Rubber Research Institute of Nigeria

Benin City, Nigeria

Rubber Research Institute of Nigeria

Benin City, Nigeria
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Aigbodion A.I.,National University of the South | Aigbodion A.I.,Rubber Research Institute of Nigeria | Ressia J.A.,National University of the South | Ressia J.A.,National University of Central Buenos Aires | And 3 more authors.
Journal of Applied Polymer Science | Year: 2010

The effect of the hydrogenation of the terminal vinyl groups on the peroxide modification and rheological properties of high - density polyethylene (HDPE) was investigated. The aim of the study was to determine exclusively the effect of the terminal vinyl groups on the peroxide crosslinking and rheological properties of HDPE with one polymer type. This was achieved by hydrogenation of the terminal vinyl groups of a commercial HDPE to obtain an identical material from a structural point of view, which differed only in the nature of the terminal unsaturations, and the comparison of its level of peroxide crosslinking with that of the original polymer. Hydrogenated and unhydrogenated polymer samples were modified at 170°C with different amounts of organic peroxide ranging from 125 to 5000 ppm. Changes in the molecular structure were determined by Fourier transform infrared spectroscopy, size exclusion chromatography, and rheological measurements. Hydrogenation of the terminal groups of the original polymer significantly reduced the rate of modification or crosslinking. The dynamic viscosity and elasticity increased with the level of peroxide modification. Unhydrogenated samples exhibited rapid increases in viscosity and elastic modulus, whereas their hydrogenated counterparts required about 500% of the amount of peroxide needed for the unhydrogenated sample to attain similar structural changes. © 2009 Wiley Periodicals, Inc.

Ogbebor N.O.,Rubber Research Institute of Nigeria | Adekunle A.T.,University of Benin | Eghafona O.N.,University of Benin | Ogboghodo A.I.,University of Benin
Fungal Biology | Year: 2015

The study was conducted to evaluate invitro and invivo control of fungal antagonists on Rigidoporus lignosus (klotzsch) Imaz in Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg. in the rain forest zone of Nigeria. Invitro assessments of biological agents were carried out in dixenic cultures in Petri plates. Invivo tests were carried out in the nursery using Hypocrea virens and Hypocrea jecorina. Significant differences were observed with the dual inoculations of fungal antagonists and R. lignosus inoculated the same day, and the antagonists inoculated 24h before inoculation of R. lignosus. Hypocrea jecorina was most effective in the control of R. lignosus with percentage inhibition of 86.83%. Hypocrea virens, H. jecorina, Trichoderma spirale, Trichoderma sp., Trichoderma sp. Pers, and Hypocrea lixii were effective on R. lignosus. Fungal antagonists inoculated 24h before inoculation of R. lignosus exhibited higher inhibitory efficacies than antagonists and R. lignosus inoculated the same day. In the invivo evaluation of fungi antagonists on R. lignosus, seedlings in H. jecorina treatment at 60dand H. virens treatment at 150dafter inoculations respectively had the highest plant heaths (highest length of stem and length of tap rot, lowest plant death, and least foliar symptom) compared to the control. Mortality rate was higher at 60dafter inoculation and decline from the third months onward. Significant differences were observed between the control and R. lignosus treatment in all the parameters evaluated. © 2014 The British Mycological Society.

Ebewele R.O.,University of Benin | Iyayi A.F.,Rubber Research Institute of Nigeria | Hymore F.K.,Covenant University
International Journal of Physical Sciences | Year: 2010

Rubber seeds from the rubber tree (hevea brasiliensis) are in abundance in Nigeria from which nonedible oil could be obtained. However, the seeds are wasted in the rubber plantations annually even though the extractable oil has potential technical applications. If the full potentials of the oil are to be realized, there is need to have a data base information on the oil extraction process and its properties. Rubber seeds were collected from different rubber clones and extracted first by n-hexane to determine the yield characteristics. Second, the seeds were extracted by a hydraulic press at varied operating conditions: pressure range (5-8MPa), temperatures, 40-90°C; and moisture content, 7-16%. The effect of particle size and other operating variables on oil yield were studied. The physico-chemical properties of the extracted oil were evaluated. It was found that the percentage oil yield from the seeds of the rubber clone NIG800 at 45.03% was higher than the yield from other clones; GTI (40.21%) and RRIM 707 (38.42%) when the particle size of 1.16 mm was used. Oil yield increased with increase in temperature and pressure. Maximum oil yield was obtained during mechanical pressing at a moisture content of 10% (wt), temperature of 70°C and pressure of 8MPa. The physicochemical characteristics of the oil showed high incidence of free fatty acid (FFA) of 37.96% (wt) and the high iodine value (IV) of 142.45 is indicative of the presence of high unsaturation. Rubber seed oil could therefore serve as semi-drying oil used in ingredients for surface coating and in the formulation of products where the presence of unsaturation is important. © 2010 Academic Journals.

Ebewele R.O.,University of Benin | Iyayi A.F.,Rubber Research Institute of Nigeria | Hymore F.K.,Covenant University
International Journal of Physical Sciences | Year: 2010

Some studies have shown that rubber seed oil (RSO) from the seed of rubber tree (hevea brasiliensis) has potential technical applications. However, the high free fatty acid (FFA) associated with the oil may be a limiting factor in its applications. In this study, crude rubber seed oil (RSO) containing 37.69% FFA was deacidified using 4.3-5.6% of glycerol. The reactions were carried out at a pressure of 20mmHg in the presence of zinc dust and zinc chloride catalysts added separately at high temperature (150 - 2500C). The progress of the reaction was monitored by determining the FFA at various time intervals. The FFA content in the RSO was reduced to 1.5% in six hours when 4.3% glycerol was used with zinc dust at a temperature of 2000C while the triglycerides content of the oil increased from 40.32% in the crude oil to 80.62% in the deacidified RSO. The study showed that this process is effective in the deacidification of RSO without loss of neutral glycerides as in alkali neutralization. ©2010 Academic Journals.

Omorusi V.I.,Rubber Research Institute of Nigeria | Ayanru D.K.G.,University of Benin
International Journal of Agriculture and Biology | Year: 2011

A screen house study was conducted to evaluate the effects of a compound fertilizer (NPK) on the response of cassava (Manihot esculenta Crantz) to diseases, pests and mycorrhizal symbiosis. Soil drenches of NPK (15 - 15 - 15, N - P 2O 5- K 2O) were applied at the rates of 0.083 g (10 kg ha -1) and 0.832 g (100 kg ha -1) per 4.2 kg soil. Mycorrhizal spores in rhizosphere soil and root colonization of cassava by arbuscular mycorrhizal (AM) fungi were estimated at 5.5 months. Shoot heights and girths (cm) were assessed at 5.5 months. Incidence of pests-cassava green spider mites (Mononychellus tanajoa Bondar) (CGM), cassava mealybug (Phenaccocus manihoti Matt-Ferr.) (CM), African cassava mosaic disease (ACMD) and cercospora leaf spot disease (CLSD) were rated on varying scales. Mycorrhizal spores and root colonization were significantly higher in the control experiments (P< 0.01) with percentage decreases of 67 and 83% per g/soil of spores and root colonization of 61 and 83%, in the 10 and 100 kg ha -1, respectively. NPK fertilizer significantly increased plant vigour (stem & girth) (P<0.01), with increases by 16.82 to 36.45% for height and 15.20 to 25.45% for girth. Mycorrhizal symbiosis was lowest in plants amended with the highest fertilizer dosage. NPK concentrations diminished CGM, CM (P< 0.01) and ACMD (P< 0.05). However, no significant effects on CLSD infection were obtained. © 2011 Friends Science Publishers.

Ikhuoria E.U.,University of Benin | Okieimen F.E.,University of Benin | Obazee E.O.,Rubber Research Institute of Nigeria | Erhabor T.,University of Benin
African Journal of Biotechnology | Year: 2011

Rubber seed oil alkyd was post-polymerized with styrene monomer at ratios of 1:2, 1:4, 1:6, 1:8, and 1:10 at 100°C for 3 h (samples i - v) and 6 h (samples A - B), to obtain two sets of styrenated alkyds. The styrenated alkyds and the rubber seed oil alkyd were all characterized and evaluated by standard methods, for their physico-chemical properties, drying schedule and chemical resistance. All the resins showed good properties. However, the styrenated alkyds gave a faster drying time, even in the absence of a drier. Unlike the unstyrenated alkyd which is only resistance to water, brine and acidic media, the styrenated alkyds were also resistant to alkali. The styrenated alkyds prepared over a period of 6 h gave shorter drying time than those prepared in 3 h, irrespective of the alkyd - styrene ratios. © 2011 Academic Journals.

Ogbebor O.J.,Rubber Research Institute of Nigeria | Okwu U.N.,Rubber Research Institute of Nigeria | Okieimen F.E.,University of Benin | Okuonghae D.,University of Benin
Chemical Industry and Chemical Engineering Quarterly | Year: 2010

Elastomers based on natural rubber (NR) and silica and clay fillers have been investigated for their physico-mechanical properties. The various mixes were compounded in a Banbury-Pullen laboratory mill and vulcanized using the efficient vulcanization system. The oscillating disc rheometer (ODR) was used for determination of cure characteristics. It was estimated that replacement of silica with clay up to 30 phr (50% replacement) increased the compound cure rate with a reduction in absolute torque level (T max) of the natural rubber mix. Scorch time (Ts2) was observed to be the highest at a 30/30 filler ratio. Hardness and tensile properties of obtained elastomeric materials were studied. The results show a decrease in parameters as the replacement of silica with natural clay progresses. There was improvement in elongation at break with the increase of clay content. The replacement of silica filler with clay reduced the abrasion properties (mg loss/1000 rev.).

Ogbebor O.J.,Rubber Research Institute of Nigeria | Okieimen F.E.,University of Benin | Ogbeifun D.E.,University of Benin | Okwu U.N.,Rubber Research Institute of Nigeria
Chemical Industry and Chemical Engineering Quarterly | Year: 2015

Organokaolin samples, through the incorporation of cationic hexadecyltrimethylammonium bromide in various concentrations (50, 100 and 200% cation exchange capacity, CEC) into kaolin clay’s interlayer spaces have been prepared. The samples were characterized using XRD and FTIR to get information on structural composition and characteristic bonds on modification. These clays were further used as fillers in natural rubber compounds with a semi-ultra-delayed action accelerator scheme. The X-ray diffraction analysis showed marginal increase in basal (d(001)) spacing of kaolin platelets from 4.01 to 4.90 nm. Changes in the clay’s molecular environment induced by ion-exchange process were followed by FTIR measurements revealing various CTAB+ influenced absorption peaks as modification progressed. Cure characteristics, scorch (ts2) and cure (t90) time of the organokaolin filled natural rubber composites were observed to be better than those of the 40 phr bulk kaolin across the CEC organophilization concentrations and filler loadings studied. Vulcanizate properties showed considerable increase in M100, M200, M300, TS and elongation at break (%) indicating its potential as an organomodified filler. Hardness (IRHD) and abrasion resistance showed similar trend as tensile properties, with the incorporation of organoclay. © 2015, CI and CEQ. All rights reserved.

Bakare I.O.,Rubber Research Institute of Nigeria | Bakare I.O.,Universiti Sains Malaysia | Okieimen F.E.,University of Benin | Pavithran C.,Indian National Institute for Interdisciplinary Science and Technology | And 2 more authors.
Materials and Design | Year: 2010

The development of high-performance composite materials from locally sourced and renewable materials was investigated. Rubber seed oil polyurethane resin synthesized using rubber seed monoglyceride derived from glycerolysis of the oil was used as matrix in the composite samples. Rubber seed oil-based polyurethane composite reinforced with unidirectional sisal fibers were prepared and characterized. Results showed that the properties of unidirectional fiber-reinforced rubber seed oil-based polyurethane composites gave good thermal and mechanical properties. Also, the values of tensile strengths and flexural moduli of the polyurethane composites were more than tenfold and about twofold higher than un-reinforced rubber seed oil-based polyurethane. The improved thermal stability and the scanning electron micrographs of the fracture surface of the composites were attributed to good fiber-matrix interaction. These results indicate that high-performance " all natural products" composite materials can be developed from resources that are readily available locally. © 2010 Elsevier Ltd.

Bosah O.,Delta State University, Abraka | Igeleke C.A.,Benson Idahosa University | Omorusi V.I.,Rubber Research Institute of Nigeria
International Journal of Agriculture and Biology | Year: 2010

In this study, pure cultures of three antagonistic fungi, Trichoderma, Penicillium and Aspergillus species and a fungal pathogen, Sclerotium sp. were obtained after inoculation on potato dextrose agar (PDA) fortified with antibiotics to prevent bacterial contamination. Pathogenicity test was carried out when the antagonistic isolates were inoculated on PDA 24 h before and after Sclerotium inoculation. Of the three fungal antagonists evaluated for inhibitory efficacy, Trichoderma sp. proved to be the most effective as it exhibited the greatest inhibition to Sclerotium sp. (P<0.01) both at the initial and final tests. This was closely followed by Aspergillus sp. with inhibitory effect on the pathogen at both trials (P<0.01). However Penicillium sp. was slightly inhibitory against Sclerotium. Percentage inhibitions of the antagonists on Sclerotium by Trichoderma, Aspergillus, and Penicillium, were up to 81.36-80.29%, 88.35-73.12% and 56.98-46.24%, at the 6th day of inhibition at both trials, respectively. The result implied that the extent of inhibition by the fungi provides the use of potential antagonists capable of controlling the pathogenicity of Sclerotium sp. in crops for sustainable agriculture. © 2010 Friends Science Publishers.

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