聚己内酯在聚己内酯/聚乙烯基甲基醚共混体系中的结晶研究

通过示差扫描量热(DSC)、广角X射线衍射(WAXD)、小角X射线散射(SAXS)研究了聚己内酯(PCL)/聚乙烯基甲基醚(PVME)共混体系中PCL的结晶行为.研究结果表明,共混聚合物中PCL的结晶度几乎不随体系的组成而发生变化.共混物中PVME的存在没有改变PCL的晶体结构,但是随着PVME含量的增加,片晶之间的距离则大,这主要是由于非晶层增厚引起的.     

硅烷接枝hdpe的拉曼光谱

高密度聚乙烯;硅烷;接枝;结晶;拉曼光谱     

Formation of ring calcium oxalate patterns induced by domains in DPPC Langmuir-Blodgett films

The ring patterns of calcium oxalate crystals were induced by domains in Langmuir-Blodgett （LB） films of dipalmitoylpho- sphatidylcboline （DPPC）. The result was explained by the defects at the ring boundaries of liquid condensed （LC） and liquid expanded （LE） phases of LB film. These boundaries could provide less free energy and much more nucleating sites for COM crystals.     

CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE FILLED WITH SiO2 NANOPARTICLES

Oleic acid （OA）-modified SiO2 （OA-m-SiO2） nanoparticles were prepared using surface modification method. Infrared spectroscopy （IR） was used to investigate the structure of the OA-m-SiO2 nanoparticles, and the result showed that OA attached onto the surface of SiO2 nanoparticles through esterification. Effect of OA concentration on the dispersion stability of OA-m-SiO2 in heptane was also studied, and the result indicated that OA-m-SiO2 nanoparticles were dispersed in heptane more stably than the unmodified ones. OA-m-SiO2 nanoparticles can also be dispersed in polypropylene （PP） matrix in nano-scale. The effect of OA-m-SiO2 on crystallization of PP was studied by means of DSC. It was found that the introduction of OA-m-SiO2 resulted in significant increase in the crystallization temperature, crystallization degree and crystallization rate of PP, and OA-m-SiO2 could effectively induce the formation of β-crystal PP. Effect of OA-m-SiO2 content on mechanical properties of PP/OA-m-SiO2 nanocomposites was also studied. The results show that OA-m-SiO2 can significantly improve the mechanical properties of PP.     

纳米磁性液体对多元多相体系结晶特性的影响

以HCFC141b气体水合物结晶生成体系为对象,通过实验研究了磁场作用下纳米磁性液体对多元多相体系结晶生成特性的影响.重点研究了互不相容的水相与HCFC141b液相间、水相与气相(水蒸汽与HCFC141b蒸气)间的质量传递现象.结果发现,在旋转磁场作用下,纳米磁性液体能显著增强相间的质量传递和热量传递,使得结晶生成性能包括生成温度、生成速率等得到很大的提高.     

Influence of Nucleation Agents Concentration on Crystallization Structure and Properties of Glass-ceramics

Deep color glass-ceramics is prepared by using gold tailings as the main raw material, and Cr2O3 is added as nucleation agent. Influence of different Cr2O3 additions on crystallization structure and properties of CaO-MgO-Al2O3-SiO2 glass-ceramics has been discussed so as to select optimum additions. DTA is employed to determine optimum crystallization and nucleation temperatures; XRD and SEM are used to characterize microstructure of each sample; and performance indexes, such as water absorption, bulk density, flexural strength and so on, are also determined. Experimental results show that when 3wt% Cr2O3 is introduced, fine glass-ceramics with diopside as the main crystal and Ca-Fe diopside as the second-crystal is obtained, and its corresponding performance indexes are as follows: water absorption 0.12%, bulk density 2.56 g/cm3, and flexural strength 70.01 Mpa.     

KIO4-结晶紫体系-微波消解催化动力学光度法测定中草药中的痕量铜

铜是人体必需的微量元素之一,人体内铜的含量为100～150mg。铜在人体中具有造血,促进骨骼、血管和皮肤健康的生理功能,是人体中超氧化物歧化酶(SOD)的重要成分。因此建立高灵敏度测定水、食物、药物中铜的方法十分重要。催化动力学光度法测定痕量铜的研究报道较多〔1-3〕,但利用KIO4氧化结晶紫(CV)作为测定铜的方法则未见报道。笔者发现在pH5.0的HAc-NaAc缓冲体系中,痕量铜对KIO4氧化CV的褪色反应有明显的催化作用,探讨了反应的最佳条件,建立了催化动力学光度法测定铜的新方法,研究了动力学参数。该法可应用于水、食物、中草药中痕…     

聚丙烯/锡氟磷酸盐玻璃复合材料的结构与性能

锡氟磷酸盐玻璃(Pglass)具有较低的玻璃化转变温度,在常规聚合物加工温度窗口内具有熔融流动性,是一种新型的无机类聚合物玻璃。本文采用双螺杆挤出机制备了聚丙烯(PP)/Pglass有机聚合物/无机玻璃复合材料,并对其相形貌、界面性能、流动性能、结晶性能、力学性能和热稳定性能进行了研究。结果表明:Pglass以微米级颗粒分散在PP基体中,且两相之间界面明显、相容性较差。Pglass的添加使复合材料的熔体剪切粘度降低。Pglass的存在促进了基体PP的结晶。复合材料的弹性模量随着Pglass含量的增加而增加。Pglass提高了复合材料的热稳定性。     

聚丙烯/无机纳米粒子复合材料的发泡行为

利用型腔体积可控注塑发泡装备制备聚丙烯/无机纳米粒子微发泡复合材料,通过复合材料的流变行为和结晶行为,分析了无机纳米粒子对聚丙烯发泡行为的影响。结果表明:无机纳米粒子有促进气泡异相成核作用,同时无机纳米粒子引入可以提高聚丙烯黏弹响应和降温结晶起始温度,起到了抑制泡孔结构恶化的作用,显著改善了聚丙烯的泡孔结构;在聚丙烯材料中添加纳米CaCO3、纳米OMMT、纳米SiO2进行发泡,以PP/OMMT发泡材料的发泡质量最理想,其泡孔密度和尺寸分别为2×106个/cm3和24.2μm。     

光学纯度对聚左旋乳酸结晶与熔融行为的影响

通过示差扫描量热仪(DSC)和广角X射线衍射仪(WAXD)研究了聚左旋乳酸(PLLA)的光学纯度(91.6%、93.3%、94.0%、97.0%、98.4%)对聚乳酸结晶和熔融行为的影响。 在非等温结晶过程中,随着光学纯度的提高,聚乳酸的结晶峰值温度、熔点、熔融焓均提高。 在等温结晶过程中,PLLA的半结晶时间(t_1/2)随着光学纯度的增加而减少,在结晶温度100~110 ℃区间内半结晶时间均达到最小值;含有不同光学纯度PLLA的Avrami指数n≈3,表明光学纯度的变化不能改变聚乳酸以三维球晶生长的异相成核机理。 随着光学纯度的增加,聚乳酸δ-晶型转变为α-晶型的临界温度升高。 聚乳酸的结晶和熔融行为对光学纯度具有依赖性。