高抗冲抗静电聚碳酸酯复合材料的研制

以导电炭黑、聚碳酸酯(PC)和苯乙烯-乙烯/丁烯-苯乙烯共聚物(SEBS)作为基体材料,通过熔融共混的方法制备了高抗冲抗静电复合材料.研究了炭黑类型、炭黑用量、基体树脂组成对电性能和力学性能的影响.结果表明,以高结构性的导电炭黑CB3000为导电填料,PC/SEBS在80/20质量比时,能够获得电性能和力学性能俱佳的复合材料.PC/SEBS/CB3000(90/10/3.5)体系在保持导电性能的同时实现了脆韧转变,缺口冲击强度达到50 kJ/m<'2.经扫描电镜(SEM)分析表明,双连续结构的形成是PC/SEBS/CB复合材料实现脆韧转变的主要原因.     

PP/SEBS/MH复合材料的制备及其性能研究

采用极限氧指数（LOI）和热重分析（TGA）研究了聚丙烯（PP）/氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物（SEBS）/氢氧化镁（MH）复合材料的阻燃性能和热降解行为;探讨了SEBS和MH分别对PP/SEBS共混体系和PP/SEBS/MH复合材料力学性能和熔体流动速率的影响。结果表明：PP/SEBS/MH复合材料的力学性能和加工流动性能随着MH的质量分数增加而降低;复合材料高温下的热稳定性得到提高,MH分解吸热降低材料的热降解速率;MH以吸热方式在凝缩相和气相中发挥阻燃作用,复合材料阻燃性能得到提高,当MH的质量分数为60%时,LOI可达26.3%。     

LDPE/SEBS/CB电致形状记忆复合材料的结构与性能

通过熔融共混法将热塑性弹性体氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物(SEBS)和低密度聚乙烯(LDPE)制成形状记忆聚合物(SMP)材料;在SMP材料中填充导电炭黑(CB),制成具有电致形状记忆特性的LDPE/SEBS/CB复合材料。通过SEM、DSC分析和力学性能、电性能、记忆性能测试,研究了CB含量对电致SMP材料结构与性能的影响。结果表明:当CB含量达到20%时,LDPE/SEBS/CB复合形状记忆材料的体积电阻率降至103Ω·cm左右,CB的导电网络趋于稳定;并且LDPE/SEBS/CB(2:2:1)复合形状记忆材料的形状固定率约90%,常温拉伸和高温拉伸时均表现出较高的形状回复率(约90%),拉伸模量约170MPa,拉伸强度约9.5MPa,断裂伸长率约400%。     

（PE-HD／SEBS）-g-MAH对PE-HD／木粉复合材料增容的研究

采用转矩流变仪制备出马来酸酐（MAH）接枝PE-HD）／氢化（苯乙烯-丁二烯-苯乙烯）共聚物（SEBS）（PE-HD/SEBS）-g-MAH作为PE-HD／共混物木粉复合材料的界面相容剂，并研究了制备过程中转矩的变化，结果表明，体系的转矩随着MAH和引发剂过氧化二异丙苯含量的增加而增加，苯乙烯促进了MAH和PE-HD／SEIKS的反应；通过傅里叶红外分析证实了MAH接枝到聚合物上。（PE-HD／SEBS）-g-MAH能明显地提高PE-HD／木粉复合材料的力学性能，当其添加量为2％（质量分数，下同）时复合材料的拉伸强度、弯曲强度和冲击强度分别增加了157％、146％和145％；扫描电镜也能观察到加入相容剂的复合材料界面粘接非常好，进一步证实了（PE-HD／SEBS）-g-MAH提高了复合材料的界面相容性。     

PC／SAN／SEBS合金的形态结构和动态流变性能

将苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物（SEBS）引入到聚碳酸酯（PC）犀乙烯-丙烯腈共聚物（SAN）合金中，制备了性能优良的PC／SAN／SEBS合金。研究了SEBS含量对合金力学性能的影响，以及合金的动态流变性能。结果表明，SEBS的加入大大提高了PC／SAN合金的冲击强度和断裂伸长率，使合金的冲击强度从不含SEBS的130J／m增加至SEBS含量为7％（质量分数，下同）的971J／m，同时断裂伸长率从23．8％增加至119％；但合金的拉伸强度和弯曲强度以及维卡软化温度却有所降低。同时，SEBS的加入使PC／SAN合金的线性黏弹性范围变窄，并且使合金表现出明显的剪切变稀行为。扫描电镜分析结果表明，SEBS与PC具有更好的相容性，SEBS在PC／SAN／SEI峪合金中大部分分布在PC相中。     

SEBS—g—MAH对PO／PBT共混物性能影响

利用双螺杆挤出机制备聚碳酸酯（Pc）／聚对苯二甲酸丁二醇酯（PBT）／-B来酸酐接枝氢化苯乙烯-丁二烯啕E乙烯共聚物（SEBS-g—MAH）的共混物。通过扫描电子显微镜（SEM）、平板流变仪研究了SEBS-g—MAH对PC／PBT共混物的机械性能、断面形态结构、动态力学行为的影响。结果表明：SEBS-g—MAH提高了PC／PBT共混物的相容性,随着SEBS-g—MAH用量的增加,共混物的缺口冲击强度和断裂伸长率上升,拉伸强度和弯曲强度下降。当SEBS—g-MAH质量分数为5％时共混物的综合性能最佳,同时,SEBS-g—MAH的加入,并未对PC／PBT共混物的成型加工性能产生不良影响。     

交替多层TPU／SEBS复合材料阻尼隔声性能的研究

用自行设计的微层挤出体系制备了热塑性聚氨酯弹性体／苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物（TPU／SEBSS）交替多层复合材料,同时准备了同组分的传统共混样品。实验结果结果表明：与传统共混样品相比,交替多层TPU／SEBS复合材料具有更宽的阻尼温域、更高的隔音系数和更优异的力学性能。并且随着层数的增加,其阻尼、隔声和力学性能提高。     

PTT/SEBS复合材料的制备及其流变性能

采用熔融共混法,将聚对苯二甲酸丙二酯（PTT）纤维与氢化苯乙烯-丁二烯-苯乙烯嵌段共聚物（SEBS）弹性体共混制备PTT/SEBS复合材料,考察了SEBS弹性体含量对复合材料力学性能的影响,以及剪切速率、温度对复合材料流变性能的影响,并分析了复合材料的亚微相态。结果表明：加入SEBS弹性体使PTT/SEBS复合材料的拉伸强度提高,断裂拉伸应变降低;随着SEBS弹性体含量的增加,PTT/SEBS复合材料的流动阻力增大,流变性能降低。     

SBS改性PP基导电复合材料

采用(苯乙烯/丁二烯/苯乙烯)共聚物(SBS)改性聚丙烯(PP)为基体,炭黑(CB)为导电填料制备了导电复合材料。研究了导电复合材料的电性能及力学性能;同时探讨了CB在PP/SBS基体中富集的相关影响因素。结果表明,在基体中加入质量分数为20%的SBS可以大幅提高同等CB含量下导电复合材料的电导率,增加材料的韧性;在CB质量分数仅为10%的情况下富集效果更为明显。     

炭黑对ASA/天然石墨复合材料的电磁屏蔽性能影响

通过熔融共混方法制备导电高分子复合材料丙烯腈-苯乙烯-丙烯酸酯共聚物(ASA)/天然石墨(NGR)/炭黑(CB),采用电磁屏蔽测量仪、四探针电阻率测量仪和动态热机械分析仪对复合材料的电性能和力学性能进行详细研究.结果 表明,ASA/NGR复合材料的体积电阻率随着炭黑含量增加而增加;同时在30 MHz～1500 MHz范...     

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.     

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.     

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.     

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.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.