In this work, calcium oxide (CaO) extracted from eggshell impregnated with magnetite (Fe₃O₄) is prepared successfully and it had been applied on transesterification of palm oil off-grade. Prior experiment, the eggshells material are powdered and calcined at 900 °C then impregnated with Fe₃O₄ and recalcined. The obtained Fe₃O₄/CaO catalyst is characterized using X-ray diffraction and Braunaeur–Emmet–Teller (BET) surface area. The influence of various parameters including recalcined time and temperature are investigated. The prepared catalyst is tested for transesterification of palm oil off-grade to produce biodiesel in which the optimal conditions of a methanol/palm oil off-grade molar ratio of 10:1, the catalyst weight of 6%, the reaction temperature of 70 °C, and the reaction time of 2 h. The transesterification product was analyzed using GC-MS, which showed the biodiesel yield of 90% at the recalcined temperature of 600 °C and reaction time of 2 h. It has been noted that the catalyst activity is achieved when the moderate recalcination temperature is applied and the disordered structure of the catalyst is maintained. This study also confirms that CaO impregnated with Fe₃O₄ could be a solid catalyst for the biodiesel synthesis through transesterification reaction of palm oil off-grade.

The use of natural rubber to resist bitumen is usually prone to degradation and aging. One method to overcome this problem is the addition of antioxidants. This study aims to determine the effect of the addition of antioxidants 1,2-dihydro-2,2,4-trimethyl-quinoline (TMQ) on natural rubber modified asphalt crepe rubber and its performance in short-term and long-term aging conditions. The modified rubber asphalt mixture’s manufacture begins by melting the crepe rubber at 200 °C before being mixed in asphalt at 165 °C. Addition of antioxidant TMQ during the stirring process of the mixture of asphalt and melted rubber. The crepe rubber content was 8, 10, and 12% w/w, while the TMQ content was 1, 2, and 3% w/w of the total sample weight. The modified asphalt samples’ characterization included penetration, softening point, weight loss after a rolling thin film oven test (RTFOT), penetration after RTFOT, and Marshall test. Review of the performance of asphalt under short-term aging conditions using a dynamic shear rheometer (DSR). Evaluation of asphalt performance under long-term aging conditions using Fourier-transform infrared spectroscopy (FTIR). The results showed that the fact that the best-modified asphalt product was the addition of 10% crepe rubber and 2% TMQ. The best-modified asphalt characteristics have penetration 68.70 dmm, softening point 55.45 °C, weight loss only 0.0579%, penetration after RTFOT 59.60, Marshall stability 1403.96 kg with optimum asphalt content of 5.50%, and rutting factor (G*/Sinδ) 6.91 kPa and 16.1 kPa before and after RTFOT. Overall, the modified crepe rubber asphalt can improve the performance of the asphalt in terms of durability. Simultaneously, the antioxidant TMQ works very well in increasing the resistance of bitumen to aging in the conditions of short-term aging and long-term aging.

Vulcanization is an important step in the manufacture of solid tires in which the crosslinking process occurs. In vulcanization, the materials commonly used as activators and coactivators are ZnO and stearic acid, respectively. In this research, ZnO and stearic acid were replaced with zinc stearate to improve the characteristics of vulcanized rubber. Zinc stearate was applied in four formulas with a composition of 5 to 9 phr. A formula that is often used in the rubber industry was used as a comparison, and ZnO and stearic acid of 5 phr and 2.5 phr, respectively, were applied. The rubber compound for solid tire production was developed using an open mill at a compounding temperature of 45 °C ± 5 °C. The vulcanization process of developing the rubber compound into vulcanized rubber was carried out at 150 °C for 20 min. Rubber compound test results showed that the use of zinc stearate at a ratio of 8 phr accelerated the curing time (t₉₀) between 58.3% and 69%, the scorch time (ts2) between 22.4% and 95.5%, and the torque delta (Δ_s) between 17.67 and 24.21 kg-cm. In addition, the vulcanized rubber mechanical properties test results for the compression set parameter increased between 28.6% and 57.1%. Scan results with SEM–EDS showed that using ZS could improve the homogeneous distribution of the material in the vulcanized matrix of solid tire rubber.

Infrastructure developments in recent decades have led to increasing demand for high-performance paints for construction and decorative purposes. Emulsion paint is water-based paint that is commonly used for coating the internal and external surfaces of a building. The quality and performance of this emulsion paint are highly dependent on its constituent components, such as binders, pigment, solvents, and additives. Emulsion paints initially used conventional formaldehyde-based binders and were, for some reason, prohibited from being used in paints due to health and environmental issues. The development of bio-based paints with natural rubber latex (NRL) has the potential to be developed as an emulsion paint binder. The results showed that NRL grafting of styrene monomer or MMA showed much better resistance to wet scrub and abrasion than PVAc at a monomer concentration of 20%, for styrene, and 30%, for MMA, with washability values reaching each of 11 and 12 cycles at 4% binder concentration. The NgSt20-4 and NgMMA30-4 binders’ abilities to overcome wet scrub and abrasion increased with increasing paint binder concentrations, reaching 22 and 23 cycles at 10% binder concentration. Overall, the combination of NRL grafted with MMA monomer and 30% PVAc showed better performance and could compete with commercial binders such as PVAc. Adding methyl methacrylate monomer increases the adhesion and cohesion properties of the binder and increases the binder’s resistance to scrubbing and wet abrasion. However, the combination of NRL grafted MMA and 30% PVAc showed the same effectiveness as NRL grafted MMA without PVAc, with more economical production costs.

The direct use of natural rubber latex (NRL) as a binder for emulsion paints did not produce emulsion paints with good opacity, washability resistance, and regulated touch drying time, even when mixed with polyvinyl acetate (PVAc). This study aimed to study the properties of opacity (hiding power), washability resistance, and set drying touch time of emulsion paint with a binder added from a mixture of modified natural rubber latex (NRL) and PVAc. NRL modifications included UV photodepolymerization with TiO₂ catalyst and grafting copolymerization of methyl methacrylate and styrene (NRL-g-(MMA-co-St)). NRL was mixed with PVAC at ratios of 0/100; 15/85; 25/75; 35/65; 50/50; 100/0% w/w before being used as a binder for emulsion paint. Emulsion paint samples had different binder contents, namely 2, 4, 6, and 8% w/w. Tests on paint samples included opacity using a UV-Vis spectrophotometer (EASYSPEC safas Monaco), washability using the Digital BGD 526 Wet Abrasion Scrub Tester, and drying time set using the ASTM STP500 procedure. The results showed that the opacity (hiding power), washability resistance, and set drying touch time met the emulsion paint standards for all binder levels, except the 100% w/w modified NRL composition. The higher level of NRL in the binder causes these properties to decrease and become unstable. The best opacity (hidden power), washing resistance, and drying touch time were obtained on modified NRL with a concentration of 15% w/w. The binder content in the paint was around 4% w/w, with an opacity of about 1.78% abs, washing resistance of 12 times, and the set drying touch time to 80 min.

The modification of asphalt with natural rubber is believed to enhance asphalt penetration grade (Pen Grade) 60/70. Natural rubber-type technical natural rubber with standard Indonesian rubber (SIR) 20 was chosen as an asphalt additive. However, SIR 20 as an asphalt additive directly has the rubber distribution problem in asphalt, which tends to accumulate in certain parts of the asphalt mixture. Also, the use of SIR 20 requires a very long time in the mixing process to reach homogeneity. This study aims to determine the effect of adding technical natural rubber, Standard Indonesian Rubber (SIR) 20, both with and without mastication, on the characteristics of asphalt-rubber blends. The asphalt-rubber blend was developed by melting the SIR 20 at 200 °C before mixing it with asphalt under the melting point (170 °C). Evaluation of asphalt-rubber performance is measured using tests on penetration, softening point, and Marshall stability. While the asphalt rheological characteristics reviewed are complex modulus (G*), phase angle (δ), rutting factor (G* / Sin δ) before and after short-term aging. The results showed that the mastication process of SIR 20 could accelerate the asphalt-rubber mixture's homogenization process and produce asphalt with increased performance at high temperatures. The results show the addition of 10% MSIR has the best performance with a penetration value of 58.5 dmm, a softening point of 59.1 °C, Marshall stability of 1710 kg, and rutting factor of 5.46 kPa.