Influence of rubber composition on migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates composed of NR,SBR, and BR

Migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates with different rubber compositions of natural rubber (NR), styrene–butadiene rubber (SBR), and butadiene rubber (BR) were studied at constant temperatures of 40–100°C and outdoors. Three single rubber‐based vulcanizates, three biblends, and three triblends were used. N‐Phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD) and N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD) were employed as antiozonants. Migration rates of the antiozonants became faster with increasing the temperature. The order of the migration rates in the single rubber‐based vulcanizates was BR > NR > SBR. The migration rates in the vulcanizates containing SBR, on the whole, increased with decreasing the SBR content, while those in the vulcanizates containing BR decreased with decreasing the BR content. Difference in the migration behaviors of the antiozonants depending on the rubber composition was explained both by the intermolecular interactions of the antiozonants with the matrix and by interface formed between dissimilar rubbers in the blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 237–242, 2001     

Migration behaviors of antiozonants to the surface in NR vulcanizates,depending on the season: The effect of wax

Influence of wax film on the surface of a rubber vulcanizate on migration of antiozonants was studied using NR vulcanizates containing various types of waxes. The waxes have different molecular weight distributions. N‐phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD), N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD), N,N′‐di(sec‐butyl)‐p‐phenylenediamine (SBPPD), and N,N′‐di(1,4‐dimethylpentyl)‐p‐phenylenediamine (DMPPD) were used as antiozonants. Migration experiments were performed outdoors for two months in the summer, fall, and winter. The migration rates of the antiozonants in the vulcanizate without wax are faster than those in the vulcanizates with waxes. The antiozonants migrate slower in the vulcanizate containing wax with a high‐molecular‐weight distribution than in the vulcanizate with a low one. In the summer, the migration rates of SBPPD and DMPPD are faster than those of IPPD and HPPD, respectively. But, in the fall, the migration rates of SBPPD and DMPPD are slower than those of IPPD and HPPD, respectively. The differences of migration behaviors of the antiozonants, depending on season and wax type, was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1987–1993, 1999     

Investigation of temperature sensitivity behaviors of water soluble polyacrylamides

Temperature sensitive polymers with a lower critical solution temperature (LCST) are used in a variety of industries such as the pharmaceutical, cosmetic, food, and paint. These polymers are generally of the poly(N‐alkylacrylamide) type, of which poly(N‐isopropylacrylamide) (PNIPA) is the most commonly used. More novel poly(N‐alkylacrylamide)s have also been the subject of much attention recently. In this study, N‐alkylacrylamides containing different alkyl groups were synthesized by nucleophylic substitution reactions of various amines with acryloyl chloride. They were polymerized using the solution polymerization method, and the temperature sensitivities of the polymers were investigated. For this purpose, three monomers, N,N‐diethylacrylamide, N‐cyclopropylacrylamide, and 4‐piperidineethanolacrylamide, were synthesized using diethylamine, cyclopropylamine, and 4‐piperidineethanol, as the amines, respectively. The obtained polymers, poly(N,N‐diethylacrylamide) (PDEA), poly(N‐cyclopropylacrylamide) (PCPA), and poly(4‐piperidineethanolacrylamide) (PPEA), were found to be thermoresponsive, particularly PPEA is a potential novel material that can be utilized as an alternative to the common temperature sensitive polymers. The effects of several conditions on the LCST and the critical flocculation temperature (CFT) of the polymers were also investigated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

宾馆内空气中甲醛与温度的关系分析

按季度对室内甲醛进行监测,同步记录采样点温度。监测数据按季度进行统计分析,发现宾馆内甲醛释放浓度受温度影响显著(r=0.829),且二者年变化规律呈倒"V"型,峰值出现在第3季度;在一定的时间区间内,甲醛合格率年变化趋势呈正"V"型,第3季度甲醛合格率达到全年最低点,其与采样点温度之间呈极显著负相关(r=-0.941)。甲醛的释放具有很强的季节性,其释放周期应按年进行统计。     

单向温度梯度下异质液滴的热毛细迁移

石蜡油与去离子水按多种比例混合形成异质液滴,放置在金属基板表面,在外加不均匀温度场作用下进行热毛细迁移,采用高速摄像机记录温度梯度驱动液滴从高温区迁移至低温区过程中液滴的形态,建立了理论模型. 结果表明,异质液滴的接触角随温度升高而减小,润湿性增强;异质液滴的迁移速度随粘度增加而减小,随温度梯度增加而增加,不同粘度下的速度差随温度梯度增大而增大,迁移速度随时间增加迅速降低,后缓慢减小到趋于0. 推导了迁移速度与Marangoni数Ma的关系式并进行了实验验证,迁移速度随Ma增加而显著增加,Ma越大,实验结果与模拟结果的匹配程度越高.     

Preparation and photophysical behaviors of fluorescent chitosan bearing fluorescein: Potential biomaterial as temperature/pH probes

A novel method for attaching fluorescein (via its epoxy derivative) to water‐soluble chitosan, and the temperature/pH‐sensitive qualities of fluorescence were investigated. 3‐Epoxypropoxy fluorescein (EPF) was firstly synthesized by the reaction between fluorescein and epichlorohydrin, and then water‐soluble chitosan bearing fluorescein (CS‐EPF) was prepared via ring‐opening reaction with EPF. They were characterized by the methods of ¹H NMR, MS, IR, UV–Vis, and luminescence spectra, respectively. The chemiluminescent and photophysical behaviors of EPF and CS‐EPF were studied in detail. The results showed that the fluorescent chitosan could still provide temperature and pH sensitivities similar to that of fluo‐ rescein, achieving better long‐term stability and fast equilibrium response. CS‐EPF had an excellent linear response between relative fluorescence intensity and temperature in the range of 0–60°C and two linear relationships between relative fluorescence intensity and pH in 0.0–4.14 and 8.15–13.20, respectively. This investigation may provide a convenient way to prepare low‐cost and multifunctional macromolecule biomaterial to probe pH and temperature in biological systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3960–3966, 2007     

Correlation of bitumen viscosity with temperature and pressure

A previous viscosity-temperature correlation (Puttagunta et al., 1992) is extended to include a pressure term and employed successfully in predicting the combined effect of temperature and pressure on the viscosity of Canadian bitumens and heavy oils. Predictions are made on new sets of data based on a single measurement of viscosity at 30°C and 101.3 kPa pressure; and the results show similar accuracy as obtained in the sets of data used in developing the correlation. The correlation yields an absolute average deviation between predicted and experimental viscosity of 4.79% and a correlation coefficient of 0.99 over a range of temperatures between 20 and 120°C and gauge pressures between 0 and 18 MPa.     

Testing Non‐Correlation and Non‐Causality between Multivariate ARMA Time Series

Abstract. Haugh [Journal of the American Statistical Association (1976) Vol. 71, pp. 378–85] developed an approach to the problem of testing non‐correlation (at all leads and lags) between two univariate time series. Haugh's tests however have low power against two series which are related over a long distributed lag when individual lag coefficients are relatively small. As a remedy, Koch and Yang [Journal of the American Statistical Association (1986) Vol. 8, pp. 533–44] proposed an alternative method that performs better than Haugh's under such dependencies. A multivariate extension of Haugh's procedure was proposed by El Himdi and Roy [The Canadian Journal of Statistics (1997) Vol. 25, pp. 233–56], but suffers the same weaknesses as the original univariate method. We develop here an asymptotic test generalizing Koch and Yang's method to the multivariate case. Our method includes El Himdi and Roy's as a special case. Based on the same idea, we also suggest a generalization of the El Himdi and Roy procedure for testing causality in the sense of Granger [Econometrica (1969) Vol. 37, pp. 424–38] between two multivariate series. A Monte Carlo study is conducted, which indicates that our approach performs better than El Himdi and Roy's for a wide range of models. Both procedures are applied to the problem of testing the absence of correlation between Canadian and US economic indicators, and to a brief study of causality between money and income in Canada.     

化合物的结构与颜色

颜色是物质的重要物理性质,化合物显色与很多因素有关。主要从外界温度、物质聚集状态、电子跃迁、离子极化等多个角度对化合物颜色变化的因素进行阐述和分析。     

蓄顶温度与火道温度关系模型辨识新方法

针对焦炉火道温度与蓄顶温度关系模型的辨识问题,提出了一种基于区间预估最小二乘法的模型辨识方法.此方法可以有效消除煤气交换给火道温度和蓄顶温度带来的趋势不同的影响.使用置信区间的预计算,能够避免辨识数据紧凑带来的拟合数据准确而物理意义不准确的问题.     

大气污染物与降水中酸性离子相关性研究

对二氧化硫(SO2)、二氧化氮(NO2)以及降水中的典型酸性离子浓度进行连续监测,分析了大气SO2、NO2与降雨中SO2-4、NO-3离子之间的相关性。石嘴山市五年期间SO2排放量略有降低,NO2排放量逐年增加。大气中SO2及NO2分别在2009年及2010年达到最大值,为0.08 mg·m-3及0.04 mg·m-3;SO2-4/NO-3比例逐年下降,由2007年的19.74降低至2012年的3.28;石嘴山市近年来降水类型的转变一方面原因是在SO2减排背景下的NO2大幅增加,另一方面是大气中氧化水平的不断升高,使NO2氧化率大幅增加。     

污水紫外吸光度与COD相关性的研究

紫外分光光度法测定水质COD是利用有机物吸收紫外线的特征来测量水中的有机物浓度。与传统COD监测方法相比,它是一种不用化学试剂、对样品无须加热消解、快速、简洁、无二次污染的绿色监测技术。本文通过研究生活污水和工业废水样品的紫外吸光度与化学需氧量之间的相关性,得出在水质稳定的条件下,可利用测定的紫外吸光度值推算出化学需氧量的结果。     

胆汁酸溶解度的测定与数据关联

在胆汁酸结晶过程中,温度对胆汁酸在不同有机溶剂中溶解度的影响至关重要。采用平衡法结合HPLC法测定303.15~353.15 K胆酸、鹅去氧胆酸、熊去氧胆酸在5种有机溶剂中的溶解度,分别采用多项式经验方程和理想溶液方程对实验数据进行关联。结果表明,胆酸、鹅去氧胆酸、熊去氧胆酸在不同有机溶剂中的溶解度均随温度升高而增加,这两种方程均能较好地关联溶解度实验数据,其中多项式经验方程关联的相关系数均在0.98以上。     

Atomic-scale mechanical behaviors of polycrystalline graphene under biaxial loadings and high temperature

Graphene is widely utilized due to its excellent properties. Nevertheless, the failure mechanism previously acquired by uniaxial tension needs to be optimized urgently as its service conditions become more and more demanding. Here, the mechanical behaviors of polycrystalline graphene under tensile-shear biaxial strains and high temperature were investigated by molecular dynamics simulations. We proved that the shear strain dominated the failure of polycrystalline graphene when tensile and shear loading were applied simultaneously. As the temperature rises, the structural destruction of polycrystalline graphene changes from stress-dominated to temperature-dominated. Moreover, the ultimate shear stress increases with the increase of grain size, while the ultimate strain is the opposite. The polycrystalline graphene with a large grain size has better high temperature resistance. These results extend our understanding of the mechanical properties of polycrystalline graphene and guide the design of devices composed of 2D materials under extreme conditions.     

Durability of nano ZnO antibacterial cotton fabric to sweat

In this article, an innovative method was put forward to evaluate the endurance of nano ZnO finished fabrics to sweat. The atomic absorption spectrophotometer was used to determine the concentration of zinc in immersion liquor, and at the same time, SEM experiments and biocidal tests were chosen to characterize the antibacterial performance. Half‐life time (t_1/2) of zinc concentration on the fabric was introduced to evaluate the durability to sweat. The results indicated that nano ZnO antibacterial cotton fabric was relatively sensitive to acid artificial sweat while durable in saline or alkaline solution, the t_1/2 exceeded 3000 min in them. SEM characterization and biocidal tests showed the same behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:412–416, 2007     

关于COD_(Mn)两种方法的相关性研究

长江入海口受咸淡水影响,盐度变化较大。分别通过高锰酸盐指数法和碱式高锰酸钾法对长江口不同盐度水样的CODMn进行测定,并对两种方法进行比对校正。结果表明,两组数据具有明显的正相关关系;经实际数据检验以及测量值和拟合值之间的统计检验分析得出:两组数据之间没有显著差异,两种方法显著相关。为长江口水体CODMn的监测提供了数据支撑,以解决海上和陆地COD监测之间的数据衔接问题。     

循环流化床中烟气飞灰汞迁移规律

在小型热态循环流化床试验台上进行褐煤、烟煤、无烟煤燃烧试验,研究3种典型煤的烟气气态汞和飞灰颗粒汞迁移规律。试验结果表明：褐煤、烟煤、无烟煤在燃烧过程中,炉膛温度、空截面风速、给煤量以及煤颗粒大小变化时,汞元素在烟气和飞灰之间的迁移规律相似;降低炉膛密相区温度和增大炉膛空截面风速可促进烟气气态总汞Hg^T（g）迁移到飞灰颗粒汞Hg（p）中,同时也促进烟气气态零价汞Hg⁰（g）向烟气气态二价汞Hg²⁺（g）和Hg（p）转化;增加给煤量,烟气气态总汞Hg^T（g）和烟气气态零价汞Hg⁰（g）减少,飞灰颗粒汞Hg（p）含量增加,并且影响Hg⁰（g）的转化;选择合适的煤颗粒粒度可以促进Hg⁰（g）的转化以及Hg^T（g）向Hg（p）迁移。随燃烧工况的变化,3种煤Hg^T（g）、Hg（p）和Hg⁰（g）含量变化趋势相似,但含量相差较大,Hg⁰（g）占Hg^T（g）的比例y值也不同,其中无烟煤的y值高于烟煤和褐煤的y值。     

煤焦油中含水量与密度之间的关联研究

以中煤九鑫焦化有限公司煤焦油为样品,探讨了不同温度下煤焦油水分与其密度之间的关联关系。结果表明,在不同温度下,含水质量分数4%焦油的密度随温度升高而不断降低;同一温度下,焦油密度随含水量升高而降低。实际生产中,可利用密度推算出一定温度下的焦油含水量,从而及时调整小氨水澄清槽焦油水分离以及焦油产品储槽自动控制水分脱除程度(≤4%),以减少脱水消耗蒸汽量。     

AF反应器运行参数的相关性研究

针对PTA废水特性,主要研究了AF反应器在稳定运行中一些参数的变化对处理效果的影响.根据这些参数之间的关系确立了AF反应器出水COD浓度与进水COD之间的关系,并根据连续性的数据归纳提出了其间的相关性方程,这有利于进一步研究PTA废水在污水处理装置上COD的去除关系,消除生化处理的人为因素,从而提高废水生化处理效果.     

Gelation behaviors of cellulose solution dissolved in aqueous NaOH/thiourea at low temperature

Cellulose was dissolved rapidly in 9.5 wt% NaOH/4.5 wt% thiourea aqueous solution pre-cooled to −5 °C, as a result of the formation of an inclusion complex (IC) associated with cellulose, NaOH and thiourea, which could bring cellulose to the aqueous system. To clarify the rheological behaviors of the system dissolved at low temperature, this cellulose solution was investigated by dynamic viscoelastic measurement. The shear storage modulus (G′) and loss modulus (G″) as a function of the angular frequency (ω), concentration (c), temperature (T) and weight-average molecular weight (M_w) were analyzed and discussed. The results revealed that gels could form in the cellulose solution at either high temperature or low temperature, or for longer time. Interestingly, 4 wt% cellulose solution having cellulose M_w of 12.0 × 10⁴ remained at liquid state for longer time (12 days) at the temperature ranging from 0 to 5 °C. The gels already formed at elevated temperature were irreversible, i.e., after cooling to lower temperature including the temperature of cellulose dissolution (−5 °C), they could not be dissolved to become liquid. The Arrhenius analysis of the temperature dependence of viscosity in the cellulose solution indicated that a high apparent activation energy (E_a) occurred at 0 to −5 °C, suggesting the relatively stable IC structure. However, the viscosity of the cellulose solution increased slowly with an increase in the temperature at 0-40 °C, leading to the negative E_a values. The results suggested that the cellulose solution in NaOH/thiourea system is complex to differ from normal polymer systems.