The elucidation of the role of bio-oils on the accelerated sulfur vulcanization of natural rubber (NR) compounds is discussed in this study. Two types of bio-oil, palm oil and soybean oil, were studied in direct comparison with a distillate aromatic extract oil (DAE) as a reference. The scorch and cure times of the bio-oil-extended NR compounds were shorter than those containing DAE. The use of bio-oils gave a higher cure reaction rate constant along with a lower activation energy than the use of DAE. The attenuated total reflectance-Fourier transform infrared spectroscopy analysis revealed that the fatty acid segment of the bio-oils can react with zinc oxide to give zinc carboxylate, which is then involved in and promotes the vulcanization reaction. The use of bio-oils to increase the rate of vulcanization strongly influenced the crosslink density of the obtained NR vulcanizates, yielding NR vulcanizates with a lower crosslinking density. It is proposed here that the bio-oils might consume the curing agent via the reaction between their own unsaturated fatty acid and sulfur. This was supported by the increased viscosity of the oils after exposure to sulfur at a high temperature. The tensile strength and elongation at break of the bio-oilextended NR compounds were lower and higher, respectively, than the NR extended with DAE oil due to the lower crosslink density of the bio oil-extended NR vulcanizates.

This study focuses on the properties of unfilled natural rubber compounds containing bio-oils cured with a peroxide curing system and then discusses the comparisons to those cured using the sulfur system from our previous work. Two types of bio-oils, i.e., palm oil and soybean oil, were used, and distillate aromatic extract (DAE)-based petroleum oil was employed as a reference. The bio-oils caused no significant change in the vulcanization of rubber compounds cured using peroxide. However, the compounds containing bio-oils and cured with sulfur showed a faster vulcanization than the ones with DAE. The bio-oils strongly affected the crosslink density of rubber compounds in both curing systems. The use of bio-oils caused a low crosslink density due to the possible implication of curing agents to bio-oil molecules. The properties of rubber compounds dependent on the different levels of crosslink density were also investigated. The results revealed that when the crosslink density increased, the modulus, tensile strength, and hardness of the rubber compounds increased and the elongation at break and compression set decreased. The use of bio-oils in the rubber compounds cured with different curing systems gave low modulus at 300% strain, tensile strength, and hardness but high elongation at break and compression set when compared to the ones with DAE. However, no significant change was observed for the compression set of the rubber compounds cured using sulfur. With the presence of bio-oils, the properties of rubber compounds cured with sulfur system deteriorated less than those of the ones cured with peroxide.

Coagulant type determines coagulating condition and the quality rubber that will be produced. The AbstrakPenggunaan koagulan menentukan kondisi penggumpalan dan mutu karet yang akan dihasilkan. Koagulan anjuran, asam format dan asap cair murni, masih belum digunakan secara l u a s o l e h p e t a n i k a r e t . A s a m f o r m a t menghasilkan bokar berbau busuk, berbahaya bagi manusia dan lingkungan serta harganya mahal. Sedangkan asap cair murni memerlukan konsentrasi dan dosis yang lebih banyak sehingga kurang ekonomis. Sekarang ini sudah dikembangkan koagulan Deorub formula baru yang memiliki kelebihan dibandingkan kedua koagulan anjuran tersebut. Tujuan penelitian ini adalah untuk mengetahui dan mempelajari karakteristik kondisi penggumpalan dan mutu karet yang digumpalkan dengan koagulan Deorub formula baru. Parameter yang diamati terdiri atas kondisi penggumpalan, kadar karet kering koagulum, karakteristik karet mentah, mutu teknis, karakteristik vulkanisasi, dan sifat fisik vulkanisat karet yang dihasilkan. Hasil penelitian menunjukkan bahwa waktu, pH penggumpalan, mutu teknis, modulus torsi, dan sifat fisik vulkanisat karet yang digumpalkan dengan koagulan Deorub formula baru tidak berbeda dibandingkan asam format dan lebih baik dari Deorub K. Koagulum yang digumpalkan dengan Deorub formula baru ini mempunyai warna coklat muda dan bau asap ringan dengan kadar karet kering lebih tinggi. Mutu teknis karet dari kedua koagulan juga tidak berbeda nyata.

Summary A new elastomer was successfully materialized from sunflower oil (a vegetable oil). The reaction was confirmed by Fourier Transform Infrared (FTIR) and Fourier Transform Nuclear Magnetic Resonance (FTNMR) methods. FTIR analysis indicated that amine functional groups appear at 3325 cm−1 representing N‐H stretching of primary and secondary amines and at 1645 cm−1 representing N‐H deformation of primary amines. The hydrogen bonding was confirmed with the appearance a broad peak in the region 2500–3800 cm−1. FTNMR analysis also show the appearance amine functional groups at peak 5.4 ppm in 1H NMR representing proton in amine functional groups and peaks at 151 ppm and 156.6 ppm in 13C NMR representing carbon in amine functional groups.

Since some adverse effects of using carbon black as petroleum-based filler in rubber compounding, mineral fillers may be a feasible alternative filler. This research studied the effect of the composition of pumice and clay as mineral filler in natural rubber (NR) and ethylene propylene diene monomer (EPDM) blending towards its curing characteristics and physical-mechanical properties. The effect of reinforced filled in EPDM-NR (70/30) phr blends was observed by varying 50, 70, and 90 phr of filler. While the filler was designed as the composition of pumice/clay (P/C): 20/80; 50/50; 80:20 (weight/weight). The rubber, fillers, and chemical were compounded based on ASTM D-3182. The results showed that the loading of P/C fillers in EPDM-NR blends increased scorch time and decreased cure rate index. It was found that the optimum number of filler could enhance density, modulus. Remarkably, the higher pumice composition caused the abrasion resistance and compression set improved significantly, whereas the overloading pumice and clay cause the physic-mechanical properties remained stable or evenly drop. FTIR spectra of the binary blends confirmed that the fine fillers dispersion was obtained due to some interaction bonding between silanol, aluminol of fillers with the EPDM-NR.