秸秆粉的改性及其表面极性对木塑复合材料界面的影响

通过接枝苯乙烯对秸秆粉表面进行改性,采用毛细管上升法测定了秸秆粉、改性秸秆粉的表面接触角,依据Washburn方程和Owens法,求解2种秸秆粉的表面自由能及其极性和非极性分量,并通过电子拉伸试验机、扫描电子显微镜研究了不同秸秆粉对木塑复合材料力学性能、微观形貌的影响。结果表明,改性秸秆粉的表面自由能为24.77 mN/m,体现分子色散力的非极性分量为19.79 mN/m;而秸秆粉的表面自由能为18.90 mN/m,其非极性分量为3.75 mN/m,说明接枝共聚可有效地改善秸秆粉的表面极性;与聚合物复合时,改性秸秆粉比秸秆粉具有更好的界面融合性,改性秸秆粉在基体中的分散性优于秸秆粉。     

新型表面活性剂对酞菁蓝颜料的表面处理及表面性质的研究

本文自行设计并合成出新型颜料分散剂RSJ,用于酞菁蓝颜料的表面改性处理。分别研究在不同RSJ加量条件下酞菁蓝颜料临界润湿表面张力、表面自由能、流动性以及水相中分散稳定性的改善效果,并从中发现:经RSJ0.5％～3.0％添加量改性处理后,颜料临界润湿表面能γ_c由23mN/m变为34.8mN/m,提高了51％;对水的接触角由82.4°变为47°,减小了47％。表面自由能中的色散成分γ_s~d变化不大,可以认为保持不变,但是γ_s~p却由18.9mN/m变大为27.2mN/m,使得γ_s整体提高13％。此外,流动性提高2.5倍,水中分散稳定性提高了29％。     

使用反相气相色谱法表征合成纤维表面润湿性

以聚丙烯纤维、聚癸二酰己二胺纤维和聚对苯二甲酸乙二醇酯纤维为研究对象,使用反相气相色谱法,以含有不同碳数的正烷烃和蒸馏水为探针分子,分别测定了合成纤维的表面自由能色散分量和水分子的净保留体积,表征其表面润湿性并分析影响因素。结果表明,纤维化学结构单元是合成纤维表面润湿性的决定性因素：具有非极性基团的聚丙烯纤维亲油性较好,具有极性基团的聚癸二酰己二胺纤维亲水性较好;纱线的线体结构影响合成纤维受热时的膨胀程度,从而显著影响表面自由能色散分量随温度的变化趋势。     

界面剂与共聚单体对固相接枝聚丙烯表面性质的影响

采用固相接枝方法,研究了以二甲苯为界面剂,以苯乙烯(St)、丙烯酸丁酯(BA)为接枝共聚单体对马来酸酐接枝聚丙烯(PP-g-MAH)表面性能的影响。研究结果表明,随着二甲苯用量的增加,PP- g-MAH的表面能和极性力分量呈先升后降的趋势,当w(二甲苯)=15%时,表面能(37.52 mN/m)和极性力分量(2.47 mN/m)均达到最大值;共聚单体St、BA的加入可以显著提高PP-g-MAH的表面能和极性力分量,共聚单体St的作用更为有效,其接枝物的极性力分量分别是PP-g-(MAH-co-BA)的2倍,PP- g-MAH的4.8倍。     

氧化钙的机械力化学活化

本文研究了振动磨中粉磨氧化钙(于1450℃分解碳酸钙得到)时发生的机械力化学变化及对氧化钙活性的影响。用反气相色谱技术测定了粉磨试样表面自由能的变化。发现表面自由能极性分量随粉磨的进行,开始时增大,继而减小,直至消失;表面自由能伦敦色散分量则一直增加。 将经1450℃煅烧、后经200h粉磨的氧化钙再于不同温度下加热,由于晶格应变的恢复和无定形物的再结晶,氧化钙反应活性降低。氧化钙的表面自由能下降,但表面自由能的极性分量又出现。     

反相色谱法研究玻璃纤维表面性能

用一系列非极性的正烷烃和极性溶剂为探针分子,以多种硅烷处理的玻璃纤维为固定相,进行了反相色谱实验,并以无限稀浓度下的保留体积理论处理实验结果,求得了各种硅烷处理玻纤的表面自由能色散分量,并对探针分子与纤维表面的特异相互作用作了讨论。     

RDX表面能及其分量的测定

采用Washburn薄层毛细渗透技术测定了RDX粉体的接触角和表面能及其色散、极化、电子受供体分量.选用非极性的二碘甲烷和1-溴萘作为测定RDX表面能色散分量的探针液体,极性的乙二醇和甲酰胺作为测定RDX表面能极性分量和酸、碱分量的探针液体.通过测定不同探针液体的渗透曲线,发现基于不同探针液体分子的接触角获得的RDX粉体的表面能成分彼此一致,RDX的总表面能(40.20 mJ · m-2)与理论计算结果(40.60 mJ · m-2)基本一致.测得的色散分量为23.71 mJ · m-2,极性分量为16.49 mJ · m-2,电子受体分量为1.149 mJ · m-2,电子供体分量为51.87 mJ · m-2.结果表明,在RDX的表面能中,色散分量占主要部分,而且在极性分量中电子供体碱性分量明显大于电子受体酸性分量.     

反气相色谱法研究改性累托石的表面性质

累托石的表面性质直接影响其在环境保护和催化领域中的应用,并对其复合材料的结构与力学性能影响较大.通过反气相色谱法,采用非极性和极性探针研究累托石(rectorite,REC)和经十二烷基-二甲基-苄基溴化铵处理的有机改性累托石(organic-modified rectorite with dodecyl benzyl dimethyl ammonium bromide,12-OREC)以及经十六烷基-三甲基溴化铵处理的有机改性累托石(organic-modified rectorite with hexadecyl trimethyl ammonium bromide,16-OREC)的表面性质.结果表明:表面改性直接影响其表面能的色散组分.100℃时,12-OREC和16-OREC的表面能的色散组分(24.85,30.43 mJ/m2)明显低于REC的表面能的色散组分(75.19 mJ/m2),且表面能的色散组分均随温度升高呈降低趋势,其中12-OREC的表面能的色散组分随温度降低最多.此外,经过改性的累托石其表面酸碱性也有所变化,呈酸性表面的累托石经季铵盐改性后呈碱性.     

大分子键合处理氢氧化铝的表面性质及其与常用聚合物的界面特性

本文研究了经大分子以键合方式包覆处理的氢氧化铝粉末的表面性质以及其与常用聚合物的界面特性。结果表明：（１）与末处理过的氢氧化铝相比,非极性液体与处理过的氢氧化铝压片的接触角变化较小,而极性液体与它的接触角一般明显增大。（２）改性后的氢氧化铝的表面张力均明显下降,其中表面张力有极性分量大幅度下降而色散分量稍有提高。与常见聚合物的界面张力以及它的极性分量和色散分量均降而色散分量稍有提高。与常见聚合物的     

花生壳粉表面性能及木塑复合材料界面性能的研究

通过动态法研究了浸润粉层的液体质量的平方随时间的变化规律,测定了不同探测液对花生壳的接触角。采用平衡接触角仪测定了探测液对改性聚乙烯的接触角,进而根据Focks理论推导出花生壳和改性聚乙烯的表面自由能及其极性分量和非极性分量,并计算出花生壳粉/聚乙烯复合材料的界面张力和黏附功。结果表明:相容剂Bondyram 5108的加入,使聚乙烯的极性分量和非极性分量都不同程度地增加,改善了花生壳粉在聚乙烯基体中的分散性,降低了复合材料的界面张力,增大了黏附功。     

Reduction dependent wetting properties of graphene oxide

This study reports contact angle measurements of standard, diol and aromatic solvents on graphene oxide thin films thermally reduced in ultra-high vacuum up to 900 °C. The films were chemically and morphologically characterized using respectively X-ray photoemission spectroscopy and atomic force microscopy. The characterization shows that the wetting occurs in the chemically heterogeneous regime, namely the surface roughness (3 nm) does not influence the wetting properties of the samples. Zisman, Owens–Wendt and Neumann methods have been applied in order to calculate the surface free energy of the thin films showing that the Owens–Wendt method best fit the data trends. The surface free energy varies from 51 mN/m (pristine graphene oxide) to 39 mN/m (900 °C reduced graphene oxide). A correlation between the surface chemical composition, the surface free energy and its polar and dispersive components is reported, giving a rationale to the wetting properties of graphene oxide and reduced graphene oxide.     

固体材料性质对生物垢形成的影响

从固体材料表面性质入手 ,探讨了材料的表面粗糙度、表面自由能、界面能以及材料与生物垢之间的界面能对生物垢形成的影响。实验结果表明 :在 0 2 9～ 1 82 μm内 ,材料的表面粗糙度越大越有利于生物垢的形成 ;在 11 7～ 38 3mN/m内 ,材料的表面自由能和固 -液界面能与生物垢形成之间没有简单、直接的关系 ;在 1 3～ 18 0mN/m内 ,固体材料与生物垢之间的界面能对生物垢的形成存在一个极大值 ,此时的界面能约为 3 4mN/m。     

Effect of electron beam irradiation and vinyl acetate content on the physicochemical properties of LDPE/EVA blends

The radiation‐induced crosslinking, compatibility, and surface modification of low density polyethylene/ethylene vinyl acetate blends (LDPE/EVA) were investigated. The structural and physical properties were characterized in terms of gel content, hot set, mechanical properties, contact angle, and surface free energy. The highest crosslink density was obtained at 20 wt % of EVA. Gel content of LDPE/EVA blends was increased with increasing irradiation dose, vinyl acetate (VA), and EVA contents. The hot set results are consistent with the gel content data. Mechanical testing showed that the tensile strength of samples increased with increasing irradiation dose up to 180 kGy, whereas the elongation at break was decreased with increasing irradiation dose. Contact angle measurements showed that the surface hydrophillicity of LDPE blend was increased with increasing irradiation dose and contents of both VA and EVA. The surface free energy was greatly dependent on irradiation dose and content of both VA and EVA. The total surface free energies of different LDPE formulations were in the range 17.25–32.51 mN/m, in which the polar (^pσ) and disperse (^dσ_s) values were within the range 16.52–26.6 and 0.9–5.91 mN/m, respectively. In conclusion, electron beam irradiation and blending LDPE with EVA improved the wettability or adhesion properties of LDPE/EVA blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Adhesion of Streptococcus sanguis to porous and non-porous substrates with well-defined surface energies

Adhesion of the oral bacterium Streptococcus sanguis was investigated on two series of surfaces, one solid, non-porous and one porous with a pore diameter centered around 0.2 μm. Each series consisted of four substrates with varying surface free energies: pure aluminum oxide, poly(ethylene glycol) (PEG)-modified aluminum oxide, and two types of silanized aluminum oxide. The surface composition was analyzed by ESCA and the surface free energy and acid-base character were determined by contact angle measurements using water, formamide, and diiodomethane according to van Oss and Good. Contact angle measurements were conducted on non-porous substrates which had been subjected to the same silanization procedure as the porous ones. Untreated aluminum oxide and PEG-modified aluminum oxide were both hydrophilic and gave water contact angles of less than 10°. One silanization procedure gave a surface of intermediate hydrophobicity, with a γ^tot of 47.5 mN/m; the other gave a strongly hydrophobic surface of γ^tot = 27.4 mN/m. Adhesion of S. sanguis was measured by using radiolabelled bacteria. It was demonstrated that more bacteria adhered to the porous than to the non-porous substrate and that the PEG treatment, as well as the two silanization procedures, resulted in a decrease in bacterial adhesion, in relation both to the controls treated with aqueous buffer and to surfaces treated with fresh saliva.     

Thermal decomposition of alkyl ammonium ions and its effects on surface polarity of organically treated nanoclay

The surface free energy and surface polarity of organically modified montmorillonite clay change when exposed to elevated temperatures. This was verified in this study using contact angle measurements and Wu's harmonic-mean equation. It was observed that the surface polarity of organically modified clay measured from the values of contact angle of water and diiodomethane reduced significantly owing to thermal degradation of the organic modifier of clay, the latter was confirmed by Fourier transform infra-red spectroscopy. As a consequence, nonpolar polymer, polypropylene (PP), was found to spread more on heat treated surface of organically modified clay than a polar polymer, polyamide 6 (PA6). The ramification of these phenomena on blending of PP, PA6, and organically modified clay is discussed.     

Studies on the surface free energy and surface structure of PTFE film treated with low temperature plasma

The surface free energy and surface structure of poly(tetrafluoroethylene) (PTFE) film treated with low temperature plasma in O₂, Ar, He, H₂, NH₃, and CH₄ gases are studied. The contact angles of the samples were measured, and the critical surface tension γ_c (Zisman) and γ_c (max) were determined on the basis of the Zisman's plots. Furthermore, the values of nonpolar dispersion force γ^a_s, dipole force γ^b_s, and hydrogen bonding force γ^c_s to the surface tensions for the plasma-treated samples were evaluated by the extended Fowkes equation. Mainly because of the contribution of polar force, the surface free energy and surface wettability of PTFE film which was treated with H₂, He, NH₃, Ar, and CH₄ for a short time increased greatly. Electron spectroscopy for chemical analysis (ESCA) shows that the reason was the decrease of fluorine and the increase of oxygen or nitrogen polar functional group on the surface of PTFE. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1733–1739, 1997     

高抗水水性丙烯酸酯乳液的合成、表征及其在工业滤纸中的应用

以十二烷基硫酸钠(SDS)和OP-10为复合乳化剂,丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、甲基丙烯酸十二氟庚酯(FA)为主要原料,采用预乳化半连续种子聚合法制备具有核壳结构的高抗水性丙烯酸共聚乳液。利用红外光谱、扫描电子显微镜、透射电子显微镜、接触角仪等对乳液及浸渍滤纸进行了表征;同时,讨论了核壳单体配比、乳化剂用量、引发剂用量以及含氟单体用量对反应与浸渍滤纸耐水性能的影响。结果表明,优化反应条件后,硬单体MMA配以适量FA单体为壳,制备的共聚乳液稳定性好,粒度均匀,具有明显球状和核壳结构。乳胶膜表面能随着含氟量的增加大幅度降低,当氟单体含量为16.3%时,其表面能降至19.9 m N/m。利用功能氟单体包覆于核层外表,当氟单体含量为4.7%时,原乳胶表面能从37.7 m N/m降至24.6 m N/m,所浸渍滤纸耐水性能明显优于不含氟乳液浸渍滤纸,达到"低氟高效"的效果。