• Elastomers and Composites
• /
• 제43권2호
• /
• pp.113-123
• /
• 2008

에폭시 수지는 우수한 접착력, 높은 강도, 내크리프성, 내열성, 내화학성을 나타내는 열경화성 고분자이지만, 매우 깨지기 쉬우며 균열성장에 대한 낮은 저항성을 보여 낮은 충격강도를 보인다. 그러므로 본 연구에서는 에폭시 수지에 carboxyl-terminated butadiene acrylonitrile (CTBN) 및 amine-terminated butadiene acrylonitrile(ATBN)을 변량 첨가하여 에폭시 수지의 낮은 충격강도를 향상시키고자 한다. 에폭시/CTBN, 에폭시/ATBN복합체의 충격강도(impact strength)가 큰 값을 나타낼 때 표면자유에너지(surface free energy)의 비극성 값 또한 가장 큰 값을 보였으며, 반면에 인장강도와 유리전이온도는 감소함을 보였다. CTBN 및 ATBN을 각각 15 phr 첨가한 에폭시 복합체가 높은 표면자유에너지와 충격강도를 보였다. 결론적으로 액상고무의 첨가로 에폭시 수지의 취성을 향상시켰으며, 에폭시/CTBN보다는 에폭시/ATBN복합체의 물성이 더 우수하다고 사료된다.

• Elastomers and Composites
• /
• 제33권4호
• /
• pp.281-289
• /
• 1998

4종류의 고무 즉, 천연고무(NR), styrene-butadiene copolymer(SBR), ethylene-propylene diene monomer(EPDM), brominated isobutylene-p-methyl-styrene copolymer(BIMS)의 영(Young) 탄성율을 비롯한 인장특성과 인열강도를 여러가지 가교도와 시험온도에서 측정하였다. 과가황(over-cure)의 영향을 조사하기 위해 과가교 고무컴파운드의 인장강도와 팽윤(swelling) 거동도 조사하였다. 모든 고무컴파운드에 대해 영 탄성율(E)은 가교도와 선형적인 비례관계를 보였다. EPDM이 가장 높은 기울기를 그리고 BIMS가 가장 낮은 기울기를 보였고, NR과 SBR은 이들 사이의 값을 나타내었다. 인열강도 Gc는 NR>BIMS>SBR>EPDM의 순으로 나타났다. 과가교에 따라 NR과 SBR의 가교도는 감소한 반면, BIMS는 오히려 증가하였고, EPDM은 거의 변하지 않았다.

• 폴리머
• /
• 제32권5호
• /
• pp.433-439
• /
• 2008

고분자 소재에 평판형 플라즈마 전처리 방식을 적용시켜 polyurethane foam(density : 0.27)과 rubber (butadiene rubber) 소재 표면의 접촉각 및 접착력을 향상시켰다. 플라즈마 반응기의 최적의 반응조건을 조사하기 위해서 전처리기류(질소, 아르곤, 산소, 공기), 기류의 유량($30{\sim}100\;mL/min$), 그리고 전처리 시간($0{\sim}30\;s$) 등을 변화시켜 전처리하고 polyurethane foam의 경우 진공식 플라즈마처리 방식과 상호 비교하였다. 분위기 기류인 $N_2$의 유량을 100 mL/min로 설정 후 polyurethane foam은 10 s, rubber는 3 s 동안 전처리 했을 때 가장 높은 접착박리강도를 나타내었다. 전처리 후 소재의 표면 변화는 SEM과 ATR-FTIR을 이용하여 측정하였다. 결과적으로 평판형 플라즈마 조작 방식에 의한 처리로 소재 표면의 젖음성과 접착박리강도가 개선되었음을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제85권2호
• /
• pp.275-287
• /
• 2023

The use of environmental-friendly building materials is becoming increasingly popular worldwide. Compared to the normal concrete, rubber-based concrete is considered more durable, environmentally friendly, socially and economically viable. In this investigation, M20 grade concrete was designed and the fine aggregates were replaced with crumb rubber of two different micron sizes (0.221 mm and 0.350 mm). Fly ash (FA) and silica fume (SF) replaces the binder as supplementary cementitious materials at a rate of 0, 5, 10, 15, and 20% by weight. The mechanical properties of concrete including compressive strength, tensile, and flexural strength were determined. The polynomial work expectation validates the response surface approach (RSM) concept for optimizing SF and FA substitution. The maximum compressive strength (22.53 MPa) can be observed for the concrete containing 10% crumb rubber, 15% fly ash and 15% silica fume. The reduced unit weight of the rubberized concrete may be attributed to the lower specific gravity of the rubber particles. Two-way ANOVA with a significance criterion of less than 0.001 has been utilized with modest residual error from the lack of fit and the pure error. The predictive model accurately forecasts the variable-response relationship. Since, the crumb rubber is obtained from wasted tires incorporating FA and SF as a cementitious ingredient, it helps to significantly improve mechanical properties of concrete and reduce environmental degradation.

• Geomechanics and Engineering
• /
• 제36권1호
• /
• pp.39-50
• /
• 2024

Bitumen and high-quality subangular aggregates, the two principal materials used for asphalt concrete construction, are finite and expensive materials. The general availability of crumb rubber and naturally occurring aggregates of different shapes, especially flat and elongated shapes, indicates that they are feasible alternative materials for expanding the volume of bitumen and utilizing a wider range of aggregate shapes for the development of asphalt concrete, with an associated environmental benefit. The study investigated the effect of adding up to 15% crumb rubber and aggregates sorted into different groups, i.e., rounded, elongated, flat, and their combinations, on the rheological and mechanical properties and durability of 50/70 of hot-mix asphalt pavement. The addition of crumb rubber decreased ductility and penetration but increased the softening point. For a 5.5% bitumen content, asphalt concrete briquettes consisting of 7% crumb rubber and three types of aggregate shapes, i.e., 100% rounded, a mix of 75% rounded and 25% elongated, and a mix of 75% rounded, 15% elongated and 10% flat, were associated with high Marshall stability and indirect tensile strength as well as low lateral deformation due to their high solidity and moderate angularity ratio. Also, the addition of 7% crumb rubber resulted in a significant improvement in the tensile strength ratio and rebound strain of briquettes consisting of 75% rounded and 25% elongated aggregates and those with 75% rounded, 15% elongated and 10% flat aggregates. In relation to the parameters investigated, the three groups of briquettes met some of the local (South Africa) requirements for the surface course and base course of low traffic volume roads.

• International Journal of Concrete Structures and Materials
• /
• 제7권4호
• /
• pp.295-301
• /
• 2013

This paper deals with the interfacial effects of silica fume (SF) and styrene-butadiene rubber (SBR) on compressive strength of concrete. Analyzing the compressive strength results of 32 concrete mixes performed over two water-binder ratios (0.35, 0.45), four percentages replacement of SF (0, 5, 7.5, and 10 %) and four percentages of SBR (0, 5, 10, and 15 %) were investigated. The results of the experiments were showed that in 5 % of SBR, compressive strength rises slightly, but when the polymer/binder materials ratio increases, compressive strength of concrete decreases. A mathematical model based on Abrams' law has been proposed for evaluation strength of SF-SBR concretes. The proposed model provides the opportunity to predict the compressive strength based on time of curing in water (t), and water, SF and SBR to binder materials ratios that they are shown with (w/b), (s) and (p).This understanding model might serve as useful guides for commixture concrete admixtures containing of SF and SBR. The accuracy of the proposed model is investigated. Good agreements between them are observed.

• Elastomers and Composites
• /
• 제32권5호
• /
• pp.295-301
• /
• 1997

The effects of filler types and compositions on the final properties such as tensile strength, % elongation, hardness, and specific gravity of chloroprene rubber were investigated. The fillers involved in this investigation were HAF-type carbon black, Mistron, and white clay, For each filler, the variation of filler compositions gave almost the linear effects on the all properties investigated. For a fixed filler composition, different filler types gave different influential strength on rubber properties. After linearlization of experimental data with respect to each filler composition, the simple linear addition of each property with respect to filler compositions was applied to predict the final properties of the filler included rubber systems. For the chloroprene rubber system including the fillers composed of Mistron(25phr)/HAF(20phr)/clay(35phr), the predicted properties were well in accordance with the experimental results. Similar results were obtained for other additives such as processing oil and accelerator.

• Smart Structures and Systems
• /
• 제23권2호
• /
• pp.207-214
• /
• 2019

Achieving a pervious concrete (PC) with appropriate physical and mechanical properties used in pavement have been strongly investigated through the use of different materials specifically from the global waste materials of the populated areas. Discarded tires and the rubber tire particles have been currently manufactured as the recycled waste materials. In the current study, the combination of polymer, silica fume and rubber aggregates from rubber tire particles have been used to obtain an optimized PC resulting that the PC with silica fume, polymer and rubber aggregate replacement to mineral aggregate has greater compressive and flexural strength. The related flexural and compressive strength of the produced PC has been increased 31% and 18% compared to the mineral PC concrete, also, the impact resistance has been progressed 8% compared to the mineral aggregate PC and the permeability with Open Graded Fraction Course standard (OGFC). While the manufactured PC has significantly reduced the elasticity modulus of usual pervious concrete, the impact resistance has been remarkably improved.

• Advances in concrete construction
• /
• 제14권1호
• /
• pp.15-34
• /
• 2022

The use of waste rubber in concrete can reduce natural aggregate consumption and improve some technical properties of concrete. Although there are several equations for estimating the mechanical properties of concrete containing waste rubber, limited numbers of machine learning-based models have been proposed to predict the mechanical properties of rubbercrete. In this study, an extensive database of the mechanical properties of rubbercrete was gathered from a comprehensive survey of the literature. To model the mechanical properties of rubbercrete, M5P tree and linear gene expression programming (LGEP) methods as two machine learning techniques were employed to achieve reliable mathematical equations. Two procedures of input variable selection were considered in this study. The crucial component ratios of rubbercrete and concrete age were assumed as the input variables in the first procedure. In contrast, the volumes of the coarse and fine waste rubber and the compressive strength of concrete without waste rubber were considered the second procedure of the input variables. The results show that the models obtained by LGEP are more accurate than those achieved by the M5P model tree and existing traditional equations. Besides, the volumes of the coarse and fine waste rubber and the compressive strength of concrete without waste rubber are better predictors of the mechanical properties of rubbercrete compared to the first procedure of input variable selection.

• Earthquakes and Structures
• /
• 제6권2호
• /
• pp.127-140
• /
• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.