成核剂改性聚丙烯共混体系的研究

用偏光显微镜和DSC研究了几种成核剂对聚丙烯共混体系结晶形态、结晶度、结晶温度的影响.结果表明,成核剂4030的加入,使共混体系的结晶度最大,成核剂d(自制)的加入使共混体系的最高结晶峰温度最低,也使制品收缩率最大.     

有机磷类成核剂作用下聚丙烯结晶行为及其力学性能

研究了含有不同含量成核剂的聚丙烯的结晶行为对其力学性能的影响．结果表明，当成核剂含量从0增至0．8％(质量)时，树脂的拉伸强度和弯曲强度提高了15％，弯曲模量增加了35％，结晶温度提高了10℃，由非线性Volterra积分方程得到的成核密度提高了10^4倍，而且成核聚丙烯的成核密度与其材料的力学性能之间存在着线性关系，即随着成核密度的增大，材料的拉伸和弯曲性能呈线性的增大．     

N,N′-二苯基丁二酰胺诱导生成β晶型等规聚丙烯

研究了酰胺化合物——N,N′-二苯基丁二酰胺(DPS)的用量和结晶温度对聚丙烯中β晶型含量和结晶度的影响。发现DPS是聚丙烯的高效β成核剂,随着DPS含量的增加,聚丙烯中β晶型含量不断增多。等温结晶试验表明,添加0.2%DPS的聚丙烯样品在结晶温度为120℃时生成最大含量β晶型,此时β晶型的相对含量达到89.06%。     

庚二酸/硬脂酸钙双组分成核剂对β晶型等规聚丙烯生成的影响EI北大核心

研究了在120℃等温结晶30min的条件下,庚二酸／硬脂酸钙组成比对等规聚丙烯中β晶型含量的影响,发现在0．15％（质量分数）庚二酸用量下,随着硬脂酸钙用量的增加,β晶型含量不断增大,硬脂酸钙用量在0．35％（质量分数）以上时,才能生成较高纯度的β晶型聚丙烯,说明iPP和双组分成核剂熔体混合时,庚二酸和硬脂酸钙可能“就地”发生化学反应,生成高效13晶型成核剂——庚二酸钙。还研究了在0．15％庚二酸／10．5％硬脂酸钙固定组成比下,等温结晶温度（100℃～140℃）对iPP中β晶型含量的影响,发现在130℃～140℃之间发生β→α晶型转变。     

成核PP注塑样品的非等温结晶行为与熔融特性

用DSC研究了两种成核剂成核PP的非等温结晶行为与熔融特性,致命伤中成核剂均使PP的降温结构温度提高,结晶峰半高宽变窄,结晶度与熔点略有提高,但结晶峰对称性变差,熔融峰半高宽加大,成核样品的结晶温度对冷却速率的依赖性较纯PP的小,根据过冷度和成核PP与纯PP的结晶温度之差,成核剂成核作用大小顺序为：A＞D。     

庚二酸／硬脂酸钙双组分成核剂对β晶型等规聚丙烯生成的影响

研究了在120 ℃等温结晶30 min的条件下,庚二酸/硬脂酸钙组成比对等规聚丙烯中β晶型含量的影响,发现在0.15%(质量分数)庚二酸用量下,随着硬脂酸钙用量的增加,β晶型含量不断增大,硬脂酸钙用量在0.35%(质量分数)以上时,才能生成较高纯度的β晶型聚丙烯,说明iPP和双组分成核剂熔体混合时,庚二酸和硬脂酸钙可能"就地"发生化学反应,生成高效β晶型成核剂--庚二酸钙.还研究了在0.15%庚二酸/0.5%硬脂酸钙固定组成比下,等温结晶温度(100 ℃～140 ℃)对iPP中β晶型含量的影响,发现在130 ℃～140 ℃之间发生β→α晶型转变.     

庚二酸类成核剂种类和结晶温度对等规聚丙烯中β晶型的影响——Ⅰ庚二酸、庚二酸镁和庚二酸铝的影响

研究了结晶温度(100℃~140℃)对庚二酸、庚二酸镁、庚二酸铝成核等规聚丙烯中β晶型生成的影响。发现聚丙烯熔体在120℃或130℃下等温结晶,可以产生β晶型。庚二酸是低活性β晶型成核剂,生成的β晶型不稳定,易在加热时转变为α晶型,造成DSC熔融峰变宽。庚二酸镁也是低活性β晶型成核剂,生成的β晶型含量低。庚二酸铝不是β晶型成核剂,对β晶型的生成有抑制作用。     

一种酰胺类成核剂对聚乳酸结晶行为的影响

通过自主设计合成一种含酰胺结构的新型成核剂——1,6-二苯基己烷基脲(NA6),并利用差示扫描量热仪(DSC)和偏光显微镜(POM)研究了NA6成核剂(1~8wt%)对聚乳酸(PLLA)结晶行为的影响。结果表明,随着NA6成核剂含量的增加,PLLA的结晶温度由93.8℃提高到118.6℃,结晶度由12.0%提高到65.5%;130℃时的等温结晶速率提高到0.56min-1,是纯PLLA的14.5倍。此外,NA6成核剂可显著减小PLLA的球晶尺寸,且随着成核剂含量的提高成核效果愈加明显。     

羧酸盐类β晶成核剂与α晶成核剂的复合体系对等规聚丙烯成核结晶行为的影响

采用差示扫描量热(DSC)、广角X射线衍射(WAXD)以及力学性能分析等方式考察了两种α晶成核剂和一种羧酸盐类β晶成核剂复合后对等规聚丙烯(iPP)的结晶性能、晶型结构以及力学性能的影响。结果表明,α/β复合成核剂对聚丙烯的结晶峰值温度、晶型结构以及力学性能的影响都与复合体系中结晶峰值温度较高的单一成核剂相似,说明在α/β复合成核剂体系中,两种成核剂竞争成核,结晶峰值温度较高的成核剂在结晶过程中起主导地位,而结晶峰值温度较低的成核剂成核作用较小。     

有机磷酸酯盐与羧酸盐复配成核剂对等规聚丙烯性能的影响

以2,2'-亚甲基-双-（4,6-二叔丁基苯基）磷酸钠 （NA-11）和双环[2,2,1]-庚烷-2,3-二羧酸钠 （NA-CA）2种成核剂进行复配,研究复配成核剂对等规聚丙烯（iPP）力学性能和结晶行为的影响。采用双螺杆挤出机为共混设备将成核剂与iPP共混,制备了NA-11/NA-CA/iPP复合材料。通过万能材料实验机、XRD、DSC、偏光显微镜（PLM）对其力学性能、结晶形态、微观结构进行了表征。结果表明:NA-11和NA-CA 2种成核剂复配能够显著提高iPP的拉伸性能和弯曲性能。NA-11和NA-CA复配成核剂诱导iPP形成α晶体。2种成核剂1∶1复配,添加量为0.4wt%时,iPP的结晶峰温度提高了20.3 ℃,结晶度提高了8.8%。PLM显示,NA-11和NA-CA复配成核剂使iPP球晶尺寸明显变小。NA-11和NA-CA复配成核剂具有很好的成核效果,这2种成核剂对改善聚丙烯的结晶性能和力学性能具有协同效应。      

Preparation and characterization of nano-NaX zeolite by microwave assisted hydrothermal method

In the present work, nano-NaX zeolite crystals were synthesized via microwave and conventional hydrothermal methods. The effects of reaction time, temperature and heating method on the characteristics of zeolite nanoparticles such as particle size, crystallinity, morphology, size distribution and surface area were investigated. The prepared NaX zeolite nanoparticles were characterized by the XRD, SEM, DLS, BET and XRF analysis. The results showed that both heating methods produced the NaX zeolite crystals with nano-in size. The microwave heating produced smaller zeolite nanoparticles with relatively narrower particle size distribution, required much shorter heating times and did not significantly change composition or crystallinity, compared with the conventional heating method. It was also observed that the time and temperature of microwave heating had significant effects on the prepared zeolite particles and the pure zeolite X nanoparticles or a mixture of zeolite X and A can be synthesized using the microwave heating method by control of the crystallization time and temperature.     

Reduction of crystallization temperature of the Aurivillius phase in Nd-doped SrBi2Ta2O9 thin films via substrate bias

Nd-doped SrBi₂Ta₂O₉ films were sputtered on Pt/Ta/SiO₂/Si substrates under various substrate biases. The radio frequency bias results in the reduction of the Aurivillius phase crystallization temperature. At 48 W, the crystallization temperature of film is lowered at a magnitude of about 80 °C. When the bias further increases, Aurivillius phase formation is suppressed due to too deficient Bi in film. The film deposited at 48 W after annealing at 670 °C shows ferroelectric characteristics. The remnant polarization of the films increases as the annealing temperature is increased.     

晶化温度对白泥粉煤灰玻璃陶瓷抗折强度的影响

本文以制碱白泥和粉煤灰为主要原料,添加适量添加剂,制备了白泥粉煤灰玻璃陶瓷。通过差热分析（DTA）确定了核化、晶化温度;研究了不同热处理温度对白泥粉煤灰玻璃陶瓷抗折强度的影响,并采用X射线衍射仪（XRD）和扫描电子显微镜（SEM）分析了结晶物相和微观结构。研究结果表明,热处理温度对白泥粉煤灰玻璃陶瓷的抗折强度有较大影响,最佳的热处理温度为900℃。     

Fabrication of tungsten-based metallic glasses by low purity industrial raw materials

Quaternary W₃₀Fe₃₈B_32−xC_x (x = 5, 7, 10, 13, 15 at.%) alloys have been investigated by melt-spinning method to produce metallic glasses using low purity industrial raw materials. The phase structure of these ribbons is investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The thermal stabilities of W₃₀Fe₃₈B_32−xC_x (x = 5, 7, 10, 13, 15 at.%) alloys are analyzed by differential scanning calorimeter (DSC). It is found that W₃₀Fe₃₈B₂₂C₁₀ metallic glass with 45 μm in thickness and 2 mm width can be successfully fabricated. And other alloys with the same thickness and width as W₃₀Fe₃₈B₂₂C₁₀ alloy are observed with some crystalline peaks on the halo patterns. The DSC measurements show that each alloy undergoes a two-step crystallization with the onset temperature of the first crystallization being as high as 984-1067 K. Vickers hardness and density values of W₃₀Fe₃₈B_32−xC_x (x = 7, 10, 13, 15 at.%) alloys at room temperature are 11.9-12.8 GPa and 14.5 g/cm³ at least, respectively. The effect of C addition on GFA in the W-Fe-B alloy system is discussed.     

Ferroelectric properties of Bi3.4Dy0.6Ti3O12 thin films crystallized in N2

Bi_3.4Dy_0.6Ti₃O₁₂ (BDT) ferroelectric thin films were deposited on Pt/Ti/SiO2/Si substrates by chemical solution deposition (CSD) and annealed in an N₂ environment after pre-annealing in air at 400 °C. The effect of crystallization temperature on the structural and electrical properties of the BDT films was studied. The BDT films annealed in N₂ in the temperature range of 600 °C to 750 °C were crystallized well and the average grain size increased with increasing crystallization temperature, while the remanent polarization of the films is not a monotonic function of the crystallization temperature. The BDT films crystallized at 650 °C have the largest remanent polarization value of 2P_r = 39.4 μC/cm², and a fatigue-free characteristic.     

Effects of exposure temperature on degradation of polyphenylene sulfide non-woven bag-filter media by NO2 gas at high temperature

The influence of exposure temperature and exposure time on the degradation of polyphenylene sulfide (PPS) fabric filter media was examined in detail. Although increases in the exposure temperature and time resulted in more severe damage, PPS filter media subjected to lower exposure temperatures always had lower tensile strengths than those of media subjected to higher exposure temperatures. Although the elastic modulus increased with exposure time, the hardening rate increased with exposure temperature. Crystallinity increased monotonically with exposure time at higher temperatures, whereas it increased once and then decreased with exposure time at lower temperatures. Exposure at lower temperatures led to the oxidation of S to the sulfinyl group, whereas exposure at higher temperatures induced oxidation to the sulfonyl group and substitution on the benzene ring. The change in NO₂ concentration of the exhaust gas with exposure time depended significantly on the exposure temperature. The improved model, which considered the NO₂ concentration distribution in the direction of the filter media thickness, reproduced these trends more accurately and could identify the gas–solid reaction between PPS and NO₂ gas as a homogeneous reaction at lower temperatures, and as a diffusion-controlled reaction in the product layer at higher temperatures successfully.     

Parametric and numerical study on the diffusion in a metalized amorphous binary alloys film

An amorphous Ta-Zr diffusion barrier was studied under the Cu metallization. A stack of Cu/Ta₅₀Zr₅₀/Si with a 50 nm amorphous film fabricated by co-sputtering was found to fail when annealed up to 650 °C, which is much lower than the crystallization temperature (800 °C) of the amorphous Ta₅₀Zr₅₀ film. Besides, results show that the existence of Cu layer can induce the formation of three metal silicides, namely TaSi₂, ZrSi₂ and Cu₃Si almost all at 650 °C. A mechanism for the failure of barrier film is proposed based on the change of activation energy for diffusion by the metallization-induced tensile stresses during annealing.     

Effects of Si-ion implantation on crystallization behavior of Ge2Sb2Te5 film

Crystallization and thermal stability of Ge₂Sb₂Te₅ (GST), the benchmark working material in phase-change non-volatile memory, were modified via Si-ion implantation. Through 5 × 10¹⁵ Si-ions/cm² ion-implantation, crystallization temperature increases from 165 °C to 177 °C. Furthermore, the activation energy of crystallization increases from 2.9 eV in the pristine film to 3.3 eV and 4.0 eV in films implanted with the doses of 5 × 10¹⁵ and 5 × 10¹⁶ Si-ions/cm², respectively. Temperatures corresponding to a 10-year failure-time increase from 83 °C in the pristine film to 96 °C and 107 °C in films implanted with 5 × 10¹⁵ and 5 × 10¹⁶ Si-ions/cm², respectively. Thermal stability of Si-ion implanted GST thus improves significantly. It was also found that grain growth is inhibited with higher implantation doses. In the case of the 5 × 10¹⁶ ion/cm² dose, the second-phase transition from face-centered cubic to hexagonal closed-packed structure of the GST is completely inhibited. However, crystallization time increases slightly due to Si-ion implantation.     

Effect of alkali and alkaline earth oxides on crystallization of Li2O-Al2O3-SiO2 glasses

The effect of alkali and alkaline earth oxides on the crystallization of lithia-alumina-silica glasses has been studied. Crystallization behaviour of glasses has been investigated using DTA and XRD techniques. The principal crystallization phases are identified asβ-spodumene solid solution and lithium metasilicate. The crystallization temperature of glasses decreases with increase in the values of the ionic field strength of the alkali and alkaline earth cations. Addition of these oxides at lower concentrations has no significant effect on the crystalline phases.     

Phase transformation in Mg-Sb thin films

Thermal and electrical properties of Mg-Sb films were investigated for evaluation as phase-change memory materials. Electrical resistance of as-deposited amorphous Mg-Sb films decreases with increasing temperature until an abrupt drop at the crystallization temperature, with a total of 4 orders-of-magnitude resistance change. The crystallization temperatures increases from 140 °C to 190 °C as decreasing Sb content from 72.4 to 45.9 at.%, and the melting temperature remains at around 577 °C. The temperature corresponding to 10-year data-retention is 94 °C (54.6 at.% Sb) and 128 °C (41.3 at.% Sb), respectively. Optimal compositions are proposed to be 40 to 50 at.% Sb.