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[en] Rubber-filler systems have been one of the most successful composite materials and have been widely used in industry such as tire and belts so on. Fillers reinforce rubbers by compounding and improve the mechanical and barrier properties of the rubber compounds. We need to explore the adsorption of rubber around filler particles in terms of structure analyses to clarify the correlation between the mechanical properties and the structures for rubberfiller systems. In this study, the polymer layers absorbed on silica particles in rubber-silica systems have investigated with contrast variation SANS method. Specimens were swollen by the solvents having various scattering length densities and measured their SANS intensity. We calculated the partial scattering functions by using singular value decomposition: the scattering function for polymer-polymer correlation SPP(q), the scattering function for silica- silica correlation SSS(q), and the scattering function for polymersilica correlation SPS(q) as shown in Fig.1. The analyses of SPS(q) and SSS(q) explored the existence of dense polymer layers around silica aggregates. SSS(q) reflects hierarchical structures formed by silica particles. To characterize the adsorption layer quantitatively, we calculated the scattering functions for the model consisting of the aggregation of Silica particles, the adsorption layers on the silica particles and the matrix region. We use the mass fractal model having upper limit for the aggregation of Silica particles, and object with sharp interface for the regions adsorption layers and silica aggregates to calculate the partial scattering functions. The model can well express the experimental partial scattering functions and several characteristic parameters are estimated from the analyses, such as the size of aggregates, the thickness of layers, the volume fractions of polymer of layers and matrix, and the correlation length of the matrix network. The contrast variation SANS is found to be a powerful tool of the analyses of the structures of the rubber-filler systems.
[en] Treatability of a material is fundamental in determining how much chemicals or fillers are retained in the material before it can be used for slow release fertiliser. The aim of this study was to investigate the effect of urea retention in oil palm frond and rubber wood chips treated at different urea concentrations using pressure and non-pressure treatments. Treatability of the materials was calculated based on weight percent gain. Comparative nutrient contents of the impregnated chips were also determined. Oil palm frond and rubber wood chips were treated separately with three different concentrations of urea solution (5%, 10% and 15% w/v) using vacuum-pressure or soaking process. The results showed that type of material, trea ment process and urea concentration significantly affect weight percent gain. Regardless of treatment combinations, oil palm frond chips had higher urea retention compared to rubber wood chips. For nutrient contents, treated rubber wood chips attained higher carbon content while treated oil palm frond chips had higher N content. Within the range of urea concentration stu ied, treatment with 15% urea using vacuum-pressure process was found to be the most efficient treatment combination in the development of wood waste slow release fertiliser. The release pa tern of nitrogen from both oil palm frond chips and rubber wood chips proved that these materials are suitable for the development of slow release fertiliser. (author)
[en] This paper discusses the advantages of radiation vulcanization of natural rubber latex and research and development carried out in this particular field. It emphasises types of centrifuge latex used, stability of this centrifuged latex, use of sensitizer, effect of leaching, antioxidants, use of low energy electron beam and training and human resources development in this field
[en] Genetic diversity of natural rubber clones of the in SINCHI Institute’s clone collection was assessed. Clones of Hevea brasiliensis (Willd. ex Adr. De Juss.) Muell.Arg., Hevea spp. (H. brasiliensis x H. benthamiana), and three more species of Hevea genus are a part of the collection. Seventy-two materials were characterized with twenty-eight morphological descriptors. They were later used to generate a similarity matrix through the analysis of multi-categorical variables, and to obtain clusters based on the matrix. A low variability between clones of H. brasiliensis and H. spp. was observed, presumably because of the direct descendants of most of the materials from crosses of parental PB 80, PB 5/51, PB 49 and Tjir, exception made of clone GU 1410. Clustering between some materials product of exclusive cross of PB series, a group between clones descendants of parental clones PB 86, and clustering between descendants of parental clones PB 5/51, were observed. Clones from other species of Hevea differ from this big group.
[en] A method is described for using beta-emitters (Tl204 and S35) for measuring the wearing qualities of motor-vehicle tyres, checking the homogeneity of tyre rubber, and non-contact thickness-gauging of rubberized fabrics. (author)
[fr]Le memoire expose une methode permettant d'employer des emetteurs beta (204Tl et 35S) pour la mesure de la resistance des pneumatiques d'automobiles, le controle de l'uniformite du caoutchouc des pneus et la mesure sans contact de l'epaisseur des tissus caoutchoutes. (author)
[es]Los autores describen un metodo de utilizacion de emisores β (204Tl y 35S) para la medicion de la resistencia al desgaste de los neumaticos de automovil para la verificacion de la homogeneidad del caucho destinado a la fabricacion de neumaticos y para la medicion a distancia del espesor de las telas cauchutadas. (author)
[ru]Opisana metodika ispol'zovaniya beta-izluchatelej (Tl204 i S35) dlya izmereniya velichiny iznosostojkosti avtomobil'nykh shin, dlya kontrolya gomogennosti shinnykh rezin i dlya beskontaktnogo izmereniya tolshchiny obrezinennykh tkanej. (author)
[en] Latex timber clone (LTC) rubber wood trees were introduced by Lembaga Getah Malaysia (LGM) for obtaining good yield of latex as well as the quality timber. Two juvenile clones namely RRIM2009 and RRIM2024 were selected for measuring the chemical properties based on TAPPI standards and were assessed at different height levels (top, middle and bottom). These chemical properties of wood can serve as an indicator for predicting the wood behavior for specific end usage. The findings revealed that there were significant variation between the clones and the highest value was obtained at the bottom portion except for lignin content. Clone RRIM2009 exhibited higher percentage of ash content (0.80 %) and lignin content (17.30 %). While Clone RRIM2024 has greater value of holocellulose content (58.58 %) and alpha-cellulose content (41.41 %). According to the different height levels, top portion exhibited highest lignin content (17.64 % for RRIM2009 and 16.75 % for RRIM2024). While bottom portion exhibited highest holocellulose (58.93 % for RRIM2009 and 60.56 % for RRIM2024), highest alpha-cellulose (39.75 % for RRIM2009 and 43.02 % for RRIM2024) and highest ash content (0.85 % for RRIM2009 and 0.71 % for RRIM2024). As a whole, clone RRIM2024 gave higher value except for lignin and ash content compared to RRIM2009. Thus, the potential of using such LTC rubber wood trees for specific purposes is promising. (author)
[en] Research on rubberwood fibers-thermoplastic composites have been carried out by several workers in the past several years. The main focus was to enhance the properties of the resultant composites in view of the incompatibility of the two components. Thus, efforts have been made to enhance their properties by using coupling agents, treating the fibers and modifying the matrices. In this study, the rubberwood polypropylene composite was used as a base material and the addition of epoxidized natural rubber (ENR) is to provide a damping property of the composite with the final aim to produce a sound and noise proofing products. Initially, the processing and compositions of rubberwood fibers and polypropylene was optimized at the 50:50 w/w ratio using melt blend internal mixer. The processing parameters were established. Subsequently, the mechanical properties of the composites were determined with addition of 1-4% of ENR. (Author)
[en] Full text: Low molecular weight carboxy methyl cellulose (CMC), hydroxyl ethyl cellulose (HEC), hydroxyl propyl cellulose (HPC) and methyl cellulose (MC) prepared by radiation-induced degradation were added into diluted natural concentrated latex prior to centrifuge for a purpose of reducing allergenic rubber protein in the latex. Optimum molecular weight (Mv) of CMC and HEC for such a purpose was found to be 17-18 kDa which decreased allergenic rubber protein (14-94 kDa) to an undetectable amount as determined by SDS PAGE method
[en] The tensile strength of rubber depends on a combination of contributions, in particular on the finite extensibility of chain segments between network points and on strain-induced crystallization. In order to achieve high tensile strength at high strain at break, we optimized the composition and processing parameters to gain high molecular flexibility by the cure conditions, to acquire high flexibility of sulfur bridges by the accelerator, and to increase the modulus level without losing rubber molecule flexibility by carbon black. As a result, our formula performed a tensile strength of 42.5 MPa at 25 C under ISO-37, as officially measured by the Society of Rubber Industry, Japan, in 2004.