PA1010／MGEPR共混物的流变性能研究

以尼龙1010（PA1010）为基体,以马来酸酐接枝乙丙橡胶（MGEPR）为增韧剂,采用Brabender PLE331型塑化仪制备了PA1010／MGEPR共混增韧尼龙材料,测试了PA1010／MGEPR共混物的表观粘度、非牛顿指数和粘液活化能等流变能数,并重点讨论了其流变性能。实验结果表明：共混物的表观粘度随温度升高而降低;粘流活化能随剪切速率的增而而减小。共混物熔体的表观粘度随剪切速率和剪切应力的增大而降低,非牛顿指数n小于1,符合假塑性流体流动规律。     

尼龙6/环氧树脂共混物流变性能的研究

用毛细管流变仪研究了尼龙6／环氧树脂共混物的流变性能。结果表明,在实验范围内共混物熔体为假塑性流体;随着环氧树脂用量的增加,表观粘度（ηa）增大,非牛顿指数（n）减小,熔体稠度（K）增大,粘流活化能降低。     

PP/EVA/COPET共混物流变性能的研究

采用CFT-500型毛细管流变仪研究了聚丙烯/乙烯-醋酸乙烯酯/碱溶性聚酯(PP/EVA/COPET)共混物的流变性能。结果表明:PP/EVA/COPET共混物出现剪切变稀现象,非牛顿指数小于1,熔体为假塑性流体;熔体表观粘度随EVA含量的增加呈现先减小后增大趋势,并随温度的上升而下降;EVA质量分数为15%的共混物的表观粘度最低,粘流活化能最小。     

茂金属聚乙烯(MPE)/线性低密度聚乙烯(LLDPE)共混熔体的流变学

研究了不同比例共混的茂金属聚乙烯 (MPE)和线性低密度聚乙烯 (LLDPE)熔体的流变学行为 ,讨论了共混物组成、剪切速率和剪切应力以及温度对熔体流变曲线、熔体粘度的影响 ,为MPE的共混改性提供了理论依据。结果表明 :随着LLDPE含量的增加 ,共混熔体的粘度降低 ,转变应力和非牛顿指数减小 ,粘流活化能升高 ,MPE的流动性和加工性能得到改善。     

茂金属聚乙烯（MPE）／线性低密度聚乙烯（LLDPE）共混溶体的流变学

研究了不同比例共混的茂金属聚乙烯（MPE）和线性低密度聚乙烯（LLDPE）熔体的流变学,讨论了共混物组成、剪切速率和剪切应力以及温度对熔体流变曲线、熔体粘度的影响,为MPE的共混改性提供了理论依据。结果表明：随着LLDPE含量的增加,共混熔体的粘度降低,转变应力和非牛顿指数减小,粘流活化能升高,MPE的流动性和加工性能得到改善。     

PTT/PP-g-MAH/PP共混材料形态和流变性能研究

以毛细管流变仪和扫描电子显微镜研究了聚对苯二甲酸丙二醇酯(PTT)/聚丙烯接枝马来酸酐(PP-g-MAH)/聚丙烯(PP)共混体系的形态和流变行为。讨论了共混物的组成、增容剂含量对共混物的形态、熔体流变行为的影响。结果表明:PP-g-MAH改善了PP与PTT的相容性,PP在PTT连续相中分散均匀,分散相尺寸随着增容剂含量的增加而减小。共混物熔体为假塑性流体,其非牛顿指数n、熔体黏度、黏流活化能随增容剂含量的增加而降低。     

PP/EPDM-g-MAH/TPU共混物流变行为的研究

以EPDM g MAH为增容剂 ,采用熔融共混技术制备了热塑性聚氨酯弹性体 (TPU)增韧聚丙烯 (PP)材料 ,研究了PP/EPDM g MAH/TPU共混物的流变行为 ,重点讨论了增容剂EPDM g MAH对共混物流变行为的影响。结果表明 :共混物熔体的非牛顿指数n <1,且随EPDM g MAH用量的增加而减小 ,表观粘度随剪切速率和剪切应力的增大而降低 ,熔体符合假塑性流体的流动规律 ;温度升高 ,表观粘度降低 ;随着EPDM g MAH用量的增加 ,共混物的表观粘度升高 ,粘流活化能有所减小     

热塑性淀粉/生物降解共聚酯共混物流变性能的研究

研究了热塑性淀粉(TPS)以及TPS/生物降解共聚酯共混物的流变行为,讨论了增翅剂用量、共聚酯用量和熔体温度对流变行为的影响.研究表明,TPS和TPS/生物降解共聚酯共混物熔体呈明显的非牛顿特征;增塑剂的使用可以大幅度改善淀粉的塑化行为,通过调节增塑剂用量,可以在一定范围内控制TPS的流变行为.对于共聚酯和TPS的共混体系而言,在共聚酯用量较低时,流动过程中TPS分子链受到较强剪切力作用而发生断链,共混物熔体表观黏度降低.在共聚酯用量较高时,共混物熔体黏度则表现出对温度有较大的敏感性.TPS的黏流活化能较小,TPS/生物降解共聚酯共混物的黏流活化能随共聚酯用量的增加迅速增大,且随剪切速率的增加迅速降低.     

PTT/MMT纳米复合材料的研究

采用熔融共混的方法制备了聚对苯二甲酸丙二醇酯/有机蒙脱土（PTT/MMT）纳米复合材料,通过DSC、热台偏光显微镜等研究了PTT/MMT纳米复合材料的结晶行为,测定了纳米复合材料的力学性能,并用熔体流变仪研究了PTT/MMT纳米复合材料熔体流变性能。结果表明：随着PTT/MMT纳米复合材料中蒙脱上含量的增加,PTT/MMT纳米复合材料的熔融结晶温度增高,纳米复合材料的力学性能有一定的提高;PTT-蒙脱土纳米复合材料熔体的流变性能随MMT含量的增加非牛顿性减弱,熔体的粘流活化能减小。     

PBT/PET共混体系流动性研究

用Instron 3211型毛细管流变仪及XRZ—400型熔融指数仪测试了不同PBT/PET共混体系的流动性,并将数据进行线性回归处理和温度叠加处理。发现在剪切速率为10～10~4秒~(-1)温度在255～285℃范围内,当PBT含量大于50％时,随着PBT含量的增加,共混体系流动性变好,熔体粘流活化能下降。通过实验数据分析了PBT/PET共混改性时纺丝工艺控制特点。     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Synthetic routes to nanoscale BxCyNz architectures

B_xC_yN_z nanoscale materials, hybrids of h-BN and graphite, have been recently synthesised using various techniques. Here, we present the latest advances in the synthesis and characterisation of B-C-N nanotubes and nanofibres. In particular, we focus on layered BC₂N, BN, BC and CN_x systems, reviewing their production methods as well as their structural and electronic properties. These materials may find important applications in the fabrication of nanotransistors, robust nanocomposites, conducting polymers, storage components and field emission sources.     

The System Si3N4-SiO2-Y2O3

Subsolidus phase relations were established in the system Si₃N₄-SiO₂-Y₂O₃. Four ternary compounds were confirmed, with compositions of Y₄Si₂O₇N₂, Y₂Si₃O₃N₄, YSiO₂N, and Y₁₀(SiO₄)₆N₂. The eutectic in the triangle Si₃N₄-Y₂Si₂O₇-Y₁₀(SiO₄)₆N₂ melts at 1500°C and that in the triangle Si₂N₂O-SiO₂-Y₂Si₂O₇ at 1550°C. The eutectic temperature of the Si₃N₄-Y₂Si₂O₇ join was ∼ 1520°C.