The photon scanning tunneling microscope and its applications

A simple photon scanning tunneling microscope (PSTM) is described. Its lateral resolution (similar to 10nm with a maximal scanning range of 10 mu m x 10 mu m ) is much better than that of a conventional optical microscope. Its principle, the fiber optic tip fabrication and PSTM images of different samples such as mica, HDPE and LiNbO3 are presented.

氯化原位接枝反应合成酐化CPE及结构表征

本硕士论文主要工作是利用氯化原位接枝反应对高密度聚乙烯（HDPE）进行氯化及醉基化。对上述反应体系的反应机理，产物的化学结构、链结构、反应条件对MAH接枝率（GD％）的影响以及物理机械性能等进行了详细的讨论。采用FT-IR和~1HNMR方法对氯化原位接枝反应的配化产物CPE-g-MAH进行了表征。二者均证明了MAH单体接枝到氯化聚乙烯主链上，证实了氯化原位接枝反应的可行性。并用~1HNMR，结合EI-Ms电喷雾质谱表征了氯化原位接枝共聚物CPE-g-MAH的链结构。反应过程中，主链及支链均被氯化。氯化原位接枝共聚物CPE-g-MAH凝胶含量的测定结果表明，在氯化原位接枝过程中没有交联反应的发生。论文中还研究了醉化CPE的合成过程。主要针对反应条件对MAH接枝率（GD％）的影响进行了详细的讨论，包括氯化原位接枝的温度模式、MAH单体量、氯气流量、氯含量等对MAH接枝率（GD％）的影响。同时探讨了氯化原位接枝反应历程。考查了氯化原位接枝MAH体系和氯化HDPE林系自由基浓度随时间变化的情况。接枝产物的硫化特性曲线表明：由于MAH的引入，聚合物主链上连接有酸配基团，使得氯化原位接枝共聚物CPE-g-MAH可以通过官能团之间相互反应而交联成为可能。随着MAH接枝量的升高，接枝率上升使得HDPE大分子链上带有更多MAH接枝点，CPE-g-MAH可硫化的程度相应提高。接枝产物的力学性能测试结果表明：随着MAH接枝率的增加，材料的拉伸强度上升，而材料的扯断伸长率、硬度等力学性能下降。

聚乙烯与丁腈橡胶的共混与改性

本论文工作分两部分：第一部分研究了共聚改性的聚乙烯（Surlyn）与丁腈橡胶（NBR）共混体系的相互作用，以及Surlyn/NBR共混物中Surlyn的等温结晶动力学规律；第二部分研究了具有不同结构参数的CPE对HDPE/NBR共混体系的增容改性及共混体系的交联改性。本文通过对有关体系的形态和性能进行系统分析之后，提出了动态交联——特殊相互作用的协同作用模型。

聚烯烃复合膜的附生结晶研究

本文以电子显微镜、光学显微镜为手段，系统地研究了结晶温度，样品厚度、降温速率、分子支化等因素对聚乙烯（PE）与全同立构聚丙烯（ipp）复合膜附生结晶的影响。降温速率过慢或过快均对HDPE/ipp体系的附生结晶不利。HDPE/ipp体系的附生界面层厚度在降温速率缓慢时约为900A；在降温速率过快时约为1200A；在附生结晶的最佳降温速率下的约为1800A。HDPE分子支化对PE/ipp体系的附生结晶也不利。支化越严重，附生界面层厚度越薄。在最佳降温速率下，HDPE附生界面层厚度约为1800A；LLDPE约为1200A；LDPE不足300A。以偏光显微镜研究HDPE/ipp体系的附生结晶较为成功，在HDPE厚达3600A时，仍可看到很少量的HDPE取向结晶。而以偏光显微镜研究LLDPE/ipp、LDPE/ipp体系附生结晶则较为困难。

一种纳米分辨率近场光学显微镜-光子扫描隧道显微镜

报导了一台光子扫描隧道显微镜。论述了原理，结构，光纤探针制造，信号放大以及调试中解决的几个技术问题等。图像的横向分辨率优于10nm,纵向分辨率约1nm，扫描范围10μm×10μm。还观察了云母、高密度乙烯HDPE高取向薄膜等透明材料及铌酸锂(LiNbO_3+T_i)波导的电光效应等。

The photon scanning tunneling microscope and its applications

A simple photon scanning tunneling microscope (PSTM) is described. Its lateral resolution (similar to 10nm with a maximal scanning range of 10 mu m x 10 mu m ) is much better than that of a conventional optical microscope. Its principle, the fiber optic tip fabrication and PSTM images of different samples such as mica, HDPE and LiNbO3 are presented.

电子辅照耐高温（电缆用）高分子材料改性的研究

本文以高密度聚乙烯（HDPE）为基料研制出电子辐照耐高温阻燃电线电缆绝缘材料，并对HDPE的辐射交联机制进行了讨论，辐射交联不仅发生在无定形区，结晶区对交联有贡献．对抗氧剂、敏化剂、炭黑、阻燃剂等对材料交联性质的影响做了一些试验，总结出一些规律，尤其对敏化剂在HDPE交联中的作用做了合理的阐述．阻燃剂对材料耐温等级提高很大，而且辐射交联后氧指数有所提高， 研究了HDPE与乙烯一醋酸共聚物（EVA)共混辐照后的一些性 质,EVA对HDPE的改性的有利与不利之处，还进一步探讨了用三元乙丙橡胶(EPDM),硅橡胶、氟材料来提高体系耐温等级和其它性能的办法． 耐高温皿燃线缆材料具有非常广泛的用途，它的耐温等级为135℃,氧指数可达30以上．该成果具有非常广泛的用途，填补了国内空白，为辐射加工产业化做出一定贡献．

Novel morphology of polyethylene crystals created upon melt crystallization of spin-coated film

We demonstrate a strikingly novel morphology of high-density polyethylene (HDPE) crystal obtained upon melt crystallization of spin-coated thin film. This crystal gives windmill-like morphology which contains a number of petals. A detailed inspection on this morphology reveals that each petal is actually composed of terrace-stacked PE lamellae, in which the polymer chains within crystallographic a-c planes adopt similar to 45 degrees tilting around b-axis. The surrounding domains associated with a petal of the windmill composed of twisted lamellar overgrowths with an identical orientation of their long axis, which is the crystallographic b-axis shared by the petal and its corresponding twisted lamellar overgrowths.

Structural evolution of tensile deformed high-density polyethylene at elevated temperatures: Scanning synchrotron small- and wide-angle X-ray scattering studies

The structural evolution of an ice-quenched high-density polyethylene (HDPE) subjected to uniaxial tensile deformation at elevated temperatures was examined as a function of the imposed strains by means of combined synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) techniques. The data show that when stretching an isotropic sample with the spherulitic structure, intralamellar slipping of crystalline blocks was activated at small deformations, followed by a stress-induced fragmentation and recrystallization process yielding lamellar crystallites with their normal parallel to the stretching direction. Stretching of an isothermally crystallized HDPE sample at 120 degrees C exhibited changes of the SAXS diagram with strain similar to that observed for quenched HDPE elongated at room temperature, implying that the thermal stability of the crystal blocks composing the lamellae is only dependent on the crystallization temperature.

氯化原位接枝反应制备羟基官能化CPE—结构表征

以高密度聚乙烯(HDPE)为基体,采用气-固氯化原位接枝反应合成了以氯化聚乙烯(CPE)为骨架聚合物、丙烯酸-2羟基乙酯(HEA)为支链的接枝共聚物.反应中不需要加入任何引发剂,以氯自由基引发接枝及氯代反应,得到羟基官能化CPE接枝聚合物.并用1H-NMR,FT-IR,GPC及X-射线衍射等对接枝共聚物的结构进行了表征.

Thermal and crystallization behaviors of polyethylene blends synthesized by binary late transition metal catalysts combinations

A series of reactor blends of linear and branched polyethylenes have been prepared, in the presence of modified methylaluminoxane, using a combination of 2,6-bis[1(2,6-dimethyphenylimino) pyridyl]-cobalt(II) dichloride (1), known as an active catalyst for producing linear polyethylene, and [1,4-bis(2,6-diidopropylphenyl)] acenaphthene diimine nickel(II) dibromide (2), which is active for the production of branched polyethylene. The polymerizations were performed at various levels of catalyst feed ratio at 10 bar. The linear correlation between catalyst activity and concentration of catalyst 2 suggested that the catalysts performed independently from each other. The weight-average molecular weights ((M) over bar (w)), crystalline structures, and phase structures of the blends were investigated, using a combination of gel permeation chromatography, differential scanning calorimetry, wide-angle X-ray diffraction, and small angle X-ray scattering techniques. It was found that the polymerization activities and MWs and crystallization rate of the polymers took decreasing tendency with the increase of the catalyst 2 ratios, while melting temperatures (T-m), crystalline temperatures (T,), and crystalline degrees took decreasing tendency. Long period was distinctly influenced by the amorphous component concentration.

Brittle-ductile transition of particle toughened polymers: influence of the matrix properties

It was theoretically pointed out that the product of the yield stress and yield strain of matrix polymer that determined the brittle-ductile transition (BDT) of particle toughened polymers. For given particle and test condition, the higher the product of the yield stress and the yield strain of the matrix polymer, the smaller the critical interparticle distance (IDc) of the blends was. This was why the IDc (0.15 mum) of the polypropylene (PP)/rubber blends was smaller than that (0.30 mum) of the nylon 66/rubber blends, and the IDc of the nylon 66/rubber blends was smaller than that (0.60 mum) of the high density polyethylene (HDPE)/rubber blends.

原位聚合聚乙烯/蒙脱土纳米复合材料的结晶行为

用DSC研究了HDPE与MMT负载的催化剂熔融共混和原位聚合得到的两种纳米复合材料的熔融、结晶行为和等温结晶动力学.结果表明,HDPE与熔融共混样品的结晶度、平衡熔点、球晶生长速率和结晶能力大体相同;原位聚合得到的HDPE/MMT纳米复合材料的结晶度和平衡熔点高于纯HDPE;在相同过冷度条件下熔融结晶速率和结晶能力低于纯HDPE,而在相同结晶温度Tc下,熔融结晶速率和结晶能力则高于纯HDPE.纯HDPE的晶体生长侧向单位面积表面自由能最小,其次是熔融共混样品,原位聚合样品最大,且随MMT含量的增加逐渐升高.

Mechanical and thermal properties of high-density polyethylene toughened with glass beads

Glass beads were used to improve the mechanical and thermal properties of high-density polyethylene (HDPE). HDPE/glass-bead blends were prepared in a Brabender-like apparatus, and this was followed by press molding. Static tensile measurements showed that the modulus of the HDPE/glass-bead blends increased considerably with increasing glass-bead content, whereas the yield stress remained roughly unchanged at first and then decreased slowly with increasing glass-bead content. Izod impact tests at room temperature revealed that the impact strength changed very slowly with increasing glass-bead content up to a critical value; thereafter, it increased sharply with increasing glass-bead content. That is, the lzod impact strength of the blends underwent a sharp transition with increasing glass-bead content. It was calculated that the critical interparticle distance for the HDPE/glass-bead blends at room temperature (25degreesC) was 2.5 mum. Scanning electron microscopy observations indicated that the high impact strength of the HDPE/glass-bead blends resulted from the deformation of the HDPE matrix. Dynamic mechanical analyses and thermogravimetric measurements implied that the heat resistance and heat stability of the blends tended to increase considerably with increasing glass-bead content.

Compatibilization effects of block copolymers in high density polyethylene/syndiotactic polystyrene blends

Three triblock copolymers of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) of different molecular weights and one diblock copolymer of poly[styrene-b-(ethylene-co-butylene)] (SEB) were used to compatibilize high density polyethylene/syndiotactic polystyrene (HDPE/sPS, 80/20) blend. Morphology observation showed that phase size of the dispersed sPS particles was significantly reduced on addition of all the four copolymers and the interfacial adhesion between the two phases was dramatically enhanced. Tensile strength of the blends increased at lower copolymer content but decreased with increasing copolymer content. The elongation at break of the blends improved and sharply increased with increments of the copolymers. Drop in modulus of the blend was observed on addition of the rubbery copolymers. The mechanical performance of the modified blends is strikingly dependent not only on the interfacial activity of the copolymers but also on the mechanical properties of the copolymers, particularly at the high copolymer concentration. Addition of compatibilizers to HDPE/sPS blend resulted in a significant reduction in crystallinity of both HDPE and sPS. Measurements of Vicat softening temperature of the HDPE/sPS blends show that heat resistance of HDPE is greatly improved upon incorporation of 20 wt% sPS.