马来酸酐接枝聚丙烯对云母填充聚丙烯的增容作用

以马来酸酐接枝聚丙烯（MPP）为云母填充聚丙烯（PP/mica)的界面相容剂，研究了MPP的添加量对PP/mica的力学,同观形态以及PP/mica熔体的流变行为和非等温结晶行为的影响。结果表明，加入MPP使PP/mica的国学得以全面的提高，PP/mica样品断面的电镜照片表明，MPP的加入使云母与聚丙烯的界面粘结得到改善；PP/mica熔体的表观粘度明显高其聚丙烯基体，随着MPP含量的增加，PP/mica的表观粘度下降，幂律指数也发生变化，云母对聚丙烯具有明显的成核,但随MPP含量的增加，云母的成核效率逐渐减弱。     

椰壳纤维/IPC复合材料的应力-应变曲线拟合及界面改进

采用扫描电子显微镜、万能材料试验机对椰壳纤维/抗冲共聚聚丙烯（IPC）界面改进复合材料的断面形貌、力学性能进行了研究。利用高斯函数模型拟合椰壳纤维/IPC复合材料的应力-应变曲线,得到其数学表达式,计算曲线下的面积,得到各料的韧性模量。结果表明,马来酸酐接枝聚丙烯（MAH-g-PP）作为相容剂改性的复合材料各项力学性能...     

车用内饰填充改性聚丙烯材料耐刮擦性研究

主要考察了基体树脂、增韧剂、填充剂和相容剂对聚丙烯复合材料耐刮擦性的影响,结果表明:(1)就基体树脂而言,均聚聚丙烯耐刮性优于共聚聚丙烯。(2)与其他矿物填料相比,滑石粉填充改性聚丙烯材料的耐刮性最好;另外,滑石粉粒径越小,填充改性聚丙烯材料的耐刮性越好;但当填料粒径小于1μm时,需加强其在聚合物基体中的分散或者进行预分散。(3)随着增韧剂含量增加,流动性提高,填充改性聚丙烯材料的耐刮擦性越好;但超过含量12%(wt,质量分数,下同)以后,聚丙烯材料刮擦值变化不大。(4)相容剂可以有效改善填充改性聚丙烯材料的耐刮擦性,但含量不宜超过5%。     

玻璃纤维增强阻燃PC／ABS合金性能的研究

研究玻璃纤维增强PC／ABS合金在未加相容剂和分别加入相容剂ABS-g-MAH和AS-g-MAH的力学性能。结果表明，加入相容剂之后合金的拉伸强度和弯曲强度均得到提高，其中AS-g-MAH的增容效果更好。选用符合RoHS标准的卤锑系阻燃剂改性PC／ABS合金，发现合金的阻燃性能在达到UL94V-0级时力学性能略有下降。采用SEM图片观察PC／ABS合金加相容剂以及加纤前后的微观结构，发现微观形貌特征和力学试验结果完全相符。     

LH-PP/Nano-clay共混挤出的发泡成型

以超临界CO2为发泡剂,马来酸酐接枝改性聚丙烯（PP-g-MAH）为相容剂,使用单螺杆挤出发泡系统研究了线性均聚聚丙烯（LH-PP）/纳米粘土（Nano-clay）共混物的发泡成型过程,研究了口模温度和共混配方对发泡样品膨胀率、泡孔密度以及口模压力的影响。研究发现,Nano-clay和PP-g-MAH的加入提高了LH-...     

蒙脱土对膨胀型阻燃聚丙烯的性能影响

本文以IFR为阻燃剂,蒙脱土为协效剂,MAH—g—PP为相容剂对聚丙烯进行阻燃改性。研究了阻燃剂和协效剂对聚丙烯燃烧性能、力学性能和加工性能的影响,并运用热重分析（TGA）和差热分析（DTA）表征了阻燃聚丙烯的热分解过程,结果表明：     

聚丙烯/尼龙弹性体复合体系相容性的研究

采用尼龙弹性体(PAE)对PP进行增韧增强改性,同时添加马来酸酐接枝聚丙烯(MPP)来改善PP与PAE的界面相容性。利用扫描电镜(SEM)、差示扫描量热仪(DSC)等手段及力学性能测试,比较研究了MPP对共混物结晶温度及力学性能的影响。结果表明,PAE适用于PP的增韧改性,且增韧效果取决于三元共混体系中MPP的含量;当所含MPP的质量分数达到3%,共混材料界面相容性好,共混物韧性高。     

PP镁盐晶须复合材料的性能研究

研究了镁盐晶须填充改性聚丙烯(PP)材料的力学性能以及PP-g-MAH和PP-g-GMA为相容剂对复合材料的影响等.结果表明:镁盐晶须能明显改善PP材料的拉伸强度、弯曲强度和弯曲模量等力学性能;PP-g-MAH和PP-g-GMA作为相容剂改善镁盐晶须对PP的增韧补强作用.     

多单体接枝聚丙烯增容硅灰石/聚丙烯复合材料

以自制的苯乙烯、甲基丙烯酸丁酯和马来酸酐三单体接枝改性聚丙烯(PP-SBM)为相容剂,采用熔融挤出的方法制备了硅灰石/聚丙烯(W/PP)复合材料。研究了相容剂和硅灰石用量对W/PP复合材料的力学性能及热变形温度的影响,并用光学显微镜、扫描电子显微镜、X射线衍射表征了W/PP复合材料的微观结构。结果表明,当PP-SBM和硅灰石的质量分数均为30%时,复合材料力学性能最好,拉伸强度和冲击强度分别比纯PP提高了27.3%和4.4%,维卡软化点提高了14.4℃,PP-SBM增容效果比商品马来酸酐改性聚丙烯(PP-M)好;光学显微镜分析表明硅灰石在挤出混合过程中大量断裂,长径比大幅度降低;扫描电镜、X射线衍射表征说明加入PP-SBM可以明显提高硅灰石与聚丙烯的相容性。     

三聚氰胺聚磷酸盐对竹纤维/聚丙烯复合材料力学及阻燃性能的影响

采用三聚氰胺聚磷酸盐（MPP）作为阻燃剂,加入到竹纤维/聚丙烯（BF/PP）复合毡中,制备MPP-BF/PP复合材料。采用力学测试和SEM研究MPP对MPP-BF/PP复合材料力学性能和微观形貌的影响;采用极限氧指数（LOI）、热失重（TG）和吸水率为指标研究MPP对MPP-BF/PP复合材料阻燃性、热稳定性和耐水性的影响。测试表明:MPP的质量分数小于30wt%时,MPP-BF/PP复合材料弯曲强度和冲击强度随MPP质量分数的增加先增大后减小,当MPP质量分数达到5wt%时,MPP-BF/PP复合材料呈现出最佳的弯曲强度和冲击强度;MPP在MPP-BF/PP复合材料内部均匀分布,而随着MPP质量分数的增加,MPP-BF/PP复合材料断裂面的粗糙度明显提高,即MPP与PP界面相容性变差,使其力学性能降低。LOI测试结果表明,MPP可以有效提高MPP-BF/PP复合材料的阻燃性能,当MPP质量分数为30wt%时,MPP-BF/PP复合材料LOI达到24.3%。热失重测试表明,MPP的加入可提高MPP-BF/PP复合材料的热分解温度,促进其残炭率明显增大,有利于提高MPP-BF/PP复合材料阻燃性能。耐水性能测试结果表明,MPP质量分数小于20wt%时,MPP对MPP-BF/PP复合材料的耐水性能没有明显影响。采用模糊综合评价法分析表明,MPP质量分数为10wt%时,MPP-BF/PP复合材料性能最优。      

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.     

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.     

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.     

Tc trend in high-Tc superconductors

In our previous works, we have shown that most existing ceramic superconductors can be considered to be built of superconductor-semiconductor composite and we have estimated the change in phonon spectrum of the intrinsic superconductor unit if a semiconductor unit is attached to it. Moreover, the proximity effect under the size quantization condition has been examined in the superconductor-semiconductor composite. Each of the stated effects by itself could causeT _c enhancement in general as more semiconductor blocks are added to the system. We extend our study in this paper to analyze the combined actions of phonon spectral change and proximity effect without size quantization condition onT _c variation in members of the Tl₁ series of high-T _c superconductors. Our results indicate that an optimumT _c is obtained if the stated effects are included in the idealized unit cells of the superconductors made up of a superconductor-semiconductor array.     

Anomalous Hall Effect in Sn1?x?yMnxEuyTe and Sn1?x?yMnxEryTe Mixed Crystals

The Anomalous Hall Effect (AHE) was investigated in IV–VI ferromagnetic semimagnetic semiconductors of Sn_1–x Mn _x Te codoped with either Eu or Er. The analysis of experimental data is as follows. Hall resistivity and magnetization showed that AHE coefficient R _s depends on temperature and its value decreases with thetemperature increase. We observe that above ferromagnet–paramagnet transition temperature R _s changes sign. We discuss the possible physical mechanisms responsible for observed temperature dependence of R _s , particularly change of the sign.     

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.     

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.     

Effect of pressure onTc in La2-xBaxCuO4 withx=0.125

The superconducting transition temperature,T _c , of La_2–x Ba _x CuO₄ has been measured under high pressure up to 8 GPa.T _c is found to change drastically at the pressure where the structural phase transition takes place. This finding clearly indicates that there exists an intimate relation between the crystal structure and superconductivity.