升温淋洗分级技术在聚乙烯研究中的应用

升温淋洗分级技术是根据结晶性聚合物的结晶度进行分级和表征的一项分析和制备技术，在聚烯烃非均匀性的表征和窄组成分布样品的制备中有重要应用。本文主要介绍升温淋洗分级原理、热力学模型、装置技术特点、分析方法以及在聚乙烯研究中最新应用进展。     

利用X射线衍射法测定固相氯化法氯化聚乙烯的结晶度

本实验根据X射线衍射强度理论和聚合物两相模型概念,采用逐级近似的方法,利用X射线衍射技术,测得了固相氯化法CPR的结晶度。结果表明,当Cl%≤12.0%时,随着氯含量的增加,固相氯化法CPE的结晶度逐渐减小。     

Characterization,Solar Reflectance,and Crystal Properties of Polyethylene and Ethylene Copolymer after Thermal Treatment

Various kinds of polyethylene and ethylene copolymers were prepared by non-isothermal crystallization and isothermal crystallization methods. Solar reflectance of all samples was determined by a series of characterization (UV-vis-NIR measurement, wide-angle X-ray diffraction, differential scanning calorimetry analysis, polarized optical microscopy). It was found that lamellar thickness, degree of crystallinity, and microstructure played an important role in affecting the solar reflectance of these polymers. Long-branched chains in ethylene copolymers lowered the solar reflectance by decreasing lamellar thickness and the degree of crystallinity of these polymers. The isothermal crystallization method is a way to promote lamellar thickness and the degree of crystallinity, and make the microstructure more compact.     

高性能光催化降解聚乙烯薄膜的研究

利用酸性蓝BGA染料敏化的纳米TiO2作为光催化剂, 与低密度聚乙烯(LDPE)树脂复合制备了具有可见光催化降解性能的复合塑料薄膜. 采用SEM、FTIR、VHX-100数码显微镜和高温凝胶渗透色谱(HTGPC)等分析技术系统地研究了该塑料薄膜在紫外光和太阳光照射下的降解性能. 探讨了塑料薄膜在光辐照前后的力学性能、质量和分子量变化规律. 研究结果表明, 该薄膜在经紫外线照射5 d后质量损失达到17.6％, 数均分子量由21800降低为5900; 经太阳光照射48 d后质量损失达到12.5％, 分子量降为8100. 辐照后薄膜拉伸强度和断裂伸长率显著降低, 羰基含量升高.     

氯磺化聚乙烯结构和性能研究Ⅰ.氯磺化反应及其对晶体结构的影响

氯磺化聚乙烯水解后是一种性能特异的离子交换膜。本文研究了低密度及高密度聚乙烯中空纤维氯磺化反应时间与交换容量之间的关系,并用红外光谱及广角X射线衍射法测定了氯磺化反应对聚乙烯晶体结构的影响。结果表明,氯磺化反应主要发生在聚乙烯的非晶区,最大交换容量及反应速度均与非晶区含量有关。反应对晶粒表面也有一定程度的侵蚀作用,随着交换容量的增加,结晶度下降,晶粒度减小。低密度及高密度聚乙烯的变化趋势相似,但前者比后者变化更显著。     

碳酸钙填充聚乙烯的光老化性能研究

近年来国内外对以CaCO₃为主的无机刚性粒子增强、增韧聚烯烃的基础和应用研究取得重大进展,填充的主要目的已从降低成本转向提高材料性能,展现出钙塑材料新的更广阔的应用前景。本文用人工光老化方法和红外光谱分析手段,对涉及材料使用寿命的光老化性能进行了研究,以期为这类钙材料的进一步推广应用提供更全面的理论和实际依据。     

超高分子量聚乙烯的红外光谱的特性研究

研究了超高分子量聚乙烯(M_w>1×10⁵)的红外光谱-温度特性.3条非晶谱带(1368、1352和1304cm^-1)的吸收强度均随温度升高而增大,但都比普通分子量聚乙烯增加的小,尤以高于140℃更甚.分子链中次甲基的近程构象序列分布随温度的变化不受分子量的影响,但旁式构象序列分布则随温度升高而增大.升温和降温过程的红外光谱均表明1352和1304cm^-1两谱带随结晶状态的变化比1368cm^-1更敏感.     

聚乙二醇溶液的粘度行为

本文用特性粘数、气相渗透计法和体积排除色谱法以［η］＝ｋ_θ［Ａ＋（１＋ＡＢ）Ｍ~（１／２）＋ＢＭ］形式导出聚乙二醇在四氢呋喃和水两种溶剂中的普适特性粘度方程：四氢呋喃，２５℃：［η］＝０．１２６（１＋０．００４Ｍ~（１／２））（５＋Ｍ~（１／２））水，３５℃：［η］＝０．１４０（１＋０．００４Ｍ~（１／２））（３．５＋Ｍ~（１／２））     

纳米级聚乙烯和聚丙烯微晶的高分辨透射电子显微学研究

用高分辨电子显微学方法对从极稀的二甲苯溶液中得到的纳米级聚乙烯(PE)和聚丙烯(PP)微晶进行了研究,发现这种纳米级微晶是分子堆砌不完善,但可以独立存在的一种亚稳态结构,其晶格存在着大量的弯曲、分叉、位错等缺陷,经热处理后有序程度大大提高.表明高分辨电子显微学方法是研究PE和PP纳米级微晶的亚稳态结构和稳定性的有效手段.     

Reaction Kinetics of the Radiation-Induced Grafting of Styrene on Polyethylene Film

Based on rate data obtained previously, an analysis has been made of the reaction kinetics of the radiation-induced grafting of styrene on polyethylene film by using various concentrations of methanol in the styrene. A new feature of the work involves the use of internal film concentrations of styrene and methanol computed from the Flory theory of polymer /solvent interaction, which possibly improves the accuracy of calculations of termination rate constant k_t at various methanol concentrations. A graphical plot of k_t dependence on internal film viscosity is computed from an equation of Smoluchowski. Techniques are defined which may lead to improved accuracy in the computation of rate constants.     

Reaction Kinetics of the Hydrothermal Treatment of Lignin

Lignins derived from abundant and renewable resources are nontoxic and extremely versatile in performance, qualities that have made them increasingly important in many industrial applications. We have shown recently that liquefaction of lignin extracted from aspen wood resulted in a 90% yield of liquid. In this paper, the hydrothermal treatment of five types of lignin and biomass residues was studied: Kraft pine lignin provided by MeadWestvaco, Kraft pine lignin from Sigma-Aldrich, organosolv lignin extracted from oat hull, the residues of mixed southern hardwoods, and switchgrass after hydrolysis. The yields were found dependent on the composition or structure of the raw materials, which may result from different pretreatment processes. We propose a kinetic model to describe the hydrothermal treatment of Kraft pine lignin and compare it with another model from the literature. The kinetic parameters of the presented model were estimated, including the reaction constants, the pre-exponential factor, and the activation energy of the Arrhenius equations. Results show that the presented model is well in agreement with the experiments.     

纤维素芳族酯热致液晶对PET结晶成核作用的研究

用自制的热致液晶性纤维素芳族酯(CAE)作聚对苯二甲酸乙二醇酯(PET)的成核剂,研究了PET/CAE体系(CAE含量≤1%)在110～200℃温度范围内的等温结晶动力学特性.结果表明,CAE能显著加快PET结晶速率(Z),Z随结晶温度和CAE含量变化均有极大值Z_max(T_C)和Z_max(W_CAE),Z_max(T_C)对应的温度T_max随CAE含量增加而降低,CAE促进PET结晶的作用机理与普通成核剂不同.     

液态聚碳硅烷的固化反应动力学研究

选用过氧化二异丙苯(DCP)和偶氮二异丁腈(AIBN)分别引发含乙烯基液态聚碳硅烷(VHPCS)聚合。采用非等温差示扫描量热法(DSC)研究VHPCS/DCP、VHPCS/AIBN两种体系的固化反应动力学,通过Kissinger方程和Crane方程确定相关动力学参数,并由此得出体系的n级固化模型。同时通过β-T外推法确定体系的固化工艺温度,并对体系交联机理及产物热性能进行分析。研究结果表明:VHPCS/DCP、VHPCS/AIBN二体系的活化能分别为72.17kJ/mol、94.11kJ/mol,反应级数分别为0.92、0.93。β-T外推法确定:当升温速率为0℃/min时二体系的近似凝胶化温度均为55℃,峰值温度分别为110℃、107℃,终止温度分别为129.5℃、134℃。FTIR结果表明,VHPCS的交联固化主要是通过双键的自聚合实现,交联后样品的陶瓷产率有所提高。     

Chlorination of various substrates in subcritical carbon tetrachloride

Various aliphatic hydrocarbons and the side chains of aromatic hydrocarbons were chlorinated in subcritical carbon tetrachloride. Chlorination of aromatic compounds including 1,4-disubstituted benzenes was investigated. Ketones and sulfones were stable under the employed conditions. Sulfoxides were converted into sulfides in a low to modest yields. The coupling adducts between olefins and carbon tetrachloride were obtained from the reactions of olefins.     

Some simulations on crystallinity in a typical linear low-density polyethylene

Crystallinity in ethylene/1-hexene copolymers, a type of linear low-density polyethylene, was investigated by Monte Carlo simulations. The comonomer distributions generated in the simulated chains and the melting temperatures of real chains were used to estimate the minimum crystallite thickness, which is the critical quantity for simulating crystallization in any type of polymer. Simulated values of this thickness were in good agreement with values calculated from Raman longitudinal acoustic mode (LAM) spectroscopy, except for very low 1-hexene mole fractions, where there were presumably complications from high melt viscosities and chain entanglements. The use of this information in estimating properties of these copolymers is illustrated by some preliminary results on the effects of varying amounts of this comonomer on the sizes and numbers of the polyethylene crystallites.     

聚苯乙烯固载化聚乙二醇苄醚的合成、相转移催化及机理研究

改进了聚苯乙烯固载化聚乙二醇苄醚的合成方法,并在正溴辛烷与固体NaI的亲核取代反应中考察了它们的相转移催化性能。结果表明,催化反应对n-C₈H₁₇Br浓度为表观1级。催化剂交联度越低,粒度越小,反应速率越大。大孔催化剂活性比凝胶催化剂高;聚乙二醇固载化后的活性比固载化前高,体系中水含量对反应速率也有影响。     

聚乙烯六方相

评述了聚乙烯六方相的研究历史和结论，对其晶格结构，构象特征，热力学特性及形成原因，以及在聚乙烯结晶，尤其是形成伸直链晶体的过程中的动力学角色作了较详细的说明。     

辐射交联法估算分子量分布的多分散指数——分子量分布对聚乙烯辐照交联的影响

本文考察了聚乙烯的分子量分布多分散指数对辐照交联的影响.随着多分散指数的增大,聚乙烯的辐照交联相对于Charlesby-Pinner直线关系的偏离愈大.定义了一个参数v来定量表示这种偏离的程度,v与多分散指数M_w/M_n。之间可以简洁地用经验式v=1.25-0.18(M_w/M_n)~(0.62)表示.因而可以通过这个关系,用辐照交联的技术来估算分子量分布多分散指数.     

Researches on Formation of Haloacetic Acids in Chlorination of Drinking Water by a Novel Technique

Haloacetic acids (HAAs) are formed during the chlorination of drinking water, which are harmful to peo-ple′s health due to their carcinogenic and mutagenic effects. In the present study, a detection method combin-ing methyl tert-butyl ether (MtBE) extraction with acid catalysis and gas chromatography coupled with anelectron capture detector (GC/ECD) was developed for determining HAAs. The detection limit of this method(MDL) and relative standard deviation (RSD) were below 0. 37μg/L and 6.2%, respectively. The laboratorychlorination experiments were conducted with the purpose of investigating the influences of reaction time,temperature, UV254, bromide and ammonia-nitrogen on the formation of HAAs. The results show that theformation amount of HAAs increases with increasing reaction time and temperature, respectively;and thereexists a linear relationship between the formation of HAAs and UV254. The formation amount of HAAs de-creases first and then increases as the bromide ion concentration increases, and adding NH4^ is a possible wayto control the formation of HAAs.     

熔体结晶聚乙烯晶体的高分辨电子显微学研究

聚乙烯在一定的不良溶剂中或在熔融结晶的条件下可以得到具有弧形生长边缘的单晶,对于具有弧形边的（200）晶面的形成机理,已有一些研究报道,但由于高分子链具有成千上万个结构单元,使其结晶过程很复杂,可能会导致弧形边的成因有所不同,因此对于弧形边的形成机理有不同的解释。