Abstract. Devulcanization of ground tire rubber (GTR) was done using twin screw extruder (TSE) and internal mixer (IM). Processing parameters were varied to analyze its effect on gel content. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed as qualitative technique to confirm structural change. The devulcanized rubbers with the least gel content percentage produced in both TSE and IM were then used as filler in natural rubber (NR)/coconut coir (CC) composite preparation. Effects of gel content percentage on NR/CC composite tensile strength and elongation at break were analyzed. The results show that the gel content decreased by 41% for sample processed in TSE and 50% in IM compared to control sample. Overall, the devulcanization is influenced by high energy generated by thermal or thermo-mechanical process. FTIR spectra show chemically structural changes of GTR as C=C, CH2, CH3with higher intensity for IM sample than its counterpart indicated devulcanization. The replacement of GTR to DGTR on NR/CC/GTR composites provided less network structures and resulted better tensile strength and elongation at break.

Indonesia is one of the largest natural rubber producers in the world. However, the utilization of natural rubber is still not optimal, even though with a touch of technology, natural rubber can be utilized to create technical products that have high added value. One of the rubber products is rubber airbag. The purpose of this research is to know the effect of variations of natural rubber type Standard Indonesian Rubber (SIR) 20 and ethylene propylene diene monomer (EPDM) rubber composition processed with auxiliary chemicals on the quality of mechanical properties of rubber airbag product which is considered quite optimal. Rubber compound is made from the mixture of natural rubber SIR 20 and synthetic rubber EPDM with variation of SIR 20/EPDM ratio A) 100/0; B) 90/10; C) 80/20; D) 0/100 phr. Rubber compound is made with kneader machine and open mill. Then its mechanical properties are tested in accordance with the target technical specifications to be achieved. Testing is done both before and after its immersion in sea water at 95 °C for 29 days. Test results both before and after immersion in sea water shows that the composition of natural rubber and EPDM has significant effect on mechanical properties and chemical structure of rubber compound vulcanizate. The optimum rubber compound formula for rubber airbag is sample A with 100 phr of SIR 20 composition with excellent mechanical properties of tensile strength, hardness, rebound resilience, and abrasion resistance.

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Starch blending with linear low-density polyethylene (LLDPE) is one of the plastic packaging materials alternative used for solving the plastic waste problem that difficult to degrade. Polymeric materials will change when exposed to weather that releases heat, chemistry, and light. It can be a trigger factor in the degradation process. Xenon Arc accelerated weather simulation test is one way to find out the resistance of plastic materials to weather. This study aimed to explain the effect of xenon arc light on LLDPE-starch-clay composite. In this work accelerated photodegradation tests using Xenon Arc ATLAS Ci 3000+ were carried out on LLDPE-starch-clay composite sample films. Clay, compatibilizers, and starch with a starch content of 10 wt% and 20 wt% were used to make composites masterbatch. The composite masterbatch then extruded with LLDPE and was prepared to make a film sample using Rheomex Haake Blown film. Mechanical properties of the film samples before and after xenon arc accelerated photodegradation treatment were tested using Universal Testing Machine (UTM) Shimadzu AGS-10kNG. The composite sample made from ten wt% starch showed 55% reduction in tensile strength after 14 days of degradation while sample prepared with 20 wt% starches was brittle after seven days of exposure to xenon arc light. Fourier Transform Infra-Red (FTIR) spectrophotometer test result for composite samples made from 10 wt% and 20 wt% starch after exposure to xenon arc light show increasing the intensity at the wave number of 1722 cm-1 that corresponding to carbonyl bond this proved that degradation has occurred.