Degradation of polyimide by implantation with Ar+ ions

Polyimide (PI) samples were irradiated with 200 keV Ar⁺ ions to fluences from 5 × 10¹³−1 × 10¹⁷ cm⁻² and the concentration depth profiles of implanted Ar atoms as well as of carbon and oxygen atoms of the polymer matrix were determined using the Rutherford backscattering technique. The surface polarity, sheet resistivity, and thermoelectric power of PI samples were also determined as a function of the ion fluence and temperature. As a result of the ion irradiation, the polyimide surface layer is depleted of oxygen and enriched by carbon. The sheet resistivity exhibits a minimum at the ion fluence of 5 × 10¹⁶ cm⁻² and the temperature dependence of the sheet resistivity indicates the semiconducting character of irradiated PI and the variable range hopping mechanism of charge transport. The thermoelectric power of the PI samples irradiated to high fluences is small, of the order of μV/K, and independent of temperature. This behavior is typical for metals. The simultaneous appearance of metal and semiconducting properties is probably due to the complex structure of the PI surface layer modified by the ion irradiation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 723–728, 1997     

Anomalous diffusion of iodine ions into polypropylene implanted with F+ and I+ ions

The diffusion of K and I atoms from 5 M water solution of KI into polypropylene implanted with 150 keV F⁺ and I⁺ was studied at boiling temperature. Standard Rutherford back scattering (RSB) technique was used for the determination of concentration depth profiles of diffused atoms. It was found that the I and K atoms penetrate the polymer surface layer affected by ion implantation and they are captured by trapping centers produced by electronic energy losses of implanted ions. The uptake of K atoms is several times higher than that of I atoms, and the relative K concentration exceeds the KI stoichiometric value. © 1995 John Wiley & Sons, Inc.     

Modification of adhesive properties of a polyethylene film by photografting

Graft polymerization of acrylic acid from monomer solutions in water or in bulk onto low‐density polyethylene film substrate was carried out by the method of continuous process under UV radiation. Effects of the nature of photoinitiator on acrylic acid grafting was first studied. One PI₂ and two PI₁ photoinitiators were used. Benzophenone was then retained for the following study. The influence of photoinitiator and monomer concentration was investigated by determining polymerization kinetics and grafted polymer amount. A study of surface wetting and morphological structure was then carried out on a bulk system and as a function of the photoinitiator concentration. Finally, such surface modification was studied with respect to its effect on the adhesion of an acrylic stick on its surface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2803–2811, 2004     

Modification of polyethylene by unsaturated compounds

Polyethylene was reacted with maleic anhydride and N-phenylmaleimide in solution. The effect of modification on its physico–chemical properties, such as mechanical, oxygen gas transmission, water vapor transmission, and grease resistance properties, was studied.     

淀粉改性及其与聚乙烯共混

分别采用偶联剂处理和反应共混方法对玉米淀粉进行了改性,研究了偶联剂处理淀粉的疏水性和加工性能,考察了改性淀粉的工艺条件及其与线性低密度聚乙烯(LLDPE)共混物的力学性能。结果表明,在硅烷偶联剂、钛酸酯偶联剂和铝酸酯偶联剂中,用硅烷偶联剂处理淀粉的效果较好;硅烷偶联剂处理淀粉的疏水性得到了较大的提高,其与低密度聚乙烯共混时,体系的熔体黏度变小。淀粉和丙烯酸丁酯或甲基丙烯酸甲酯在130℃高温密炼机中共混6 m in,可制得丙烯酸丁酯改性淀粉和甲基丙烯酸甲酯改性淀粉,使用少量的改性淀粉即可明显提高LLDPE/淀粉共混物的扯断伸长率,拉伸强度变化不大;该改性淀粉对LLDPE/淀粉的共混起到增容剂的作用。     

Surface modification of polyethylene and polypropylene by ion implantation

The creation of oxidized structures and double bonds in polyethylene (PE) and polypropylene (PP) samples implanted with P⁺ ions was studied. The surface polarity and the electrical conductivity of the ion-implanted polymers were also examined. As a result of the ion implantation, the polymer macromolecules are broken up and the material is degraded. An oxygen penetration into the radiation-damaged polymers is also observed, with PE being more vulnerable to the oxidation. The ion-implanted PP exhibits higher surface polarity and sheet conductivity compared to that of PE. © 1993 John Wiley & Sons, Inc.     

Li-LSX分子筛的Ag~+改性及其氧气吸附性能

采用离子交换法对Li-LSX分子筛进行Ag~+改性,利用正交实验法探究制备AgLi-LSX分子筛的最佳工艺条件,通过不同交换次数获得了不同阳离子交换度的AgLi-LSX分子筛,并采用SEM、TEM、FTIR、XRD、ICP、EDS、BET等手段对分子筛的骨架结构、晶体构型、元素含量、孔结构进行表征。结果表明,AgLi-LSX分子筛的最佳制备工艺条件为反应温度90℃,反应时间120 min,Ag~+浓度0.4 mol/L。当交换次数为2次,Ag~+交换度为51.67%时,AgLi-LSX分子筛的氧气吸附量为4.473 5 mL/g,比Li-LSX分子筛提高了96.91%,并且Ag~+改性并没有改变X型分子筛的骨架结构和晶体构型。     

Li-LSX分子筛的Ag~+改性及其氧气吸附性能

采用离子交换法对Li-LSX分子筛进行Ag⁺改性,利用正交实验法探究制备AgLi-LSX分子筛的最佳工艺条件,通过不同交换次数获得了不同阳离子交换度的AgLi-LSX分子筛,并采用SEM、TEM、FTIR、XRD、ICP、EDS、BET等手段对分子筛的骨架结构、晶体构型、元素含量、孔结构进行表征。结果表明,AgLi-LSX分子筛的最佳制备工艺条件为反应温度90℃,反应时间120 min,Ag+改性,利用正交实验法探究制备AgLi-LSX分子筛的最佳工艺条件,通过不同交换次数获得了不同阳离子交换度的AgLi-LSX分子筛,并采用SEM、TEM、FTIR、XRD、ICP、EDS、BET等手段对分子筛的骨架结构、晶体构型、元素含量、孔结构进行表征。结果表明,AgLi-LSX分子筛的最佳制备工艺条件为反应温度90℃,反应时间120 min,Ag⁺浓度0.4 mol/L。当交换次数为2次,Ag+浓度0.4 mol/L。当交换次数为2次,Ag⁺交换度为51.67%时,AgLi-LSX分子筛的氧气吸附量为4.473 5 mL/g,比Li-LSX分子筛提高了96.91%,并且Ag+交换度为51.67%时,AgLi-LSX分子筛的氧气吸附量为4.473 5 mL/g,比Li-LSX分子筛提高了96.91%,并且Ag⁺改性并没有改变X型分子筛的骨架结构和晶体构型。     

EVA改性硅烷交联聚乙烯绝缘料

使用乙烯-乙酸乙烯共聚物(EVA)对硅烷交联聚乙烯电力电缆绝缘料进行了改性。结果表明,EVA对绝缘料的熔体流动速率(MFR)、介电强度、热延伸性能影响较小,使其介电常数、热稳定性提高,体积电阻率、结晶度、交联度、拉伸强度下降。EVA的添加量在10phr之内,绝缘料的MFR、介电强度、热延伸性能、断裂伸长率、体积电阻率、交联度满足技术指标要求;EVA的添加量超过6phr时,绝缘料的拉伸强度和介电常数不能满足要求。     

Modification of cellulase by synthesized copolymer with polyethylene oxide and maleic acid anhydride

Copolymer containing functional groups such as polyethylene oxide (PEO) and maleic acid anhydride (MA) was synthesized to modify cellulase. MA was attached to the PEO allyl ester, which was the product formed by the reaction between PEO allyl alcohol and lauric acid. The number of ethylene oxide (EO) units in one PEO chain was varied from 10 to 40, and MA formed the chemical bond with the amino acid groups of the cellulase for the modification reaction. When cellulase was modified with synthesized copolymer, activity of the modified cellulase decreased slightly as the degree of modification increased. The modified enzyme showed high remaining activity regardless of a high degree of modification. At the maximum modification degree of 52%, the modified cellulase activity retained more than 65% of the unmodified native cellulase. Modified cellulase retained higher reactivity than native cellulase in an organic solvent and at various pH values. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 368–373, 2000     

聚乙二醇缩水甘油醚改性丝素蛋白研究

采用聚乙二醇400与环氧氯丙烷合成聚乙二醇缩水甘油醚(PEGO)并对丝素蛋白(SF)进行改性,采用红外光谱、X射线衍射、差式量热扫描、扫描电镜和物理性能测试对共混膜的结构和性能进行表征,表明PEGO的加入使得丝素蛋白从silkⅠ结构向silkⅡ构象转变,而当m(PEGO)∶m(SF)>50%的时候,共混膜的二级结构却呈现相反变化。共混膜的含水量由共混膜的表面粗糙度和亲水性决定,在m(PEGO)∶m(SF)<50%时,其含水量随粗糙度增加而减少;在m(PEGO)∶m(SF)>50%时,随着PEGO的增加,SF/PEGO共混膜的含水量增加。当m(PEGO)∶m(SF)=50%时,共混膜SP50具有最好的热稳定性和良好的机械性能。     

不同相对分子质量聚乙二醇对白炭黑的改性

在沉淀法制备白炭黑过程中直接对白炭黑进行改性.选用聚乙二醇(PEG)作为改性剂,研究了其加入量对白炭黑产品粒径(d 50)、吸油值及表观密度的影响,利用扫描电镜和红外光谱分析仪对改性前后白炭黑的性能进行了表征.研究结果表明:随着PEG2000加入量的增加,产品的平均粒径和表观密度减小,吸油值增大,PEG2000加入量为产品质量的2%～8%时产品吸油值的变化不大.当PEG相对分子质量大于4 000时,所得白炭黑表现为粒径及表观密度增大.随着PEG相对分子质量的增大,白炭黑的吸油值先增大后减小.红外光谱分析结果显示,PEG在一定程度上影响了二氧化硅特征峰的位置.     

Modification of asphalt by packaging waste‐polyethylene

The “white pollution” made of packaging waste polymers and its recycling has become a common issue. In this article, the retrieved waste milk‐packing bag (its main ingredients was polyethylene) was selected to modify the ordinary oil asphalt. Asphalt was modified with 1, 3, 6, and 9 wt% content of waste‐polyethylene. The results showed that the softening point and the freeze‐to‐crack stress of asphalt increased the penetration and the freeze‐to‐crack temperature decreased after modification. The comprehensive performance of raw asphalt improved noticeably. Infrared analysis suggests that waste‐polyethylene in packaging (WPE) combines the matrix of asphalt through physical mixture modification. And the modification mechanism of WPE was studied by the analysis of its micro structure, the characteristics of WPE, the effects of Crack pinning and Silver Shear yield in the decentralized process. Using waste packaging polymers to modify the asphalt proved to be an ideal way, for not only solving the problem of “white pollution”, but also for improving the performance of asphalt. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Modification of polyethylene surfaces with carbethoxy substituted carbenes and nitrenes

Carbethoxycarbene, carbethoxynitrene, and nitrene generated respectively by the pyrolysis of ethyl diazoacetate, ethyl azidoformate, chloramine and sodium hydroxyl amine-o-sulfonate are shown to irreversibly modify the surface of polyethylene as shown by wettability measurements. The nature of the modification is not fully understood; however, insertion of the carbene or nitrene into a carbon-hydrogen bond appears likely. The modified surfaces thus formed are shown to undergo several classical organic reactions as again determined by wettability measurements.     

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

The effects of low-energy (≤2 kV) Ar⁺ irradiation on the optical and structural properties of zinc oxide (ZnO) nanowires (NWs) grown by a simple and cost-effective low-temperature technique were investigated. Both photoluminescence spectra from ZnO NW-coated films and cathodoluminescence analysis of individual ZnO NWs demonstrated obvious evidences of ultraviolet/visible luminescent enhancement with respect to irradiation fluence. Annihilation of the thinner ZnO NWs after the ion bombardment was appreciated by means of high-resolution scanning electron microscopy and transmission electron microscopy (TEM), which results in an increasing NW mean diameter for increasing irradiation fluences. Corresponding structural analysis by TEM pointed out not only significant changes in the morphology but also in the microstructure of these NWs, revealing certain radiation-sensitive behavior. The possible mechanisms accounting for the decrease of the deep-level emissions in the NWs with the increasing irradiation fluences are discussed according to their structural modifications.     

Modification of properties of CaCO3‐polymerization‐filled polyethylene

CaCO₃–polyethylene (PE) compositions, containing an ultrahigh molecular polyethylene (UHMPE) interlayer between the filler surface and the PE matrix, were synthesized by two‐step polymerization of ethylene on a filler surface activated with a suitable catalyst. The properties of the compositions were studied depending on the molecular weight of the PE matrix and the thickness of the UHMPE intermediate layer at the filler particles. It was shown that the presence of UHMPE as an interlayer in chalk–UHMPE–PE compositions leads to an increase of plastic deformation of the materials as long as the M_w value of the PE matrix is higher than is the brittleness threshold for PE. Chalk–UHMPE–PE compositions exhibit a higher ability for plastic deformation compared to chalk–PE compositions based on a PE matrix of a molecular weight equal to the molecular weight of the total polymer phase (UHMPE–PE) in the first case. There is no improvment of the mechanical properties when the UHMPE is dispersed in the compositions and not as an interlayer between a filler and a matrix. This means that the method of polymerization filling allows one to incorporate the polymer interlayer with a desired nature and properties between a filler surface and polymer matrix in filled polyolefin compositions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 577–583, 2003     

Characterization of ultra-high-molecular-weight polyethylene (UHMWPE) modified by ion implantation

Surface modification of ultra high molecular weight polyethylene (UHMWPE) is induced by ion implantation of different ions at 300 keV energy. The aim of this work was the chemical, physical and mechanical characterization of the modified material in order to know deep inside about the effect of the ion beam upon the polymer.The irradiated surfaces are investigated by Raman spectroscopy, infrared absorption and micro-hardness analysis, scanning electron microscopy. Pin on disc measurements valuated the wear of the UHMWPE against a stainless steel probe; wear resistance increases of about 76% after the ion implantation. This result can be attributed to the ion bombardment inducing a micro-hardness increasing in the irradiated layers due to the high carbon surface concentration and cross-linking effects in the polymeric chains. The irradiated UHMWPE surfaces may find special applications to the field of the mobile prosthesis.