• Elastomers and Composites
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• 제51권3호
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• pp.218-225
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• 2016

In order to examine correlation between silane coupling agent and activator which affects the physical properties of silica filled natural rubber compound, such as heat buildup, rebound property, dynamic mechanical and morphological properties were measured. With incorporation of silane coupling agent, $tan{\delta}$ at $0^{\circ}C$ was increased and at $60^{\circ}C$ was decreased, which resulted in improving of wet grip and rolling resistance. When silane coupling agent which is corresponding to 8~10% of silica was used, most favorable heat build up and $tan{\delta}$ was obtained. And also when activator was used, dispersibility of silica was improved as a result of reduction of reaggregation of silica.

• Elastomers and Composites
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• 제37권4호
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• pp.234-243
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• 2002

A general scheme of a rubber structure is proposed. Using the thermomechanical method(TMA), some changes in the molecular and topological structures for uncured and cured, and unfilled and filled rubbers during processing are shown. In our investigations as region it is understood a complex structure, which is expressed at the thermomechanical curve(TMC) as a zone differed from others in thermal expansion properties. This zone is between the noticed temperatures of relaxation transitions, usually on the level like those determined by DMTA at 1Hz. These regions, which shares, are not stable, and differ in molecular-weight distribution(MWD) of chain fragments between the junctions. Differences in dynamics of the formation of the molecular and topological structures of a vulcanizate are dependent on the rubber formulation, mixing technology and curing time. Some of characteristics of these regions correlate with mechanical properties of vulcanizates what is shown for NR rubbers containing ENR or CPE as a polymeric additive. It is well known that the state of order influences diffusivity of low-molecular substances into the polymer matrix. Because of this, the two topological amorphous regions should influence the distribution of the ingredients and resulting in rubber compounds' heterogeneity, and related properties of cured rubber. Investigation of this problem is expected to be, in the future, one of the essential factors in determining further improvement of polymeric materials properties by compounding with additives and in reprocessing of rubber scrap.

• Elastomers and Composites
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• 제36권1호
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• pp.37-43
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• 2001

실리카와 카본블랙으로 보강된 SBR 배합물의 가황 특성과 bound rubber 함량 그리고 가황물의 물성에 보강제의 조성비가 미치는 영향을 연구하였다. 고무 배합물의 보강제 총 함량은 80.0 phr 이다. Bound rubber 함량은 실리카 함랑비가 증가할수록 증가하였고 점도 역시 증가하였는데, 특히 실리카 함량이 60.0 phr 이상일 때는 점도의 증가폭이 두드러지게 높아졌다. 가황시간은 실리카 함량이 증가할수록 느려졌고 가황 속도도 느려졌다. 실리카 함량비가 증가할수록 델타 토크가 증가함에도 불구하고 모둘러스는 감소하는 경향을 보였다. $60^{\circ}C$에서의 tan ${\delta}$ 값은 실리카 함량이 증가할수록 감소하였다.

• Carbon letters
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• 제9권2호
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• pp.115-120
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• 2008

Rubber reinforcing carbon black N330 was treated by physical activation under $CO_2$ to different degrees of burn-off. The mechanical properties indicating the reinforcement of SBR (Styrene-Butadiene Rubber) vulcanizates filled by activated carbon blacks, such as tensile strength, modulus at 300% strain and elongation at break were determined. During $CO_2$ activation of fresh carbon blacks, the development of microporous structure caused an increase of extremely large specific surface area and the porosity turned out to be an increasing function of the degree of burn-off. The tensile strength and modulus at 300% of activated carbon blacks filled rubber composites were improved at lower loading ratios of 20 and 30 phr, but decreased drastically after 30 phr, which is considered that it might be difficult to get a fully dispersed rubber mixture at higher loading ratios for fillers having very large specific surface areas. However, the Electromagnetic Interference (EMI) shielding effectiveness of SBR rubber composites having activated carbon black at 74% yield were improved at a large extent when compared to those having raw carbon black and increased significantly as a function of increasing loading ratio.

• Advances in materials Research
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• 제3권3호
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• pp.175-183
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• 2014

Natural rubber bound phenolic antioxidant, 2,6-di-tert-butyl-4-vinylphenol (2,6-DBVP), was prepared from natural rubber and 2,6-DBVP in both solution and melt state. The 2,6-DBVP had been synthesized from 3,5-di-tert-butyl-4-hydroxybenzaldehyde and methyltriphenylphosphonium iodide ($MePPh_3I$) by Wittig reaction ($0^{\circ}C$ for 2 hrs, $N_2$ atmosphere). The conditions for preparation of natural rubber bound 2,6-DBVP (NR-DBVP) were optimized for both solution state (1 phr BPO and 8 phr 2,6-DBVP at $70^{\circ}C$ for 2 hrs) and for melt state (1 phr BPO and 8 phr 2,6-DBVP at $70^{\circ}C$ for 10 mins, with rotor speed of 60 rpm). A thermoplastic vulcanizate was obtained using a compatibilizer, polypropylene modified with phenolic resin (PhHRJ-PP), in a closed mixer ($180^{\circ}C$ for 3 mins, rotor speed 60 rpm). The antioxidant properties of vulcanized NR-DBVP, using phenolic as the vulcanization system, were similar to NR with the conventional antioxidant BHT. In addition, the antioxidant, water leaching property of the thermoplastic vulcanizate of NR-DBVP/PP were good in comparison to a NR blend with BHT; the morphologies of these thermoplastic vulcanizates were similar.

• Elastomers and Composites
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• 제54권1호
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• pp.22-29
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• 2019

Chitosan-polyvinyl alcohol (PVA) -bamboo charcoal/silica (CS-PVA-BC/SI) hybrid fillers with compatibilized styrene-butadiene rubber (SBR) composites were fabricated by the interpenetrating polymer network (IPN) method. The structure and composition of the composite samples were characterized by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The viscoelastic behaviors of the rubber composites and their vulcanizates were explored using a rubber processing analyzer (RPA) in the rheometer, strain sweep and temperature sweep modes. The storage and loss moduli of SBR increased significantly with the incorporation of different hybrid fillers, which was attributed to the formation of an interphase between the hybrid fillers and rubber matrix, and the effective dispersion of the hybrid fillers. The mechanical properties (hardness, tensile strength, oxygen transmission rate, and swelling rate) of the composite samples were characterized in detail. From the results of the mechanical test, it was found that BC-CS-PVA0SBR had the best mechanical properties. Therefore, the BC-CS-PVA hybrid filler provided the best reinforcement effects for the SBR latex in this research.

• Elastomers and Composites
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• 제55권4호
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• pp.289-299
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• 2020

Highly aromatic (HA) oils are common processing aids used in tire tread compounds. However, they often bleed and evaporate from the vulcanizates during tire use. Thus, the mechanical and dynamical properties of the tire decrease. To overcome this problem, we investigated nonfunctionalized liquid butadiene rubber (LBR-305, Kuraray) and center-functionalized liquid butadiene rubber (C-LqBR), polymerized by anionic polymerization. In addition to the liquid butadiene rubbers, p-tert-octylphenol (P-Resin) and C5 hydrocarbon (H-Resin) tackifier resins, which can induce entanglement of rubber compounds, were researched as a processing aid to solve the bleeding problem. Liquid butadiene rubbers have significantly reduced extraction loss by crosslinking with the main rubber chain. They have also increased the abrasion resistance and showed similar or better mechanical and dynamical properties against HA oils. However, resin compounds did not show differences in extraction loss compared to HA oil compounds; instead, they showed increased wet traction.

• Elastomers and Composites
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• 제23권4호
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• pp.299-307
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• 1988

The mono-, di- and polysulfidic concentrations of the carbon black filled NR and SBR vucanizates which have different cure systems were determined. The n-decane was used as a swelling solvent. The propane-2-thiol and hexane thiol were used as specific chemical probes to cleavage the chemical crosslinks such as di- and polysulfide. In order to understand the effect of crosslink structure on the physical properties of vulcanizates, the tensile properties, fatigue failure, heat build up, compression set and viscoelastic properties were measured. From the results, the significant relationships between crosslink sturctures and physical properties, especially a gins resistance were obtained. Therefore, the better performances of the product can be satisfied by using the interpretations and approaches in this study.

• Elastomers and Composites
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• 제55권1호
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• pp.6-12
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• 2020

Poly(ethylene-co-vinyl acetate) compounds and vulcanizates containing dicumyl peroxide (DCP) (HD) were prepared, and the curing agent and reaction products were analyzed using gas chromatography/mass spectrometry (GC/MS). Samples containing trially cyanurate (TAC) and DCP (HDT) were also prepared and analyzed. Some raw DCP were decomposed in the injector region of GC to produce acetophenone. DCP was detected in the HD compound but was not observed in the HD vulcanizate, and instead acetophenone and 2-phenyl-2-propanol were detected. Both DCP and TAC were observed in the HDT compound but not in the HDT vulcanizate, where acetophenone and 2-phenyl-2-propanol were detected. Thus, some of the DCP decomposed during the compounding process. The formation mechanism for acetophenone and 2-phenyl-2-propanol during the crosslinking reaction was identified, and differences in the crosslinking reactions of HD and HDT compounds were discussed.

• Elastomers and Composites
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• 제46권1호
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• pp.70-77
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• 2011

슬러리와 접하는 환경에서 사용되는 고무 소재의 슬러리 마모 거동을 평가하기 위해 새로운 형태의 슬러리 마모시험기(Slurry Wear Tester; SWT)가 본 연구에서 제안되었다. 슬러리 마모 거동을 평가하기 위한 기본 매트릭스로 천연고무(NR)와 클로로프렌고무(CR)가 선정되었다. SWT 장치의 챔버를 채우기 위한 유체로는 35% HCl 용액과 NaCl 용액이 사용되었다. SWT의 결과는 기존의 고무 마모시험 방법들중의 하나인 건식 상태에서 시험이 진행되는 Akron 마모시험의 결과와 비교를 하였다. Akron 마모 시험의 결과에 따르면 CR이 NR 보다 더 빠른 속도로 마모가 됨을 알 수 있었으며 재료의 히스테레시스 특성이 마모에 영향을 미침을 알 수 있었다. 그러나 SWT 결과에 따르면 CR과 NR의 슬러리 마모거동은 큰 차이가 없었으며 더구나 산의 농도와 HCl 용액과 NaCl 용액에 침지된 시간에 따라서도 슬러리 마모속도에는 큰 영향이 없었다. 이는 슬러리에 포함된 유체가 마모지와 시편 사이의 마찰을 감소시켰기 때문이라고 사료되었다. 또한 Akron 마모 시험의 경우 고무 소재의 히스테레시스가 마모에 영향을 미쳤지만, SWT의 경우 유체는 반복 변형에 의해 발생되는 열을 감소시키고 마모지 표면에 남아있는 마모 찌꺼기들을 제거하였기 때문에 Akron 마모 시험의 결과와는 다른 결과를 나타내었다. 따라서 슬러리에 의한 고무 소재의 마모를 평가하는데 있어서 기존의 방식인 건식방법으로 마모 거동을 평가할 경우 잘못된 결과를 초래할 수 있음을 알 수 있었다.