PE/木粉/MRP/Nano–MH共混材料的阻燃及热分解动力学研究

目的 研究微胶囊红磷(MRP)和纳米氢氧化镁(Nano–MH)协同阻燃木塑复合材料(WPC)的阻燃效果及阻燃机理。方法 以MRP为主阻燃剂,Nano–MH为协效阻燃剂,低密度聚乙烯(LDPE)、线型低密度聚乙烯(LLDPE)和木粉为基础物质,采用二次造粒和注射成型法制备阻燃木塑材料(WPC/MRP/MH)。通过燃烧等级测定、极限氧指数(LOI)测定和热重谱图(TG)分析阻燃剂对复合材料阻燃性的影响,利用Flynne–Walle–Ozawa(FWO)方法研究WPC和WPC/MRP/MH的热分解行为,并采用Criado方法推断WPC/MRP/MH的反应机理。结果 复合材料MRP质量分数为12.5%时阻燃等级达到UL94 V–0级,LOI值高达28.3%;WPC/MRP/MH的t_onset、t_endset和t_p均高于WPC,且在热分解后期FWO方法得到的表观活化能(E_a)逐渐增加,材料热稳定性明显提高;WPC/MRP/MH的反应机理函数为g(α)=[-ln(1-α)]^1/n、f(α)...     

微胶囊红磷阻燃木塑复合材料的性能研究

目的制备微胶囊红磷阻燃木塑复合材料,研究微胶囊红磷添加量对其力学性能、耐热性能和阻燃性能的影响,并扩大其应用范围。方法以微胶囊红磷为阻燃剂,将其添加到低密度聚乙烯、线性低密度聚乙烯和木粉三元复合体系中,采用二次挤出造粒和注射成型法制备阻燃试样。研究材料的力学性能、耐热性能、应力破坏行为,确定材料的阻燃级别。结果与未添加微胶囊红磷的木塑材料相比,当微胶囊红磷添加量(质量分数)达到10%时,材料的冲击强度由17.4 kJ/m2提高到19.0 kJ/m2,抗拉强度由19.53 MPa提高到21.7 MPa,断裂伸长率提高了58.7%,初始分解温度提高了73.17℃,阻燃达到V-0级,氧指数达到28.7%。结论随着微胶囊红磷含量的增加,木塑复合材料的冲击强度、抗拉强度和断裂伸长率变大,初始分解温度提高,阻燃耐热性能变好;材料阻燃剂的添加量低,综合性能优良,在包装、建筑、家具等领域具有广泛应用前景。     

芳纶浆粕对膨胀阻燃聚丙烯性能影响

采用芳纶浆粕(PPTA-pulp)对膨胀阻燃聚丙烯(PP)进行增强改性,通过一步共混法制备了PPTA-pulp-膨胀型阻燃剂(IFR)/PP阻燃复合材料,考察了PPTA-pulp用量对PPTA-pulp-IFR/PP复合材料的力学性能、阻燃性能及热稳定性能的影响。结果表明,当硅烷偶联剂KH-550处理的PPTA-pulp质量比为5%时,膨胀阻燃复合材料的力学性能达到最佳: 拉伸强度40.0 MPa,冲击强度56.9 J·m^-1,极限氧指数LOI 28%,垂直燃烧等级达到UL-94 V-0级。复合材料的热稳定性能提高,炭残余量增加。SEM观察表明,PPTA-pulp经KH-550处理后,浆粕纤维与基体树脂的结合性较好。     

离子聚合物改性木粉/HDPE复合材料流变特性

为了提高木塑复合材料（WPC）的加工流动性能,利用离子聚合物改性WPC,通过HAAKE Minilab微量混合流变仪研究了离子聚合物改性木粉/高密度聚乙烯（HDPE）的毛细管流变特征。结果表明：添加与未添加离子聚合物的木粉/HDPE均为非牛顿流体中的假塑性流体,均呈现出“剪切变稀”的效应;随着钠离子聚合物含量的增加,改性木粉/HDPE的剪切应力和表观黏度均随着剪切速率的增大呈现降低的趋势,表明钠离子聚合物的加入可以显著改善聚合物熔体的流动特性;添加4wt%的钠离子聚合物和4wt%的锌离子聚合物的木粉/HDPE剪切应力和表观黏度均要低于添加4wt%的偶联剂马来酸酐接枝聚乙烯（MAH-g-PE）的WPC的值,表明与MAH-g-PE相比,离子聚合物更能够改善WPC的流动性能,减小熔体流动时HDPE与木粉之间的摩擦阻力;SEM分析表明,添加离子聚合物后HDPE塑料对木粉有很好的包覆效果,没有明显的界面缝隙,且在WPC断面上存在大量的毛刺纤维。     

低碳钢表面硅烷化处理对聚乙烯涂层结合强度的影响

利用硅烷偶联剂(KH-550,KH-560,KBM-7103)对低碳钢表面进行预处理,制备了聚乙烯(PE)涂层,通过对涂层的结合强度、抗热震性能等实验,研究了硅烷化处理对涂层性能的影响.结果表明:KH-560处理法能显著提高PE涂层的结合强度,比砂纸打磨、喷砂处理分别提高了40.3%,13.2%,而KH-550,KBM-7103不能显著提高PE涂层的结合强度;对于PE涂层的硅烷化处理,适宜的KH-560的浓度为5%(体积分数),水解时间为48h;"喷砂 KH-560"处理法抗热震实验后涂层的结合强度仅降低了10.9%,远低于其他处理方法热震后的下降幅度.     

偶联剂处理对玻璃纤维/尼龙复合材料力学性能的影响

采用KH-550 和KH-570 两种不同的偶联剂处理玻璃纤维, 得到的玻璃纤维增强铸型(MC) 尼龙复合材料( GFRMCN) 的力学性能差别很大。经过KH-570 处理GFRMCN 力学性能降低, 而经过KH₂550 处理能有效提高其力学性能; KH₂550 质量分数与处理的玻璃纤维质量分数之间符合定量关系式, 含量为0. 2 %时, GFRMCN的弯曲强度提高了35 % , 弯曲模量提高了72 % , 拉伸强度提高了46 % , 弹性模量提高了88 % , 冲击强度提高了41 %。KH-550 偶联剂在玻璃纤维与尼龙基体之间形成良好界面结合, 达到增强效果; 而未经处理的玻璃纤维断裂时从基体中拔出, 玻纤与尼龙界面相当于缺陷, 使MC 尼龙性能下降。      

改性氧化石墨烯/氢氧化镁/聚酰胺-6复合材料的制备和性能研究

采用γ-氨丙基三乙氧基硅烷(KH-550)改性处理氧化石墨烯(GO),添加改性后的GO,与聚酰胺-6(PA6)/氢氧化镁[Mg(OH)_2],成功制备了改性GO/PA6/Mg(OH)_2复合材料。通过红外光谱、热重分析、X-射线衍射、机械拉伸、锥形量热仪等技术手段对复合材料进行了分析和表征。结果表明,添加改性GO之后PA6/Mg(OH)_2复合材料的热分解速率大大降低,拉伸强度由32MPa提高至43MPa,在改性GO添加量为1%(wt,质量分数),Mg(OH)_2添加量为40%(wt,质量分数)条件下,制得的改性GO/Mg(OH)_2/PA6的极限氧指数达到28.5,具有较好的阻燃性能。     

PBS/杨木粉全降解木塑复合材料的加工流变性能及其应用研究

采用高级毛细管流变仪,分别测定PBS及PBS/杨木粉全降解木塑复合材料的流变性能,研究了不同挤出温度、不同木粉含量对复合材料加工性能的影响。以流变性能测试为参考,改变加工工艺,采用熔融共混法制备了PBS/杨木粉全降解木塑复合材料,并测试其性能。结果表明,随着木粉用量的增加,体系流动性明显下降,可加工的温度范围越来越窄,大致木粉填充量每提高5%,需要升高5℃才能保证粘度变化不大;不同加工工艺对所制备的PBS/杨木粉木塑复合材料性能有较大影响;综合流变性能和力学性能,木粉含量为30%、35%、40%、45%和50%的PBS/杨木粉全降解木塑复合材料的较佳加工温度分别为120、125、125、130和135℃。     

淀粉/聚乳酸挤出片材的制备及性能

采用挤出工艺制备了淀粉/聚乳酸复合片材。通过拉伸强度、断裂伸长率并结合断面形貌研究了淀粉结构、淀粉用量、硅烷偶联剂(KH-550)及甘油增塑剂的用量对挤出淀粉/聚乳酸复合片材性能的影响。结果表明,采用接枝甲基丙烯酸甲酯的改性淀粉作为填充剂,并添加适量KH-550硅烷偶联剂和甘油增塑剂及采用造粒后共挤等工艺可有效改善淀粉/聚乳酸复合片材的兼容性,提高复合材料拉伸强度和断裂伸长率,当改性淀粉含量为20份时样品的拉伸强度和断裂伸长率最大,分别为35.3 MPa和37%。     

添加纳米碳酸钙对木粉/PVC复合材料的影响

在聚氯乙烯木塑(PVC/WF)体系中加入纳米碳酸钙(NCC),采用双螺杆挤出机熔融共混造粒制备了系列NCC/WF/PVC复合材料。测试力学性能和锥形量热计燃烧性能表明,在木粉未经表面偶联剂处理时添加NCC对复合材料力学性能改善效果不明显;而木粉经偶联处理后,木塑力学性能得到有效提高,因为木粉与PVC界面粘接性能得到明显改善;在木粉经表面处理的基础上添加适量纳米碳酸钙可进一步提高复合材料的力学性能,并且阻燃性能也得以有效提高。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.