[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 S_PP(q), the scattering function for silica- silica correlation S_SS(_q), and the scattering function for polymersilica correlation S_PS(q) as shown in Fig.1. The analyses of S_PS(q) and S_SS(q) explored the existence of dense polymer layers around silica aggregates. S_SS(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)

[en] The development of radiation vulcanized rubber and its applications, characteristics of the technique, the domestic progress in radiation rubber curing and industrialization scale of radiation processing abroad were reviewed

[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] Increasing competition in the global market and high consumer expectations for quality products, encourage companies to produce quality products of international standards. The rubber industry is part of an industry group that is prioritized in its development in Indonesia. Based on these conditions, companies are always required to develop quality management systems that exist in the production process. The purpose of this study is to analyze the application of the quality management system of the crumb rubber industry to the ISO 9001: 2015 certification standard. The analysis was carried out on case studies and discussions with leaders of crumb rubber companies in Padang City. The success of the implementation is affected by indicators that influencing in ISO 9001: 2015 certification standards. Based on the results of the case study it can be seen that PT B has implemented an integrated quality management system in the company’s business processes. On the other hand, PT A still needs much improvement in implementing an integrated quality management system and integrated with the company’s business processes. It can be concluded that a strong top management commitment is not supported by the application of a quality management system. The implementation of a quality management system has not been optimally demonstrated by the company’s quality control documentation system is still incomplete and the company has not involved all aspects of the company in the implementation of quality management systems. (paper)

[en] One of the common sterilization method used in Malaysia is gamma radiation because it is the fastest, easiest and the most importanty it is a cold process. However, there is one major drawback to this method because gamma sterilization requires relatively high irradiation dose; minimum of 25 kGy as required by ISO 11137 standard. This high sterilization dose is known of it capability to break chemical bonds in a medical devices and caused its mechanical properties (tensile strenght) to decline. In this study, hybrid gamma-peroxide vulcanized natural rubber latex (HGPVL) films were post-gamma irradiated at 25 and 35 kGy to investigate the extent of damage or degradation when the samples were exposed to extreme irradiation dose. At 25 and 35 kGy post-gamma irradiation, tensile strenght of HGPVL films were found to decrease at 8.0 % and 15 % respectively compared to control (26.5 MPa) due to degradation of their polymeric network. (author)

[en] The rubber tree lace bug, Leptopharsa heveae Drake and Poor occurs in high populations in rubber tree plantations and it is a limiting factor in rubber production due to the loss of photosynthetic tissue. The control of the pest has been made mainly with chemical products, which cause environmental contamination. The alternative would be the use of biological control agents, however, information about L. heveae natural enemies are scarce. The parasitoid Erythmelus tingitiphagus (Soares) parasitize eggs of the rubber tree lace bug. The aim of this study was to verify the occurrence of E. tingitiphagus in plantations of several rubber tree clones, located in Itiquira town, Mato Grosso State. The plant leaflets of the clones RRIM 600, PR 255, GT 1, PB 235 and PB 217 were collected weekly from October 2005 to February 2006. Parasitism was recorded during the entire study period. The parasitism rate of L. heveae eggs in the different clones ranged from 16.8 to 20.6%. (author)