Starch, Poly(lactic acid), and Poly(vinyl alcohol) Blends

Research on biodegradable materials has been stimulated due to concern regarding the persistence of plastic wastes. Blending starch with poly(lactic acid) (PLA) is one of the most promising efforts because starch is an abundant and cheap biopolymer and PLA is biodegradable with good mechanical properties. Poly(vinyl alcohol) (PVOH) contains unhydrolytic residual groups of poly(vinyl acetate) and also has good compatibility with starch. It was added to a starch and PLA blend (50:50, w/w) to enhance compatibility and improve mechanical properties. PVOH (M_W 6,000) at 10%, 20%, 30%, 40%, 50% (by weight) based on the total weight of starch and PLA, and 30% PVOH at various molecular weights (M_W 6,000, 25,000, 78,000, and 125,000 dalton) were added to starch/PLA blends. PVOH interacted with starch. At proportions greater than 30%, PVOH form a continuous phase with starch. Tensile strength of the starch/PLA blends increased as PVOH concentration increased up to 40% and decreased as PVOH molecular weight increased. The increasing molecular weight of PVOH slightly affected water absorption, but increasing PVOH concentration to 40% or 50% increased water absorption. Effects of moisture content on the starch/PLA/PVOH blend also were explored. The blend containing gelatinized starch had higher tensile strength. However, gelatinized starch also resulted in increased water absorption.     

Lightweight Concrete Containing an Alkaline Resistant Starch-Based Aquagel

Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength.     

Leaching of styrene and other aromatic compounds in drinking water from PS bottles

Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene （PS） bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as ＂purge and trap＂ and analysed by gas chromatograph-mass spectrometer （GC/MS）. Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 μg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 μg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks.     

模糊事故树在分析氯乙烯单体槽爆炸风险中的应用

在对氯乙烯单体槽爆炸事故构建事故树的基础上,根据现场设备实际运行状况的统计及依据专家经验所提供的模糊信息,运用模糊事故树理论,引入L-R型模糊数,应用其尖态型隶属函数,对氯乙烯单体槽进行了模糊可靠性分析,求出了氯乙烯单体槽爆炸事故的模糊概率可能性分布;并利用结构重要度系数近似值法对其进行结构重要度分析,运用对事故树底部事件进行排序分级的加权结构重要度分析法,确立了影响系统的最主要因素,为系统安全分析提供了新的方法和途径。     

高分子量高纯度阳离子聚丙烯酰胺的合成

以丙烯酰胺与丙烯酰氧乙基三甲基氯化铵为单体,在复合引发剂的作用下,选择水溶液共聚法合成高分子量与高纯度阳离子型聚丙烯酰胺(CPAM)。实验表明,有机偶氮引发剂A用量0.5‰、氧化还原引发剂用量0.45‰、还原剂与氧化剂摩尔比2∶1、反应体系pH为4与反应时间5 h条件下,CPAM分子量为1 042万,且溶解性好。通过对聚合物残单含量影响因素添加剂用量、反应时间的研究,结果表明,添加剂EDTA和增溶剂D对残留AM含量影响小,而苯甲酸钠对聚合物残留AM的含量影响显著;延长反应时间至7 h,残单含量可降低至0.27%,CPAM的纯度高。通过与国内外3种同类型产品进行对比,结果表明,自制产品的分子量明显高于其他产品,且残单含量比国内产品降低了50%～75%。     

Compositional Limitations in Poly–3–Hydroxyalkanoates Produced by Pseudomonas oleovorans

It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.     

气相色谱法测定空气和废气中氯乙烯的改进

因填充柱装柱繁琐,柱效低,最低检出浓度高,不能判别无组织废气中氯乙烯的浓度是否达到《大气污染物综合排放标准》（GB16297—1996）排放限值的要求;用毛细管柱能满足分析的要求。     

二甲基二烯丙基氯化铵的合成

为制备聚二甲基二烯丙基氯化铵絮凝剂,采用二步法制备了二甲基二烯丙基氯化铵单体,即在强碱性条件下由烯丙基氯和二甲胺反应先生成二收藏 －烯丙基叔胺,将该叔胺分离出来并再次加入烯丙基氯同会２丙介质中结晶析出委胺晶体。     

丁二烯装置中乙烯基乙炔危险性研究

根据丁二烯装置中高级炔烃的特点和危险性,通过爆炸极限测定仪和爆轰管研究并确定了温度对乙烯基乙炔爆炸极限的影响,确定了不同温度下乙烯基乙炔的安全分压,确定了氮气稀释对乙烯基乙炔安全分压的影响,掌握了乙烯基乙炔的燃爆特性和分解特性。研究表明:乙烯基乙炔易发生分解失控或气相燃爆,且发生分解失控时后果严重。为了确保丁二烯装置中乙烯基乙炔的安全使用,建议在低温和低分压下使用乙烯基乙炔。     

PVC/PES相容性及对共混超滤膜性能的影响

研究了聚氯乙烯(PVC)与聚醚砜(PES)共混体系相容性及其对共混膜性能的影响。利用溶解度参数原则和混合热焓原则进行理论预测,用铸膜液粘度法进行实验表征,均说明该体系为部分相容体系,且其相容性与组成及共混温度有关。通过对共混膜传质特性的考察,表明铸膜液的相容性会明显影响共混膜的性能;采用共混法可以改善膜性能。