Characterization of polyethylene glycol-modified proteins by semi-aqueous capillary electrophoresis

A new program to characterize polyethylene glycol-modified (PEGylated) proteins is outlined using capillary zone electrophoresis (CZE). PEGylated ribonuclease A and lysozyme were selected as examples. Five separation procedures were compared to select out the mixed buffer of acetonitrile-water (1:1, v/v) at pH 2.5 as the best to characterize the PEGylated proteins without sample pretreatment. Polyethylene oxide (PEO) with a high molecular mass of 8X10(6) was applied to rinse the capillary to form a dynamic coating which would decrease the undesirable proteins adsorbed to the inner wall of the silica. The electroosmotic flow (EOF) mobility of the five procedures was determined, respectively. It is found that acetonitrile is mainly responsible for the good resolution of PEGylated proteins with the help of PEO coating in the semi-aqueous system. The low EOF mobility and current in the semi-aqueous system might also have some responsibility for the high resolution. The semi-aqueous procedure described in this paper also demonstrates higher resolution of natural proteins than aqueous ones. (C) 2001 Elsevier Science B.V. All rights reserved.

Preparation of a novel polysulfone/polyethylene oxide/silicone rubber multilayer composite membrane for hydrogen-nitrogen separation

A novel poly sulfone/polyethylene oxide/silicone rubber (PSOPEO/SR) multilayer composite membrane was fabricated by double coating polysulfone substrate membrane with polyethylene oxide and silicone rubber. Gas permeation experiments were performed at 30 degrees C for hydrogen and nitrogen. PSf(PEO/SR membrane displayed high and steady performance for H-2/N-2: permeances of H-2 and N-2 of 49.51 and 0.601 GPU, respectively, and H-2/N-2 ideal separation factor of 82.3. It was explained that layer interfaces due to the introduction of PEO layer act as the permselective media and are responsible for the higher H-2/N-2 ideal separation factor which has exceeded the intrinsic permselectivities of the three polymers used in this study. (c) 2005 Elsevier B.V. All rights reserved.

The effect of nucleation time on the growth of a microvoid in a viscoelastic material

In this paper, discussions are focused on the growth of a nucleated void in a viscoelastic material. The in situ tensile tests of specimens made of high-density polyethylene, filled with spherical glass beads (HDPE/GB) are carried out under SEM. The experimental result indicates that the microvoid nucleation is induced by the partially interfacial debonding of particles. By means of the Laplace transform and the Eshelby's equivalent inclusion method, a new analytical expression of the void strain at different nucleation times is derived. It can be seen that the strain of the nucleated void depends not only on the remote strain history, but also on the nucleation time. This expression is also illustrated by numerical examples, and is found to be of great usefulness in the study of damage evolution in viscoelastic materials.

Effect of Surface Condition of Electrode on the Surface Melting of Material by Laser-Guided Micro-Arc Discharge

This paper studies the surface melting in the atmosphere by YAG laser-guided micro-arc discharge. In three kinds of surface conditions (free, oiled, and polyethylene covered), we try to control the diameter and the power density of discharge pit. It is found that the power density of 3 x 10(6) W/cm(2) of discharge pit on the oiled surface is moderate to form the melted layer thicker than that of the others, adapting to strengthen the surface of material, and the power density of 1.07 x 10(7) W/cm(2) of discharge pit on the polyethylene-covered surface is highest to form the deepest discharge pit among them, adapting to remove the material.

On the influence zone and the prediction of tensile strength of particulate polymeric composites

An intended numerical investigation is carried out. The results indicate that, even if a perfect adhesive bond is preserved between the particles and matrix materials, the two-phase element cell model is unable to predict the strength increment of the particulate polymeric composites (PPC). To explore the main reinforcing mechanism, additional microscopic experiment is performed. An ''influence zone'' was observed around each particle which is measured about 2 to 10 micrometers in thickness for a glass-polyethylene mixture. Then, an improved computational model is presented to include the ''influence zone'' effect and several mechanical behaviors of PPC are well simulated through this new model.

普通烟草与毛曼陀罗族间体细胞杂交的研究

采用PEG／DMSO融合法，从普通烟草(Nicotiana tabacum L.cv.Xanthi nc)叶肉和毛曼陀罗(Datura innoxia Mill.)茎或叶愈伤组织原生质体融合获得I5株花盆中健康生长的族间体细胞杂种植株;其中11株是在没有选择压力的条件下获得，4株则是在有IOA和R6G选择系统存在下获得。同时获得一株试管开花且形态异常的植株和一株花盆中生长的嵌合植株。lOmM IOA和I5μ g／ml R6G均能分别有效地抑制烟草叶肉和毛曼陀罗愈伤组织原生质体的分裂;10% DMSO能显著提高原生质体融合率;PEG种类并不重要，但浓度则很重要;BAP较ZT，KT对植株分化有更好的诱导效果。杂种的形态、细胞、同工酶、Southern杂交，花粉育性分析结果如下：1、l5株杂种较双亲普遍株型矮小，生长缓慢，形态接近烟草但不很正常，根据形态特征可分为两种类型：(1)共有8株，其叶片大小、形状、颜色、开花习惯、花类型（单花）等均与毛曼陀罗接近，但子房败育;(2)共有7株，其株型、叶片形状、颜色、光滑度、花形状、类型（圆锥状花序）、颜色更接近烟草，但少数杂种开单花或先单花后圆锥状花序或先单花后两种花并存，且开花时间不一，部分子房败育。2、杂种染色体数目大都在60～90之间，个别者较少(48条)或较多(125条)，没有一株为双二倍体(2n=96)，并全部为混倍体。3、15株杂种植株均有双亲的细胞色素氧化酶同工酶特征谱带;大部分都有双亲的过氧化物酶同工酶特征谱带，少都仅具烟草的谱带。4、Hae Ⅲ／水稻rDNA的Southern杂交分析表明杂种1较双亲多一条谱带，杂种2较双亲也多一条弱带，其它杂种尚待定。5、花粉活力测定表明毛曼陀罗（种子再生而来）的为99%，烟草（原生质体再生而来）为80～90%，而杂种的为24～61%，育性普遍低于双亲。

Site-directed PEGylation of trichosanthin retained its anti-HIV activity with reduced potency in vitro

Trichosanthin (TCS) was the first ribosome inactivating protein found to possess anti-HIV-1 activity. Phase I/II clinical trial of this compound had been done. Antigenicity and short plasma half-life were the major side effects preventing further clinical trial. Modification of TCS is therefore necessary to revive the interest to develop this compound as an anti-HIV agent. Three potential antigenic sites (Ser-7, Lys-173, and Gln-219) were identified by computer modeling. Through site-directed mutagenesis, these three antigenic amino acids were mutated to a cysteine residue resulting in 3 TCS mutants, namely S7C, K173C, and Q219C. These mutants were further coupled to polyethylene glycol with a molecular size of 20 kDa (PEG) via the cysteine residue. This produced another three TCS derivatives, namely PEG(20)k-S7C, PEG(20)k-K173C, and PEG(20)k-Q219C. PEGylation had been widely used recently to decrease immunogenicity by masking the antigenic sites and prolong plasma half-life by expanding the molecular size. The in vitro anti-HIV-1 activity of these mutants and derivatives was tested. Results showed that the anti-HIV-1 activity of S7C, K173C, and Q219C was decreased by about 1.5- to 5.5-fold with slightly lower cytotoxicity. On the other hand, PEGylation produced larger decrease (20- to 30-fold) in anti-HIV activity. Cytotoxicity was, however, weakened only slightly by about 3-fold. The in vitro study showed that the anti-HIV activity of PEGylated TCS was retained with reduced potency. The in vivo activity is expected to have only slightly changed due to other beneficial effects like prolonged half-life. (C) 2004 Elsevier Inc. All rights reserved.

THE RESPONSES OF Microcystis TO SEDIMENT ENVIRONMENTS AND THE ASSESSMENT FOR ITS OVERWINTERING - A SIMULATION STUDY IN A NOVEL DEVICE

A novel multi-cell device made of organic glass was designed to study morphological and physiological characteristics of Microcystis population trapped in simulated sediment conditions. Changes of colonial morphology and antioxidant activities of the population were observed and measured over the range of 31-day incubation. During the incubation, the antioxidant enzyme activities fluctuated significantly in sediment environments. The activities of catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (NIDA) reached the highest on the 11(th) day, 6(th) day and 6(th) day. respectively, and then dropped down remarkably in the following days. The ratios of Fv/Fm and the maximal electron transfer rate (ETRm) declined during the initial days (1 similar to 11(th) day), but rebounded on the 16(th) day, which were consistent with the variations of total protein. In the end of incubation. gas vacuoles were hard]), observed and the gelatinous sheath was partly disappeared in the population of Microcystis. Nevertheless, the remaining populations. upon transferred to culture medium, were able to grow though experiencing a longer lag phase of nine days. The results indicated that the sediment environments were able to cause negative effects on M. aeruginosa cells. The cells, however, responded to against the possible damage afterwards. It is thus proposed the acute responses in the population during the early stage of sedimentation could be of importance in aiding the long-term survivor of Microcystis and recruitment in lake sediments. The present study also demonstrated the utility of the device in simulating the sediment environments for further investigation.

Broad host range plasmid-based gene transfer system in the cyanobacterium Gloeobacter violaceus which lacks thylakoids

Gloeobacter violaceus, a cyanobacterium lack of thylakoids, is refractory to genetic manipulations because its cells are enveloped by a thick gelatinous sheath and in colonial form. In this study, a large number of single cells were obtained by repeated pumping with a syringe with the gelatinous sheath removed. And an exogenous broad host range plasmid pKT210 was conjugatively transferred into G. violaceus. Analyses with dot-blot hybridization and restriction mapping showed that the exogenous plasmid pKT210 had been introduced into G. violaceus and stably maintained with no alteration in its structure. pKT210 extracted from G. violaceus exconjugants could be transformed into the mcr - mrr - E. coli strain DH10B but not the mcr(+) mrr(+) strain DH5alpha, which suggests that a methylase system may be present in G. violaceus.

原位聚合制备聚乙烯多相材料的微结构调控

聚合物多相材料的制备作为丰富材料品种，扩展材料用途的重要手段受到了广泛地关注和深入地研究。传统的熔融共混法制备聚合物多相材料时，一般需要加入增容剂来改善各相之间的相容性，从而使多相材料的性能达到预期的目标。但是由于增容剂本身也存在分散状态的问题，所以它的加入对多相材料的性能的影响比较复杂。因此，本论文致力于用原位共聚接枝的方法和粒子破碎的方法解决多相材料的界面结合和相分散问题。首先，采用对分散相进行共聚功能化改性的方法，使分散相与乙烯共聚，聚合过程中原位生成聚乙烯接枝物，这种聚乙烯接枝物能起到增容两相的作用，提高两相界面的粘结性，将这种方法应用到有机聚苯乙烯粒子和无机磁性钴粒子体系中，并分别进行了详细的研究；其次，通过聚苯乙烯载体的结构设计，使聚苯乙烯载体催化剂具有较高并且可控的活性，在较高的活性下，聚苯乙烯载体可以破碎，破碎后的聚苯乙烯均匀地分散到乙烯聚合产物中，并且碎片达到纳米级，用这种方法可以改善多相材料的相分散。 本论文的主要工作和研究结果总结如下： 1、采用悬浮聚合制备了交联聚苯乙烯粒子（c-PS），并且在聚苯乙烯粒子的表面引入了双键；c-PS粒子在乙烯填充聚合时，可以与乙烯共聚，从而制备了表面接枝聚乙烯的聚苯乙烯微球（PS-g-PE）；PS-g-PE微球上的聚乙烯的结晶温度与纯聚乙烯的结晶温度相比提高了6℃，说明聚乙烯与聚苯乙烯间的化学连接促进了PE的结晶；PS-g-PE与PE共混后，聚苯乙烯粒子与聚乙烯基体间的界面粘结增强。 2、采用乳液聚合制备了共聚型和不可共聚型交联聚苯乙烯乳胶粒子；将两种聚苯乙烯粒子用于乙烯填充聚合制备了聚苯乙烯/聚乙烯纳米共混材料，结果发现，共聚型聚苯乙烯/聚乙烯的断面上，两相间的界面模糊，并且拉伸断面上也没有不可共聚聚苯乙烯体系中由于拉应力作用而产生的空穴，超薄切片的透射电镜结果同样说明了可共聚型聚苯乙烯体系中界面粘结性的提高；当共聚型聚苯乙烯乳胶粒子的填充量较大（20 wt%）时，聚乙烯共混材料的凝胶含量比较高，说明有更多的共聚型聚苯乙烯在聚乙烯中充当交联点。总之，共聚型聚苯乙烯的填充量在非常少时（0.1 wt%）就能达到很好的改性效果。 3、采用阴离子共聚制备了两亲性的聚苯乙烯-b-聚-2-乙烯基吡啶嵌段共聚物（PS-b-P2VP）和聚4-（3-丁烯基）苯乙烯-聚苯乙烯-聚2乙烯基吡啶的三嵌段共聚物（PBSt-b-PS-b-P2VP）；两个嵌段共聚物在甲苯中均能自组装形成以PVP为核、PS为壳的胶束；Co2(CO)8在PS-b-PVP和PBSt-b-PS-b-P2VP甲苯胶束中热分解得到了由胶束稳定分散的Co磁流体；无水无氧的钴磁流体与乙烯填充聚合后得到了磁性聚乙烯纳米复合材料；钴纳米粒子在聚乙烯中稳定分散，不会发生聚集；PBSt-b-PS-b-P2VP与乙烯共聚后，纳米粒子与聚乙烯基体的相容性进一步提高，从而解决了金属纳米粒子在聚合物中的分散以及界面增强的问题。 4、采用悬浮聚合制备了三种溶胀能力不同的聚苯乙烯交联粒子，研究了溶胀时间对聚苯乙烯载体溶胀程度的影响，以及溶胀程度对乙烯聚合和产物聚乙烯形态的影响；实验结果发现溶胀程度较大、溶胀能力较强的聚苯乙烯载体的负载量和活性都较高；通过提高载体的溶胀程度可以增加催化剂对乙烯聚合的催化活性，最终使载体充分破碎分散到乙烯聚合产物中，原位形成纳米级聚乙烯共混物；乙烯聚合的动力学研究表明载体的破碎是一个由外向内逐步发生的过程；适当的活性可以控制载体破碎的速度，从而得到颗粒形态较好的聚乙烯产物。

低分子量马来酸酐化聚丁二烯橡胶改性聚乙烯增韧尼龙6

尼龙6是世界上使用最广泛的工程塑料之一，由于尼龙6大分子链中含有酰胺键能形成氢键，使其具有强韧、耐磨、耐冲击、耐疲劳、耐腐蚀等优异的特性。但是尼龙6存在低温和干态冲击性能差，吸水性大等弱点，不能满足汽车、电子、机械等行业对材料高韧性的需求。利用橡胶和弹性体对尼龙6进行增韧已经取得了很大的成功，但无法解决成本较高且基体材料刚性损失过大这一难题。实践证明，具有硬核软壳结构核壳粒子在增韧半晶性高聚物时，可以有效提高橡胶的增韧效率，减少体系拉伸强度和模量的损失。然而具有这种结构的核壳粒子合成过程复杂，成本很高，工业应用前景很小；而用传统的反应增容方法原位制备核壳粒子时，由于橡胶分子量大，黏度高，流动性差等特点限制了在反应中原位生成核－壳结构粒子的效率，影响最终的增韧效果。本论文首次尝试用低分子量的马来酸酐化聚丁二烯橡胶通过反应挤出的方法接枝改性聚乙烯，对尼龙6进行增韧，利用聚丁二烯橡胶分子链上的马来酸酐基团和尼龙6分子链的端氨基反应，在尼龙6基体中原位形成以聚乙烯为核，聚丁二烯为壳的核壳粒子，结果得到了高韧性、良好刚性的改性尼龙6。 实验证实该含有双键的低分子量橡胶能够成功的接枝到聚乙烯分子主链上，由于橡胶的马来酸酐化程度很高（14wt%），在同尼龙6共混过程中大大提高马酐基团和尼龙6端氨基之间反应生成的接枝共聚物的效率，可以有效减小两相间的界面张力，改善聚乙烯在尼龙6基体中的分散。通过透射电镜观察共混物内部形态结构发现，共混体系中形成了以聚乙烯为核，橡胶为壳的核－壳结构粒子。这种核－壳粒子对尼龙6有良好的增韧效果。当聚丁二烯橡胶的含量仅为1.5wt%时，尼龙6的冲击强度可以达到1100J/m，而拉伸强度还能保持在47.3MPa。 通过对核壳增韧体系冲击断面和拉伸力学曲线的分析我们发现，由于增韧体系中能够形成软壳硬核的核－壳结构粒子，在外力作用下，由橡胶相构成的壳结构能在聚乙烯核与基体之间形成纤维结构，这种纤维结构不仅能够改变体系的应力状态，引发基体屈服，而且大大增强了分散相粒子同基体之间的界面强度，提高体系的刚性。同时，由于两相间纤维结构的存在，材料内部形成一个类似“物理交联”的网络，材料表现出类橡胶的弹性拉伸性能，没有明显的屈服。 传统的S. Wu的逾渗理论不能很好预测这种核壳增韧体系的性能。Corté 和Leibler的模型不仅考虑了基体树脂的特性（ , , ）,而且还将分散相粒子尺寸（d）也考虑了进去，更好地预测了体系的脆韧转变点。同时在基体树脂相同，且都能增韧的前提下，可以通过Corté 和Leibler模型中参数C（代表分散相粒子能够引发基体发生屈服的能力）的大小预测增韧体系程度的大小，C值越大，体系增韧效果越好。 通过对从上述增韧体系中抽提出的原位生成的PE-g-PB-g-PA6接枝共聚物的热力学和形貌分析发现，PA6链段被限制在宽50-70nm条带状连续结构中，其运动能力受到限制，因此在结晶过程中PA6嵌段的扩散速度降低。导致在通常的结晶速率条件下（10oC/min）结晶不完善，其结晶度﹑结晶温度﹑熔融温度都有所降低，形成以γ晶型为主的不完善结晶。由于在PE和PA6链段之间由一个短的柔性PB链段相连接，因此PA6链段不能同PE发生共结晶，作为连续相PE的结晶行为受到接枝共聚物的影响要小很多。 关键词：低分子量马来酸酐化聚丁二烯橡胶，聚乙烯，尼龙6，核－壳结构，增韧，受限结晶。

茂金属支化及线性聚乙烯结晶行为的软物质特征

本论文以茂金属支化及线性聚乙烯为研究对象，系统的研究了共聚物体系结晶序列长度的多分散性以及动力学效应控制的聚合物结晶有序化过程：以茂金属支化聚乙烯为研究对象，提出了结晶序列长度多分散性的概念，并建立了一整套以热分级技术为基础的定量表征结晶序列长度多分散性的方法。从这一概念出发成功的解释了支化聚乙烯等温结晶后的双重熔融峰现象，不同长度的结晶序列在等温结晶过程中形成折叠链和捆束状晶体，它们具有不同的热力学稳定性，升温过程中形成熔融双峰。不仅如此，结晶序列长度多分散性的概念被成功的应用到聚丙烯体系，为监测和表征双向拉伸聚丙烯（BOPP）微观结构提供了新的研究方法和指标。对两个极端序列长度体系结晶行为的研究表明，聚合物结晶是能量效应、墒效应和动力学效应共同作用的结果。对短结晶序列在受限环境下的结晶熔融行为的研究证明除结晶完善过程外还存在非晶区嫡减的过程；线性聚乙烯在超薄膜条件下，结晶初始成核受到抑制，结晶从较厚的部分开始，超薄膜中的分子通过扩散过程在已经结晶的表面成核结晶，分子扩散过程成为结晶速率控制步骤，得到典型的支化晶体；分子在结晶前沿的吸附与解吸附过程是能量效应的体现，决定支化结晶的特征宽度，结晶温度越高，解吸附概率越大，结晶越宽，反之亦然；分子链在晶体中沿b轴倾斜约350，使得在生长面与基板成锐角的一侧分子的构象受到限制，导致结晶速率降低，结晶生长速度的不对称导致结晶形态的不对称。

茂金属线性低密度聚乙烯的光氧化和热力学降解研究

聚乙烯是广泛应用的合成高分子材料之一，工业化己有几十年历史，为适应不断扩展的加工及应用的要求，氧化降解反应一直是较活跃的研究领域。目前为止，一些氧化降解的规律和机理已经确定，某些还在积极地研究探索之中。茂金属线性低密度聚乙烯（m-LLDPE）是进入九十年代以后才出现的采用新型茂金属催化剂催化合成的树脂，与传统 Ziegler-Natta线性低密度聚乙烯（LLDPE）相比，其具有分子量分布窄，共聚单体在主链中分布均匀的特点，决定了它具有比传统LLDPE更加优异的使用性能，因而在生产生活中得到广泛应用。目前对其氧化降解的研究较少，因此对m-LLDPE的氧化及稳定性的研究对指导其应用有着积极的意义。本论文选择催化剂和共聚单体类型不同的三种m-LLDPE和两种传统LLDPE对比研究了m-LLDPE的光氧化和热力学降解稳定性，而且研究了过渡金属化合物光敏化剂对它的热力学降解的影响，热力学降解和光敏化剂对m-LLDPE的光、热氧化稳定性的影响。化测试方法表征m-LLDPE的光氧俐反应，长时间光氧化后支化度和结晶度都有不同程度的上升，光氧化速率主要受亚乙烯基双链浓度的影响，受支化度的影响不明显。因此在合成m-LLDPE的过程中应该合理设计茂金属催化剂，降低聚合产品中亚乙烯基双键的浓度，提高它的光氧化稳定性。采用熔体流动速率、流变法和红外光谱法研究了m-LLDPE和传统LLDPE在密炼过程中的热力学降解反应，和光敏化剂对热力学降解反应的影响，利用氧化诱导温度法快速表征热力学降解对m-LLDPE和LLDPE的氧化稳定性的影响，并利用自然光曝晒测试碳基指数和力学性能的变化和热氧化观察脆化时间的方法研究了热力学降解对它们的光、热氧化稳定性的影响，为m-LLDPE在气候条件下应用提供理论依据。共聚单体类型相同的m-LLDPEI和m-LLDPEZ相比较，m-LLDPEI在热力学降解过程中生成更多的氧化产物，光敏化剂硬脂酸钻和乙酰基丙酮钻对m-LLDPEI热力学降解生成氧化产物的敏化作用更强，也更显著地降低了密炼后样品的氧化诱导温度。流变法不仅表征了m-LLDPEI热力学降解过程中的分子结构的变化，也反映了样品的热稳定性。共聚单体类型不同的m-LLDPE3和LLDPEZ相比较，热力学降解后熔体流动速率下降得多，但拨基指数上升较少，这是m-LLDPE3密炼过程中熔融粘度较高的原因。光敏化剂更强烈得增强了LLDPE2的热力学降解过程中氧化产物的形成。热力学降解明显的降低了 LLDPE2的光氧化稳定性而没有对m-LLDPE3的光氧化稳定性产生明显作用，同时敏化剂对LLDPE2的光氧化敏化作用也更强烈一些。本文还研究了光敏化剂硬脂酸钻和硬脂酸铁对三种共聚单体类型不同的传统LLDPE和LDPE的光敏化效果，发现光敏化剂对不同链结构的聚乙烯的光敏化效果存在很大的差异，光敏化作用的顺序为：乙烯一辛烯共聚LLDPE＜乙烯一丁烯共聚LLDPE＜LDPE，光敏化效果并不随敏化剂浓度的增大而增强。从红外光谱可以分析聚乙烯中亚乙烯基浓度越高，光照过程中形成的氢过氧化物浓度越高，光敏化剂的敏化效果越强。

聚乙烯的结晶形态及高分辨电子显微学研究

高分辨电子显微学研究能从分子水平上直接观察到其他手段所无法得到的信息。但是由于衬度低和耐辐照性能差的缘故使其在高聚物特别是柔性链高分子结晶行为的研究上受到了很大的限制。本论文的研究工作从高聚物样品的统计电子噪声分辨率的各种影响因素出发，对样品的制备，电镜观察状态，底片及成像条件等各个方面进行了系统的分析和改进，克服了柔性链高分子耐辐照性能差的限制，首次成功地得到了聚乙烯这种极不耐辐照损伤的柔性链聚合物晶体的高分辨结构像，为高分辨电子显微学在柔性链聚合物中的应用提供了新的信息和依据，拓宽了高分辨电子显微学的应用领域，也为高分子的凝聚态结构和结晶行为研究提供了新的信，急。聚合物的形态研究，尤其是单晶的形态结构研究，一直是高分子物理中的一项重要研究内容。因为高分子的形态研究是联系高分子结构与高分子材料性质的桥梁和纽带，而且高分子熔体结晶的研究比溶液结晶更接近实际的加工情况，因此研究熔体单晶的形态结构对高分子材料的物理性能具有非常重要的意义。茂金属短链支化聚乙烯具有分子量分布窄，支化分布均匀的特点，其独特的结构使其具有很好的加工性能，而且在学术研究方面可以作为结构模型研究含有支链的高分子结晶行为，有很高的学术研究价值。在本论文的研究中得到了支化聚乙烯的熔体单晶，而且获得了不同温度下熔体单晶随温度变化的形态的改变。随着结晶温度的改变，茂金属催化短链丁基支化聚乙烯的熔体单晶的形态发生了一系列的变化，在结晶温度114℃时，单晶的形态为截顶菱形，可以明显的观察到直的｛110}生长面，在118℃时的透镜形单晶中｛110｝生长面很小而不能被观察到，仅能观察到弧形化的｛200｝生长面。在所有的结晶温度下熔体单晶的形态是沿着b轴不对称生长的。单晶形态的不对称是由于折叠链的倾斜导致单晶内部结构的不对称而引起的。在相同的结晶温度下形成的同一单晶的厚度是不均一的，这主要是由于分子链的倾斜使得两个侧向的｛200｝生长面内的折叠链的表面自由能不同，从而分子链的折叠长度不同而导致单晶出现两种不同的厚度。在低结晶温度下形成的弯曲形的丁基支化聚乙烯其弯曲的径向生长上都是沿着b轴方向生长的，弯曲作用主要是由于两个｛200）区域的生长速率不同引起的。