熔融共混法制备PP/EVA/PP-g-MAH复合材料的性能研究

采用溶液接枝法首先制备出聚丙烯接枝马来酸酐(PP-g-MAH),分析了影响接枝率的因素,确定了最佳工艺参数。并采用熔融共混法制备PP/EVA/PP-g-MAH复合材料。相对于PP/EVA共混物,加入一定量的PP-g-MAH对于复合材料的拉伸性能和冲击性能都有不同程度的改善。PP-g-MAH加入改善了PP与EVA的相容性。     

胶粉/聚烯烃类热塑性硫化胶共混材料的研究

研究胶粉/聚烯烃类热塑性硫化胶(TPV)共混材料的力学性能、耐油性、热稳定性、动态力学性能及材料的界面増容,并采用扫描电镜对共混材料的断面微观形貌进行了表征分析。研究结果表明:TPV/胶粉共混材料的力学性能随着胶粉粒径的减小而提高;增容剂PP-g-MAH可有效地改善胶粉与TPV的相容性,提高共混材料的力学性能;同时,胶粉和增容剂的加入增强了TPV的耐油性。     

BR/EVA/HIPS TPV的制备和性能研究

采用苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改善BR/乙烯-乙酸乙烯酯共聚物(EVA)/高抗冲聚苯乙烯(HIPS)共混物的界面相容性,通过动态硫化法制备BR/EVA/HIPS TPV,并对其性能进行研究.结果表明:未加入SBS的BR/EVA/HIPS共混物未表现出橡胶类弹性体特征,而加入适量SBS的共混物表现出典型橡胶类弹性体特征;当SBS用量为8～12份时,BR/EVA/HIPS TPV的综合物理性能较好,拉伸断面平滑,界面相容性良好.     

回收聚丙烯/胶粉/木粉复合材料性能研究

研究了木粉用量、相容剂用量、胶粉用量对以聚丙烯(PP)为基体树脂制备木塑复合材料力学性能、加工性能的影响。结果表明,随着木粉用量的增加,木塑体系拉伸强度先升高后降低,体系冲击强度、断裂伸长率逐渐降低,且木塑体系的混炼变得越来越困难;随着胶粉用量的增加,体系拉伸强度不断下降,而体系冲击强度总体趋势为逐渐增大;马来酸酐接枝PP(PP-g-MAH)用量为10份时,体系综合力学性能最好。     

废胶粉/聚丙烯接枝物共混材料的制备与性能

采用熔融接枝法分别制备了高强度和高熔体流动速率的聚丙烯接枝马来酸酐共聚物,以改善聚丙烯与胶粉间的界面相容性,提高废胶粉/聚丙烯接枝物共混材料的力学性能和流动性.力学性能测试结果表明,随着废胶粉用量的增加,废胶粉/聚丙烯接枝物共混材料的拉伸性能下降,扯断伸长率和缺口冲击强度均增大,熔体流动速率减小,流动性变差.由热重分析...     

不同促进剂对PP/PP-g-MAH/脱硫胶粉共混物性能影响

选用促进剂N–环己基–2–苯并噻唑次磺酰胺(CZ)、四甲基秋兰姆(TMTD)和N–叔丁基–2–苯并噻唑次磺酰胺(NZ)作为脱硫再生剂,分别对废旧胶粉进行改性,制备脱硫再生胶粉,然后制备聚丙烯(PP)/马来酸酐接枝PP(PP-g-MAH)/脱硫胶粉共混物,研究共混物力学性能、流动性能、断面形貌、流变性能和热性能的影响。结果表明,添加促进剂TMTD的共混物力学性能和流动性能最好,拉伸强度为12.15 MPa,断裂伸长率为22.17%,缺口冲击强度为17.11 kJ/m²,熔体流动速率为2.867 g/(10 min);随着角频率增加,共混物的复数黏度减小,储能模量增大,当角频率相同时,添加促进剂TMTD的共混物的复数黏度最小,储能模量最大;添加促进剂后共混物两相间的相容性较好,提高了界面粘接力,以添加促进剂TMTD的效果最好。添加促进剂后共混物的熔点和结晶温度均增大,其中,添加促进剂TMTD的共混物的熔点最高,结晶温度最低。     

SAN/高胶粉/有机硅共混物的制备与性能研究

利用熔融共混法制备了苯乙烯-丙烯腈共聚物(SAN)/高胶粉/有机硅共混物,研究了高胶粉和有机硅用量对共混物力学性能和流动性能的影响。结果表明:随着高胶粉用量的增加,共混物的冲击强度提高,流动性能下降,当高胶粉/SAN=30/70时,共混物综合性能最佳;当有机硅用量为0.2%时,共混物的刚性和流动性能变化不大,但冲击强度得到大幅度提高。     

TPV及PP-g-MAH对回收PET的改性研究

以马来酸酐接枝聚丙烯(PP-g-MAH)为相容剂,回收聚对苯二甲酸乙二醇酯(rPET)为基体材料,动态硫化热塑性弹性体(TPV)为增韧材料,制备了rPET/TPV/PP-g-MAH共混物。用SEM、DMA及DSC分析了TPV及PP-g-MAH对rPET断面结构、储能模量和结晶性能的影响,并测试了共混物的力学性能。结果表明:加入9.95%TPV后,rPET/TPV共混物的熔融温度下降了2.33℃,结晶温度提高了2.82℃,断裂伸长率及缺口冲击强度明显提高,弯曲强度和拉伸强度略有下降;加入PP-g-MAH后,TPV球状粒子嵌入rPET基体材料中,共混物的相容性提高,储能模量明显增大,刚性增强,弯曲强度和拉伸强度有所提高;与纯rPET相比,含1.8%PP-g-MAH的rPET/TPV/PP-g-MAH共混物的断裂伸长率提高了129.06%,缺口冲击强度提高了47.02%。     

废旧胶粉/聚丙烯共混物的制备及性能研究

熔融接枝法制得的马来酸酐接枝聚丙烯5076(MAH-g-5076)可改善聚丙烯与废旧胶粉的界面相容性,高熔体质量流动速率聚丙烯MF650Y可改善废旧胶粉/聚丙烯共混物的流动性能,利用双螺杆挤出机挤出制得高性能、易加工的废旧胶粉/聚丙烯共混物,研究MF650Y用量对共混物性能的影响。结果表明:随着MF650Y用量(MF650Y和MAH-g-5076用量共30份)的增大,共混物的拉伸强度先增大后减小,在MF650Y用量为5~10份范围内达到最大值,拉断伸长率呈现震荡减小趋势,熔体质量流动速率增大;随着角频率的增大,共混物的复数粘度(η*)减小,储能模量(G′)和损耗模量趋于增大,当MF650Y用量为5份时,共混物的η*和G′最大;MF650Y用量为10份时有助于保护C=C键及抑制交联反应,此时聚丙烯与废旧胶粉相容性较好,两相界面结合能力较强,共混物无明显孔洞。     

茂金属聚烯烃弹性体/聚丙烯热塑性硫化胶的制备与性能研究

采用双螺杆挤出机制备茂金属聚烯烃弹性体(POE)/聚丙烯(PP)热塑性硫化胶(TPV),考察硫化剂双25用量、助硫化剂TAIC用量和POE/PP共混比对TPV微观结构、动态力学性能、物理性能和耐热空气老化性能的影响。结果表明,硫化剂双25用量为2份、助硫化剂TAIC用量为5份、POE/PP共混比为60/40~70/30时,在保证POE/PP TPV顺利挤出的前提下,POE/PP TPV的综合性能较优。     

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.