关于碱-集料反应的几个理论问题

本文详细评述了碱-集料反应的分类、膨胀机理、Ca(OH)_2的作用和混合材的抑制机理。认为所谓的碱-硅酸盐反应实质上很可能是传统的碱-硅酸反应。碱-硅酸反应主要是吸水引起膨胀。碱-碳酸盐反应是由原地化学反应和结晶压引起膨胀。目前比较一致的意见认为Ca(OH)_2对促进碱-集料反应起着重要作用。最后本文从水泥的碱度和界面化学反应的角度分析了混合材的抑制机理。     

硫酸盐侵蚀下钙矾石的形成和膨胀机理研究现状

钙矾石是水泥混凝土硫酸盐侵蚀过程中的重要产物之一,钙矾石的形成可能会引起混凝土膨胀、开裂,本文在讨论水泥混凝土中钙矾石的形成和形貌的基础上,从钙矾石的形成环境-反应机理-形貌-膨胀机理出发综述了不同反应机制下形成的钙矾石对应的膨胀性能及钙矾石型硫酸盐侵蚀的膨胀机理,最后对钙矾石型硫酸盐侵蚀现状进行了总结.     

高性能混凝土构件中碱硅酸反应与延迟性钙矾石形成共存破坏

针对短期服役4 a即开裂破坏的某混凝土构件,采用化学分析、X射线荧光分析、X射线衍射分析和热重分析检测了混凝土芯样浆体的化学和矿物组成,采用岩相法和扫描电镜/能谱分析观测了芯样的微观结构。结果表明:混凝土中部分细集料和少量粗集料发生了明显的碱硅酸反应;混凝土浆体-集料界面区存在大量不同形貌钙矾石异常富集生长,且在浆体-集料界面区发现相伴而生的碱硅酸凝胶和钙矾石产物。混凝土构件破坏是一较为典型的碱硅酸反应与延迟性钙矾石形成共存破坏案例。     

集料粒径与ASR膨胀关系及膨胀预测研究进展

综述了集料粒径与碱硅酸反应(ASR)膨胀关系的研究现状,指出了ASR膨胀研究存在的局限性,阐述了大粒径、多级配集料ASR膨胀规律研究的必要性.介绍了几种ASR膨胀机理及ASR膨胀预测模型,并指出基于碱硅酸反应活化能的测定预测ASR膨胀将可能成为今后研究的一个热点.     

钢渣水泥的耐久性研究

本文对钢渣水泥(SLC)的长期强度、硫酸盐侵蚀、碳酸盐侵蚀、海水侵蚀及碱-集料反应等性能进行了实验研究。研究结果表明:钢渣水泥比纯硅酸盐水泥后期强度高,耐磨性好,抗硫酸盐、碳酸盐和海水侵蚀能力强,碱-集料反应体积膨胀量小。此外,本文还研究了钢渣水泥的水化机理和孔结构性能。     

循环流化床锅炉炉内脱硫灰渣的水化特性研究

比较循环流化床(CFB)锅炉炉内脱硫灰渣与粉煤灰的性质的差异;分析炉内脱硫灰渣的水化胶凝特性,指出活性的Al2O3和活性的SiO2等无定形物质是CFB锅炉灰渣的活性来源,脱硫灰渣中大量存在的CaO和Ⅱ-CaSO4成分对火山灰活性起到了激发作用,使其具有更加明显的胶凝性质;认为CaO和Ⅱ-CaSO4是参与脱硫灰渣水化反应的主要物质,水化过程形成的钙矾石是引起水化产物膨胀的主要原因,水化后SO2-4的浓度对钙矾石的长期稳定性有着关键影响,而灰渣中的CaO对水化过程的体积膨胀则起到间接作用.     

LiOH抑制碱-硅酸反应膨胀及其应用研究

研究了沸石化珍珠岩混凝土在KOH,LiOH溶液中压蒸膨胀行为,通过扫描电镜和能量散射谱对产物的形貌和组成进行了分析,说明LiOH抑制碱-硅酸反应膨胀的机理主要是在集料周围形成了含锂盐的非膨胀性产物,含锂产物层的形成对活性集料起保护作用而阻止了碱的进一步侵蚀。研究了由碱-硅酸活性集料和碱-碳酸盐活性集料制成的混凝土在各种碱中的膨胀行为。结果表明：混凝土在相同摩尔浓度的碱中压蒸,在NaOH溶液中膨胀最大,在LiOH溶液中膨胀最小。在应用LiOH抑制碱-硅酸反应膨胀促进碱-碳酸盐反应膨胀的双重作用下,在Spratt细粒硅质灰岩中,少量的白云石在碱环境中可发生去白云石化作用而对膨胀有贡献,也即尽管Spratt灰岩中碱-硅酸反应是主要的,但也存在碱-碳酸盐反应。     

钙矾石形成机理的研究

采用液相离子浓度测定与固相物相分析的方法,分析了离子浓度变化规律与钙矾石形成的关系,考察了矿物种类与含量、石灰浓度、二不石膏掺量对钙矾石形成的影响。结果表明：钙矾石形成是由[AI(OH)6]^3-八面体,铝氧八面体与钙多面体交替排列成形钙铝多面柱与SO4^2-进入柱间沟槽3个过程串联形成,其中速率最慢的[AI(OH)6]^3-形成过程为钙矾石形成的控制步骤。形成钙矾石诸离子中,[AIO2^-]最低,是影响钙矾石形成速率的最活跃因素。     

碱对钙矾石结晶及溶解性能的影响

主要通过C3A-CaSO4.2H2O,在不同碱性溶液中钙矾石的形成、晶体形貌变化以及制备得到的纯钙矾石在不同碱性溶液中的溶解来研究碱对钙矾石结晶、溶解性能的影响,并采用XRD、SEM以及ICP等分析方法进行表征.研究结果表明,碱对钙矾石的形成有促进作用,还会影响钙矾石晶体形貌.钙矾石在不同碱性溶液中具有不一致溶特性,OH-对钙矾石中A l(OH)4-、Ca2 和SO42-溶出能力具有抑制作用.     

碱矿渣水泥砂浆的碱集料反应膨胀研究

通过测长试验,研究了三类碱矿渣水泥(AASC)砂浆的碱集料反应(AAR)引起的膨胀;分析了碱组分种类、碱质量分数、活性集料质量分数和矿渣种类等因素对AASC砂浆AAR膨胀率的影响.综合宏观和微观测试结果,探讨了碱矿渣混凝土的碱集料反应机理.结果表明,AASC系统出现危险性碱集料反应的可能性远低于普通水泥系统.     

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。