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     

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）与未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，其中表面张力的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下降。（３）用弹性体处理的氢氧化铝的     

表面活性剂在不同固体表面的润湿性能研究进展

综述了表面活性剂在不同极性固体表面的润湿性能研究进展,主要总结了表面活性剂在石英和玻璃等极性表面、聚甲基丙烯酸甲酯(PMMA)等中等极性表面、聚四氟乙烯(PTFE)等非极性表面的润湿作用规律及影响因素。结合作者的研究工作,特别阐述了系列表面活性剂在煤沥青表面的润湿规律。对表面活性剂在固体表面的应用趋势进行了展望。     

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。     

聚合物填料的润湿和化学法表面处理

聚合物填料表面自由能值低，属于非极性憎水性表面，为改善聚合物润湿性能，必须采用化学法进行表面处理，从根本上改变聚合物填料的表面分子结构，使憎水基团变为亲水基团。文中介绍了三种化学表面处理方法：光氯化法、液相法、气相法。     

温度对杨木木粉表面自由能和表面极性的影响

通过毛细管上升法测定了经过不同温度处理的杨木木粉的表面接触角,依据Washburn方程和Owens-wendt-Kaelble法,求解了经过不同温度处理的杨木木粉的表面自由能及其极性分量和非极性分量。结果表明,杨木木粉的表面自由能为23.43 mN/m,体现分子色散力的非极性分量为4.64 mN/m,在处理时间为2 h的条件下,随着处理温度的上升,杨木木粉的总表面自由能略有下降,体现其分子色散力的非极性表面自由能上升,体现其表面极性值的极性表面自由能下降,并分析了上述结果的原因。     

难粘聚合物的辐射表面接枝改性

<正> 聚四氟乙烯(PTFE)、聚乙烯(PE)、聚丙烯(PP)和聚甲醛(POM)等是目前国防及国民经济各部门广泛使用的热塑性聚合物。它们具有优良的物理、机械和电性能,其缺点是难于使用一般的极性粘合剂直接进行粘合,需在粘合前进行表面处理,方能有高的粘合强度,因而这些聚合物素有“难粘聚合物”之称。聚合物难粘的主要原因是表面张力低、表面非极性与粘合剂的溶解度参数差值大及表面存有弱的界面层等。     

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。     

竹纤维的表面能分析及其增强PP复合材料的力学性能

通过先碱处理再偶联剂处理的方法对竹纤维进行表面改性,采用非织造-模压工艺制备了竹纤维增强聚丙烯(PP)复合材料。根据Owens-Wendt法分别计算了碱处理和在此基础上偶联剂处理的竹纤维的表面能以及极性分量和非极性分量,研究了碱处理中Na OH溶液浓度及偶联剂处理中硅烷偶联剂溶液浓度对竹纤维表面能的影响,并探索了竹纤维的表面能与复合材料力学性能的关系。结果表明,随着Na OH溶液浓度增大,竹纤维表面能呈增大趋势,拉伸强度呈降低趋势;碱处理的竹纤维增强PP复合材料的力学性能受竹纤维表面能和本身强度的综合影响,当Na OH溶液浓度为5%时,复合材料的综合力学性能最优。在Na OH溶液浓度为5%的碱处理基础上进行偶联剂处理可大幅提高竹纤维的非极性分量,随着硅烷偶联剂溶液浓度的增加,竹纤维的表面能降低;复合材料的力学性能与偶联剂处理后竹纤维表面能的变化没有对应关系,当偶联剂溶液浓度为3%时,复合材料的力学性能最优。     

磷酸表面改性Kevlar纤维及其复合材料性能的研究

采用磷酸溶液对芳纶纤维(Kevlar)进行了表面改性,通过考察其表面化学结构、元素组成、表面形貌及表面粗糙度的变化研究了磷酸对Kevlar纤维表面改性的效果.结果发现,改性后的纤维表面引入了含氧基团,并产生了明显的刻蚀作用.利用溶液预浸渍工艺和高温模压成型技术制备了Kevlar增强双马来酰亚胺树脂(BMI)复合材料,通...     

Surface modification of PTFE by 60Co γ-ray irradiation

Surface carboxyl groups were formed during the ⁶⁰Co γ-ray irradiation of poly(tetrafluoroethylene) (PTFE) in air. Fourier transform infrared spectroscopy enables the detection of surface carboxyl groups. The contact angles were used to calculate the dispersive and polar components of the surface free energy according to a two-liquid method. The γ-ray irradiation of PTFE mainly caused degradation of the polymer. The concentration of carboxyl groups, the wettability, the friction, and the dispersive and polar components of the surface energy and the crystallinity on PTFE surface were increased, while the particle size of PTFE decreased with increasing irradiation dose. A highly modified PTFE was used to reduce the aqueous liquid repellent properties of PTFE. A 20 kGy dose for modified PTFE surface was suitable in air additivity in antifriction, anticorrosion, antifouling, lubrication, and noise reduction coatings. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 435–441, 1998     

Studies on γradiation treatment of poly(tetrafluoroethylene) powder

γ-Irradiation of poly(tetrafluoroethylene) (PTFE) in the presence of air results in degradation of polymer chains by insertion of oxygen. At first, in the low-dose range below 400 kGy, a rise in crystallinity can be observed due to main chain scission in the amorphous part of the macromolecules. Dose increase up to approximately 1000 kGy causes progressive degradation of molecular weight as well as a growing degree of carboxylation of PTFE and increased concentration of trifluoromethyl groups in near-surface regions. At constant irradiation temperature, the properties of irradiated PTFE hardly depend on dose rate and starting material. The degree of carboxylation of the irradiated unsintered PTFE is appreciably lower in comparison with electron-irradiated PTFE under comparable conditions. © 1996 John Wiley & Sons, Inc.     

Thermal stability of electron beam-irradiated polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) was subjected to 1 MeV electron beam irradiation in air. The thermal stability and the degradation fragments of the irradiated polymer were studied in dependence on the radiation dose up to 4 MGy by thermogravimetric analysis coupled with mass spectrometry. The TGA results confirm the known decrease in the thermal stability of irradiated PTFE with increasing radiation dose. At the thermal degradation, CO₂, HF, and fluorocarbon fragments are evolved from the irradiated samples. CO₂ and HF are formed by decomposition of peroxy radicals up to 250°C. In addition, low molecular weight fluorocarbons are desorbed from the irradiated PTFE. At temperatures above 300°C, CO₂ is formed by the decarboxylation of radiation-induced COOH groups inside the PTFE. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2287–2291, 1997     

Water vapor solubility of poly(lactic acid) films modified the surface by vacuum ultraviolet irradiation

Surface modification of poly(lactic acid) (PLA) film is performed via 172 nm excimer lamp irradiation. Effects on water vapor solubility and physical properties via vacuum ultraviolet (VUV) irradiation are studied systematically. After VUV irradiation, water vapor solubility increases approximately 11–43% in the low‐pressure region and approximately 20–38% in the high‐pressure region as surface hydrophilicity increased. The increase is attributed to hydrogen bonding with the carboxyl groups because of VUV radiation. The modified layer is significantly swelling after water vapor sorption. The hydrophilic layer forms a thickness of 2–3 μm from the irradiated surface via VUV radiation, but no changes are observed inside the irradiated film. Therefore, PLA film solubility after irradiation is enhanced by hydrophilicity and the swelling effect of the surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42200.     

Photolithography of polytetrafluoroethylene for adhesion

Irradiation of polytetrafluoroethylene (PTFE) with Mg(Kα) X-rays is shown to protect the surface against the chemical etching steps used to prepare PTFE for adhesion. Preirradiated etched samples of PTFE have adhesion strengths to epoxies of less than 3% of that for nonirradiated etched samples. The major portion of this decrease in adhesion strength occurs for X-ray exposures of less than 10 min and failure in every case occurs in PTFE and not in the bonded transition region. XPS measurements (20 Å sampling depth) show little difference in F content between irradiated and nonirradiated samples, but thermal desorption shows increasing short chain fluorocarbon desorption with irradiation time. These results are consistent with previous studies showing that irradiation produces free radicals that lead to branching and/or crosslinking, and a surface rich in low molecular weight fluorocarbons. The crosslinked surface is resistant to deep (10,000 Å) chemical attack and rich in short chain fluorocarbons; both effects are expected to lead to weak adhesive bonding.     

Interfacial adhesion between polyurethane binder and poly(tetrafluoroethylene) powder in bonded solid lubricant films

Poly(tetrafluoroethylene) (PTFE) powder was irradiated with ⁶⁰Co γ-rays to improve its dispersing ability in polyurethane (PU) as a binder. The bonded solid lubricant films of the irradiated PTFE were prepared on an AISI 1045 steel block by spraying and curing at ambient temperature, with PU as the binder. The tribological properties of bonded solid lubricant films with the PTFE pigment volume fraction were examined on a ring-on-block friction and wear tester. The interfacial adhesion between the PU binder and PTFE powder was investigated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), immersion heat, and X-ray photoelectron spectroscopy (XPS). It was found that γ-ray irradiation increases the activity of the PTFE powder surface and improves the interfacial adhesion between the PTFE powder and the PU binder, which is helpful for improving the wear resistance of the corresponding bonded solid lubricant films.     

Effects of vacuum ultraviolet on the structure and optical properties of poly(tetrafluoroethylene) films

The effects of vacuum ultraviolet (VUV) at wavelengths of 5–200 nm on the microscopic structure and optical properties of poly(tetrafluoroethylene) (PTFE) films were investigated. X‐ray photoelectron spectroscopy analysis showed that the C_1s spectra changed from a single peak at 292.8 eV to multiplex peaks with binding energies of 284.6, 286.6, 288.6, 290.5, and 293.0 eV after VUV irradiation at 680 esh. With an increasing irradiation dose, the C_1s peaks at 290.5 and 293.0 eV disappeared. After the PTFE film specimens irradiated at 1600 esh were sputtered with argon ions for 3 min, the C_1s peaks at 290.5 and 293.0 eV appeared again, and the height of the peaks at 286.6 and 288.6 eV increased. The content of fluorine decreased after VUV irradiation. The content of fluorine in the film surface layer decreased significantly with the increase in the VUV intensity, but it did not change with the irradiation dose. Fourier transform infrared (FTIR) analysis results indicated that some conjugated bonds, such as ? FC?CF? , were formed during VUV irradiation, but no CH absorption bands were observed in the FTIR spectra; this indicated that the increase in the height of the C_1s peak at 284.6 eV arose mainly from the carbon–carbon bonds, that is, from carbonification. The spectral transmittance of the PTFE film decreased gradually with an increasing VUV irradiation dose, and at a given dose, the lower the intensity was of the VUV irradiation, the greater the change was in the spectral transmittance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 115–121, 2003     

Functionalization of irradiated PTFE micropowder with methacryl‐ or hydroxy groups for chemical coupling of PTFE with different matrix polymers

This article describes the modification of electron beam irradiated polytetrafluoroethylene (PTFE) material (500 kGy) into a functionalised micropowder, bearing methacrylate or hydroxy groups. The aim of this work is to achieve compatibilization of modified PTFE in a variety of matrix polymers, such as elastomers and duromers. It is well known that irradiation of high molecular PTFE in the presence of air, followed by annealing with water vapor, leads to a functionalization of the PTFE micropowder, containing carboxylic acid groups. For sufficient stability of the coupling of the functional groups that are to be introduced via these acid groups, a transformation into amide groups is necessary, and can be performed by the reaction of the electron beam irradiated PTFE with ε‐caprolactam in the first step. The corresponding acid‐terminated PTFE–oligoamide is then reacted with functional epoxy monomers, like glycidol or glycidyl methacrylate, to obtain the functionalised PTFE micropowders (PTFE‐OH and PTFE‐MA). As the number of COOH groups in the electron beam irradiated PTFE is not very high, IR‐spectroscopic identification of the functional groups is not very distinct. To find evidence for the existence/reactivity of the additionally introduced functional groups, model reactions have been performed, where PTFE‐MA is reacted with methyl methacrylate/AIBN. IR spectroscopic analysis of the reaction products shows characteristic absorption bands of PMMA, indicating successful graft polymerization of PMMA to PTFE‐MA. For PTFE‐OH, reaction with cyclohexylisocyanate leads to a bisurethane adduct, which shows a strong urethane absorption in the IR spectrum. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2819–2824, 2006     

Radiation grafting of vinyl monomers onto poly(tetrafluoroethylene) powder produced by γ irradiation and properties of grafted poly(tetrafluoroethylene) filled low density polyethylene

Scrap poly(tetrafluoroethylene) (PTFE) was γ irradiated under an ambient atmosphere in order to produce extensive chain scission and oxidative degradation. After irradiation the PTFE was ground into a fine powder (2°‐PTFE) and grafted with styrene (St), vinyl acetate (VAc), and 4‐vinylpyridine (4‐VP) by using the direct irradiation technique. The grafted PTFE were then blended with low density polyethylene (LDPE). The study covered the characterization of irradiated PTFE and grafted 2°‐PTFE powder with various methods. Mechanical grinding was found to reduce trapped radicals formed during the irradiation process faster than the annealing process. Grafting on 2°‐PTFE was followed by gravimetric analysis, TGA, and the change in the particle size of the samples. Although we reached almost 20% grafting by weight in the St and 4‐VP monomers, VAc grafting was found to be maximum at around 8% by weight at the maximum absorbed dose. The addition of VAc grafted 2°‐PTFE into LDPE produced better final mechanical properties with a fine dispersion. However, as may be expected, the incorporation of the other two 2°‐PTFEs into LDPE showed low film quality and poor mechanical properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 816–826, 2001     

Effects of irradiation on the mechanical,electrical, and flammability properties of (low‐density polyethylene)/(ethylene‐[vinyl acetate] copolymer) blends containing alumina trihydrate

Alumina trihydrate (ATH) was added to (low‐density polyethylene)/(ethylene‐[vinyl acetate] copolymer) blends (LPEs) to enhance their flame resistance. The addition of substantial amounts of ATH has been known to have deleterious effects on the mechanical properties of such blends. Hence, electron beam irradiation was used to improve the mechanical properties of our ATH‐filled LPE specimens. The specimens were irradiated at 50 to 150 kGy before being cut into specified shapes for analysis. The increase in the irradiation dosage increased the gel content as a result of the formation of crosslinked networks. Also, the flame resistance of the LPE blends was enhanced by increasing both the loading level of ATH and the irradiation dosage. However, a high ATH loading level reduced tensile strength and elongation at break. Nevertheless, the electron beam irradiation maintained the tensile strength and elongation of the ATH‐filled blends. In addition, a higher content of ATH in the LPE blends showed reactive interaction with irradiation effects. A higher amount of ATH reduced the electrical resistivity of the blends, but analysis of their surface and volume resistivity showed that the electrical resistance of the ATH‐filled LPE blends could be improved by electron beam irradiation in the range of 50 to 150 kGy. J. VINYL ADDIT. TECHNOL., 20:91–98, 2014. © 2014 Society of Plastics Engineers