PP/POE/BaSO4共混体系界面相互作用表征与拉伸断裂形态研究

设计了三种具有不同界面相互作用的PP/POE/BaSO4三元复合体系，SEM观察和DSC分析证明三元复合体系中形成了两种形态结构。即完全分离结构与核壳包覆结构。采用拉伸屈服强度定量表征了界面相互作用的强弱，研究了界面相互作用对三元复合体系拉伸断裂形态的影响。研究结果表明，体系的界面相互作用对其拉伸屈服强度和断裂伸长率有明显影响。     

纳米SiO2/PEA复合粒子的制备和表征

在经预处理的SiO2表面上通过乳液聚合反应接枝丙烯酸乙酯,用FT-IR和XPS对制备的纳米SiO2/PEA复合粒子进行了表征,研究了由复合粒子填充的PP/POE/SiO2复合材料的力学性能、结晶性能和结构形态。结果表明:通过乳液聚合反应成功地将EA接枝到纳米SiO2的表面上;由复合粒子填充的PP/POE/SiO2复合材料,纳米SiO2在基体中的分散尺寸约为100 nm,分布较均匀,复合材料的冲击强度和断裂伸长率均得到提高,在SiO2含量4%(质量分数)时,PPβ晶峰的强度最强。     

纳米无机粒子改性聚丙烯的研究

利用双螺杆挤出机,通过熔融共混工艺制备了聚丙烯(PP)/聚烯烃热塑性弹性体(POE)/无机纳米粒子复合材料。利用扫描电子显微镜(SEM)观察了不同体系的断面形态,并测试了复合材料的力学性能。研究结果表明,对纳米粒子进行表面改性和用适当的共混方法,可以提高复合材料的冲击性能。     

PP/PMMA接枝剑麻纤维复合材料的结构和性能

用注塑成型方法制备了PP／PMMA接枝剑麻纤维（SF）复合材料，研究了它的热性能、晶态结构、微观结构和力学性能。结果表明PMMA表面接枝的SF增强了PP与SF之间的作用力，改善了PP／SF的热稳定性，降低了PP相的熔点，同时SF的加入诱导了β－晶型PP的生成，提高了PP相的结晶度，降低了无定型PP的玻璃化转变温度。PMMA接枝的SF提高了PP的模量，对PP有明显的增韧效果。     

尼龙6/马来酸酐-苯乙烯多单体接枝聚丙烯反应共混物

用双螺杆挤出机制备了聚丙烯(PP)与尼龙6(PA6)的共混物．先用多组分熔融接枝的方法将马来酸杆（MAH）和苯乙烯（St）共同接枝于聚丙烯（PP）上，制得多单体接枝聚丙烯PP-g-(MAH-St），该接枝物具有较高的MAH接枝率。利用MFR、SEM、TEM和力学性能测试等分析方法，研究了多组分熔融接枝聚丙烯PP-g-(MAH-St)对PA6/PP共混物的形态结构和力学性能等的影响。结果表明，PP-g-(MAH-St)中的酸酐基团与PA6末端的氨基发生化学反应，原位形成的PP-PA6共聚物能有效地改善PA6与PP的相容性，可以使PP均匀地分散在PA6基体中，相区尺寸明显减小，可至0.1μm，并使共混物的力学性能得到均衡的提高，冲击韧性的提高尤其显著，达到了橡胶改性所难以达到的效果。     

多单体熔融接枝PP增容PP/PVC共混体系的力学和流变性能研究

合成了一种新型的多单体接枝物PP－g-(St-co-MMA),研究了其对PP／PVC共混体系的增容作用。讨论了接枝物用量对共混物力学性能和流变行为的影响，并通过扫描电镜（SEM）对共混物的亚微观相结构进行了分析。结果表明，该接枝物对PP／PVC共混体系有较好的增容效果，材料的力学性能在接枝物用量为6份时出现峰值；加入接枝物能使体系的熔体粘度增加，并且在所研究的温度和压力范围内共混物熔体呈典型的假设性流体特性。     

聚合物/热塑性弹性体/纳米无机粒子三元复合材料的增韧增强研究进展

介绍了聚合物/热塑性弹性体/纳米无机粒子三元复合材料的形态结构及增韧机理,分析了热塑性弹性体、纳米无机粒子、加工工艺、界面性能4个方面对聚合物/热塑性弹性体/纳米无机粒子三元复合材料形态和性能的影响。热塑性弹性体和纳米无机粒子对聚合物有协同增韧增强作用,加料顺序是形态结构的最主要影响因素,聚合物的力学性能非常依赖热塑性弹性体和纳米无机粒子在聚合物中的存在形态。最后,展望了该体系未来的研究方向。     

新型乙-丁共聚弹性体/聚丙烯共混体系的结构形态与力学性能

利用偏光显微镜,X射线衍射仪和动态力学粘弹谱研究了新型乙－丁共聚弹性体（PEB）改性PP的PP／PEB共混物的形态结构,结果表明,在PP／PEB共混物中,两者在非晶区有良好的相互渗透性,PEB阻碍了PP球晶的形成,使其微晶尺寸变小,弹性体PEB的加入,可以明显地起到增韧PP的目的。     

PP/POE/滑石粉三元复合材料的研究

研究了弹性体(POE)、滑石粉、偶联剂和填料处理方式对聚丙烯(PP)的力学性能、加工性能、结晶行为以及无机粒子在基体中分散形态的影响。结果表明,PP 2(K 7726)/POE(80/20)二元共混体系的综合性能较好;采用方式C(将两种偶联剂按1∶1的质量比,先加钛酸酯后加硅烷处理滑石粉)制得的PP 2/POE/T a lc(80/20/25)三元复合材料的力学性能比其它两种方式有显著提高。偏光显微镜(PLM)研究表明,方式C处理的滑石粉在体系中分散性最好;扫描电镜(SEM)显示,三元复合体系由PP 2/POE耗能少的空洞化断裂方式向耗能多的剪切屈服方式转变;DSC表明,采用方式C处理的滑石粉对聚丙烯的成核作用减弱。     

弹性体增韧聚丙烯共混体系的研究

用弹性体对聚丙烯(PP)增韧改性,探讨了基体树脂、POE/EPDM、HDPE的用量对共混体系力学性能的影响,并通过扫描电镜观察冲击断面,研究共混物的形态结构。结果表明,用POE橡胶来增韧和用EPDM增韧相比,前者使材料有更好的弯曲强度和弯曲模量;两者对拉伸强度的影响不大;后者使材料的冲击强度较大。     

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.     

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 $\text{0.10 ?}\text{x}\text{? 0.14}$.