Kuala Lumpur, Malaysia
Kuala Lumpur, Malaysia

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Electrically-conductive (in the region of 10-3 S.cm-1) epoxidized natural rubber-polyaniline dodecylbenzenesulfonate [ENR-PAni.DBSA] blend was prepared, and the effect of incorporation of WO3 on its corrosion inhibition behaviour for carbon steel was assessed for the first time. It was found that the electrical conductivity of this blend could be enhanced by up to an order of magnitude for WO3 loadings of 20.0-22.5 wt.%. From both total immersion and electrochemical corrosion tests, ENR-PAni.DBSA blends with 20.0-22.5 wt.% of WO3 were found to be the best corrosion inhibitors for carbon steel, in both acid and artificial brine environments. However, a blend containing a higher WO3 content (i.e. 25.0 wt.%) showed a significant poorer corrosion inhibition behaviour for carbon steel due to its more severe phase separation and porosity between the ENR host matrix and WO3. © Smithers Information Ltd., 2017.


A pre-optimised poly(butadiene-co-acrylonitrile)-polyaniline dodecylbenzenesulphonate (NBR-PAni.DBSA) blend with useful electrical conductivity (in the region of 10-3 S.cm-1) was prepared and the effect of incorporation of titanium oxide (TiO2) on its corrosion inhibition behaviour for carbon steel was successfully assessed for the first time. It was found that the electrical conductivity of this blend can be enhanced up to a magnitude order for TiO2 loadings, 20.0-22.5 wt %. As found from both total immersion and electrochemical corrosion tests, NBRPAni.DBSA blends with 20.0-22.5 wt % of TiO2 are deemed to be the best corrosion inhibitor for carbon steel, either in acid or artificial brine environment. However, a blend consisting of very high TiO2 content (i.e. 25.0 wt %) showed a significant poorer corrosion inhibition behaviour for carbon steel due to its more serious phase separation and porosity problem between the NBR host matrix and TiO2.


Chow K.-S.,Rubber Research Institute of Malaysia | Ghazali A.-K.,Codon Genomics SB | Hoh C.-C.,Codon Genomics SB | Mohd-Zainuddin Z.,Rubber Research Institute of Malaysia
BMC Research Notes | Year: 2014

Background: One of the concerns of assembling de novo transcriptomes is determining the amount of read sequences required to ensure a comprehensive coverage of genes expressed in a particular sample. In this report, we describe the use of Illumina paired-end RNA-Seq (PE RNA-Seq) reads from Hevea brasiliensis (rubber tree) bark to devise a transcript mapping approach for the estimation of the read amount needed for deep transcriptome coverage. Findings. We optimized the assembly of a Hevea bark transcriptome based on 16 Gb Illumina PE RNA-Seq reads using the Oases assembler across a range of k-mer sizes. We then assessed assembly quality based on transcript N50 length and transcript mapping statistics in relation to (a) known Hevea cDNAs with complete open reading frames, (b) a set of core eukaryotic genes and (c) Hevea genome scaffolds. This was followed by a systematic transcript mapping process where sub-assemblies from a series of incremental amounts of bark transcripts were aligned to transcripts from the entire bark transcriptome assembly. The exercise served to relate read amounts to the degree of transcript mapping level, the latter being an indicator of the coverage of gene transcripts expressed in the sample. As read amounts or datasize increased toward 16 Gb, the number of transcripts mapped to the entire bark assembly approached saturation. A colour matrix was subsequently generated to illustrate sequencing depth requirement in relation to the degree of coverage of total sample transcripts. Conclusions: We devised a procedure, the "transcript mapping saturation test", to estimate the amount of RNA-Seq reads needed for deep coverage of transcriptomes. For Hevea de novo assembly, we propose generating between 5-8 Gb reads, whereby around 90% transcript coverage could be achieved with optimized k-mers and transcript N50 length. The principle behind this methodology may also be applied to other non-model plants, or with reads from other second generation sequencing platforms. © 2014 Chow et al.; licensee BioMed Central Ltd.


Blends of poly(butadiene-co-acrylonitrile) [NBR] and poly aniline dodecylbenzenesulphonate [PAni.DBSA] with electrical conductivities up to 10 -1 S.cm -1, have been successfully prepared using the technique of solution mixing and casting. Compatibility of both NBR and PAni.DBSA was found to be maximised by the introduction of hydroquinone as a compatibiliser. Blends prepared with added hydroquinone exhibited the lowest electrical conductivity percolation threshold and were more conductive than the ones without any compatibiliser. Transmission electron micrographs of blends with added compatibiliser showed the lowest level of phase separation. FT-IR spectra and DSC thermal of blends with added compatibiliser also showed the largest peak and temperature shifts, respectively. These phenomenons occured due to the higher intermolecular interactions between the two blended polymers in the presence of hydroquinone.


Thermoplastic vulcanisates [TPVs] based on natural rubber, polypropylene and dodecylbenzenesulfonic acid-doped polyaniline [PAni.DBSA] with useful electrical conductivities (up to about 1.2 S cm-1) were produced by using an internal mixer. A very low electrical percolation threshold (about 2.0 wt.%/1.13 volume % of PAni.DBSA) was achieved for TPVs prepared via this method. All the TPVs exhibited useful physical properties and also a reasonable good electromagnetic interference shielding effectiveness [EMI SE]. The TPVs could be recycled up to 4 times without significant loss of their EMI SE, electrical and physical properties. © Smithers Information Ltd., 2016.


Yong K.C.,Rubber Research Institute of Malaysia
Rubber Chemistry and Technology | Year: 2011

Colorable, sulfur-vulcanized epoxidized natural rubber-polyaniline dodecylbenzenesulfonate (ENR-PAni.DBSA) blends with good electrical conductivities (up to 10 -1 S · cm -1) and good mechanical properties (including high damping) were successfully prepared. An effect of conductive filler particle's surface area and shape was studied for the vulcanized blends by testing them through 900 cycles of straining. The elongated shape of PAni.DBSA particles (as observed by using transmission electron microscope) did contribute to the very low percolation threshold for unstrained samples (about 3.0 wt. % of PAni.DBSA loading) and the reproducible electrical behavior (≥95% retention of original unstrained value) for samples under straining cycles. With the ideal mechanical properties and reproducible electrical behavior, these vulcanized blends do have good potential to be used as flexible smart materials that can correspond to the straining process.


Electron beam irradiation technique was successfully used for the first time in order to crosslink the natural rubber-polyaniline dodecylbenzenesulphonate [NR-PAni. DBSA] blends. Significant increases in crosslink densities of all blends with doses of irradiation up to 200 kGy were obtained and a reasonably high crosslink density level (in the order of 10 4 mol/cm3) was achieved. All electron beam-irradiated NR-PAni.DBSA blends showed good tensile properties with tensile strength up to about 19.7 MPa. This kind of irradiation induced-crosslink technique at doses up to 200 kGy also did not affect electrical properties after being sufficiently stabilised for at least 24 hours. The irradiated NR-PAni.DBSA blends also exhibited good electrical properties, i.e. a single conductivity percolation threshold and high conductivities up to the order of l0-2 S.cm -1. In other words, there is a good potential of using electron beam irradiation technique to prepare highly crosslinked, electrically conductive NR-PAni.DBSA blends.


Yong K.C.,Rubber Research Institute of Malaysia
Journal of Applied Polymer Science | Year: 2012

Dicumyl peroxide (DCP) vulcanized poly(butadiene-co-acrylonitrile)- polyaniline dodecylbenzenesulfonate [NBR-PAni.DBSA] blends were successfully prepared by using the practical thermomechanical mixing method. The effect of alignment of PAni.DBSA particles on the mechanical and electrical properties of vulcanized blends was studied (by passing the blends through a two roll-mills). All vulcanized blends strained parallel to the flow direction when passed through the two roll-mills had their electrical conductivities enhanced with increasing strain in tension. Good historical memory in term of the electrical conductivities during three cycles of straining (with 300 times of strain loading and unloading motion for each cycle) was observed for all vulcanized blends (99% retention of original value before straining). These vulcanized blends also showed better mechanical properties (i.e., higher tensile strength and tear strength) than the ones strained perpendicularly to the flow direction. With the ideal mechanical properties and reversible electrical behavior, this type of blend can potentially emerge as a new class of flexible smart material. © 2011 Wiley Periodicals, Inc.


Yong K.C.,Rubber Research Institute of Malaysia
Rubber Chemistry and Technology | Year: 2013

The electron beam irradiation technique was successfully used to cross-link poly(butadiene-co-acrylonitrile)-polyaniline dodecylbenzenesulfonate [NBR-PAni.DBSA] blends. Significant increase in cross-linking densities of all blends with doses of irradiation (up to 200 kGy) was observed, and a reasonably high cross-linking density level (in the order of 1030 m -3) also was achieved. All electron beam-irradiated NBR-PAni.DBSA blends exhibited good tensile properties (with tensile strength up to ∼20 MPa), with values that are comparable to those of similar blends cross-linked with either conventional sulfur or peroxide techniques. This kind of irradiation-induced cross-linking technique (at doses up to 200 kGy) also did not interrupt the blends' electrical properties after the blends were sufficiently stabilized for at least 24 h. The irradiated NBR-PAni.DBSA blends also possessed good electrical properties, that is, a single conductivity percolation threshold and high conductivities up to the order of 10-2 S.cm-1. All of these findings indicate a good potential for using the electron beam irradiation technique to prepare highly cross-linked, electrically conductive NBR-PAni.DBSA blends.


Yong K.C.,Rubber Research Institute of Malaysia
Journal of Rubber Research | Year: 2011

Sulphur-vulcanised epoxidised natural rubber [ENR]-carbon black printex XE2B blends with high electrical conductivities (up to 10-1 S.cm -1), exhibiting good tensile properties and high damping were successfully prepared by using an internal mixer. Effect of carbon black's surface area and structure on electrical behaviour was studied for the vulcanised blends by testing them through a series of straining cycles (i.e. a total of 900 times of strain loading and unloading process). Carbon black printex XE2 B particles with 'hollowed out' shape and higher surface area were observed by using a transmission electron microscope. The carbon black printex XE2B characteristics contributed to the very low percolation threshold (i.e. 3.0 wt % of printex XE2B loading) and also the reproducible electrical conductivity of its blend under straining process (z.95% retention of original unstrained value). With good mechanical properties and reproducible electrical behaviour, the sulphur-vulcanised ENR-carbon black printex XE2B blends (with printex XE 2 B loadings, 5.0-40.0 wt %) have potential to be used as a raw material for manufacturing flexible smart sensor devices.

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