Effects of hygrothermally decomposed polyurethane on the curing and mechanical properties of carbon black‐filled epoxidized natural rubber vulcanizates

Hygrothermally decomposed polyurethane (HD‐PUR) was mixed up to 20 phr in epoxidized natural rubber (with 50 mol % epoxidation; ENR50) recipes, and the curing and mechanical behaviors were studied. Mechanical testing of the ENR50/HD‐PUR vulcanizates determined the tensile, tear, compression‐set, hardness, abrasion, hysteresis, and resilience properties. No significant changes were observed in the tensile properties with the incorporation of HD‐PUR. The ENR50 compounds showed an increase in compression set with increasing HD‐PUR content. Rubbers cured by a semi‐efficient vulcanization system gave the best overall performance. A further improvement in curing and mechanical properties was achieved by the carbon black grade N330 being replaced with a more active grade (N375). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2265–2276, 2002     

环氧化天然橡胶内胎气密性和实用性的研究

采用与ＩＲ内胎、ＮＲ内胎平行对比的方法研究了静态及装车使用条件下环氧化天然橡胶（ＥＮＲ）内胎的保压性，测试了三种橡胶内胎及胶料试样对空气的透过率。数据表明，ＥＮＲ内胎的气密性与ＩＲ内胎的气密性相近，远优于ＮＲ内胎的气密性。ＥＮＲ内胎使用性能良好，冬季在北纬４６°森林山区使用未发现不耐低温问题。３年５个月库存后外观完好，物理机械性能无明显变化     

The effect of di-2-ethylhexyl phthalate on the thermo-oxidative ageing of poly(vinyl chloride)/epoxidized natural rubber blends

The effect of di-2-ethylhexyl phthalate (DOP) plasticizer on the degradation behaviour of 50/50 poly(vinyl chloride)/epoxidized natural rubber (PVC/ENR) blend was studied by long-term exposure to ambient conditions (27–30°C) in the laboratory. While the unplasticized blend showed obvious changes in physical properties such as hardening, loss of elasticity and embrittlement, the plasticized blend retained its properties. Thermo-oxidative ageing studies were carried out by evaluating the mechanical properties before and after ageing in an air oven at 80°C for 168 h. The relatively rapid degradation of PVC/ENR blend has been attributed to the high concentration of epoxy groups and the occurrence of ring-opening reactions to form ether crosslinks. It was found that the plasticizer confers adequate stabilization upon the addition of a certain threshold amount. The optimum amount of plasticizer required to adequately stabilize the blend is 20 phr. Above this there is a tendency for plasticizer migration to occur. The use of an antioxidant in conjunction with the plasticizer further stabilizes the blend. The general trend is of decrease in mechanical and physical properties with increase in DOP concentration. In addition, ease of processing also increases as indicated by the torque maxima and minima obtained from the Brabender plastograms.     

NR/NBR/环氧化天然橡胶共混物的动态力学性能

研究了对叔丁基酚醛树脂用量对NR／NBR／环氧化天然橡胶（ENR）共混物动态力学性能的影响。加对叔丁基酚醛树酯的NR／NBR／ENR共混物有2个动态力学损耗峰（分别对应共混物的玻璃化转变温度Tg1和Tg2）。随着对叔丁基酚醛树脂用量（0－15份）增大,共混物的Tg1基本不变,Tg2则逐渐升高;温度为Tg1的共混物损耗因子（tanδ）峰值化不大,温度为Tg2的共混物tanδ峰值则逐渐增大。通过调节对叔丁基酚醛树脂用量可以改变共混物在0和65℃附近的tanδ值,从而获得抗湿滑性能好、滚动损失小的新型胎面材料。     

EPDM/ENR共混胶力学性能的研究

探讨了三元乙丙橡胶(EPDM)和环氧化天然橡胶(ENR)的共混比、加料顺序、硫化体系对EPDM/ENR共混物的硫化特性、力学性能和耐热空气老化性能的影响。结果表明,共混比不同,共混胶的性能均有差异,且共混物的力学性能低于单组分的线性加和值,但综合比较而言,当EPDM/ENR=40/60时共混胶的力学性能较好;在所研究的四种加料顺序中,以配合剂先与EPDM制成母炼胶后再与ENR共混的这一种加料顺序下所得的共混物硫化胶的力学性能最好;采用半有效硫化体系所制得的共混物硫化胶的力学性能较好。     

解读2013 年度ENR 国际承包商250 强

2013 年度美国《工程新闻记录》评选的国际承包商榜单从225 强增加到250 强,在这一变化之下,对新的国际承包商250 强的情况进行了分析。从进榜企业的规模、效益、业务领域、行业及地区分布等方面对ENR 国际承包商250 强2012年的表现进行了统计分析。特别关注了2012 年国际承包市场上竞争热点地区和发展趋势。入围国际承包商250 强的中国内地企业被作为分析的重点,同时也追踪了近5 年ENR 国际承包商10 强的变动情况及市场和行业分布。对近5 年中国内地企业在榜单上的表现进行了纵向比较。通过深入分析2013 年度国际承包商250 强榜单,全面解读国际承包市场的变革和发展,为中国内地企业了解海外市场格局,拓展国际承包业务提供数据分析基础。     

基于ENR数据分析的中国大型设计院发展趋势

中国勘察设计行业正面临着全球化、中国经济结构转型和国家实施“走出去”的开放战略等诸多机遇与挑战,所以对未来发展有一个相对准确的分析和预测有着很重要的意义.本文通过对近七年来ENR 发布数据的分析,找到了世界大型设计公司与国际化之间存在的一些联系,然后通过对不同国家和地区设计公司之间的比较,结合各自的国情和经济发展水平,给出了未来中国大型设计院可能的发展趋势预测,即中国大型设计院依靠巨大的国内市场,在体量上会很快跻身世界大型设计院的“第一梯队”,但与西方竞争对手相比,在国际市场仍然存在相当大的差距,如果不能尽快建立完善的全球网络和平台,中国大型设计院有可能止步于海外中高端市场.     

2011年ENR国际蓄包商225强解析

美国《工程新闻纪录》（ENR）根据2010年国际承包商的营业收入,得到了2011年国际承包商225强和全球承包商225强的排名情况。本文介绍了2010年国际承包市场发展概况．并进行历史的纵向对比以及区域间的横向对比分析。中国大陆共有51家企业进入国际承包商225强,比上年减少3家．营业额增长了13．0％。中国建筑企业的海外承包市场仍局限于亚、非和中东市场,核心竞争力仍需进一步提升。     

Melt compounded epoxidized natural rubber/layered silicate nanocomposites: structure-properties relationships

Epoxidized natural rubber (ENR)-layered silicate composites were produced by melt compounding and sulfur curing. Pristine (sodium bentonite and sodium fluorohectorite) and organophilic modified silicates (organoclays with primary amine and quaternary ammonium modifications) were introduced in 10 parts per hundred rubber (phr) in the recipes and their effect on the curing and (thermo)mechanical properties determined. The dispersion state of the silicates was studied by X-ray diffraction and transmission electron microscopy. Fastest curing and best mechanical properties were found for the ENR containing the organoclay with primary amine modification. This organoclay was partly exfoliated, partly intercalated and partly confined (reaggregated). Due to the high shearing during compounding the pristine fluorohectorite was also intercalated by ENR. The complex dispersion state of the layered silicates was well reflected in the glass transition relaxation, which showed multiple peaks. Intercalation/exfoliation of the silicates were best displayed in stiffness- and strength-related mechanical parameters.     

2006年度国际市场最大225家承包商市场分析

介绍了美国《工程新闻纪录》周刊所做的2006年度国际市场225家最大承包商的排名情况,并对这一排名进行了分析和对比。2006年度225强国际承包商的国际市场营业额从2005年的1894亿美元上升到2006年的2244亿美元,上升幅度18.5%,进入225强的中国承包商有49家,营业总额比2005年增长61.8%,显示了中国承包商发展的良好势头。