氧化铝及碳纤维对EPDM/MVQ共混胶性能的影响

选用EPDM/MVQ共混胶为基体,研究了氧化铝、碳纤维/氧化铝对EPDM/MVQ共混胶力学性能、导热性能及导电性能的影响。结果表明,随着氧化铝用量的增加,共混胶的力学性能下降,导热性能增加,电阻变化不大;当氧化铝用量为200份时,复合材料的拉伸强度达到4.5MPa,导热系数达到1.1W/(m·k),选用氧化铝/碳纤维混合填料体系,当氧化铝和碳纤维的用量分别为100份和15份时,复合材料的拉伸强度达到4.8MPa,导热系数达到0.66 W/(m·k)。     

炭黑/再生橡胶复合填料对天然橡胶补强性能的影响

针对传统橡胶基补强填料在补强橡胶基体时容易发生团聚,形成缺陷结构,降低橡胶制品的综合性能问题,研究了炭黑/再生橡胶(CB/RR)和炭黑/胶粉(CB/GTR)复合填料填充天然橡胶(NR)硫化胶的物理机械性能和动态力学性能,分别探讨了不同用量比的CB/RR以及CB/GTR复合填料对NR综合性能的影响。结果表明,当CB/GTR并用时,随着GTR用量增加,并用胶拉伸强度、拉断伸长率、硬度、储能模量和损耗模量均逐渐降低;与CB/GTR并用相比,CB/RR并用填充NR的硫化速率慢,损耗因子低,拉伸强度、拉断伸长率、硬度、储能模量和损耗模量更高。当CB/RR填料并用质量比为30/30时,NR硫化胶的物理机械性能和界面相容性较好,NR硫化胶表面光滑平整,其拉伸强度最大可达22.5MPa,比同比例下CB/GTR填充胶的拉伸强度提高了10.6MPa。     

短切碳纤维增强天然橡胶/丁苯橡胶复合材料性能研究

用聚丙烯腈短切碳纤维(Carbon fiber,简称CF)作为增强剂,天然橡胶(NR)与丁苯橡胶(SBR)作为基相制备了CF/NR/SBR橡胶复合材料,研究了短切碳纤维用量对CF/NR/SBR复合材料的硫化特性、拉伸强度、邵尔硬度、撕裂强度、阿克隆磨耗及导热系数等性能的影响。研究结果表明,随着CF用量的增加,复合材料拉伸强度逐渐减小,最大损失量达到16%,复合材料的硬度逐渐增大,最大增加量达到36%;复合材料的撕裂强度先增加后降低,在碳纤维用量为5份时达到最大值,最大增加量达到37%;复合材料的导热性能逐渐提高,最大增加量达到43%。     

纳米碳酸钙/二氧化硅复合粒子对丁苯橡胶物理机械性能的影响

采用溶胶沉淀法制备了纳米CaCO3/SiO2复合粒子,并用不同改性剂对其进行表面改性,考察了改性复合粒子对丁苯橡胶(SBR)物理机械性能的影响,同时与硬脂酸钠改性纳米CaCO3填充的SBR硫化胶做了比较。结果表明,CaCO3/SiO2复合粒子粒径为40～50 nm,大小均匀,表面粗糙,SiO2包覆在纳米CaCO3表面,具有核壳结构;硬脂酸钠改性复合粒子填充SBR硫化胶的拉伸强度、撕裂强度、永久变形和邵尔A硬度均大于改性纳米CaCO3填充SBR硫化胶,最大拉伸强度可达到13.6 MPa,两者的300%定伸应力和扯断伸长率相当;用硬脂酸钠和Si 69协同改性的纳米CaCO3/SiO2填充SBR硫化胶的拉伸强度、300%定伸应力、撕裂强度和邵尔A硬度均明显优于硬脂酸钠改性复合粒子填充的SBR硫化胶,最大拉伸强度达到14.1 MPa,扯断伸长率减小,低填充量时两者的永久变形差别不大,高填充量时前者的永久变形低于后者。     

弓弦大麻纤维补强填料在天然橡胶中的应用研究

研究了填充弓弦大麻纤维（BHF）填料和炭黑的天然橡胶（NR）胶料的硫化特性和物理性能。结果表明,随着填料用量增大,硫化胶的焦烧时间和硫化时间缩短,而最大转矩增大;硫化胶的拉断伸长率和回弹值降低,而硬度、定伸应力、耐磨性能及密度提高。当填料用量为40份时,两种硫化胶的拉伸强度达到最大值。填充炭黑的NR硫化胶的拉伸强度约为填充BHF填料硫化胶的1.5倍,这可能是由BHF填料较高的水分含量和较大的粒径所致,但是填充BHF填料的NR硫化胶具有更高的硬度。     

炭黑对CR/TPI并用胶性能的影响

研究了炭黑种类及用量对CR/TPI并用胶的影响.结果表明:随着炭黑粒径的增大,混炼胶焦烧时间有增大的趋势,正硫化时间也随之延长;硫化胶交联程度降低;硫化胶的拉伸强度、断裂伸长率、压缩生热温升、屈挠性能和炭黑分散度随之降低;常温下回弹性能、磨耗性能提高;硫化胶的老化性能略有提高.添加炭黑N330硫化胶的综合性能最好.随着炭黑N330用量的增加,硫化胶拉伸强度先增大后减少,炭黑40份左右达到最大值,断裂伸长率减少,磨耗性能和屈挠性能降低,压缩生热温升、邵尔A硬度增大,常温下回弹性能提高.     

改性氧化石墨烯对不同橡胶硫化胶性能的影响

采用聚乙烯吡咯烷酮对氧化石墨烯（GO）进行改性,制备了改性氧化石墨烯（PGO）,研究了PGO对天然橡胶（NR）、羧基丁腈橡胶（XNBR）及丁苯橡胶（SBR）硫化胶性能的影响。结果表明,PGO在NR、XNBR和SBR中均能较好地分散。当加入3份PGO时,PGO/NR硫化胶的拉伸强度、撕裂强度和导热系数比GO/NR硫化胶分别提高了82.0%、51.1%和6.5%;PGO/XNBR硫化胶的撕裂强度和导热系数比GO/XNBR硫化胶提高了53.8%和25.7%,而对拉伸强度影响不大;PGO/SBR硫化胶的拉伸强度、撕裂强度和导热系数比GO/SBR硫化胶分别提高了72.0%、24.2%和14.4%。     

正交实验设计法研究NR/EPDM共混胶性能

通过采用正交实验设计法研究NR/EPDM共混胶的各项性能,通过改变补强剂、软化剂、促进剂用量测试共混胶料的拉伸强度、撕裂强度、硬度、拉断伸长率、100%定伸应力、屈挠性能。结果表明:硫载体促进剂的加入可以提高硫化胶的拉伸强度、撕裂强度,使共混胶交联更加完全;硫化胶的拉断伸长率随着炭黑用量的增加而降低;软化剂的加入可以降低硫化胶的硬度,也可以提高硫化胶的屈挠次数。     

HNBR/FKM共混比对HNBR共混胶力学性能及耐热油性能的影响

研究了HNBR/FKM共混比对HNBR共混胶力学性能及耐热油性能的影响,研究表明,随着HNBR/FKM共混胶中氟橡胶共混比的增加,共混胶的硫化程度先增大后基本不变,硫化时间变长;共混胶100%定伸应力上升,硬度变大,拉伸强度先变大后变小,扯断伸长率减小;经热空气老化后,共混胶硬度明显变大,拉伸强度变大但比老化前小,扯断伸长率减小;经热油老化后,共混胶硬度变大且比老化前大,拉伸强度变大但比老化前小,扯断伸长率也降低,50%定伸应力变大,质量变化率和体积变化率为负值,且绝对值变大;共混胶的耐低温性能变差。     

碳纳米管增强氢化丁腈橡胶的性能

以碳纳米管(CNTs)为增强填料,考察了CNTs用量对氢化丁腈橡胶(HNBR)混炼胶硫化特性及硫化胶物理机械性能、高温拉伸性能和耐老化性能的影响,并研究了CNTs增强HNBR硫化胶的动态力学性能和加工性能,表征了CNTs在橡胶中的分散状况。结果表明,随着CNTs用量的增加,HNBR混炼胶的硫化效率提高,且具有优异的抗硫化返原能力,HNBR硫化胶的拉伸强度变化不大,邵尔A硬度、100%定伸应力和撕裂强度逐渐提高,扯断伸长率和回弹性减小,高温扯断伸长率减小,高温拉伸强度和100%定伸应力提高;CNTs增强HNBR硫化胶老化后的拉伸强度无明显变化,邵尔A硬度和100%定伸应力提高,扯断伸长率减小。相比未增强HNBR硫化胶,CNTs增强HNBR硫化胶的弹性模量增大,损耗因子峰值减小,加工性能得到改善;CNTs在橡胶基体中整体分散比较均匀,局部存在团聚现象。     

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.