Paracrystalline lattice distortion in the near-surface region of melt-crystallized polyethylene films evaluated by synchrotron-sourced grazing-incidence X-ray diffraction
Paracrystalline lattice distortion in the near-surface region of melt-crystallized polyethylene films evaluated by synchrotron-sourced grazing-incidence X-ray diffraction
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DOI：
10.1021/ma034526q
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发表时间：
2003-07
期刊：
影响因子：
5.5
通讯作者：
Hirohiko Yakabe;S. Sasaki;O. Sakata;A. Takahara;T. Kajiyama
中科院分区：
文献类型：
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作者：
Hirohiko Yakabe;S. Sasaki;O. Sakata;A. Takahara;T. Kajiyama
聚合物材料的物理性质如粘附力和摩擦力与材料表面的分子聚集结构有关。然而，结晶聚合物的表面主要从形态学和化学的角度进行了研究。在聚乙烯（PE）的情况下，结晶聚合物的一个典型的例子，其固体膜的表面形态可视化的层状尺度的原子力显微镜和透射电子显微镜。1-3然而，在PE膜的表面的晶体结构尚未澄清。阐明薄膜表面的晶体结构对于从分子水平理解薄膜的表面性质是非常重要的。掠入射X射线衍射（GIXD），使用倏逝X射线最近已被应用于评估链堆积结构和链取向的结晶聚合物的近表面区域。4-8在这项研究中，通过同步辐射源GIXD测量研究了熔融结晶的PE膜的近表面区域中的晶格的尺寸和畸变。被用作样本。薄膜厚度为ca。在氮气氛下，通过浸涂方法，从HDPE的1.0重量%对二甲苯溶液在硅衬底的结晶（110）平面上制备400 nm的纳米晶体。所用硅衬底的尺寸为1英寸。直径3 mm，厚度3 mm。将由此制备的PE膜在约20 ° C下熔融。443 K，然后在Tc = 378、383、388和393 K下等温结晶24 h。通过掠入射广角X射线衍射（GIXD）的面内测量研究了薄膜近表面区域的晶体结构。在300 K下用安装在SPring-8的BL-13 XU光束线处的六轴衍射仪（日本同步辐射研究所，兵库，日本）对膜进行GIXD测量。9本研究中使用的单色入射X射线的波长λ为0.1285或0.1280 nm。入射狭缝处的光束尺寸为
Physical properties of polymeric materials such as adhesion and friction relate to molecular aggregation structure in the material’s surface. However, the surface of crystalline polymers has been studied mainly from morphological and chemical points of view. In the case of polyethylene (PE), a typical example of crystalline polymers, the surface morphology of its solid films was visualized in the lamellar scale by atomic force microscopy and transmission electron microscopy. 1-3 However, the crystal structure at the surface of PE films has not yet been clarified. Clarification of the crystal structure on the film surface is quite important for understanding the surface property from the molecular level. A grazing incidence X-ray diffraction (GIXD) using evanescent X-rays has recently been applied for evaluating chainpacking structure and chain orientation in the nearsurface region of crystalline polymers. 4-8 In this study, the dimension and distortion of the crystal lattice in the near-surface region of melt-crystallized PE films were investigated by synchrotron-sourced GIXD measurements.A high-density polyethylene (HDPE, MI) 14, Mitsui Chemicals, Inc.) was used as a sample. Films with a thickness of ca. 400 nm were prepared on the crystallographic (110) plane of silicon substrates from a 1.0 wt% p-xylene solution of HDPE by a dip-coating method under a nitrogen atmosphere. The size of silicon substrates used was 1 in. in diameter and 3 mm in thickness. The thus-prepared PE films were melted at ca. 443 K and then isothermally crystallized at Tc) 378, 383, 388, and 393 K for 24 h. The crystal structure in the near-surface region of the films was investigated by in-plane measurements of grazing-incidence wide-angle X-ray diffraction (GIXD). GIXD measurements were carried out on the films at 300 K with a six-axis diffractometer installed at a BL-13XU beamline of SPring-8 (Japan Synchrotron Radiation Research Institute, Hyogo, Japan). 9 The wavelength, λ, of monochromatized incident X-rays used in this study was 0.1285 or 0.1280 nm. The beam size at incident slits was