固井水泥石增韧材料的研究进展

固井水泥石这类脆性材料在井下复杂应力环境下易破坏,导致其封固能力下降.增韧材料可增韧降脆水泥石;水泥石完整性评价方法可用于指导增韧材料研发.本文全面介绍了晶须/纤维、纳米材料、胶乳和颗粒等固井水泥石增韧材料及内源增韧的国内外研究成果,分析了各类增韧材料的特点及发展趋势;本文阐述了增韧力学指标存在的问题,并综述了目前固井领域的水泥石完整性评价方法.通过全面总结固井水泥石增韧材料的研究进展,就增韧材料的发展方向提出建议.随着油气勘探向深部、低渗透、海洋和非常规领域的延伸,水泥石韧性要求越来越高,水泥石增韧材料及技术将会有更加广阔的应用前景.     

微细橡胶粉对油井水泥基复合材料性能的影响

为降低固井水泥石脆性,保持固井水泥环的完整性,解决油气井开采安全隐患.本文将微细橡胶粉添加到水泥基复合材料中.通过抗压强度和抗折强度变化规律,考察橡胶粉的最优掺量;通过三轴力学测试、渗透性实验,考察橡胶粉对水泥石复合材料变形能力的影响和抗渗性能影响;通过比表面积、粒度分布和微观形貌,表征橡胶粉特性,并对水泥石进行微观形貌分析,探讨其增韧降脆机理.结果发现,最优掺量为0.5％,在此掺量时水泥石弹性模量降低34.3％,孔隙度变小,抗渗性能提高,既能增强水泥石的塑性和弹性变形能力又使水泥石结构更为致密;橡胶粉比表面积0.4187 m2/g,平均粒度64.4865μm,与水泥石基体接触面积大;微细橡胶粉与水泥石基体粘结紧密,能吸收大量能量、填充水泥石孔隙,有效降低水泥石脆性.     

动态冲击下纤维素固井水泥石力学性能及增韧机理研究

为研究动载荷下纤维素固井水泥石抗冲击性能及内部纤维素增韧机理,采用杆径50 mm的霍普金森杆(SHPB)对不同纤维素加量的油井水泥石进行动态加载,并利用高速摄影仪记录破裂形貌.通过动载荷下的应力-应变、韧性及总能量吸收图等研究纤维素固井水泥石的力学性能.利于扫描电镜SEM研究纤维素的微观增韧机理及纤维素对水泥基材料的增韧作用.结果 表明,动载荷下,纤维素水泥石的强度、韧性及能量吸收能力在加量0.3％时最高.纤维素水泥石表面裂纹量少且曲折度并不明显,破裂程度较轻.纤维素的增韧机理为拔出机制、裂纹偏转,弯曲机制由于冲击速度太快,基体变硬而被抑制.     

水泥石吸水吸油体积变形性能及其机理

研究了聚合物乳液改性水泥石的吸水、吸油规律及其吸水、吸油后的线性膨胀性能,并基于实验结果建立了轴向膨胀应变与饱和体积吸水、吸油率的相关关系。吸水、吸油性能测试结果发现:空白水泥石饱和质量吸水率远大于其饱和吸油率,表明有大量孔径更细的毛细孔并不能被油侵入,这是由于油与水泥石较小的毛细作用导致。轴向膨胀应变测试结果显示,空白水泥石初期大量的吸水并不导致显著的体积膨胀,浸水后期较小的体积吸水率却导致明显的体积膨胀。聚合物改性水泥石的饱和质量吸水率与空白水泥石相当,但由于成膜聚合物对毛细孔的阻塞作用,明显降低了水泥石的质量吸水速率。同时,聚合物膜本身的吸油性导致聚合物改性水泥石的饱和质量吸油率略大于空白水泥石。由于聚合物对水泥石孔隙的细化作用,聚合物改性水泥石的吸水、吸油膨胀性均明显大于空白水泥石。采用吸水、吸油速率公式,通过实验测量水泥基材料的吸水、吸油速率系数,可定量评价水泥基材料的渗透性。所建立的水泥石吸水、吸油轴向线性膨胀率公式可用于实际工程中预测水泥石膨胀量的大小。     

稀土电解槽石墨内衬氧化腐蚀-应力损伤耦合本构模型

利用Weibull分布函数表征石墨内衬微元强度分布,对石墨内衬氧化腐蚀劣化的力学性质进行研究,建立石墨内衬单轴压缩下力学损伤本构关系。考虑石墨内衬氧化腐蚀作用下孔隙率变化,引入石墨内衬化学损伤变量,得到氧化腐蚀损伤本构关系。根据推广的lemaitre应变等效原理,综合考虑氧化腐蚀-应力损伤耦合作用影响,建立石墨内衬氧化腐蚀-应力损伤耦合本构模型。利用CT显微技术获取受到氧化腐蚀的试样孔隙结构演化图像,通过石墨内衬在不同氧化腐蚀时间下的单轴压缩实验得到应力-应变曲线,检验氧化腐蚀-应力损伤耦合本构模型的合理性。结果表明:模型预测曲线和实验结果基本吻合,能较客观地反映石墨内衬氧化腐蚀下损伤演化特性。     

荷载-冻融耦合作用下充填层自密实混凝土的耐久性及损伤模型

为掌握处于冻融服役环境条件下充填层自密实混凝土(SCC)的耐久性,设计了轴压荷载-冻融耦合作用模拟试验,对比研究了SCC在冻融循环作用、荷载-冻融循环耦合作用下的质量、峰值应力、峰值应变等参数随冻融循环次数的变化规律;结合统计损伤理论,建立了相应的损伤本构模型,讨论了损伤变量与冻融循环作用次数的变化关系。结果表明:相较于单一冻融作用,1/3应力水平的轴压荷载与冻融循环耦合作用下的充填层自密实混凝土劣化速率更大,此时难以抵抗300次冻融循环作用,掺适量聚丙烯纤维或橡胶粉可较好改善其在荷载-冻融循环耦合作用下的耐久性。所建立的损伤本构模型可较好地描述荷载-冻融耦合作用后混凝土应力-应变关系,其损伤变量与冻融次数具有良好相关性。     

基于最小耗能理论的混凝土力学本构模型研究

为了准确描述复杂应力下混凝土应力应变关系,通过对混凝土进行不同围压作用下三轴压缩试验,考虑轴、径向应力和球应力对轴向应变的影响,结合最小能耗原理建立一种混凝土损伤本构模型,得出:该模型对混凝土峰前应力应变变化趋势预测基本一致,而对于峰后变形虽有出入,但是总体上较好地描述混凝土峰后应力应变关系.最后,试验曲线与拟合曲线也具有较高的拟合度,说明了模型的正确性与合理性,也对实际工程具有指导意义.     

硫酸钠侵蚀对蒸养粉煤灰水泥石氯离子固化性能的影响

采用等温吸附平衡法,并借助X射线衍射仪,研究了硫酸钠腐蚀溶液对蒸养条件下不同静养时间水泥石中固化态氯离子稳定性的影响.结果表明:固化态氯离子在硫酸钠溶液腐蚀环境下易失去稳定性,重新转变成游离态;标准养护条件下水泥石固化氯离子能力以及水泥石中固化态氯离子耐硫酸盐腐蚀能力均高于蒸汽养护条件下;掺加粉煤灰会有效提高水泥石固化氯离子的能力,但对硫酸盐环境下水泥石中固化态氯离子的稳定性存在一定程度的负面影响;静养时间4h时,水泥石氯离子固化性能最优,静养时间6h时,水泥石中固化态氯离子的稳定性较好.     

纳米压痕研究碳纳米管固井水泥石微观力学性能

为更好探索碳纳米管增强固井水泥石力学性能的微观机理,采用纳米压痕技术对固井水泥石的微观力学性能进行研究.以空白固井水泥石和掺碳纳米管固井水泥石为研究对象.通过对压痕模量进行测试和统计分析,得到水化产物中毛细孔、低密度C-S-H、高密度C-S-H以及超高密度C-S-H的含量.结果表明:和空白水泥石相比,掺入碳纳米管的水泥石中孔隙含量更少,高密度C-S-H以及超高密度C-S-H的含量则更高.实验证明,碳纳米管的掺入能够加速水泥水化反应的进行,促进Ca(OH)2的结晶化,并最终提高水泥石的宏观力学性能.     

稠油热采条件下矿渣对磷铝酸盐水泥石耐高温性影响研究

针对硅酸盐水泥石经热力采油后耐高温性能急剧衰退的问题.采用具备更好耐高温特性的磷铝酸盐水泥,但是磷铝酸盐水泥高温后的抗压强度仍存在一定的衰退的问题,实验通过在磷铝酸盐水泥中掺入矿渣改善磷铝酸盐水泥石耐高温特性并采用XRD及SEM测试手段分析机理.结果表明:加入矿渣不仅有利于水泥石低温强度的发展,而且能够明显改善磷铝酸盐水泥石的耐高温特性;矿渣加入后C2ASH8的形成有利于水泥石低温下的强度发展,C3AS2 H2的形成有利于水泥石高温后的强度发展,同时,为提高水泥石的耐高温特性应尽量避免高温后C3 ASH4的生成.加入矿渣后的水泥石经高温养护后晶体结构发育良好,排列致密,从而使得水泥石具有良好的抗高温性能,进而有利于改善水泥环的完整性.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。