SMA增容PA6/ABS共混物的结构和力学性能

以苯乙烯一马来酸酐共聚@(SMA)D增容剂,研究了共混工艺对PA6/ABS共混物结构和力学性能的影响.结果表明:以ABS为基体时,加入增容剂SMA后,PA6分散相尺寸变小且均匀地分散于ABS中,显著改善了共混物的冲击、拉伸性能;当以ABS为基体、PA6为分散相时,共混物的结构和力学性能强烈地受共混工艺的影响,SMA先与ABS共混,再与PA6共混,共混物的分散相尺寸最小,力学性能最好;当以PA6为基体、ABS为分散相时,共混物的结构和力学性能基本不受共混工艺的影响.     

PC/PBT共混体系相容性及其性能的研究

根据相容性理论 ,自制了几种PC与PBT的相容剂 ,讨论了相容剂对PC/PBT共混物力学性能的影响。研究表明 :加入相容剂改善了PBT与PC两相间的相容性 ,共混体系力学性能得到提高。通过红外光谱分析得知 ,PBT与PC之间的酯交换反应促进了PBT/PC共混体系的相容性     

尼龙共混复合材料的摩擦学性能研究

研究制备了三种共混型尼龙复合材料UHMWPE／PA66、MAH—g—EPDM／PA66、UH—MWPE／MAH—g—EPDM／PA66，对比评价了三种材料和纯尼龙66的摩擦学性能，对UHMWPE、MAH—g—EPDM对PA66摩擦磨损性能的影响进行了微观分析。摩擦磨损试验及SEM分析表明，MAH—g—EPDM／PA66材料具有良好的摩擦学性能和界面形态。MAH—g—EPDM明显提高尼龙的摩擦学性能，三元共混物的磨损过程中可以生成良好的聚合物转移膜。     

技术文摘专栏

CM/EVM共混物相态、相容牲及硫化体系的研究 【摘要】：研究了不同配比下CM／EVM共混胶形态结构、相容性及共混硫化胶的硫化体系。结果表明：CM／EVM共混胶的相态结构与共混比有关,在共混比为50／50P~发生相转变。CM／EVM共混物均具有一个Tg,且介于上述两种纯胶配方的Tg之间,玻璃化转变的区域范围及程度因配方中两组分的比例不同而不同,     

多壁碳纳米管改性UHMWPE的热膨胀和摩擦学性能研究

为了降低摩擦副用聚合物的热膨胀系数,用多壁碳纳米管(MWCNTs)改性超高分子量聚乙烯(UHM-WPE),通过热压成型法制备MWCNTs/UHMWPE复合材料.通过测量电导率计算渗流阈值来表征分散性;用热膨胀仪(DIL)测试复合材料的热膨胀率,并在干摩擦环境下,测试不同MWCNTs含量复合材料的摩擦学性能.结果表明:通...     

Nylon-6/PET共混物增容方法的研究

分别用对甲苯磺酸(TsOH)与钛酸酯偶联剂作为Nylon-6与PET酯-酰胺交换反应的催化剂,以达到原位增容Nylon-6/PET共混物的目的,通过扫描电镜(SEM)观察了共混物的结构形态,SEM观察表明这两种催化剂都具有增容作用。共混物的力学性能与熔体流动速率测试结果表明,催化剂的加入,降低了Nylon-6与PET的分子量。     

热塑性聚酰亚胺/聚醚醚酮机械共混物的研究

以机械共混的方式制备了热塑性聚酰亚胺／聚醚醚酮（TPI／PEEK）共混物；用熔体流动速率仪研究了共混物的流变性能，用差示扫描量热仪考察了共混物的相容性和热性能，用广角X射线衍射仪研究了共混物的形态和结晶性能。结果表明：共混物的熔体流动指数随PEEK含量的降低和熔体温度的升高而增加；共混物为不相容体系；随TPI含量的减少，共混体系中PEEK的结晶温度和熔点分别升高，而结晶度降低，X射线衍射的结晶峰越来越明显，峰面积也随之增大。     

氧化锌晶须/聚醚砜复合材料的制备及摩擦学性能研究

采用机械共混-模压成型方法制备了ZnOw/PTFE/PES复合材料,通过摩擦磨损实验方法对材料的摩擦学性能进行了研究,并用SEM对磨损表面进行了观察和分析,探讨了复合材料的磨损机制。结果表明:用机械共混-模压法能制得摩擦学性能优良的ZnOw/PTFE/PES复合材料;随着ZnOw含量的增加,复合材料的磨损机制由黏着磨损及疲劳磨损、轻微的黏着磨损向磨粒磨损及疲劳磨损的转变。     

PEG/壳聚糖相变材料储热性能研究

用物理共混法将PEG和壳聚糖共混物改性,得到具有固-固相变性能的储能材料,用DSC具体研究了PEG的质量分数及PEG的相对分子质量对共混材料的相变温度和相变焓的影响。结果表明,不同相对分子质量的PEG在63～68℃之间具有较大的相变焓,且相变焓在180～220J/g之间,均可做为相变储能材料;相对分子质量为8000的PEG相对于其他的PEG更适宜做相变储能材料,共混物中PEG的质量分数低于85%时才表现为固-固相变材料。     

多壁碳纳米管/聚吡咯导电复合材料的制备及性能

以羧基化多壁碳纳米管(MWCNTs)和吡咯单体为反应物,通过原位聚合方法成功制备了MWCNTs/聚吡咯(PPy)导电复合材料;通过傅里叶红外光谱仪、扫描电镜、热重分析仪及四探针电导仪对复合材料的结构与性能进行了表征。结果表明:羧基化MWCNTs高的长径比和大的比表面积使得复合材料比纯PPy的电导率和热稳定性能有显著提高;随着MWCNTs含量增加,复合材料的电导率和热稳定型均明显提高;当MWCNTs质量分数为20%时,复合材料的电导率达到11.1S·cm-1。     

GT/CAD/CAPP/PDM/ERP系统集成研究

研究ETO生产方式下以成组技术为基础的CAD/CAPP/PDM/ERP的集成方法,包括面向CAD/CAPP/PDM/ERP的集成的成组信息编码,基于成组编码的CAD/PDM集成、CAPP/PDM集成和PDM/ERP集成.提出了基于成组技术的CAD/CAPP/PDM/ERP集成框架,研究了贯穿于CAD、CAPP、PDM与ERP系统的统一的成组编码方案和信息编码方案.     

Cylindrical specimens for KIC of rocks

Stress intensity factors for pairs of diametrically opposite radial cracks on the inside of a jacketed pressurized hole in a thick cylinder have been calculated by using finite element technique. Burst tests on thick cylinder rock samples under above conditions have been performed and the K_IC values for Antrim Shale and Limestone determined. The method is very convenient for rocks whose samples are often available in form of cylindrical bars drawn as cores from underground drilling.     

Analysis of the Rk surface roughness parameter proposals

European manufacturers have proposed a set of surface roughness parameters based on an examination of the variation in slope of the bearing ratio curve of a surface profile. It is shown, that the proposed procedure provides no useful information, and indeed is misleading, since the bearing ratio curve of even a normally-distributed random surface profile exhibits the expected variation in slope when plotted on rectangular coordinates. On the other hand, the desired information is readily obtained by a similar examination of the cumulative height distribution of a surface profile (the unity complement of the bearing ratio) when it is plotted on normal probability coordinates.     

基于太赫兹光谱的人参和西洋参鉴别

为了快速区分人参和西洋参，依据两者所含的人参皂苷在太赫兹波段具有不同指纹光谱，提出了一种基于人参皂苷的太赫兹光谱鉴别人参和西洋参的方法。采用MATLAB软件识别人参和西洋参的太赫兹光谱，同时根据太赫兹光谱特征并通过标准的主成分分析(PCA)区分出人参、西洋参。实验结果表明，基于太赫兹光谱的主成分分析可精确区分出人参、西洋参，并且还可以应用于其他类似物质的区分中。     

Near-field second harmonic imaging of the c/a/c/a polydomain structure of epitaxial PbZrxTi1–xO3 thin films

Near-field optical second harmonic microscopy has been applied to imaging of the c/a/c/a polydomain structure of epitaxial PbZr _x Ti_{1– x} O₃ thin films in the 0 <  x  < 0.4 range. Comparison of the near-field optical images and the results of atomic force microscopy and X-ray diffraction studies show that an optical resolution of the order of 100 nm is achieved. Symmetry properties of the near-field second harmonic signal allow us to obtain good optical contrast between the local second harmonic generation in c- and a-domains. Experimentally measured near-field second harmonic images have been compared with the results of theoretical calculations. Good agreement between theory and experiment is demonstrated.     

Characterization of cast Al86Mn3Be11 alloy

An Al₈₆Mn₃Be₁₁ alloy cast into copper mould was subjected to metallographic investigation. The as-cast microstructure consisted of a quasicrystalline icosahedral phase (i-phase), Be₄AlMn phase and, occasionally, a hexagonal phase. Al-rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be₄AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i-phase was approximately Al₅₂Mn₁₈Be₃₀, containing an appreciable amount of Be. The average composition of the hexagonal phase was Al₆₆Mn₂₁Be₁₃. Deep etching and particle extraction provided a deep insight into the three-dimensional morphology of the i-phase and the hexagonal phase, whereas Be₄AlMn was slightly attacked by the etchant. The i-phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be₄AlMn was rather irregular in shape. The morphology of the i-phase can be explained by predominant growth in 3-fold directions and the lowest energy of the 5-fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i-phase, and the polycrystalline nature of the Be₄AlMn phase.     

机械加工与自动化

分析了目前机械制造企业的CAD/CAX应用概况,提出了一种面向企业的CAD/CAM/CAPP/PDM/ERP系统的集成框架和实施内容,以适应现代企业的需要.     

Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites

The domain structures of Zn₃B₇O₁₃Cl, Zn₃B₇O₁₃Br and Zn₃B₇O₁₃I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.     

Electron microscopy of crack/particle interactions in Al2O3/SiC nanocomposites

Crack/particle interactions in alumina/silicon carbide nanocomposites have been investigated by scanning electron microscopy and transmission electron microscopy, with cracks induced by Vickers microindentation. Intergranular cracks are frequently deflected into grains by SiC particles on grain boundaries inclined to the average direction of crack propagation. This mechanism is proposed to explain the change in the fracture mode from intergranular fracture for monolithic alumina to predominantly transgranular fracture for the nanocomposites. Neither stress-induced microcracking around SiC particles nor significant crack deflection by intragranular particles was found to occur in the nanocomposites. It is argued that an addition of nanoparticles may not be a promising approach for increasing the toughness of alumina.     

Investigation on the impact behavior of Al2O3-SiC-MgO nanoceramic/metal laminated composite

Lightweight laminated composites containing a ceramic front layer and a metallic backing layer were used in order to protect people, moving equipment, and mobile vehicles from high velocity impact and the increased mobility of mobile vehicles. In this study, by adding10 vol% SiC and 500 ppm MgO nanoscale particles on the microstructure of Al ₂ O ₃ matrix and applying optimum sintering conditions, ceramic performance against high-speed projectile impact was improved. To perform this investigation, a number of target samples with two different types of front layers (alumina and Al ₂ O ₃-SiC-MgO nanocomposite ceramic) were produced. Impact tests were conducted on these samples using 7.62 mm projectiles with a velocity of 820 ± 15 m/s. The amount of bulge and bending of the backing layer caused by impact tests was measured. The results of the impact tests on the samples made of Al ₂ O ₃-SiC-MgO nanocomposite ceramics and alumina were also compared and analyzed. The results indicate that the substitution of Al ₂ O ₃-SiC-MgO ceramic layer — which is proffered in this paper — instead of pure alumina ceramic layer, decreases the areal-density of the samples by at least 30% and improves mechanical properties by about a 60% increase in flexural strength and 100% growth of the energy distribution factor, which impressively increases impact energy absorption.