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Abstrak :
Graft copolymerization of an acrylonitrile monomer onto Deproteinized Natural Rubber (DPNR) is an important process in the modification of Natural Rubber (NR) to increase its oil resistance. However, coagulation at the beginning of the process was a problem causing a copolymerization foil to occur. The presence of a styrene monomer is therefore expected to improve the emulsion condition so that coagulation can be prevented in the early reaction step. For comparison purposes, the processes with and without styrene were investigated. The influence of the concentration of styrene as well as the ratio of the DPNR:monomer on the stabilization process were also observed. The results showed that the addition of styrene could improve the stabilization process as proven by Fourier Transform Infrared Spectroscopy (FTIR). The presence of the functional group of CºN at FTIR proved the production of the polyacrylonitrile in the mixture. The investigation showed that the concentration of styrene monomer, which led to the emulsion stability, is up to 1.5 wt% concentration of styrene at the ratio of DPNR:monomer (M) of 70:30 wt%.

Abstrak :
Penelitian ini bertujuan untuk mendapatkan kopolimer cangkok DPNR-g-PAN/PS yang tahan terhadap DME dengan melakukan uji perendaman terhadap DME berdasarkan pengaruh rasio monomer akrilonitril dan stirena. Hasil penelitian menunjukkan bahwa monomer akrilonitril (AN) dapat dicangkokkan pada karet alam dengan stirena (ST) sebagai ko-monomer. Dari karakteristik analisis spektrum dengan FTIR didapatkan gugus CN dan gugus benzena yang merupakan gugus dari poliakrilonitril (PAN) dan polistirena (PS). Karakterisasi temperatur transisi gelas (Tg) dengan DSC menunjukkan bahwa nilai Tg kopolimer DPNR-g-PAN/PS lebih tinggi dari Tg DPNR. Dari karakteristik Efisiensi Cangkok (EC) didapatkan nilai tertinggi adalah 73,21%. Berdasarkan karakteristik cure didapatkan bahwa semakin kecil rasio AN/ST, nilai optimum cure semakin tinggi dan scorch time yang semakin rendah. Hasil dari sifat-sifat fisik tensile strength, elongation at break dan hardness menunjukkan keberhasilan kopolimerisasi. Pengujian DPNR dan DPNR-g-PAN/PS dilakukan dalam DME. Semakin besar komposisi monomer (M) dan AN, semakin kecil persentase swelling massa dan volume. Komposisi AN untuk swelling terendah adalah 92%. Komposisi ST optimal untuk memperkecil shrinkage adalah 20%. Swelling massa dan volume terrendah dicapai pada 23,14% dan 31,90%. Shrinkage massa dan volume terrendah dicapai pada masing-masing -3,64% dan -3,86%. Pada analisis spektrum FTIR karet vulkanisat, kemungkinan putusnya ikatan rangkap C=C hanya karena interaksi DME pada DPNR bebas. Hal ini yang menimbulkan terjadinya shrinkage. Kehadiran PAN sebagai polimer bebas dapat berfungsi sebagai penahan difusi, sehingga total PAN yang tergrafting dan PAN bebas dapat memperkecil swelling dan shrinkage. Pada perubahan sifat fisik, interaksi karet DPNR ataupun DPNR-g-PAN/PS dengan DME menyebabkan menurunnya nilai tensile strength, elongation at break dan hardness. Pada analisis SEM terlihat perbedaan yang terjadi akibat swelling dan shrinkage massa dan volume setelah perendaman. Pada pengujian perbandingan dengan Nitrile Butadiene Rubber (NBR) hasil menunjukkan bahwa daya tahan terhadap DME adalah NBR-1 < DPNR-g-PAN/PS < NBR-2. Dari hasil pengujian-pengujian dapat disimpulkan bahwa proses kopolimerisasi cangkok dapat meningkatkan daya tahan karet alam terhadap DME.

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This study aims to obtain graft copolymer DPNR-g-PAN/PS which is resistant to immersion DME. The immersion test of the DME based on the ratio acrylonitrile and styrene monomer. The results showed that the monomer acrylonitrile (AN) can be grafted on natural rubber with styrene (ST) as co-monomer. From the characteristics of the FTIR spectrum analysis obtained CN groups and clusters of benzene which is a group of polyacrylonitrile (PAN) and polystyrene (PS). Characterization of the glass transition temperature (Tg) by DSC shows that Tg values copolymer DPNR-g-PAN/PS higher than Tg DPNR. The characteristics of the Grafting Efficiency (GE) obtained the highest value is 73.21%. Based on the cure characteristics, it was found that the smaller the ratio AN/ST, the higher of the optimum cure and the lower scorch time. The results of the physical properties of tensile strength, elongation at break and hardness show success copolymerization. The immersion test DPNR and DPNR-g-PAN/PS performed in DME. The larger the monomer composition (M) and AN, the smaller the percentage of swelling mass and volume. The composition of AN to the lowest swelling is 92%. ST optimal composition to minimize the shrinkage is 20%. The lowest of the swelling mass and volume reached at 23.14% and 31.90% respectively. Mass and volume shrinkage achieved at the lowest -3.64% and -3.86% respectively. In the FTIR spectrum analysis of vulcanized rubber, the possibility of the outbreak of the C=C double bond simply because of the interaction of the DPNR free and DME. This has led to an shrinkage. The presence of PAN as a free polymer can serve as a diffusion barrier, so that the total PAN grafted and PAN free can reduce swelling and shrinkage. On the change of physical properties, interaction DPNR rubber or DPNR-g-PAN/PS with DME caused a decline in the value of tensile strength, elongation at break and hardness. In the SEM analysis of visible differences that occur due to swelling and shrinkage of mass and volume after immersion. In comparative testing with a Nitrile Butadiene Rubber (NBR) results indicate that resistance to DME is NBR-1 < DPNR-g-PAN/PS < NBR-2. From the results of the tests can be concluded that the graft copolymerization process can improve the resistance of natural rubber to the DME.

Abstrak :
This study aimed to determine the effect of using acrylonitrile butadiene styrene in place of conventional wax material on treatment pattern removal in the investment casting process. There are three controllable process variables that can affect treatment pattern removal, which include temperature increase, holding time and the number of layers of ceramic shell that have been considered for comparison. Comparison among the effects of temperature increase, holding time and numbers of ceramic shell layers on the ceramic shell was analyzed using ANOVA. It was found that temperature increase (Tx), holding time (t) and number of layers of ceramic shell (N) contribute significantly to the length of the crack (l) on the ceramic shell. The crack in the ceramic shell?s surface was analyzed using scanning electron microscope photos. Less layers number cause the increase of crack length. The combination between temperature upraise and longer holding time cause cracking delay. The experimental is conducted by using 3 (three) variants for each of layers number, temperature and holding time. The layers number is ranging between 7-9 layers. Temperature increase from room temperature until 1300oC. The layers number variant is ranging between 180-300 seconds. It was concluded that a longer holding time will result in a more intact ceramic shell, as longer holding times yield short crack lengths.

Abstrak :
This study aimed to determine the effect of using acrylonitrile butadiene styrene in place of conventional wax material on treatment pattern removal in the investment casting process. There are three controllable process variables that can affect treatment pattern removal, which include temperature increase, holding time and the number of layers of ceramic shell that have been considered for comparison. Comparison among the effects of temperature increase, holding time and numbers of ceramic shell layers on the ceramic shell was analyzed using ANOVA. It was found that temperature increase (Tx), holding time (t) and number of layers of ceramic shell (N) contribute significantly to the length of the crack (l) on the ceramic shell. The crack in the ceramic shell’s surface was analyzed using scanning electron microscope photos. Less layers number cause the increase of crack length. The combination between temperature upraise and longer holding time cause cracking delay. The experimental is conducted by using 3 (three) variants for each of layers number, temperature and holding time. The layers number is ranging between 7-9 layers. Temperature increase from room temperature until 1300oC. The layers number variant is ranging between 180-300 seconds. It was concluded that a longer holding time will result in a more intact ceramic shell, as longer holding times yield short crack lengths.