铁铝酸盐水泥专用速凝剂的研究

本文通过试验较全面地研究了各种速凝剂对铁铝酸盐水泥的适应性,结果表明,仅JA速凝剂具有明显的促凝效果。在此基础上,又研究了不同水灰比条件下,JA速凝剂对铁铝酸盐水泥凝结时间的影响情况,同时探索了该速凝剂对铁铝酸盐水泥强度的影响规律。     

无碱液体速凝剂与水泥的适应性及水化促凝机理分析

通过微、宏观测试分析,研究了无碱液体速凝剂与水泥基材料的适应性及其水化促凝机理.结果表明:自制无碱液体速凝剂对实验中的三种水泥初凝时间均小于3 min 31 s,终凝时间均小于7min 35 s表现出良好的适应性,与聚羧酸超塑化剂或萘系超塑化剂复掺时,降低水灰比至0.32时,水泥凝结时间均可达到JC477-2005要求;通过XRD、TG/DTA与SEM分析微观结构得出,速凝剂对1～28 d的水化产物的类型基本没有影响.在掺入速凝剂的水泥-速凝剂-水体系中,速凝剂的主要成分硫酸铝与CH生成微细针柱状AFt,其主要是通过液相反应-沉淀过程形成.结晶水化产物的生长、发展,在水泥颗粒间交叉连续生成网络型结构,而加速凝结;水泥水化早期生成的CH被速凝剂消耗,且形成钙矾石加速了硅酸二钙(C2S)、硅酸三钙(C3S)的水化进程,使水泥快速凝结硬化.     

低碱液体速凝剂的制备及性能研究

采用硫酸铝、氟化钠、三乙醇胺、尿素和水在70℃制备了一种低碱液体速凝剂,系统探究了该低碱速凝剂各组分对凝结时间的影响,筛选出最佳制备工艺参数,并研究了其对基准水泥凝结时间和胶砂抗压强度的影响。结果表明:最佳配比为:硫酸铝、氟化钠、三乙醇胺、尿素、水所占质量百分比分别为57%、11%、2%、1%、29%;当速凝剂掺量为6%时,可使基准水泥的初凝时间缩短至1min 55 s,终凝时间2min 52 s,水泥胶砂1 d抗压强度为7. 04 MPa,28 d强度保留率为118%。该低碱液体速凝剂具有较好的速凝效果。     

喷射混凝土用新型液体无碱速凝剂的制备及性能研究

试验以二乙醇胺、磷酸和浓硫酸合成二乙醇胺磷酸酯添加剂,同时结合硫酸铝、氟硅酸镁、偏铝酸钠、二乙醇胺和水为原料,在65℃条件下合成了一种新型硫酸铝/偏铝酸钠液体无碱速凝剂。通过对基准水泥净浆初、终凝时间的测定及水泥胶砂抗压强度的测量,系统研究了该新型液体无碱速凝剂不同成分组成对混凝土凝结时间及抗压强度的影响。结果表明当水、硫酸铝、偏铝酸钠、二乙醇胺、氟硅酸镁、二乙醇胺磷酸酯所占质量百分比分别为32.8%、55.9%、2.4%、2.1%、5.5%、1.3%时,速凝剂的效果最好,且当速凝剂掺量为6%时,可使基准水泥的初凝时间不超过1 min 20 s,终凝时间不超过3 min 31 s;水泥胶砂1 d抗压强度为7.5 MPa,28 d为42.9 MPa,28 d保留率达到118%,达到一等品要求。     

用钢渣改善磷渣硅酸盐水泥性能的试验研究

研究了在磷渣硅酸盐水泥中掺加少量的钢渣对该水泥性能的影响。结果表明,添加不超过6%的钢渣后,磷渣水泥的抗压强度降低约10%,而水泥初凝时间和终凝时间分别减少了117min和62min以上;当采用钢渣、磷渣加小于3%水共同混合和混磨两种处理方式,水泥初凝时间和终凝时间可继续缩短95min和150min以上,并以混磨方式缩短凝结时间更明显,初凝时间和终凝时间最多分别缩短186min和209min。同时采用陈化处理,可大幅提高该水泥的早期强度,并随陈化时间的延长而增加,而水泥凝结时间则较未陈化时约增加20～40min。     

增强型无碱液体速凝剂的制备及其性能研究

采用超声加热技术,以无机物和有机物为主要原料制备了一种喷射混凝土用增强型无碱液体速凝剂(HSA)。研究了水泥凝结时间、砂浆及混凝土力学性能和耐久性能进行了研究,并通过孔结构分析研究了其促凝机理。试验结果表明,SA掺量为5%时,所制备的无碱液体速凝剂初凝时间小于4 min,终凝时间小于8 min,混凝土1 d抗压强度比可提高193.3%,28 d抗压强度比可提高118.5%。     

一种新型无碱液态速凝剂的研究

试验采用硫酸铝(Al2(SO4)3)、多聚磷酸钠(STPP)、乙二胺四乙酸二钠(EDTA)、二乙醇胺(DEA)和甘油(GL)等药品,通过有机-无机复合的方法合成了一种硫酸铝型无碱液体速凝剂,并研究了其对水泥凝结时间和胶砂抗压强度的影响,此外,还通过综合热分析等微观检测手段研究了掺加速凝剂之后水泥的水化过程.结果表明:当速凝剂掺量为8％时,可使基准水泥的初凝时间缩短至2 min 40 s,终凝时间6 min 20 s;1d抗压强度达到16.16MPa,28 d抗压强度保留率为109.9％;速凝剂能有效地加快水泥水化,但对水化产物的类型基本没有影响;水泥在短时间内能够迅速凝结的主要原因是速凝剂对于初始水化期的促进作用;而提高胶砂抗压强度的主要原因是速凝剂缩短了水泥水化的诱导期,使水化加速期被提前.     

SL型液体低碱混凝土速凝剂的研究

本文介绍了一种低碱液体混凝土速凝剂，可用于喷射混凝土的湿喷工艺施工。作者对速凝剂的促凝效果、掺速凝剂的水泥浆体的强度发展以及该速凝剂对不同水泥的适应性进行了研究，并研究了温度变化对该速凝剂的促凝效果的影响。     

不同碱度液体速凝剂的高低温适应性及促凝机理

研究了偏铝酸钠、硅酸钠、硫酸铝3种典型液体速凝剂常用组分在高低温下对水泥浆的促凝规律、温度敏感性及其对水泥水化的影响机理。结果表明:铝酸钠和硫酸铝掺量为3%,硅酸钠速凝剂掺量为5%时可满足JC477—2005的初凝时间≤5 min、终凝时间≤12 min的要求;硅酸钠速凝剂的促凝性能受温度的影响较大;两类碱性的速凝剂(偏铝酸钠和硅酸钠)能够有效提高砂浆块的早期抗压强度,而硫酸铝对早期强度的影响较小;偏铝酸钠对28 d抗压强度的不利影响较大,其它两类速凝剂对28 d抗压强度的影响较小;偏铝酸钠速凝剂通过消耗石膏,生成铝相水化产物来促进凝结;硫酸铝通过形成大量钙矾石晶体搭接使水泥浆体失去流动性;硅酸钠通过消耗石膏和生成早期水化硅酸钙达到速凝效果。     

有碱无碱液体速凝剂双掺性能的研究

研究了有碱无碱液体速凝剂双掺的作用效果。测试了有碱无碱液体速凝剂双掺时水泥的凝结时间、水泥胶砂的1 d抗压强度、28 d抗压强度比和90 d抗压强度保留值。试验结果表明,有碱无碱液体速凝剂双掺时具有良好的速凝效果。有碱无碱液体速凝剂按照5∶5的质量比双掺时,在掺量5%的条件下,能够满足水泥的初凝时间5 min、终凝时间12 min;水泥砂浆的1 d抗压强度7.0 MPa,28 d抗压强度比90%,90 d抗压强度保留值100%。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.