The vulcanization kinetics of Ethylene-propylene diene monomer (EPDM) rubber thermal insulation was studied by using rheometer under isothermal condition at different temperatures. The rheometry analysis was used to determine the cure kinetic parameters and predicting the optimum curing time of EPDM thermal insulation. The experimental results revealed that the curing curves of EPDM thermal insulation were marching and the optimum curing time decreased with the increasing of temperature. The kinetic parameters were determined from the autocatalytic model that showed a close fitting with the experimental results. It also indicated a suitability of autocatalytic model in characterizing the cure kinetics. The optimum curing time was predicted from autocatalytic model and the kinetic parameters were obtained by using the relationship between degree of conversion, cure temperature, and cure time. The predictions of cure time provided information on the actual curing characteristic of EPDM thermal insulation. The mechanical properties of EPDM thermal insulation with different vulcanization temperatures showed the same hardness, tensile strength and modulus at 300%, except at temperature 70 o C, while the elongation at breaking point decreased with the increasing temperature of vulcanization.

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Reinforcement of silica in tire tread compounds is known to reduce hysteresis or energy loss, which leads to a production of energy-saving tires. Even though silica–silane technology has been well established, further development to enhance its performance is still needed. One of the approaches is to use hybrid or dual filler. The use of silica-organomodified montmorillonite (MMT) dual filler in the reinforcement of natural rubber (NR) truck tire tread compounds is investigated. The NR-MMT master batches were prepared by using the in situ organomodified and latex compounding method. Because the surface-modifying agent or surfactant is a key factor in determining the level of MMT dispersion in the rubber matrix, the effect of quaternary amine salt (Q) contents on mechanical and dynamic properties of NR tread compounds reinforced by silica-MMT was studied. The results revealed that MMT and Q can effectively reduce the filler–filler interaction and complex viscosity owing to a good dispersion of MMT and silica in the NR matrix and Q, which acts as a dispersing agent in addition to the silane coupling agent used in the compound, leading to improvement in tensile, abrasion resistance, and dynamic mechanical properties with an increasing amount of Q. Furthermore, at the optimum content of the surfactant used (36 wt%), the silica-MMT–reinforced NR exhibited improved tensile strength (+4%), wet grip, and rolling resistance, respectively, as indicated by loss tangent at 0 °C (+6%) and 60 °C (−15%), while maintaining a modulus at 300% strain and abrasion resistance as compared with the silica-NR reference compound. Such a dual-filler system demonstrates its potential use for tire treads with better performance.

AbstrakPada saat ini terdapat ± 40 ribu ha areal perkebunan karet rakyat berumur tua dan kurang produktif yang siap diremajakan. Upaya peremajaan karet rakyat terkendala oleh tidak tersedianya sumberdana yang dimiliki petani dan kesiapan kelembagaan peremajaan. Tulisan ini akan menganalisis upaya memberikan solusi alternatif sumber pembiayaan dan kelembagaan peremajaan karet rakyat.Hasil analisis menunjukkan bahwa peremajaan karet rakyat dapat dilakukan dengan Model Peremajaan Karet Partisipatif dan menerapkan teknologi karet anjuran budidaya tanaman, panen/penyadapan, dan pasca panen. Pembiayaan peremajaan karet rakyat dapat dilakukan dengan alternatif memanfaatkan nilai jual kayu karet dan kredit bank. Analisis kelayakan finansial peremajaan karet rakyat menunjukkan bahwa penggunaan sumber pembiayaan dari hasil penjualan kayu karet dan kredit bank disertai dengan penanaman tanaman sela dinilai layak untuk dilakukan.Kata kunci: analisis finansial, model partisipatif, sumber dana, kayu karet. AbstractAt present there are ± 40 thousand hectares of old and unproductive rubber plantation area which is ready to be replanted. Efforts to replant the rubber