MEK wiping prior to chlorination to improve the adhesion of vulcanized SBR rubber containing paraffin wax

In this study, it was shown that the degree of effectiveness produced by halogenation with trichloroisocyanuric acid (TCI) was influenced by previous methyl ethyl ketone (MEK) wiping of a synthetic vulcanized styrene-butadiene rubber (R2) surface. The MEK wiping of the R2 rubber surface prior to chlorination with TCI removed the paraffin wax layer from the surface, which favoured the chlorination and oxidation reactions of the rubber. Chlorination with TCI decreased the contact angle values (increased the wettability) mainly due to the creation of C–Cl and C=O moieties, as well as roughness. The amount of these chemical moieties increased when the MEK wiping was applied prior to chlorination, so higher degrees of chlorination and oxidation were obtained on the R2 rubber surface. T-peel strength values increased more markedly if the MEK wiping was carried out before chlorination with TCI, in agreement with the higher degree of modifications produced in the R2 rubber surface. In fact, a cohesive failure in the R2 rubber was obtained in the adhesive joint produced with MEK wiped + TCI chlorinated R2 rubber.     

Plasma etching and plasma polymerization coating of carbon fibers. Part 2. Characterization of plasma polymer coated carbon fibers

Unsized AS-4 carbon fibers were subjected to RF plasma etching and/or plasma polymerization coating in order to enhance their adhesion to vinyl ester resin. Ar, N₂ and O₂ were utilized for plasma etching, and acetylene, butadiene and acrylonitrile were used for plasma polymerization coating. Etching and coating conditions were optimized in terms of plasma power, treatment time, and gas (or monomer) pressure by measuring the interfacial adhesion strength. Interfacial adhesion was evaluated using micro-droplet specimens prepared with vinyl ester resin and plasma etched and/or plasma polymer coated carbon fibers. Surface modified fibers were characterized by SEM, XPS, FT-IR, α-Step, dynamic contact angle analyzer (DCA) and tensile strength measurements. Interfacial adhesion between plasma etched and/or plasma polymer coated carbon fibers and vinyl ester resin was reported previously (Part 1), and characterization results are discussed is this paper (Part 2). Gas plasma etching resulted in preferential etching of the fiber surface along the draw direction and decreased the tensile strength, while plasma polymer coatings altered neither the surface topography of fibers nor the tensile strength. Water contact angle decreased with plasma etching, as well as with acrylonitrile and acetylene plasma polymer coatings, but did not change with butadiene plasma polymer coating. FT-IR and XPS analyses revealed the presence of functional groups in plasma polymer coatings.     

苯胺的等离子体聚合

以苯胺为单体,在等离子体条件下聚合得到了致密的黄色有机膜,用红外和紫外—可见吸收谱及 xps 等方法研究聚合成的有机薄膜的成分和结构,初步试验了质子化对其电阻率的影响。     

Surface modification and degradation of poly(lactic acid) films by Ar-plasma

Surface modification of poly(lactic acid) (PLA) film surface by Ar-plasma was investigated by contact angle measurements and XPS in order to answer the following two questions. (1) Could the Ar-plasma modify the PLA film surfaces? (2) What chemical reactions occurred on the film surfaces during the Ar-plasma treatment? The Ar-plasma treatment did not lead to hydrophilic modification of the PLA film surface, but to degradation reactions of the PLA film. Poor modification may be due to instability of the carbon radicals formed from C—O bond scission in the PLA chains by the Ar-plasma.     

Improving the adhesion properties of polypropylene using a liquid-phase sulfonation treatment

This work describes the effects of a stable, short-reaction time, liquid-phase sulfonation technique aimed at improving the adhesion properties of polypropylene. The relationships among SO₃ concentration (0.15, 0.2, and 0.3 N), treatment time, surface chemistry, and adhesion debond strength have been investigated for polypropylene (PP) sheets sulfonated with SO₃ dissolved in 1,1,2-trichloro 1,2,2-trifluoroethane and neutralized using ammonium hydroxide (NH₄OH) or polyethyleneimine (PEI). It was confirmed that PEI neutralized specimens, compared to untreated PP, exhibited a larger increase in debond strength (~269% increase) than similarly treated specimens neutralized with NH₄OH (~210% increase). ATR-FTIR spectroscopy indicates the formation of sulfonic acid, ethylenic, ketone and alcoholic hydroxyl groups. These results are supported by X-ray photoelectron spectroscopy (XPS) that show the O : C ratios increasing from 0.03 to 0.25 for both the NH₄OH and PEI, and the S : C atomic ratios increasing from 0.0 to 0.05 and 0.06 for the NH₄OH and PEI, respectively. Furthermore, XPS examination of PEI neutralized specimens revealed a nitrogenated surface (~6%), providing evidence that PEI had grafted onto the sulfonated surface. The observed increases in adhesion are attributed to formation of polar functionalities and increased wettability (as measured by water contact angle measurements). The neutralizing agent also affects degree of adhesion improvement: the PEI causes larger increases in adhesion compared to the NH₄OH. The physical effects of sulfonation were examined using environmental scanning electron microscopy (ESEM), which showed crack formation after 2 min of treatment. Sulfonation times beyond 5 min degraded the polymer surface (severe microcracking and sloughing of the surface layer) decreasing the adhesion debond strength.     

退火温度对铪棒织构及腐蚀性能的影响

采用X射线衍射（XRD）研究了不同退火温度下铪棒宏观织构的演变,采用场发射扫描电子显微镜（SEM）、X射线能谱分析（EDS）、X射线光电子能谱分析（XPS）研究了铪棒在360℃/18.6MPa进行28天水腐蚀后腐蚀产物的形貌、成分以及对腐蚀产物价态及迁移进行了表征。结果表明：热轧态的铪棒在RD-TD投影面出现了四种织构,表现为轴向复合织构。基面﹛0002﹜织构在各个阶段表现出很强的遗传性,其余织构均发生了不同变化。铪棒的腐蚀层由10～100nm的铪的氧化物颗粒堆积形成,柱面﹛10-10﹜退火织构比基面﹛0002﹜织构腐蚀速度快。腐蚀层优先形成Hf(4-x)+中间态氧化物,在生长过程中Hf(4-x)+失去电子变成Hf4+,与氧结合形成HfO2。