团状模塑料/丁苯橡胶/甲基乙烯基硅橡胶绝缘复合材料的性能研究

制备玻璃纤维团状模塑料(DMC)/丁苯橡胶(SBR)/甲基乙烯基硅橡胶(MVQ)绝缘复合材料,并对其性能进行研究。结果表明:与采用顺丁橡胶、丁腈橡胶、丙烯酸酯橡胶和三元乙丙橡胶作相容剂相比,采用SBR作相容剂可以改善DMC和MVQ间的相容性,提高DMC/SBR/MVQ绝缘复合材料的性能,DMC/SBR/MVQ的最佳配比为60/25/75;DMC/SBR/MVQ绝缘复合材料最佳混炼工艺为分步法加入白炭黑、分批法加入DMC,分别将MVQ和SBR进行混炼,再将两种混炼胶共混均匀;最佳硫化条件为180℃/1.2 MPa×15 min。在此条件下制备的DMC/SBR/MVQ绝缘复合材料的电绝缘性能良好,阻燃性能达到电缆绝缘材料的要求。     

DMC/MVQ绝缘复合材料的制备及性能表征

针对硅橡胶力学性能差的特点,本工作以硅橡胶（MVQ）为基相,以团状模塑料（DMC）为增强相,以丁苯橡胶（SBR）为相容剂来制备DMC/MVQ绝缘复合材料,研究了SBR的用量对MVQ性能的影响。结果表明：SBR和MVQ共混制得的并用胶性能要比纯MVQ的性能好,其最佳配比为DMC 60phr,SBR 25phr,MVQ 75phr;制备的复合材料体积电阻率都在4.9×1012Ω.m以上,复合材料的绝缘性能良好;通过扫描电镜分析（SEM）和动态热机械分析（DMA）,研究了复合材料的相容性,SBR的加入改善了DMC/MVQ绝缘复合材料的相容性,增加了界面相互作用,提高了DMC/MVQ绝缘复合材料的性能。     

甲基乙烯基硅橡胶/有机蒙脱土母炼胶纳米复合材料的制备、结构与性能

采用溶液插层法和母炼胶混炼工艺制备了甲基乙烯基硅橡胶(MVQ)/有机蒙脱土母炼胶(OMMT-MB)纳米复合材料,通过X射线衍射(XRD)、透射电子显微镜(TEM)对复合材料进行了表征,研究了复合材料的拉伸性能与热稳定性能,并与直接共混法制备的MVQ/有机蒙脱土(OMMT)复合材料和MVQ/白炭黑复合材料进行了对比,分析了OMMT的增强机理.结果表明,MVQ/OMMT-MB纳米复合材料中的OMMT完全剥离,且均匀分散在MVQ基体中;当OMMT质量分数为20%时,MVQ/OMMT-MB复合材料的拉伸性能优于MVQ/OMMT复合材料,拉伸强度和扯断伸长率分别增大至1.41 MPa、490%;其与MVQ/白炭黑复合材料相比,两者的拉伸强度相当,扯断伸长率增大了30%;MVQ/OMMT-MB复合材料的热稳定性略优于MVQ/OMMT复合材料,但比MVQ/白炭黑复合材料差.     

团状模塑料增强硅橡胶绝缘材料性能的影响因素

以甲基乙烯基硅橡胶(MVQ)为基质、团状模塑料(DMC)为增强剂、丁苯橡胶(SBR)为相容剂制备DMC/SBR/MVQ绝缘复合材料,考察了SBR和DMC用量对材料力学性能、相容性、绝缘性的影响,并对材料进行了动态热机械分析、傅里叶变换红外光谱分析。结果表明,SBR作为相容剂,可以改善DMC与MVQ的相容性,提高绝缘复合材料的力学性能,在DMC/SBR/MVQ(质量比)为60/25/75时,力学性能最佳。不同质量比下的DMC/SBR/MVQ绝缘复合材料的体积电阻率都在4.8×1012Ω·m以上,绝缘性能良好;当三者质量比为60/25/75时,材料的体积电阻率最高,绝缘性最好。DMC的加入提高了SBR/MVQ绝缘复合材料的耐热性能。     

DMC补强EPDM/MVQ并用胶的性能研究

采用添加短纤维的不饱和聚酯（DMC）填充EPDM／基乙烯基硅橡胶（MVQ）并用胶。研究其物理性能和耐热老化性能。结果表明，添加DMC后。EPDM／MVQ并用胶的邵尔A型硬度和拉伸强度大幅提高，耐热老化性能较好，兼具EPDM，MVQ和DMC的优点。EPDM／MVQ并用胶的较优配方为：EPDM25，MVQ75，DMC80，白炭黑40，氧化锌5，防老剂D1，硫化剂DCP6，促进剂DM0．8。     

团状模塑料/丙烯酸酯橡胶复合材料的性能研究

试验研究团状模塑料(DMC)/丙烯酸酯橡胶(ACM)复合材料的性能.结果表明,DMC和ACM具有相容性,可发生交联反应;DMC/ACM复合材料的优化试验配方为ACM 100,DMC 50,白炭黑 70,铝酸酯偶联剂 2.5,氧化锌 3,硬脂酸 4,硬脂酸钠 0.5,防老剂D 3,硫化剂DCP 3,硫黄 4,促进剂M 2;最佳硫化条件为145 ℃/10 MPa×30 min.     

碳纤维/硅橡胶/氟橡胶复合材料的制备

以硅橡胶(MVQ)/氟橡胶(FKM)并用胶为基相、碳纤维(CF)为补强相制备CF/MVQ/FKM复合材料。最佳配方为:FKM混炼胶90,MVQ混炼胶10,白炭黑20,硅烷偶联剂KH590 2.5,CF(纤维长度为12 mm)8;其中FKM混炼胶配方为FKM 100,氢氧化钙6,氧化镁3,3~#硫化剂3;MVQ混炼胶配方为MVQ 100,氧化锌3,三氧化二铁1,防老剂D 1,硫化剂DCP 5,促进剂M 1.5。最佳一段和二段硫化条件分别为170℃/10 MPa×30 min和200℃(常压)×2 h。     

硅橡胶/有机改性蒙脱土纳米复合材料的性能研究

用熔体插层法制备甲基乙烯基硅橡胶(MVQ)/有机改性蒙脱土(OMMT)纳米复合材料并研究其微观结构和性能。结果表明:OMMT改性剂疏水性从优到劣的顺序为I.44P,I.30P,Bengel434,I.44P和I.30P在MVQ中的分散性优于Bengel434;MVQ/OMMT纳米复合材料的物理性能和热稳定性从优到劣的顺序为MVQ/I.44P,MVQ/I.30P,MVQ/Bengel434纳米复合材料;添加40份I.44P的MVQ/I.44P纳米复合材料的100%定伸应力、拉伸强度和撕裂强度比纯胶有较大提高。     

碳纤维/硅橡胶/氟橡胶复合材料制备及表征

以硅橡胶（MVQ）/氟橡胶（FKM）并用胶为基相、碳纤维（CF）为增强相制备CK/MVQ/FKM复合材料。最佳配方为：FKM混炼胶　90,MVQ混炼胶　10,白炭黑　20,硅烷偶联剂KH590　2.5,碳纤维（纤维长度为12 mm）　8;其中FKM混炼胶配方为FKM　100,氢氧化钙　6,氧化镁　3,3#硫化剂　3;MVQ混炼胶配方为硅橡胶　100,氧化锌　3,三氧化二铁　1,防老剂D　1,促进剂M　1.5,硫化剂DCP　5。最佳一段和二段硫化条件分别为170 ℃/10 MPa×30 min和200 ℃（常压）×2 h。     

石墨烯/硅橡胶复合材料性能的研究

分别采用热解还原法和溶液法制备石墨烯(TrG)和TrG/硅橡胶(MVQ)复合材料,并对TrG/MVQ复合材料的导电性能和物理性能进行研究。结果表明:TrG能够明显提高MVQ的导电性能,随着TrG用量的增大,TrG/MVQ复合材料的体积电阻率明显降低,TrG的渗滤阈值为0.019 4;TrG对MVQ具有补强作用,随着TrG用量的增大,TrG/MVQ复合材料的邵尔A型硬度和拉伸强度明显提高;TrG在MVQ基体中分散良好,部分互相交错搭接在一起,形成了贯通的导电网络。     

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.     

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.     

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.