超高分子量聚乙烯纤维复合表面改性及其橡胶基复合材料的力学性能

针对超高分子量聚乙烯(UHMWPE)纤维与基体之间界面结合强度低的问题,采用超声波结合铬酸溶液氧化的复合工艺对UHMWPE纤维进行表面处理,并将处理后的纤维加入到天然橡胶(NR)中制备短切UHMWPE纤维/NR复合材料。结果表明:复合改性工艺可有效增加纤维表面粗糙度及表面含氧官能团含量,最佳改性工艺条件为:按照重铬酸钾、水及浓硫酸的质量比7∶12∶150配置铬酸溶液,将含有一定质量UHMWPE纤维的铬酸溶液放入35℃的超声波清洗仪中氧化5min,其中超声波频率为100kHz。与纯NR样品相比,在UHMWPE纤维与NR的质量比为0~6∶100范围内,随着处理后短纤维含量的增加,复合材料的拉伸强度逐渐减小,最大损失量达到50%;复合材料的硬度不断增大,最大增加量达到96%;复合材料的撕裂强度先增大后减小,在UHMWPE纤维与NR的质量比为5∶100时达到最大值,最大增加量达到49%。     

聚全氟乙丙烯改性超高分子量聚乙烯的性能研究

以纯超高聚乙烯(UHMWPE)为基础原料,添加高密度聚乙烯、乙烯-丙烯酸酯共聚物、纳米SiO₂等改性剂,制备了UHMWPE改性混合物。研究了聚全氟乙丙烯(FEP)的加入和用量,对UHMWPE改性混合物力学性能及磨耗性能、熔融性能及热性能的影响。结果表明:添加FEP前后,改性混合物体系中纳米粒子都有较好的分散,拉伸强度和冲击强度以及热性能变化不大,但添加FEP后聚合物体系的磨耗几乎下降了50%,熔融性有一定的改善。当FEP用量较少时,随着FEP用量的增加,改性混合物的拉伸强度和冲击强度都上升;当FEP用量超过2%时,随着随着FEP用量的增加,改性混合物的拉伸强度和冲击强度都下降;在FEP用量达到2%时,改性混合物的磨耗是最低的。     

芳纶纤维和超高分子量聚乙烯纤维制备工程用纤维/水泥复合材料的适用性

研究了两种高强合成纤维在工程用纤维/水泥复合材料制备过程中的适用性,其中,芳纶纤维的表面为亲水性,超高分子量聚乙烯（UHMWPE）纤维的表面为憎水性。研究结果表明:工程用芳纶纤维/水泥复合材料拉伸破坏过程中无应变硬化能力且表现为单裂纹破坏现象;工程用UHMWPE纤维/水泥复合材料拉伸破坏过程中表现出良好的应变硬化能力和多裂纹开裂特性。因此,两种纤维相比,UHMWPE纤维适宜于工程用纤维/水泥复合材料的制备。随着水胶比的降低,工程用UHMWPE纤维/水泥复合材料抗拉强度增大,但应变硬化能力降低,因此,在制备工程用UHMWPE纤维/水泥复合材料的过程中,应协调纤维抗拉强度和基体与纤维之间界面过渡区的品质。      

Medical-grade ultra-high molecular weight polyethylene: past,current and future

Ultra-high molecular weight polyethylene is a semi-crystalline polymer (45–60%) with six decades of orthopaedic applications. This polymer has a high fracture toughness (30?kJ?m^?2) which comes from the molecular weight and the chain entanglements. Adverse alteration of the properties may lead to the part's pre-mature failure. This paper reviews the current manufacturing methods, and their effect on the properties of the polymer. The review also focused on the attempts of enhancing the polymer properties. The main cause of failure is implant loosing owing to the polymeric wear particles. Many manufacturers have attempted to enhance the wear and oxidation properties of the polymer, and the outcome of the new technologies is critically reviewed. Finally, the review explores the potential for future developments.

This review was submitted as part of the 2018 Materials Literature Review Prize of the Institute of Materials, Minerals and Mining run by the Editorial Board of MST. Sponsorship of the prize by TWI Ltd is gratefully acknowledged.     

自增强高密度聚乙烯/超高分子量聚乙烯复合材料制备与表征

用自制模具制备出自增强高密度聚乙烯(HDPE)/超高分子量聚乙烯(UHMWPE)棒材.通过SEM观察、X射线分析、DSC分析以及力学性能测试,研究了挤出自增强HDPE/UHMWPE棒材微观结构和力学性能.研究结果表明,在HDPE和UHMWPE最佳配比为8:2的情况下,自增强试样的拉伸强度、抗弯强度和弹性模量分别为168.5、164.8MPa和4.9GPa,比未增强试样分别提高了534.9%、261.2%和408.3%.与普通模压试样相比,自增强试样内部有大量的微纤结构和串晶互锁结构,结晶度获得提高,(110)面和(200)面的峰值均获得提高,并且熔点向高温区发生漂移.     

Friction and wear properties of UHMWPE/nano-MMT composites under oilfield sewage condition

A new stabilizer material ultra-high molecular weight polyethylene (UHMWPE) was reinforced with modified nano-montmorillonite (MMT) in different contents. Tribological properties of the materials, together with the polyamide (PA) material used as stabilizer for the purpose of comparison, were tested against a J55 steel counterfact on a reciprocating tribometer under oilfield sewage condition. The experimental conditions were a contact pressure 7.0 MPa, a stroke length of 15 mm, and a reciprocating frequency of 1 Hz. The results show that the 10 wt.% nano-MMT composite exhibits the lowest friction coefficient and the best wear resistance among all specimens; that furrow and larger area of brittleness break are dominant for the PA specimen, and that plowed scratches and abrasive wear are dominant for the 10 wt.% nano-MMT composite. The new material proves to be better than PA material when used as stabilizer materials.     

Experimental and numerical studies of the notch strengthening behaviour of semi-crystalline ultra-high molecular weight polyethylene

In the present work, both experimental work and Finite Element Modeling (FEM) have been used to study the effects of notch geometry on the stress/strain behaviour and fracture of the ultra-high molecular weight polyethylene (UHMWPE) at quasi static conditions. The effects of notch profile radii on UHMWPE fracture behaviour, predicted stress/strain distribution, triaxial state of stress and hydrostatic pressure across the neck have been studied. Different techniques have been used to study the effects of notch geometry on the UHMWPE properties. Differential Scanning Calorimetry (DSC) has been used to study the changes in the tested material crystallinity. The universal testing machine has been used to measure the changes in the tested material mechanical properties. The SEM has been used to examine the change in the tested material fracture surface. Finally, the Finite Element Code (ANSYS10) has been used to investigate the effects of notch geometry on the predicted stress/strain distribution across the neck. The results show a notch strengthening behaviour for the tested material, where the axial yield properties increased significantly with the reduction of notch radii, while the axial ultimate properties decreased significantly for the notched specimens compared with plain ones. Also the predicted stress/strain distribution and stress triaxiality show a strong dependence on the notch geometry. The remarkable effects of notch geometry on the predicted stress/strains distributions across the neck show the importance of careful design of UHMWPE artificial joint components with the aim to eliminate the presence of stress risers such as undercuts and fillets.     

石墨烯多壁碳纳米管/超高分子量聚乙烯导电复合材料的制备及性能

为了比较超高分子量聚乙烯(UHMWPE)在单一填充和混合填充时, 复合材料导电性的差别。在超声和肼的作用下, 通过对氧化石墨烯(GO)、 多壁碳纳米管(MWCNTs)和超高分子量聚乙烯水/乙醇分散液减压蒸馏及热压制备了隔离型MWCNTs/UHMWPE、 石墨烯(GNS)/UHMWPE和MWCNTs-GNS/UHMWPE导电复合材料。经SEM、 TEM测试发现, 导电填料分散于UHMWPE颗粒表面, 热压后形成隔离结构。隔离型的MWCNTs/UHMWPE和GNS/UHMWPE复合材料均表现出较低的导电逾渗(0.148%和0.059%, 体积分数,下同), 但MWCNTs/UHMWPE复合材料的电导率(2.0×10^-2 S/m, 1.0%, 质量分数, 下同)明显高于相同填料含量下的GNS/UHMWPE复合材料。 MWCNTs-GNS/UHMWPE复合材料表现出了更低的逾渗(0.039%) 和较高导电性能(1.0×10^-2 S/m, 1.0%), 其拉伸强度和断裂伸长率随填充剂含量的增加呈现出先上升后下降的趋势。     

Experimental investigation on mechanical behaviour,modelling and optimization of wear parameters of B4C and graphite reinforced aluminium hybrid composites

Aluminium alloy (AA) 6061 and 7075 were reinforced with 10 wt.% of boron carbide (B₄C) and 5 wt.% of graphite through liquid casting technique. The Scanning Electron Microscope (SEM) and Energy Dispersive Spectrum (EDS) were used for the characterization of composites. The wear experiment was carried out by using a pin-on-disc apparatus with various input parameters like applied load (10, 20, and 30 N), sliding speed (0.6, 0.8, and 1.0 m/s) and sliding distance (1000, 1500, and 2000 m). Response Surface Methodology (RSM) using MINITAB 14 software was used to analyse the wear rate of hybrid composites and aluminium alloys. The worn surfaces of hybrid composites and base alloys were studied through SEM and EDS systems and some useful conclusions were made.     

三元层状陶瓷Ti_3AlC_2/超高分子量聚乙烯复合材料的制备及性能

为了增强超高分子量聚乙烯(UHMWPE)的性能,研究采用表面改性的Ti_3AlC_2填充UHMWPE,通过热压成型制备了Ti_3AlC_2/UHMWPE复合材料。采用SEM观察复合材料的微观结构,表明Ti_3AlC_2均匀分散在UHMWPE基体中,表面处理后的填料与基体界面熔合较好;热分析结果表明,Ti_3AlC_2的添加降低了UHMWPE的结晶度和结晶热焓,同时提高了聚合物的热传导性;DMA分析结果表明,添加Ti_3AlC_2有效地提高了Ti_3AlC_2/UHMWPE复合材料的抗蠕变性能,得益于无机粒子改善了复合材料的硬度和刚性,提高了复合材料抗外界应力变形能力;摩擦学性能分析表明,适量的Ti_3AlC_2(质量分数≤15wt%)填充UHMWPE能有效提高复合材料的减磨抗摩性能,同时磨痕表面形貌分析结果表明,Ti_3AlC_2/UHMWPE复合材料的摩擦磨损机制由粘着磨损向磨粒磨损转变。     

Optimization of reinforcement content and sliding distance for AlSi7Mg/SiCp composites using response surface methodology

Extruded AlSi7 Mg alloy based SiC_p reinforced (AlSi7 Mg/SiC_p) composites and the matrix alloy were wear tested on a pin on disk type tester. The work was planned so that some response surface (RS) models can be used to examine the wear behaviour of composite samples. The effects of friction load, sliding distance and reinforcement content on the wear rate and weight loss of AlSi7 Mg/SiC_p composites were evaluated by using RS optimization procedure. In the applications of RS models to engineering problems, the estimated RS models usually have a maximum or a minimum point. Through this article the RS optimization procedure was employed to optimize the reinforcement content and sliding distance for the minimization of wear rate and weight loss of tested composites. During the tests, the values of reinforcement content, friction load and sliding distance were changed on the intervals (0%, 20%), (49 N, 169 N), (100 m, 1000 m), respectively. It was shown that there exists some optimum values of reinforcement content and some optimum values of sliding distance which minimize the wear rates also weight losses of tested composites for some fixed values of friction load in the experimental region. In this concern, the average value of optimum reinforcement contents and the average value of optimum sliding distances of AlSi7 Mg/SiC_p composites minimizing the wear rate were found as 13% and 595 m, respectively. Also the average value of optimum reinforcement content minimizing the weight loss was found as 13%.     

Flexural fatigue resistance of ultra-high molecular weight polyethylene at ambient and low temperature

Specimens of ultra-high molecular weight polyethylene have been subjected to flexural fatigue tests at −40° and 23°C, and the temperature of some of the specimens recorded throughout the test. It is found that when the specimen life exceeds 10⁶ cycles, the temperature of the specimen stabilizes. However, if the temperature of the specimen does not reach equilibrium with the testing temperature, the specimen life is short (< 10⁴ cycles). The stabilization of the speciment temperature is related to a critical stress level, which is different for each testing temperature.     

超高分子量聚乙烯纤维/环氧复合材料的吸湿行为及吸湿应力分析

为了揭示超高分子量聚乙烯(UHMWPE)纤维增强环氧树脂基复合材料的吸湿机制,利用ABAQUS有限元软件,建立二维模型,对此类复合材料的吸湿行为及吸湿应力进行研究。模拟计算了两种不同纤维分布模型内部的水分浓度场分布; 根据获得的水分浓度场,对两种模型随温度及时间变化的吸湿应力场进行了分析。结果表明: 水分在两种模型中的扩散都符合Fick扩散定律,纤维按正六边形分布模型比纤维随机分布模型更早达到吸湿平衡,但后者更符合实际情况,也与实验结果比较吻合; 长时间的吸湿会导致材料内部吸湿应力达到很高的水平(>60 MPa),温度越高,越早达到吸湿平衡,应力越大,最大的吸湿应力出现在纤维聚集最密集的基体区域,纤维随机分布模型的吸湿应力水平高于纤维按正六边形分布模型。     

Effects of screen-grid bias voltage on the microstructure and properties of the ultrahigh molecular weight polyethylene (UHMWPE) modified by oxygen plasma

The specimens of ultrahigh molecular weight polyethylene (UHMWPE) were treated by oxygen plasma using a pulse-biased screen-grid technique under different negative bias conditions. The screen-grid was used to provide an electric field to accelerate the oxygen ions towards the UHMWPE substrate during the plasma treatment process. The effects of the screen-grid voltage on the surface microstructure, wettability, mechanical properties and wear resistance of UHMWPE were investigated. It was found that the degree of crosslinking, oxidation, wettability and surface roughness of UHMWPE can be increased with the increasing of the screen-grid voltage. Owing to the increase of the degree of crosslinking, the hardened layer formed on the surface of the UHMWPE samples was also strengthened greatly with the increase of the grid voltage. However, the wear results indicated that the UHMWPE sample modified at higher bias voltage exhibits poor wear performance, which could be mainly related to the embrittlement resulted from the aggravation of oxidation.     

Electrochemical treatment of deproteinated whey wastewater and optimization of treatment conditions with response surface methodology

Electrochemical treatment of deproteinated whey wastewater produced during cheese manufacture was studied as an alternative treatment method for the first time in literature. Through the preliminary batch runs, appropriate electrode material was determined as iron due to high removal efficiency of chemical oxygen demand (COD), and turbidity. The electrochemical treatment conditions were optimized through response surface methodology (RSM), where applied voltage was kept in the range, electrolyte concentration was minimized, waste concentration and COD removal percent were maximized at 25 degrees C. Optimum conditions at 25 degrees C were estimated through RSM as 11.29 V applied voltage, 100% waste concentration (containing 40 g/L lactose) and 19.87 g/L electrolyte concentration to achieve 29.27% COD removal. However, highest COD removal through the set of runs was found as 53.32% within 8h. These results reveal the applicability of electrochemical treatment to the deproteinated whey wastewater as an alternative advanced wastewater treatment method.     

Preparation and optimization of doxorubicin-loaded albumin nanoparticles using response surface methodology

Background: The objective of this work was to optimize the preparation of doxorubicin-loaded albumin nanoparticles (Dox-A-Nps) through desolvation procedures using response surface methodology (RSM). A central composite design (CCD) for four factors at five levels was used in this study.

Method: Albumin nanoparticles were prepared through a desolvation method and were optimized in the aid of CCD. Albumin concentration, amount of doxorubicin, pH values, and percentage of glutaraldehyde were selected as independent variables, particle size, zeta potential, drug loading, encapsulation efficiency, and nanoparticles yield were chosen as response variables. RSM and multiple response optimizations utilizing a quadratic polynomial equation were used to obtain an optimal formulation.

Results: The optimal formulation for Dox-A-Nps was composed of albumin concentration of 17?mg/ml, amount of doxorubicin of 2?mg/ml, pH value is 9 and percentage of glutaraldehyde of 125% of the theoretic amount, under which the optimized conditions gave rise to the actual average value of mean particle size (151?±?0.43?nm), zeta potential (?18.8?±?0.21 mV), drug loading efficiency (21.4?±?0.70%), drug entrapment efficiency (76.9?±?0.21%) and nanoparticles yield (82.0?±?0.34%). The storage stability experiments proved that Dox-A-Nps stable in 4°C over the period of 4 months. The in vitro experiments showed a burst release at the initial stage and followed by a prolonged release of Dox from albumin nanoparticles up to 60?h.

Conclusions: This study showed that the RSM-CCD method could efficiently be applied for the modeling of nanoparticles, which laid the foundation of the further research of immuno nanoparticles.     

超高分子量聚乙烯表面金属化及类金刚石薄膜沉积复合处理研究

采用超高分子量聚乙烯(UHMWPE)表面金属化及类金刚石薄膜沉积复合处理工艺,提高超高分子量聚乙烯的耐磨性.首先采用磁过滤阴极真空弧源沉积技术(FCVA)在UHMWPE表面制备约30nm钛金属层,使UHMWPE表面金属化,然后再沉积DLC薄膜,研究结果表明,UHMWPE表面金属化后,DLC薄膜沉积过程中,电荷累积效应消...     

Study on three-body abrasive wear behavior of functionally graded Al/TiB2 composite using response surface methodology

Functionally graded LM13 Al/10?wt% TiB₂ metal matrix composite has successfully produced under centrifugal casting. Hollow cylindrical composite with dimensions 150?×?150?×?15?mm was produced under rotating centrifugal speed of 1100?rpm. Microstructural characteristics were studied on the composite surfaces at distance of 1, 5.5, and 10?mm from outer periphery of the casting, and the results revealed that surface at distance of 1?mm has presence of more reinforcement particles. An objective of this study was to characterize abrasion wear behavior at the composite surfaces using dry abrasion tester. Mathematical models were developed using response surface methodology to study the relationship of parameters such as load, speed, and distance from outer periphery with abrasion wear rate. Face centered Central Composite Design with 20 experiments was preferred for dry abrasion test. Adequacy of model was predicted through analysis of variance, and the significance test result shows that load has major impact on the wear rate. The optimized parametric condition to obtain minimum wear rate was found as load of 33?N, speed of 112?rpm, and distance of 1?mm from outer periphery. Scanning electron microscopy analysis done at worn out surface showed maximum wear resistance at the outer periphery.     

Effect of oxy-hydrogen blending with gasoline on vehicle performance parameters and optimization using response surface methodology

ABSTRACT

Rapid decline in fossil fuel reservoirs has attracted researchers to use a variety of fuel blends in Spark ignition (SI) and Compression ignition (CI) engines demonstrating similar performance and lower emissions. Oxy-hydrogen gas obtained through electrolysis has been successfully tested for this use. This paper presents a two wheeler chassis dynamometer based study of a two wheeler loaded with newly developed single cylinder variable compression ratio (VCR) engine utilizing different blends of gasoline and oxy-hydrogen gas. Variation in fuel average performance (FAP), wheel power (WP) and acceleration performance (AP) due to oxy-hydrogen blending with gasoline is studied and compared with neat gasoline at five different gears. Further multi objective optimization of FAP and WP is carried out using response surface methodology (RSM). Regression models are postulated for predicting FAP and WP at different levels of compression ratio (CR) and oxy-hydrogen gasoline blends. Interaction between CR and oxy-hydrogen-gasoline blending is also studied and discussed. Modification carried out on an engine improves vehicle performance parameters and oxy-hydrogen gasoline blending further enhances the improvements. Maximum FAP and WP in top gear is obtained at highest CR of 11.57:1 and a oxy-hydrogen gasoline blend with 112.558 ml/min flow rate of oxy-hydrogen gas.     

Determination of optimum operating conditions of carmine decoloration by UV/H2O2 using response surface methodology

In this study, the photolytic decoloration of carmine (C.I. Natural Red 4) via UV radiation in the presence of H2O2 was optimized using response surface methodology (RSM). According to analysis of variance (ANOVA) results, the proposed model can be used to navigate the design space. It was found that the response of carmine degradation is very sensitive to the independent factors of carmine concentration, H2O2 concentration, pH and reaction time. The proposed model for D-optimal design fitted very well with the experimental data with R2 and R(adj)2 correlation coefficients of 0.998 and 0.997, respectively.