-sesquiphellandrene, and camphene.     

Transparent,electrically conductive,and flexible films made from multiwalled carbon nanotube/epoxy composites

Optically transparent, conductive, and mechanically flexible epoxy thin films are produced in the present study. Two types of multiwalled carbon nanotubes (MWCNTs) with different aspect ratios are dispersed in epoxy resin through an ultrasonication process. The MWCNT content is varied during the preparation of the thin films. The light transmittance and electrical conductivity of the thin films are characterized. Results show that composites containing MWCNTs with a lower aspect ratio exhibit enhanced electrical conductivity compared to those with a higher aspect ratio. A sheet resistance as low as 100 Ω/sq with nearly 60% optical transparency in 550 nm is achieved with the addition of MWCNTs in epoxy. In summary, transparent, conductive, and flexible MWCNT/epoxy thin films are successfully produced, and the properties of such films are governed by the aspect ratio and content of MWCNTs.     

Thermal and mechanical behavior of natural rubber latex‐silica aerogel film

A major problem in most natural rubber latex (NRL) commonly encountered like other polymer is susceptibility to mechanical properties and thermal degradation; particularly in thin film due to the presence of double bonds in the main chain. Therefore, it is desirable to seek for ways of improving these properties. Silica aerogel is a material with extraordinary properties was believed to have potential enhance properties in NRL films because of its high specific surface area. Therefore, based on the unique character of silica aerogel, NRL‐silica aerogel film was developed by latex compounding and dry coagulant dipping to form thin film where silica aerogel acts as filler. Silica aerogel, synthesized from rice husk was dispersed in a ball‐mill using distilled water for NRL compounding. Results indicate that increasing silica aerogel loading enhances the mechanical properties of the NRL‐silica aerogel film. Effects of postvulcanization processes were also investigated, whereby the best reinforcing effect was obtained at 4 phr silica aerogel loading with leaching postvulcanization condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of different types of filler and filler loadings on the properties of carboxylated acrylonitrile–butadiene rubber latex films

The effects of different types of fillers and filler loadings on the properties of carboxylated nitrile rubber (XNBR) latex were identified. Silica, mica, carbon black (CB; N330), and calcium carbonate (CaCO₃) were used as fillers with filler loadings of 10, 15, and 20 parts per hundred rubber. Furnace ashing and Fourier transform infrared analysis proved that interaction existed between the fillers and XNBR latex films. The morphology of the filled XNBR films was significantly different for different types of fillers. Mica and CaCO₃ fillers showed uneven distribution within the XNBR film, whereas other fillers, such as silica and CB, showed homogeneous distribution within the films. In the observation, silica and mica fillers also illustrated some degree of agglomeration. The mechanical properties (e.g., tensile and tear strengths) showed different trends with different types of fillers used. For silica and mica fillers, the mechanical properties increased with filler loadings up to a certain loading, and decreased with higher filler loadings. For CB filler, the mechanical properties increased gradually with increasing filler loadings. CaCO₃ fillers did not increase the mechanical properties. The crosslinking density of the XNBR films increased when they were incorporated with fillers because of the presence of elastomer–filler and filler–filler interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Biomolecular Characterization of Diazotrophs Isolated from the Tropical Soil in Malaysia

This study was conducted to evaluate selected biomolecular characteristics of rice root-associated diazotrophs isolated from the Tanjong Karang rice irrigation project area of Malaysia. Soil and rice plant samples were collected from seven soil series belonging to order Inceptisol (USDA soil taxonomy). A total of 38 diazotrophs were isolated using a nitrogen-free medium. The biochemical properties of the isolated bacteria, such as nitrogenase activity, indoleacetic acid (IAA) production and sugar utilization, were measured. According to a cluster analysis of Jaccard’s similarity coefficients, the genetic similarities among the isolated diazotrophs ranged from 10% to 100%. A dendogram constructed using the unweighted pair-group method with arithmetic mean (UPGMA) showed that the isolated diazotrophs clustered into 12 groups. The genomic DNA rep-PCR data were subjected to a principal component analysis, and the first four principal components (PC) accounted for 52.46% of the total variation among the 38 diazotrophs. The 10 diazotrophs that tested highly positive in the acetylene reduction assay (ARA) were identified as Bacillus spp. (9 diazotrophs) and Burkholderia sp. (Sb16) using the partial 16S rRNA gene sequence analysis. In the analysis of the biochemical characteristics, three principal components were accounted for approximately 85% of the total variation among the identified diazotrophs. The examination of root colonization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) proved that two of the isolated diazotrophs (Sb16 and Sb26) were able to colonize the surface and interior of rice roots and fixed 22%–24% of the total tissue nitrogen from the atmosphere. In general, the tropical soils (Inceptisols) of the Tanjong Karang rice irrigation project area in Malaysia harbor a diverse group of diazotrophs that exhibit a large variation of biomolecular characteristics.