高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物共混体系的结晶行为

通过ＤＳＣ和ＷＡＸＤ研究了高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物（ＨＤＰＥ／ＬＤＰＥ／ＥＶＡ）三元共混体系的热行为和结晶性能。发现当ＨＤＰＥ含量小于４０％时，ＥＶＡ对ＬＤＰＥ起稀释剂作用，促进ＨＤＰＥ、ＬＤＰＥ的晶相分离，使ＨＤＰＥ、ＬＤＰＥ单独结晶．当ＨＤＰＥ含量高于４０％时，ＬＤＰＥ片晶进入ＨＤＰＥ晶相。形成与ＬＤＰＥ在片晶水平上的共晶。     

高密度聚乙烯／低密度聚乙烯／乙烯—醋酸乙烯共聚物共混体系的结晶行为

通过ＤＳＣ和ＷＡＸＤ研究了高密度聚乙烯／低密度聚乙烯／乙烯－醋酸乙烯共聚物（ＨＤＰＥ／ＬＤＰＥ／ＥＶＡ）三元共混体系的热行为和结晶性能，发现当ＨＤＰＥ含量小于４０％时，ＥＶＡ对ＬＤＰＥ起稀释剂作用，促进ＨＤＰＥ、ＬＤＰＥ的晶相分离，使ＨＤＰＥ、ＬＤＰＥ单独结晶，当ＨＤＰＥ含量高于４０％时，ＬＤＰＥ片晶入进ＨＤＰＥ晶相，形成与ＬＤＰＥ在片晶水平上的共晶。     

含羧酸共生稀土光敏剂的低密度聚乙烯膜紫外光氧化降解

含羧酸共生稀土光敏剂的低密度聚乙烯膜紫外光氧化降解林宜超（福建省测试技术研究所福州３５０００３）近年来，许多作者先后研究并开发出含硬脂酸铈（ＣｅＳｔ３）光敏剂的可控光降解低密度聚乙烯（ＬＤＰＥ）［１，２］、高密度聚乙烯［３］、聚丙烯［４］、聚苯乙烯...     

HDPE/LDPE共混物形变过程中的结构变化及机理

聚合物熔体结晶由于链缠结等因素的影响,其形态结构非常复杂,这给研究结晶聚合物的微观结构,特别是聚合物在拉伸过程中的形态变化带来很大困难．本文将高密度聚乙烯（ＨＤＰＥ）和低密度聚乙烯（ＬＤＰＥ）两种不相容的组分进行共混,使少量ＨＤＰＥ分散在ＬＤＰＥ中,...     

热致液晶（LC70）／PET共混物的结构与性能

采用ＷＡＸＤ、ＤＳＣ、ＰＯＭ、ＳＥＭ和力学测试方法研究了ＬＣ７０／ＰＥＴ原位复合材料的结构与性能。结果表明,当ＬＣ７０／ＰＥＴ＜２０％时,ＬＣ７０对ＰＥＴ的结晶生长具有一定促进作用;当ＬＣ７０／ＰＥＴ＞３０％时,共混物结晶能力迅速下降,结晶放热和熔融焓明显降低。     

聚乙烯光引发交联过程中的表面光氧化和光稳定

通过测定凝胶含量并利用红外-光声光谱和光电子能谱对光交联聚乙烯表面氧化程度和氧化产物进行了研究.结果表明,聚乙烯光交联过程中随着光照时间的增加,表面光氧化加剧,氧化产物主要是氢过氧化物和含羰基的化合物.考察了预辐照和添加受阻胺型光稳定剂对聚乙烯光交联过程的影响,发现这两种方法都能有效地降低光交联聚乙烯(XLPE)的表面氧化,但有些光稳定剂会降低XLPE的交联度.     

极低密度聚乙烯与其它聚乙烯的共混

从结构角度，用ＤＳＣ，ＷＡＸＤ，ＳＡＸＳ研究了聚乙烯（ＰＥ）家族中极低密度聚乙烯（ＶＬＤＰＥ）与其它ＰＥ的互容性．ＨＤＰＥ／ＶＬＤＰＥ是共晶互容的，以其大量无规部分“溶解”了ＨＤＰＥ的结晶缺陷部分，提高了ＨＤＰＥ的Ｔｃ，Ｔｍ，Ｘｃ，结晶峰半高宽变窄，晶胞参数随组成而有最低值．ＶＬＤＰＥ与ＬＬＤＰＥ结构极为相似，ＤＳＣ及ＷＡＸＤ证明其共混物是共晶相容体系．ＬＤＰＥ／ＶＬＤＰＥ的结晶度符合按组成的计算值，但晶胞参数ａ，ｂ以及晶粒尺寸增大，ＤＳＣ上有分别相应于两组份的两个Ｔｍ；ＶＬＤＰＥ的Ｔｃ，Ｔｍ峰高之和高于按组份的计算值，ＬＤＰＥ的Ｔｍ，Ｔｃ则低于计算值．认为是正如ＬＬＤＰＥ／ＬＤＰＥ，ＬＤＰＥ向充满整个体积的ＶＬＤＰＥ中不断填入，以ＶＬＤＰＥ为晶核而结晶，形成相分离的不相容体系．     

色谱质谱联用技术研究30%二甲基二乙氧基硅烷70%正硅酸乙酯复合醇盐 …

采用色谱质谱联用技术研究了１种复合醇盐：３０％二甲基二乙氧基硅烷／７０％正硅酸乙酯的水解聚合过程，并由此分析了这两种有机－无机醇盐的相互作用机制和聚合方式，实验结果指出，ＤＤＳ的添加抑制了ＴＥＯＳ的自聚合，使得体系中形成了大量的ＤＤＳ的自聚合环状分子以及ＴＥＯＳ和ＤＤＳ的共聚合高分子，由于后者对水解聚合的加速作用，使得３０％ＤＤＳ／７０％ＴＥＯＳ系统具有最短的凝胶时间。     

戊二醛合成跟踪分析

用气相色谱法对液 液相转移反应萃取法合成戊二醛（ＧＡ）反应进行跟踪分析,采用φ３ｍｍ×４ｍ［ｍ（ＳＥ ３０）∶ｍ（硅烷化１０１白色担体）＝１５∶１００］＋φ３ｍｍ×２ｍ［ｍ（ＰＥＧ ２０Ｍ）∶ｍ（硅烷化１０１白色担体）＝１０∶１００］不锈钢柱,双柱双氢焰程序升温,升温程序为７０℃（４ｍｉｎ）１０℃／ｍｉｎ１４０℃（６ｍｉｎ）。Ｎ２４５ｍＬ／ｍｉｎ,Ｈ２６５ｍＬ／ｍｉｎ,空气３００ｍＬ／ｍｉｎ,汽化温度１８５℃,检测温度１８５℃。所建立的方法能较好地分离环戊烯、溶剂、氧化中间产物、ＧＡ、内标、氧化副产物。     

聚丙烯酸酯无皂水溶胶阻尼涂料动态力学性能的研究

用分步溶液聚合法合成了两种丙烯酸酯共聚物的共混物［Ｐ（ＢＡ－ＨＥＭＡ－ＡＡ）／Ｐ（ＭＭＡ－ＨＥＭＡ－ＡＡ）Ａ］，制成无皂水溶胶，加入交联剂配成涂料。两种共聚物既可相互贯穿缠结，又可通过交联剂交联，使涂膜同时具有物理交联和化学交联。用动态力学分析法（ＤＭＡ）、扭辫分析法（ＴＢＡ）考察了涂膜的动态力学性能，表明涂膜具有ＩＰＮ结构，并有良好的阻尼性能。     

交联方法对交联聚乙烯结晶行为的影响

研究了硅烷交联聚乙烯和过氧化物交联聚乙烯由于结晶和交联的顺序不同而造成的结晶行为的差异，交联密度相同时，过氧化物交联聚乙烯的结晶度和熔点明显低于硅烷交联聚乙烯，交联聚烯非等温结晶动力学表明：交联前后聚乙烯的Ａｖｒａｍｉ指数ｎ基本不变，交联后，半结晶期ｔ１／２延长、结晶速率常数ＺＣ下降，其中过氧化物交联聚乙烯的变化幅度大于硅烷交联聚乙烯。     

Swelling Behavior of pH-Sensitive Copolymers Containing 2-Acrylamido-2-Methyl Propane Sulfonic Acid and Acrylic Acid Crosslinked with Vinyl Trimethoxy Silane Crosslinker

Copolymers of 2-acrylamido-2-methyl propane sulfonic acid and acrylic acid were crosslinked in the presence of different mol% of either vinyl trimethoxy silane (VTMS) as the crosslinking agent under acidic conditions or N,N-methylenebisacrylamide (MBA) as crosslinker using solution radical polymerization. The resultant xerogels were characterized by extracting the soluble fractions and measuring the equilibrium water content. Soluble fractions of the crosslinked networks were reduced by varying the MBA and VTMS concentrations. The surface morphology of the crosslinked polymers was observed by scanning electron microscope. The influence of pH on the swelling behavior of gels was investigated. The swelling behaviors of the resulting gels show pH sensitivity.     

EQUILIBRIUM SWELLING PROPERTIES OF LIGHTLY CROSSLINKED ISOTROPIC NETWORKS: NATURAL RUBBER CROSSLINKED IN DRY STATE

Lightly crosslinked natural rubber (NR) networks have been characterized by equilibrium swelling in toluene. A good agreement between the equilibrium swelling crosslink-junction densities (μ_E) and the values expected from the stoichiometry of dicumyl peroxide decomposition (μ_c) has been obtained using Flory's early equation of state. The applicable value of χ = 0.37 was found to compare equally well and is in tandem with the previously reported literature values of χ = 0.391 and χ = 0.35 from swelling and heat of mixing measurements, respectively.

At low crosslink-junction densities i.e., μ_E ≤ 4.2 mM.l^?1 corresponding on average to 4 crosslink-junctions per cis 1,4-poly-isoprene chain and below, network formation is found to be incomplete. The approach used also provides a simple way of differentiating lightly crosslinked networks from the state of gelation.     

Synthesis and swelling behavior of thermosensitive hydrogels based on N-substituted acrylamides and sodium acrylate

A series of hydrogels based on N-isopropylacrylamide, sodium acrylate, and N-tert-butylacrylamide were synthesized by free radical polymerization in a mixture of dioxane and water with tetra(ethylene glycol) diacrylate as the crosslinker and benzoyl peroxide as the initiator. The swelling behavior including the swelling rate of the crosslinked gels in water was studied with gravimetric method. The swelling ratio of the gel (0.1 mol% crosslinking) can reach 420 g/g at 20 °C and such a gel can release 96% of the water absorbed at 40 °C. The lower critical swelling temperature (LCST) of the copolymers can be adjusted by changing the chemical composition of the polymers. Such crosslinked gels can be potentially used as thermosensitive superabsorbent because of their high water uptake and thermal sensitivity.     

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

 用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

Determination of the degree of swelling and crosslinking of extremely small polymer gel quantities by analytical ultracentrifugation

The degree of crosslinking of very small amounts of polymer gel, encountered in the characterization of the molecular structure of rubber polymers or of polymers in powder form, cannot be determined satisfactorily by measurement of elasticity or conventional swelling. Therefore a method has been developed which enables us to determine the degree of crosslinking of such polymer systems reliably. This method is based on the measurement of equilibrium swelling by sedimentation in the analytical ultracentrifuge. The degree of swelling can either be used directly as a relative measure of the average degree of crosslinking or as basis for calculating the average degree of polymerization of the molecule chains between two crosslink sites according to the theory of Flory and Rehner. The efficiency of the method is demonstrated by several examples of application (differently crosslinked polybutadienes, gel portions of various polychloroprenes and polyurethane foams).Dedicated to Dr. Gerhard Fritz on the occasion of his 60th birthday.     

聚乙烯交联过程结构演化的流变学研究

采用耐压等级分别为35kV及110kV的两种不同商业化可交联聚乙烯(XLPE)电缆料为研究模型,考察其化学交联过程中结构演化与线性黏弹响应的关系.研究结果表明,流变学方法可敏感表征较低温度、较长时间下XLPE交联过程的结构演化.随着交联温度的升高,体系预交联时间缩短,而黏弹特性的变化速率不变;交联导致体系弹性和黏性均增加,但弹性增加幅度远大于黏性增加幅度.比较两种样品交联过程的流变行为,发现随着交联反应的进行,两者的黏性增长速率基本一致,但35kV电缆料样品的弹性增长略大.采用低频率区域(频率末端区)的动态储能模量(G′),计算体系交联点之间的平均分子量(Mc),以表征样品的交联密度.同时用常规的溶胀平衡法研究了两种电缆料Mc与交联时间的依赖关系.     

k-型卡拉胶/聚乙烯吡咯烷酮共混水凝胶的辐射制备及性质研究

采用辐射技术制备了κ-型卡拉胶(KC)/聚乙烯基吡咯烷酮(PVP)共混水凝胶,研究了共混凝胶内KC含量、PVP的分子量和辐照剂量等对KC/PVP共混水凝胶性质的影响.实验发现,KC与高分子量的PVP(k-90)共混后在一定剂量范围内辐照可得到高强度、高溶胀行为的KC/PVP共混水凝胶,随着共混凝胶内KC含量的增加,凝胶强度及溶胀性能均显著提高.分析表明,KC与高分子量的PVP共混后,在较低剂量下KC的降解被抑制,从而获得一种由物理交联的KC和化学交联的PVP形成的互穿网络(IPN)凝胶.     

Reversible crosslinking in cellulose. VII. Memory effect of the crosslinking medium in the dyeing of crosslinked cotton

Cellulose β-mercaptoethylaminocarboxylate made from unmercerized cotton was partially oxidized in various solvents of different swelling power followed by treatment with excess methyl iodide to yield partially disulfide-crosslinked cotton samples of about the same degrees of crosslinking containing sulfonium groups of about the same contents. The effect of the solvent in crosslinking on the equilibrium and kinetics of dyeing with three dyes (Orange II, Direct Scarlet B, and Direct Sky Blue A) of different molecular size was investigated. The 1:1 ionic bonding was observed at equilibrium between sulfonic acid groups in dye molecules and sulfonium groups in modified cottons in cases of Orange II and Direct Scarlet B. The equilibrium uptake of the largest dye, Direct Sky Blue A, was much influenced by the solvent used in crosslinking; the higher the degree of swelling in crosslinking, the larger the equilibrium uptake. The diffusion rate of Direct Scarlet B was much affected by the solvent used; the higher the degree of swelling, the higher the diffusion rate. The pore structure of the crosslinked cotton was discussed. The crosslinked cotton seemed to have a “memory” of the state at the time of crosslinking and to have a tendency to come back close to that state when placed in a dye bath.