热稳定剂在PVC化学建材中对比研究

聚氯乙烯(PVC)自1872年面世以来,广受世人瞩目,但因其稳定性差,受热超过100℃就会脱氯化氢反应,产生的氯化氢对PVC的热降解又有催化作用,使其色泽加厚,强度下降,导致加工及应用的困难。随着PVC专用稳定剂的逐渐开发,PVC目前已成为产量最大、用途最广的塑料品种之一。本文着重研讨一下热稳定剂在PVC异型制品中的稳定机理、性能对比及其发展方向。1 稳定机理1.1中和氯化氢 如弱有机酸的碱金属或碱土金属盐类,无机盐     

PVC复合稀土热稳定体系加工与应用性能

研究不同稳定体系对聚氯乙烯(PVC)的加工流变行为、力学性能和维卡软化点的影响,通过对比,评价复合稀土稳定剂的综合性能结果表明,复合稀土稳定体系具有良好的综合加工性能,大大改善PVC材料的力学性能.扫描电镜及红外光谱分析证实,稀土热稳定剂具有偶联增韧作用;热分析结果表明,PVC-HREC(稀土稳定剂)体系在氮气中的热降解反应较为简单,为一步反应,通过外推得到其起始降解温度和终止降解温度分别为264.82,325.47 ℃.     

聚氯乙烯/蒙脱土复合材料的动态热降解动力学

采用热重分析仪研究了聚氯乙烯(PVC)／蒙脱土复合材料的热降解过程，比较了钠基蒙脱土(MMT)和烷基季铵盐改性的有机蒙脱土(OMMT)对PVC热稳定性和PVC热降解过程的影响．采用Friedman法研究了PVC和PVC／MMT(OMMT)复合材料的热降解动力学，并计算得到其表观活化能Ea．结果表明，在PVC热降解第一阶段，MMT和OMMT均能提高PVC的热分解温度和减少质量损失，从而提高PVC的热稳定性；PVC和PVC／MMT(OMMT)复合材料的Ea基本相近；MMT和OMMT对PVC的热降解速度有影响，但并没有改变PVc热降解机理．     

聚氯乙烯稳定性的研究 Ⅴ硬脂酸钡和硬脂酸镉的稳定作用

硬脂酸皂在工业生产中早已被使采用为聚氯乙烯(PVC)的稳定剂,但其对聚氯乙烯的稳定作用却仍需进行深入研究。本文研究了聚氯乙烯加进硬脂酸钡和硬脂酸镉后的热稳定性,以及环氧豆油、亚磷酸三苯酯对钡、镉皂稳定剂的稳定作用的影响。结果表明:1.钡、镉皂会加速PVC的受热失HCl作用,同时吸收PVC分解产生的HCl;而皂类和HCl反应所生成的氯化物对PVC失HCl有催化作用。2.钡,镉皂共同使用有协同怍用。3.环氧豆油和亚磷酸三苯酯对钡、镉皂的稳定作用有增效作用。提出了硬脂酸皂对PVC的热稳定作用,不在于抑制或减慢PVC的分解HCl,而可能是和PVC反应破坏因失HCl而生成的共轭双键;这样一方面起了抑制变色作用,另一方面使发生在双键上的降解和交联反应受到减弱,从而延缓了PVC的性能的受热破环,提高了聚氯乙烯的热稳定性。     

PVC树脂热稳定性评价的检测分析

PVC树脂在加工和使用过程中,产生热降解释放出氯化氢,并因为多烯双键的生存和增多而使颜色加深。PVC热稳定性测试方法均是基于此原理设定的,如何提高PVC树脂的热稳定性满足用户的需求已成为众多聚氯乙烯生产企业竞相研究的课题和追求的目标,同时检测部门将此检测项目列为重点研究分析,主要有变色法、刚果红法、白度法、pH值法、电导法等,这里主要介绍静态稳定性刚果红法、老化白度法及双辊炼塑动态热稳定性。三种PVC树脂热稳定性评价的检测方法,分析了在测试过程中的检测细节。     

聚氯乙烯热稳定剂研究新进展

随着人们环保意识的逐渐加强,传统的聚氯乙烯(PVC)热稳定剂,如铅盐类稳定剂已受到了一定的使用限制,因此相应地研究和开发出了一系列新型的PVC热稳定剂,如稀土类、钙锌(Ca/Zn)复合类和有机类热稳定剂.它们几乎是无毒的或低毒的化合物.本文概述了PVC热降解机理,国内外新型热稳定剂的种类、特点及其发展趋势.     

N-正丁基马来酰胺酸镧对PVC热稳定性的研究

以正丁胺、顺丁烯二酸酐、氯化镧和氢氧化钠为原料,分步合成热稳定剂N-正丁基马来酰胺酸镧(LaX_3),采用傅里叶红外光谱表征其结构,并通过刚果红试验研究其对聚氯乙烯(PVC)热稳定性的影响,应用热重分析仪研究不同升温速率对PVC热解反应的影响,并根据Flynn-Wall-Ozawa(FWO)法进行动力学计算,得到PVC和PVC/LaX_3的热解活化能。结果表明:加入LaX_3后,PVC的热降解温度提高了32℃,热稳定时间提高了15 min,反应活化能增加了33.53 kJ/mol。LaX_3可以作为PVC的热稳定剂使用。     

金属氧化物对聚氯乙烯热降解性能的影响

研究了二氧化锰(MnO2)和氧化铁(Fe2O3)对聚氯乙烯(PVC)热降解和热氧化降解过程的影响。电导率测试得出：PVC在空气和氮气环境下热降解时，都表现出自诱导脱氯化氢反应特征，而MnO2一定程度上消除了PVC热降解时自加速反应特征，Fe2O3实质性地改变了氯化氢释放规律，随时间的推移，使氯化氢释放量缓慢线性增加。热失重法与差热分析量热法显示MnO2和Fe2O3均阻止了氯化氢挥发释放过程，且加速了PVC主链断裂与挥发过程。     

PVC热稳定性的测试及机理研究

介绍用刚果红试纸测试加入稀土热稳定剂的PVC的热稳定性能 ,并讨论了PVC的降解机理及稀土热稳定剂的作用机理     

PVC热稳定性的测试及机理研究

介绍用刚果红试纸测试加入稀土热稳定剂的PVC的热稳定性能，并讨论了PVC的降解机理及稀土热稳定剂的作用机理。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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