FRS-XRSA与SAXS研究硬弹性聚丙烯的结晶度、取向与超结构——Ⅰ.退火时间的影响

 硬弹性材料是近二十年发展起来的一种新型的、具有开发前景的高聚物材料,但目前只利用其多孔透气性而作人工肺等。为了开发这种硬弹性,人们对其加工-结构-物性之间的关系仍在进行着不懈的研究。本文利用FRS-XRSA与SAXS研究退火条件对HEPP结晶、取向与超结构的影响。FRS-XRSA是作者为研完择优取向聚合物结晶与取向而提出的一种理论分析。结果指出:当T_an取130℃,则获得稳定结构的t_an应大于40min。与前人工作不同之点是,HEPP纤维中的片晶不是伸展的,而是扭曲或双重取向的。当退火时间增加,扭曲的片晶逐渐伸展。从SAXS得到的长周期与从WAXD得到的结晶度与晶粒度指出,片晶是由两层晶粒砌成。     

FRS-XRSA与SAXS研究硬弹性聚丙烯的结晶度、取向与超结构——Ⅱ.退火温度的影响

本文是继应用WAXD与SAXS研究退火时间对HEPP结构影响后的第二部分工作,即退火温度的影响。结果指出:FRS-XRSA是研究择优取向聚合物结晶与取向的合理方法;HEPP的X_c~x与L_(kkl)随T_(an)存在着熔融-结晶-再熔融及趋于平稳的过程,当t_(an)=30min,T_(an)≥140℃是较佳结晶条件;与前人工作不同,HEPP中的片晶似呈扭曲状,且随T_(an)增加,扭曲片晶向伸展片晶转变,当T_(an)≥140℃,伸展取向渐趋稳定;SAXS结果指出,d随T_(an)线性增加,d_c在T_(an)从110°—120℃出现剧变增厚,d_0的变化与晶粒的熔融和片晶的增厚相对应,片晶层是由二层晶粒堆砌而成。T_(an)与t_(an)相比,两者对HEPP的结构都有明显的影响。     

FRS-XRSA与SAXS研究硬弹性聚丙烯的结晶度、取向与超结构——Ⅰ.退火时间的影响

硬弹性材料是近二十年发展起来的一种新型的、具有开发前景的高聚物材料,但目前只利用其多孔透气性而作人工肺等。为了开发这种硬弹性,人们对其加工-结构-物性之间的关系仍在进行着不懈的研究。本文利用FRS-XRSA与SAXS研究退火条件对HEPP结晶、取向与超结构的影响。FRS-XRSA是作者为研完择优取向聚合物结晶与取向而提出的一种理论分析。结果指出:当T_(an)取130℃,则获得稳定结构的t_(an)应大于40min。与前人工作不同之点是,HEPP纤维中的片晶不是伸展的,而是扭曲或双重取向的。当退火时间增加,扭曲的片晶逐渐伸展。从SAXS得到的长周期与从WAXD得到的结晶度与晶粒度指出,片晶是由两层晶粒砌成。     

热历史对聚醚醚酮及其碳纤维复合材料——Ⅱ.熔融行为的影响

 本文利用差示扫描量热仪(DSC)研究了聚醚醚酮(PEEK)和以PEEK为基体的碳纤维复合材料(APC-2)的热历史对它们熔融行为的影响。在200—315℃结晶并退火热处理后,试样的DSC曲线上出现了两个吸热峰。低温吸热峰(峰温T′_m)较小,并与结晶和退火温度(T_c与在不同T_c下生成的不完整晶体的熔融和重结晶过程有关,而T_m的出现则与完整晶体的熔融过程有关。实验结果表明,T′_m与T_c之间呈线性关系。按文献报道的方法,将T′_m与T_c的直线外推至与T′_m=T_c直线相交,其交点温度即为平衡熔点.结果表明,PEEK和APC-2试样的“平衡熔点”受不同热历史条件下生成晶体的完整程度的影响。当结晶并退火时间越长,求出的“平衡熔点”值越低,并与理论值接近。实验结果还表明,碳纤维表面具有促进PEEK树脂基体晶体完整化的作用,因而导致APC-2试样中PEEK树脂基体的熔点高于纯PEEK树脂。     

N-异丙基丙烯酰胺温度敏感性水凝胶相转变动力学研究及其应用

 研究指出表观二级动力学方程可以很好地描述N-异丙基丙烯酰胺水凝胶的溶胀和消溶胀动力学.即溶胀动力学方程为dR/dt=k₁(R_e-R)²,消溶胀动力学方程为-dR/dt=k_c(R-R_e)².把这种水凝胶用于分离高分子水溶液时可引入“单位溶张比分离循环的合理时耗”这样一个参量.它根据溶胀和消溶胀过程中的起始溶胀比、平衡溶胀比、表观溶胀动力学常数和表观消溶胀动力学常数求出.具体公式为△t₁(T_s,T_c)=2/[R_c(T_s)-R₀(T_s)]²k_s(T_s)+15/[R₀(T_c)- R_s(T_c)]²k_c(T_c)^1/2在理想情况下,分离过程的“总合理时耗”与△t_1成正比,比例系数为分离过程中的除水总量与干凝胶用量的比值,即△t_r=W_W/WG·△t₁.当根据二个动力学方程求得的总时耗计算值处于(0.9△t_r,1.1△t_r)范围内时,表明所选干凝胶用量和循环溶胀比区段均合适.     

聚对苯二甲酸乙二酯的熔融双峰与形态

非晶PET等温结晶后,用DSC、WAXD、SAXS、密度和透射电镜等方法,考察了结晶PET在升温过程中的结构变化,进一步证实了过程中发生部分熔融再结晶;同时形态也起了明显变化:片晶增厚,片晶侧向尺寸增大,由节瘤状晶粒堆砌部分地转变为典型的片晶堆砌,构成片晶的微晶尺寸增大,晶体趋于完善,折迭表面的规则折迭增加。这样,在等温结晶时生成的结构状态转变为更稳定的形态,因而相应地在DSC曲线上出现两个熔融峰。     

SAXS研究四臂聚氧化乙烯片晶的增厚

使用小角X光散射(SAXS)方法研究了每臂分子量为5000的四臂聚氧化乙烯在从熔点以上的温度淬火到室温后,在室温到熔点前的温度区域里片晶的增厚过程.采用一维相关函数分析方法分析了SAXS数据,获得了样品的长周期、线性结晶度、结晶层和无定形层厚度随温度的变化.按照这些参数在升温过程中的演变规律,确定了3个特征区域.Ⅰ区约在26~45℃内,存在着3种不同厚度的片晶,最厚的片晶层厚度为9.3 nm,线性结晶度、长周期、结晶层和无定形层厚度等参数基本不变,称为不变区.Ⅱ区约在45~52℃之间,这些参数都发生变化,SAXS的主峰分化为两个主要的峰,长周期、结晶层和无定形层厚度开始增加,但是,线性结晶度升高后又降低,称为转变区.Ⅲ区约在52~60℃之间,体系中只有单一厚度的片晶,其厚度不断增厚,到60℃结晶层厚度达15.8 nm,称为增厚区.从分子运动和片晶亚稳定本质分析,可以解释实验上观察到的3个区域发生变化的本质:在不变区里,主要的分子运动几乎被冻结,不可能发生可检测到的片晶结构变化.在转变区里,分子运动开始起作用,未结晶的分子开始结晶.同时,薄片晶会熔融,尔后又重新结晶.在增厚区里,线性结晶度和结晶层厚度增加,也意味着熔融-重结晶过程还在继续,直至达到这个样品可能形成的最厚片晶的熔点.实验观察到的熔融-重结晶过程的本质是聚合物片晶的亚稳态特性,稳定性低的薄片晶向稳定性高的厚片晶转变,即一个典型的奥斯瓦尔德熟化(Ostwald ripening).     

聚乙烯醇/聚乙烯基吡咯烷酮共混体系的结晶行为

用DSC、WAXD和SAXS研究了聚乙烯醇(PVAl)/聚乙烯基吡咯烷酮(PVP)共混体系的结晶行为.PVAl的结晶度随PVP含量增加而减少,并存在结晶度为零的组成(PVAl)的重量分数约为50％.与纯PVAl相比,共混物的温度区间T_m-T_g减小,表明PVP对PVAl的结晶起抑制作用.共混物中PVAl的结晶速度下降,具体表现为PVAl过冷区随PVP含量增加而扩大,动力学速度常数减小,球晶增长速度下降.纯PVAl和共混体系的等温结晶速率均遵循Avrami方程.退火样品的长周期、片晶厚度和过渡层厚度大于相同组成未退火样品.两者长周期随PVP含量增长加显著增大,片晶厚度增长次之,过渡层厚度变化不大.     

在高压CO_2中聚乙二醇-聚己内酯嵌段共聚物的结晶行为

通过广角X射线衍射(WAXD)和小角X射线散射(SAXS)方法研究了PEO-b-PCL在CO2中的结晶形貌和片晶厚度的变化,利用高压示差扫描量热仪(HP DSC)考察了压力对熔融和等温结晶过程的影响.结果表明,PEO-b-PCL的结晶度、片晶厚度、熔融温度均随压力的升高而减小,结晶结构变得不完善.在等温结晶过程中,结晶速率随压力的升高而下降,结晶过程处于成核控制区,Avrami指数n在3.7~4.7,表明晶体的生长方式为三维生长.     

关于超高分子量聚丙烯超拉伸膜的结构性能的研究——Ⅰ.拉伸取向过程的表征

 用超高分子量聚丙烯的对二甲苯溶液中冷却析出的结晶沉积压制成的结晶垫,经热拉伸制备了不同拉伸倍数的薄膜.与用低分子量聚丙烯制备的结晶垫或熔融结晶物不同,超高分子量聚丙烯的结晶垫显示出极高的拉伸变形性能,因而制得了高达69倍的拉伸样品.WAXD照片表明在未拉伸的结晶垫中,微晶的c轴沿结晶垫法线方向择优取向,但仅经2-4倍的拉伸,微晶即发生破裂,且产生的较小的折叠链微晶已转向沿拉伸轴方向取向;晶区取向因子在拉伸过程中迅速增加并在较低拉伸倍数下即接近于理想取向.但非晶区取向因子在整个拉伸领域中增加缓慢.随拉伸倍数的增大,晶粒尺寸D₁₁₀及D₀₄₀逐渐减小;而长周期L逐渐增加.这表明在高倍拉伸样品中存在着折叠链被从片晶中拉出并部分形成伸直链结晶的转变.     

SYNTHESIS AND REACTIONS OF SOME 2-THIENYL- AND 2-THENOYL-DERIVATIVES OF THIAZOLE AND THIADIAZOLINE AND THEIR SELENIUM ANALOGS

Abstract

2-(Thiocyanatoacetyl)thiophene 2 and its selenium analog 3 couple with diazotized anilines and yield 3-aryl-2-imino-5-(2-thenoyl)-2,3-dihydro-1,3,4-thiadiazoles 6 and 3-aryl-2-imino-5-(2-thenoyl)-2,3-dihydro-1,3,4-selenadiazoles 7 respectively. The reactions of both 6 and 7 with nitrous acid, acetic anhydride and benzoyl chloride are described. Azo coupling of 2-amino-4-(2-thienyl)thiazole 17 and its selenazole analog 18 with diazotized anilines yielded the arylazo derivatives 19 and 20 respectively. Reaction of the hydrazidoyl bromide 16 with potassium thiocyanate, potassium selenocyanate, thiourea and selenourea yields 6, 7, 19, and 20 respectively.     

聚壬酰胺的制备纺丝及结构与性能测定

9-氨基壬酸系从癸二酸经单酯化、氨化和Hofmann重排制得。该单体以10克规模在玻璃管中和以4公斤量在15升聚合釜中,于260℃聚合成聚壬酰胺。聚合物在288℃纺丝,120℃牵伸,得到尼龙-9纤维。测定了聚合物和纤维的结构和多种性能。     

PHOTOLYSIS AND RADIOLYSIS OF NITROMETHANE AND NITROETHANE

Abstract— Prolonged photolysis of nitromethane and nitroethane in liquid and vapour phases, with simultaneous photolysis of the nitrogen dioxide formed, was studied in the absence and presence of cupric oxide. A high-pressure quartz immersion lamp providing the full range of visible and u.v. spectrum, with a high output of radiation at 366 and 313 mμ, was employed as source of light. The products of photolysis were detected by microanalytical methods, infrared-absorption spectrum analysis and gas chromatography. Photolysis of liquid nitro-alkanes resulted in formation of many compounds; saturated hydrocarbons, and in the case of nitroethane, ethylene, were submitted to detailed examination. Photolysis in the vapour phase was carried out in a specially designed glass apparatus. The main products were nitrogen dioxide, aldehydes and polyaldehydes; hydrocarbons were not estimated.
Liquid nitromethane and nitroethane were also irradiated with γ-rays from a ⁶⁰Co source. The radiolysis products were similiar to those obtained on photolysis. The mechanism of photolytic decomposition of nitroalkanes is proposed and discussed.     

温度及pH敏感N-异丙基丙烯酰胺/β-环糊精水凝胶的合成与性能研究

用顺丁烯二酸酐 (MAH)对具有分子包结能力的 β 环糊精 (β CD)进行化学改性 ,合成出了丁烯二酸单酯化 β CD单体 (MAH β CD) .通过氧化还原自由基引发MAH β CD与N 异丙基丙烯酰胺 (NIPA)聚合 ,合成出含 β CD结构单元的新型水凝胶 .用核磁共振、红外光谱及元素分析对MAH β CD单体及共聚物的结构和组成进行了表征 .溶胀研究结果表明 ,该水凝胶具有较好的pH、温度及离子强度敏感性 ;并且水凝胶在较高羧基(—COOH)含量和弱碱环境中 ,仍能表现出明显的温敏性     

生物质热解、加氢热解及其与煤共热解的热重研究

在加压热天平上用非等温热重法进行生物质（锯末、稻壳）在Ｎ２气氛下的热解和加氢热解研究。考察了升温速率（５～２５℃／ｍｉｎ）和压力（０．１～７ＭＰａ）的影响，求取了热解动力学参数，并研究了生物质与煤在常压Ｎ２气下的共热解过程。研究结果表明：生物质在４００℃左右即完成热解反应，总失重率大于７０％（Ｗ％，ｄａｆ．），热解时仅一个峰位于３００℃左右；与煤热解行为相同，随升温速率及压力的升高，转化率下降，ＤＴＧ峰移向高温，但由于热解反应在较低温度下进行，氧气的存在对生物质热解ＴＧ和ＤＴＧ的影响远小于煤热解。证明生物质热解以其内部氢对自由基的饱和及分子重排反应为主。生物质热解可用一级反应动力学处理，主要热解阶段及表现活化能分别为：锯末，２６７～３１４℃，６９．６６ｋＪ／ｍｏｌ；稻壳，２８３～３１０℃，５３．４５ｋＪ／ｍｏｌ；生物质由于与煤的热分解温度相差很大，因而在其共热解过程中无协同作用。     

CHLOROPHYLL a AND CAROTENOID AGGREGATES AND ENERGY MIGRATION IN MONOLAYERS AND THIN FILMS

Abstract— The spectra of absorption, fluorescence and excitation of monolayers and thin films containing chlorophyll a together with a carotenoid (cis-β-carotene, trans-β-carotene, fucoxanthin, or zeaxanthin), were measured at — 196°C. The concentration ratios used, (Chl)/(Car), were 6:1, 4:1, 3:1, 2:1, 1:1 and 1:3, and the area densities, 3·70, 2·55, 1·76, 0·71, 0·37 and 0·17 nm²/pigment molecule. In dilute monolayers, (3·70 nm²/molecule), with a constant concentration ratio (Chl)/(Car) = 3:1, evidence of three β-carotene forms, with absorption bands at 460, 500 and 520 nm (C₄₆₀, C₅₀₀ and C₅₂₀), and of a chlorophyll a form with an absorption band at 669–672 (Chl_669–672) was found. On increasing the density to 0·2–0·3 nm²/molecule, a conversion of C₄₆₀ and C₅₂₀ into C₅₀₀, was observed, and several more additional (probably more strongly aggregated) chlorophyll a forms appeared, with absorption bands at 672–733 nm. With excess carotene [(Chi)/(Car) = 1:3] the forms C₄₆₀, C₅₀₀, C₅₂₀ and Chl_669–672 were present even in the most dense films (0·2–0·3 nm²/molecule). The same was found with other carotenoids: if one of the pigments was in excess, aggregated forms of the other tended to disappear. In the transfer of energy from carotenoids to chlorophyll a, C₅₀₀ was found to be the main donor. In layers with a concentration ratio (Chl)/(Car) = 3:1, the efficiency of transfer was less than 10 per cent at the lowest density used (3·70 nm²/molecule); it increased to 50 per cent, as the density was increased to 0·20 nm²/molecule. When the relative concentration of the carotenoid was increased to (Chl)/(Car) = 1:1, the efficiency of energy transfer dropped to 25 per cent even at 0·20 nm²/molecule. It seems that the efficiency of energy transfer between carotene molecules (prior to its transfer to chlorophyll a) is low, and effective transfer occurs only between β-carotene and immediately adjacent chlorophyll a molecules.     

SURFACE ENTHALPY AND ENTROPY AND THE PHYSICO-CHEMICAL NATURE OF HYDROPHOBIC AND HYDROPHILIC INTERACTIONS

The attractive Interactions between typically hydrophobic molecules such as hexane or CCl₄, and the repulsive Interactions between extremely hydrophilic molecules such as poly(ethylene oxide) (PEO), when immersed in water, as well as the interactions between these molecules and water, have been examined from a surface thermodynamic viewpoint, taking the changes in surface free energy into account, as a function of temperature. It was found that attractive hydrophobic Interactions are not, as vas generally believed up to now, invariably entropic. Hydrophobic Interactions can be mainly enthalpic or mainly entropic, or more or less equal mixtures of both, depending on each individual case; however, all hydrophobic interactions are polar (in the sense of Lewis acid-base) in nature. Repulsive hydrophilic interactions are enthalpic, and also polar in nature. The interaction between hydrophobic solutes and water is mainly enthalpic, and is apolar in nature.     

N-苯基马来酰亚胺与环己烯共聚物的制备和表征

Ｎ苯基马来酰亚胺（ＰＨＭＩ）是一种很有应用价值的共聚单体,它能赋予共聚物很好的耐热性．有关ＰＨＭＩ与甲基丙烯酸甲酯、苯乙烯及乙烯基醚的二元共聚合反应已有文献报道［１～３］．而有关ＰＨＭＩ与环烯烃特别是环己烯的共聚合研究除我们所做的工作外［４］,报道甚少．作者研究了ＰＨＭＩ与环己烯在溶液中的二元共聚合反应,并对所得的共聚物进行了表征．１　原料ＰＨＭＩ,自制,ｍ．ｐ．８８－７℃;元素分析Ｃ,６９－３３;Ｈ,４－０７;Ｎ,８－１０;理论值Ｃ,６９－３６;Ｈ,４－０７;Ｎ,８－０９,１ＨＮＭＲ（δ）…     

MECHANICS AND THE EVOLUTION AND FUNCTIONAL MORPHOLOGY OF CONCHOSTRACAN CARAPACE MECHANICS AND THE EVOLUTION AND FUNCTIONAL MORPHOLOGY OF CONCHOSTRACAN CARAPACE

Conchostracans, with a laterally compressed body enclosed between two symmetric valves, live swimming in fresh or brackish water. The carapace valve has a number of growth bands with various sculptures. The general trend of sculptural evolution is from smooth to punctate-minute polygon-medium reticulation-large reticulation, while these punctate, polygonal and various reticulate patterns may separately develop into various radial ridges. The development of sculpture can be well explained by mechanical principle. Functional morphology of carapace is discussed in the light of mechanics in this paper.