车用耐刮擦聚丙烯材料的制备及其性能研究

车用聚丙烯(PP)在使用中易受到刮伤从而影响产品美观及使用性能。研究PP耐刮擦性能的影响因素,改善PP耐刮擦性能是满足车用耐刮擦PP市场需求的重要前提。以PP为基材,探究了4种不同作用机理的耐刮擦剂(芥酸酰胺、硅酮母粒、滑石粉和聚硅氧烷)对PP力学性能、热性能、结晶性能和耐刮擦性能的影响,并利用偏光显微镜和超景深三维显微镜观察PP材料刮擦表面的形貌。结果表明:4种耐刮擦剂使部分PP材料的冲击强度或弯曲强度显著提高,但拉伸强度均小幅度降低;芥酸酰胺、硅酮母粒和聚硅氧烷不改变PP的结晶形貌和结晶行为,滑石粉则破坏PP的结晶性能;4种耐刮擦剂均降低PP的摩擦系数和色差值(ΔL),改善其耐刮擦性能,其中聚硅氧烷不仅能改善PP的耐刮擦性能,其ΔL下降约89%,并能有效抑制PP的析出发黏和发白现象。     

滑石粉/聚丙烯复合材料结晶度与相间形态对其力学性能的影响

用偶联剂改性的滑石粉（Talc）与聚丙烯（PP）共混制备Talc／PP复合材料,测试了复合材料的力学性能。用广角X射线衍射仪对聚丙烯的结晶状况进行了表征,计算了复合材料中聚丙烯的结晶度;用扫描电镜观察了样条的断口形貌,讨论了滑石粉填充量对材料结晶性能与相态结构的影响．以及PP相结晶度和体系的微相结构对复合材料的拉伸、弯曲及冲击性能的影响。实验结果表明,滑石粉的加入对复合材料的结晶行为、相态结构和力学性能有影响。在15％的滑石粉填充量时,聚丙烯相的结晶度达到最大值,材料的拉伸强度、弯曲强度也基本上达到最大值,而冲击强度却降到最低。扫描电镜照片显示,PP基体的结晶形态与复合材料的相态结构随滑石粉含量的改变而变化。     

PP/POE/高岭土三元复合材料的力学及热性能

研究了高岭土和乙烯-辛烯共聚物弹性体(POE)填充聚丙烯(PP)制备的PP/POE/高岭土三元复合材料的力学和热力学性能。结果表明,POE和高岭土不能提高PP的拉伸强度,但高岭土可以显著提高PP/POE的杨氏模量。POE降低了PP的弯曲强度和弯曲模量,但PP/POE/高岭土三元复合材料的弯曲强度和弯曲模量显著高于PP/POE和PP。POE和高岭土可以显著提高PP的冲击强度,当高岭土和POE的填充份数分别为10份和5份时,PP/POE/高岭土复合材料的冲击强度最大。高岭土的添加可以提高PP的结晶温度,加快PP的结晶速率,促进PP的异相成核。合适含量的高岭土可以提高PP的熔融温度,改善PP的耐热性能。     

滑石粉填充二醋酸纤维素复合材料的性能研究

采用熔融共混方法制备了二醋酸纤维素(CA)/三醋酸甘油酯(GT)/滑石粉(Talc)(CA/GT/Talc)复合材料。研究了滑石粉的粒径、表面处理工艺和添加量对复合材料力学性能、耐热性能、转矩流变性能及微观结构的影响。结果表明,滑石粉的加入有效改善了复合材料的力学性能。并且滑石粉的粒径越小越有利于复合体系的力学性能的提高。5000目滑石粉经过表面处理后对复合体系的力学性能效果更好。复合材料的拉伸强度、断裂伸长率及冲击强度随着滑石粉用量的增加呈先上升后下降的趋势,在5000目改性滑石粉用量为2%(wt,质量分数)条件下,制得的CA/GT/Talc复合材料与未添加滑石粉的CA/GT体系相比,拉伸强度从62.00MPa提高至81.63MPa,断裂伸长率从13.8%增加至52.0%,缺口冲击强度为17.05kJ/m~2,增加约4倍。     

凹凸棒石/弹性体协同改性聚丙烯

通过熔融共混法,制得了聚丙烯(PP)/硅烷偶联剂改性的天然凹凸棒石(OATT)/聚烯烃弹性体(POE)三元复合材料和PP/OATT、PP/凹凸棒石(ATT)二元复合材料,研究了复合材料的力学性能、流变性能和热性能。力学性能研究结果表明:在二元体系中,复合材料的拉伸强度随着ATT和OATT含量提高而提高,但是在相同凹凸棒石含量下,PP/OATT复合材料的拉伸强度提高更显著;PP/ATT复合材料的冲击强度与纯PP比较没有提高反而下降,而PP/OATT的冲击强度则随着OATT含量提高先增后降,并在OATT含量为1%时达到最大值。在PP/OATT/POE三元体系中,当固定PP/OATT比例为100/5时,POE含量达到5%,复合材料冲击强度为8.91KJ/m2,与未加POE体系相比提高了21.10%;当POE含量增加到15%时,复合材料冲击强度提高了44.80%,并且其拉伸强度基本得到保持,说明POE和OATT对PP具有明显的协同增韧增强效果。流变曲线分析表明,在低的剪切速率下,改性的凹凸棒石对PP复合材料的流动性能有较好改善。DSC分析结果表明,POE和OATT均能有效地促进PP结晶,并且OATT/POE二元组分对...     

滑石粉粒径对聚乳酸的结晶行为和力学性能研究

本文研究了不同粒径的滑石粉对聚乳酸(PLA)结晶性能和力学性能的影响。通过差示扫描量热仪研究了不同比例的PLA/滑石粉体系的结晶熔融行为,并使用热台偏光显微镜对PLA/滑石粉体系的结晶形态进行了表征。通过实验分析得出,滑石粉添加量相同时,其粒径越小,PLA的结晶度越高,成核效果越好。且随结晶度增大,其拉伸强度提高,但是断裂伸长率有所下降;滑石粉粒径大小相同时,随滑石粉添加量的增加,PLA结晶度增加,拉伸强度提高。     

硼酸锌含量对麦秸秆/PP复合材料耐霉菌腐蚀性能的影响

为探讨防霉剂硼酸锌对麦秸秆/聚丙烯(PP)复合材料耐霉菌腐蚀性能的影响,对添加不同含量硼酸锌的麦秸秆/PP复合材料进行了霉菌加速腐蚀实验。测试其腐蚀后的力学性能、颜色变化和吸水性,采用FTIR分析其官能团的变化,采用体视显微镜观察并分析复合材料表面霉菌生长情况及表面微观结构。结果表明:硼酸锌对麦秸秆/PP复合材料耐腐蚀性能有较好的改善作用,硼酸锌最佳添加量为2wt%,麦秸秆/PP复合材料腐蚀后表面霉菌生长较少,其弯曲强度、弯曲弹性模量、拉伸强度和冲击强度比不添加硼酸锌分别提高6.5%、50.2%、6.8%和11.1%,吸水率和色差值降低23.9%和30.7%。含量为2wt%的硼酸锌能够有效阻止霉菌菌丝腐蚀麦秸秆/PP复合材料的麦秸秆纤维素和半纤维素,而硼酸锌含量较高时会影响复合材料的界面,导致界面处麦秸秆纤维更易受霉菌腐蚀作用。     

功能化聚丙烯对纳米SiO2/聚丙烯复合材料性能的影响

以环氧功能化聚丙烯(PP-g-GMA)作为纳米SiO2/PP复合材料的增容剂,研究了PP-g-GMA对复合材料力学、结晶和流变性能的影响.研究结果表明,PP-g-GMA的加入使PP复合材料的拉伸强度、冲击强度提高;使PP的结晶峰温明显提高,使复合材料的储能模量和复合黏度均明显高于纯PP.     

PP/SBS复合材料共混改性及性能研究

分别采用一阶、二阶熔融共混的方法制备出PP/SBS复合材料,研究了该复合材料体系中不同含量的弹性体SBS对PP性能的影响。并通过冲击、拉伸和熔融指数等实验,分析了共混物中SBS的含量对PP的冲击强度、拉伸强度、断裂伸长率和熔融指数等性能的影响。结果表明:在PP中加入了不同含量的弹性体SBS,对其各种性能的影响均不相同,通过对比一阶和二阶共混工艺的性能,还得到二阶共混比一阶共混工艺性能好;同时得到在基体PP中加入15%的SBS,其综合性能最好,并且还大大改善了PP的冲击强度和韧性,使其性能得以提高。     

改性纳米碱式氯化镁晶须填充ABS/PP复合材料的力学性能

本文通过熔融共混法在接枝了PMMA的碱式氯化镁（g-BMC）表面包覆TPE橡胶层,制得BMC母料,再将其与PP、ABS共混复合制备出ABS/PP复合材料,分别考察了BMC母料、g-BMC以及PP三者不同添加量对复合材料力学性能的影响。结果表明,在试验用量范围内,BMC/ABS复合材料的冲击强度和熔融指数随着BMC填料含量的增加而增大。当BMC母料含量为15%,g-BMC含量为55%时具有较好的冲击性能;当PP含量为9%-10%时,BMC/PP/ABS复合材料的拉伸强度和冲击强度最好;BMC填料含量对复合材料的拉伸强度影响较小,但随其用量增加复合材料的冲击强度有明显提高。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.