稀土纳米母粒改性聚苯硫醚复合材料的研究

采用稀土表面改性剂对纳米碳酸钙进行表面改性并表征;考察了稀土纳米母粒含量对聚苯硫醚加工性能和力学性能的影响。研究了聚苯硫醚/纳米母粒/玻纤(GF)复合材料的力学性能、电性能及微观结构。结果表明:经稀土表面改性剂处理制备的稀土纳米母粒加入量及复合材料制备工艺对复合材料的加工性能和力学性能有较大的影响;随着稀土纳米母粒含量的增加,复合材料的力学性能呈先增加后降低的趋势,其电绝缘性能也得到一定程度的提高。     

过氧化物母粒对PP/炭黑导电复合材料的影响

采用含有过氧化物的聚丙烯(PP)母粒,通过熔融共混法制备了不同熔体流动速率(MFR)的PP/炭黑导电复合材料,并研究了复合材料的流变性能、结晶性能、力学性能及导电性能。结果表明:PP过氧化物母粒的加入有效改善了PP/炭黑导电复合材料的流动性。PP过氧化物母粒质量分数为2.2%时,复合材料的结晶度是25.96%,拉伸强度、冲击强度分别达到25.96 MPa、73.70 kJ/m~2。PP过氧化物母粒的加入对复合材料导电性能的影响较小。     

GF增强母粒对微发泡PP/GF复合材料力学性能的影响

采用熔融共混挤出的方法制备了A、B两种玻璃纤维(GF)增强母粒。将两种母粒与自制发泡母粒、助剂母粒按一定比例混合,在二次开模条件下制备了PP/GF复合微发泡材料,研究了两种GF增强母粒对微发泡PP/GF复合材料力学性能的影响,同时还探讨了结晶行为对微发泡复合材料力学性能的影响。结果表明:A母粒制备的微发泡PP/GF复合材料性能优于B母粒,在GF含量为30%时,A母粒制备的微发泡复合材料的拉伸强度和冲击强度分别为55.72 MPa、7.58 kJ/m2,与B母粒制备的发泡PP/GF复合材料比较,其拉伸强度和冲击强度分别提高了9.97 MPa、1.1 kJ/m2。     

聚乙烯抗静电母粒的制备及抗静电性能研究

研究了纳米碳酸钙和LLDPE 7144用量对聚乙烯管材性能的影响,制备了聚乙烯用抗静电母粒,研究了不同抗静电剂及其用量对聚乙烯复合材料抗静电性能的影响,确定了可满足聚乙烯管材性能指标要求的抗静电母粒配方。     

聚甲醛/弹性体/纳米碳酸钙复合材料的制备及性能研究

采用双螺杆熔融共混的方法,以4种不同的混合顺序,制备了聚甲醛/热塑性聚氨酯弹性体/纳米碳酸钙（POM/TPU/nano-CaCO3）复合材料。通过力学性能测试、偏光显微镜、差示扫描量热仪、熔体流动速率仪和扫描电子显微镜,考察了nano-CaCO3的用量对POM/TPU(90/10)复合材料力学性能的影响,并探讨了共混方式对复合材料力学性能及微观结构形态的影响。结果表明,4 %的nano-CaCO3与TPU预先混合制成母粒再与POM共混得到的复合材料中POM晶粒发生明显细化,缺口冲击强度高达12.5 kJ/m2,冲击性能较为优异。     

VC-BA/纳米CaCO3复合母粒增韧PVC

采用氯乙烯-丙烯酸丁酯共聚弹性体(VC-BA)和经表面处理的纳米碳酸钙(nano-CaCO_3)制备VC- BA/nano-CaCO_3复合母粒,再用该复合母粒与聚氯乙烯(PVC)共混,制备了VC-BA/nano-CaCO_3复合母粒增韧的PVC复合材料。复合母粒中m(VC-BA)/m(nano-CaCO_3)为2:3时,增韧效果最佳。nano-CaCO_3与VC-BA有协同增韧作用,且nano-CaCO_3能够补强。当PVC和复合母粒质量比为100:20时,材料的冲击强度达到49.5 kJ/m~2,是纯PVC的10倍,拉伸强度为51.0 MPa。     

碳酸钙晶须补强炭黑/天然橡胶/丁腈橡胶复合材料的性能研究

采用钛酸酯偶联剂对碳酸钙晶须进行改性,研究改性碳酸钙晶须对炭黑/天然橡胶/丁腈橡胶复合材料性能的影响。结果表明:改性后碳酸钙晶须的表面性质改变,有效改善了碳酸钙晶须与橡胶基体的相容性,提高了复合材料的物理性能和储能模量,增强了Payne效应,对耐油性能影响不大;当改性碳酸钙晶须用量为4份时,复合材料的综合性能最佳。     

PP/LGF复合材料的膨胀性阻燃与协效阻燃性能

采用膨胀型阻燃剂(IFR)及协效剂海泡石(SP)对长玻璃纤维增强聚丙烯(PP/LGF)复合材料进行阻燃,通过双螺杆挤出机制备了PP/LGF母粒,IFR母粒和SP母粒,然后将这3种母粒通过注塑机制备了PP/LGF/IFR/SP复合材料,通过极限氧指数(LOI)、垂直燃烧测试、锥形量热仪、热重分析、扫描电子显微镜、力学性能测试等表征PP/LGF各阻燃复合体系的性能。结果表明,当IFR质量分数为22%时,PP/LGF/IFR阻燃复合材料的LOI为28.8%,且垂直燃烧等级达到V–0级;锥形量热仪测试结果表明加入IFR及SP后阻燃复合体系的第一热释放速率峰值降低,而第二热释放速率峰消失;SP质量分数为1%,IFR质量分数为21%的PP/LGF/IFR/SP阻燃复合材料LOI为29.6%,垂直燃烧等级达到V–0级,热释放速率峰值和总热释放量得到有效降低,热稳定性最好,且燃烧时产生致密的炭层覆盖于玻璃纤维表面,同时加入1%SP后复合材料的力学性能下降幅度相对较小。     

聚烯烃/木粉微孔复合材料结构与性能研究

制备了聚烯烃/木粉微孔复合材料,研究了基体树脂种类、木粉用量、发泡母粒用量等因素对复合材料密度、孔隙率、力学性能和微观结构的影响。结果表明:基体树脂性能对木塑微孔复合材料的拉伸强度影响较大;增加木粉用量,复合材料力学性能下降,密度上升;增加发泡母粒用量,复合材料的孔隙率增大,密度下降,力学性能先升后降;试验范围内,发泡母粒最佳用量约为1%。     

碳酸钙晶须增强炭黑NRNBR橡胶复合材料的研究

天然橡胶（NR）与丁腈橡胶（NBR）共混,共混胶兼并NR物理机械性能及NBR耐油性能,但炭黑补强/NR/NBR橡胶复合材料物理机械性能相比炭黑补强NR橡胶复合材料差。在炭黑补强/NR/NBR橡胶复合材料中,加入碳酸钙晶须旨在增强复合材料物理机械性能,提高其使用范围。本文采用钛酸酯偶联剂对碳酸钙晶须进行改性,研究改性后碳酸钙晶须对炭黑/ NR/ NBR橡胶复合材料性能的影响。结果表明：钛酸酯偶联剂改性后的碳酸钙晶须,表面性能改变,有效提高了碳酸钙晶须与炭黑/NR/NBR橡胶复合材料的相容性。当碳酸钙晶须用量为4份时,复合材料的综合性能最佳,有效改善复合材料Payne效应。     

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.