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High-density thermoplastic vulcanizates based on LLDPE/NR for truck ﬂoor mats application Dwi Wahini Nurhajati; Umi Reza Lestari
Majalah Kulit, Karet, dan Plastik Vol 37, No 2 (2021): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20543/mkkp.v37i2.7159

The use of thermoplastic vulcanizates (TPVs) that was obtained from a blend of thermoplastics and natural rubbers are considered suitable for the automotive applications purpose. To modify the performance of TPVs to a high density TPVs, the high density filler such as bismuth oxide (Bi₂O₃) was added. The focus of this study was on the development of a high density TPVs based on linear low density polyethylene (LLDPE)/natural rubber (NR) blend with different proportions of Bi₂O₃ filler that meets with requirements for truck floor mats materials. The high density TPVs were prepared by melt blending in a Kneader. Bismuth oxide filler loading was varied by 50; 150; 200; 250 phr and 300 phr. An increase in the weight load of bismuth oxide in TPVs increase density, hardness, and volume loss but reduce the tensile properties, tearing strength, and burning rate of high density TPVs. The test results showed that the TPVs containing 250 phr Bi₂O₃ was a promising candidate for use as a truck floor base.

Biodegradable plastics from linier low-density polyethylene and polysaccharide: The influence of polysaccharide and acetic acid Dwi Wahini Nurhajati; Bidhari Pidhatika; Syaiful Harjanto
Majalah Kulit, Karet, dan Plastik Vol 35, No 1 (2019): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

Global problems associated with conventional, non-biodegradable plastics have urged the society to use more eco-friendly biodegradable plastics. In this study, linear low-density polyethylene (LLDPE) was co-compounded with cassava-based thermoplastic starch (TPS) to prepare biodegradable plastics (i.e. plastics that can be degraded by microbes), in which three different LLDPE/TPS ratios were studied. Acetic acid was used to hydrolyze the polysaccharides by breaking the branched amylopectin that causes the TPS-containing composites brittle and stiff. The biodegradation properties of the LLDPE/TPS composites were determined by observing the level of microbial growth on the sample surface after incubation with potato dextrose agar medium that was inoculated with Penicillium sp. and Aspergillus niger. Burial test in a humid composting medium was also performed to validate the biodegradation properties. The mass change (%) was calculated in relative to the initial mass before burial test. The physical properties (tensile strength and elongation at break) of the bioplastics were determined using universal testing machine before and after burial treatment. The morphology of the sample surface was evaluated using scanning electron microscopy. The results showed that the microbial growth increases with increasing TPS content. Negative mass changes were observed on all samples that contain TPS, with increase in the magnitude with increasing TPS content. The tensile strength tends to increase in the first 28 days of burial period in a composting medium then decreases and plateaus, while the elongation at break decreases with increasing burial period. Moreover, samples that contain acetic acid showed less microbial attachment and less biodegradation compared to samples that does not contain acetic acid.

Pengaruh penambahan pati tapioka terhadap sifat mekanis dan struktur komposit high density polyethylene Dwi Wahini Nurhajati; Ihda Novia Indrajati; Hesty Eka Mayasari; Muhammad Sholeh
Majalah Kulit, Karet, dan Plastik Vol 34, No 2 (2018): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

Telah dilakukan penelitian tentang pengaruh penambahan pati tapioka terhadap sifat mekanis dan struktur komposit plastik high density polyethylene (HDPE). Komposit HDPE berisi pati tapioka dibuat menggunakan internal mixer Haake Rheomix pada suhu 130°C dan kecepatan rotor 40 rpm selama 15 menit. Pati tapioka sebelum dibuat komposit dicampur lebih dulu dengan gliserol, air dan asam asetat. Jumlah pati di dalam komposit HDPE divariasi 30, 40, 50, 60, dan 70%. Penambahan pati tapioka menurunkan sifat kuat tarik namun meningkatkan nilai perpanjangan putus dan densitas komposit HDPE. Perlakuan aging terhadap komposit HDPE yang berisi pati tapioka ≥ 50% menaikkan sifat kuat tarik namun menurunkan sifat perpanjangan putusnya. Difraktogram XRD komposit HDPE memperlihatkan bahwa penambahan pati tapioka menyebabkan terjadinya pergeseran nilai 2-theta dan penurunan intensitasnya. Spektra FTIR komposit HDPE yang berisi pati tapioka memperlihatkan pergeseran panjang gelombang yang diduga terjadinya transisi amorf-kristal.

Reologi, sifat aging, termal, dan swelling dari campuran EPDM/NR dengan bahan pengisi carbon black N220 Arum Yuniari; Dwi Wahini Nurhajati; Indiah Ratna Dewi; Ike Setyorini
Majalah Kulit, Karet, dan Plastik Vol 32, No 1 (2016): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

The blends of EPDM and NR are immiscible in nature and incompatible. Introducing maleic anhydride as a compatibilizer into the blends was expected to produce compatible blends with balanced mechanical properties. The purpose of this research was to determine the effect of EPDM/NR ratio on the rheological, aging, thermal and swelling properties of the blends. The variation of EPDM/NR ratio were 100/0, 80/20, 70/30, 60/40, 50/50, and 40/60 phr. The blends were mixed using two roll mill. The results showed that the addition of NR affects the maximum torque, scorch time, and optimum vulcanization time. In the blends, EPDM plays an important role in improving aging, swelling, thermal properties.

Characterization of ethylene–vinyl acetate (EVA)/modified starch expanded compounds for outsole material Dwi Wahini Nurhajati; Umi Reza Lestari; Gunawan Priambodo
Majalah Kulit, Karet, dan Plastik Vol 37, No 1 (2021): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20543/mkkp.v37i1.6916

The use of non-biodegradable material in shoe components has negative impacts on environmental sustainability when disposed into landfills due to poor biodegradability. This study prepared ethylene–vinyl acetate (EVA)/modified starch expanded compounds as outsole material to overcome environmental pollution. This research aimed to investigate the effects of EVA/modified starch ratio on the properties of the compound. Ethylene-vinyl acetate (EVA) copolymer was blended with a modified cassava starch in various amounts (10-50 phr) using a two-roll mill. Effect of modified starch content was characterized its tensile strength, elongation at break, tearing strength, 50% permanent set, density, abrasion resistance, flex resistance, biodegradability, and morphology. The optimum value of tensile strength (61.33 kg/cm²), elongation at break (895%), and tear strength (16.62 N/mm) were obtained for samples containing 20 phr modified starch. The EVA compound containing 30 phr of starch showed the optimum 50% permanent set (4.85%) and the highest abrasion resistance with the smallest volume loss of 439.99 mm³. The addition of modified starch up to 50 phr provided good flexural resistance to 150000 number of cycles. The morphology image showed that distribution of modified starch particles was not homogeneously dispersed in the EVA/modified starch expanded compound. Incorporation of modified starch in EVA compound was improving its biodegradability.

Pengaruh bahan pengisi serat kaca terhadap sifat fisik dan kristalinitas polipaduan PC/ABS Dwi Wahini Nurhajati; Muhammad Sholeh; Ihda Novia Indrajati; Ike Setyorini
Majalah Kulit, Karet, dan Plastik Vol 33, No 1 (2017): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

This research aimed to determine the effects of the addition of glass fibers on the physical and crystallinity properties of PC/ABS polyblends. The ratio of PC/ABS used in this research was 75/25, while the addition of glass fibers ranged from 0; 5; 10; to 15 phr (based on the weight of PC/ABS). Polyblends of PC/ABS/glass fibers were prepared in a twin screw extruder. The test results showed that density and tensile strength of PC/ABS polyblends increased with an increase in the glass fiber content. The presence of glass fibers decreased MFI and impact strength of these PC/ABS polyblends. The functional groups were determined by the fourier transform infrared (FTIR) spectrophotometer while crystallinity was examined using X-ray diffractometer (XRD).Keywords: PC/ABS polyblend, glass fiber, physical properties, crystallinity.

Pengaruh pemlastis nabati terhadap sifat elastomer termoplastik berbasis campuran karet alam/poli propilena Dwi Wahini Nurhajati; Supraptiningsih Supraptiningsih; Nursamsi Sarengat
Majalah Kulit, Karet, dan Plastik Vol 31, No 2 (2015): Majalah Kulit, Karet, dan Plastik
Publisher : Center for Leather, Rubber, and Plastic Ministry of Industry, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20543/mkkp.v31i2.506

Vegetable plasticizer is a plasticizer that is derived from renewable raw materials, that are used as an alternative to petroleum-based plasticizer. The purpose of this research was to compare the effect of the vegetable and plasticizer with petroleum plasticizers on the mechanical properties of (Thermoplastic Elastomer) TPE. Vegetable plasticizer used in this study is a modified castor oil. Natural rubber/polypropylene (KA/PP) based TPE was made in an internal mixer at a temperature of 180ºC with a variousvarious ratio KA/PP ratio and type of plasticizer. In general, modified castor oil as a plasticizer has a more positive effect on the mechanical properties of TPE in various ratios of KA/PP, is mainly related to improvement of properties of tensile strength, elongation at break and flexing resistance 100 kcs. The best formula of TPE is a TPE that is composed of KA/PP 60/40 using modified castor oil. XRD results showed that TPE is dominated by amorphous phase.Keywords: castor oil, natural rubber, polypropylene, TPE.ABSTRAK Pemlastis nabati merupakan pemlastis yang berasal dari bahan baku yang terbarukan yang digunakan sebagai alternatif untuk pemlastis berbasis minyak bumi. Tujuan penelitian ini untuk membandingkan pengaruh pemlastis nabati dengan pemlastis dari minyak bumi terhadap sifat mekanik elastomer termoplastik. Pemlastis nabati yang digunakan dalam penelitian ini adalah minyak jarak yang telah dimodifikasi. TPE berbasis campuran kompon karet alam (KA)/poli propilena (PP) dibuat di dalam internal mikser pada suhu 180°C dengan variasi perbandingan KA/PP dan jenis pemlastis. Secara umum minyak jarak termodifikasi sebagai pemlastis mempunyai pengaruh yang lebih positif terhadap sifat fisis TPE pada berbagai rasio KA/PP terutama terkait perbaikan sifat kuat tarik, perpanjangan putus dan ketahanan retak lentur. Formula TPE terbaik adalah TPE yang dikomposisi dari KA/PP pada rasio KA/PP 60/40 menggunakan pemlastis minyak jarak. Hasil XRD memperlihatkan bahwa TPE hasil penelitian didominasi fasa amorf. Kata kunci: karet alam, minyak jarak, poli propilena, TPE

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