废胶粉／HDPE热塑性弹性体的制备研究

考察了废胶粉粒径和用量、共混时间、温度以及EVA用量对废胶粉/高密度聚乙烯(WRP/HDPE)力学性能的影响.获得了制备性能良好的WRP/HDPE共混物的条件为:WRP/HDPE的质量比为50/25、共混时间为22 min、共混温度为170 ℃以及EVA用量为总质量的23%.共混材料的微观结构研究结果表明,EVA的加入增强了共混物之间的界面结合力,提高了共混物的物理机械性能.力学性能的研究表明,该共混材料可作为热塑弹性体使用.     

废胶粉填充改性RHDPE增容研究

研究了废胶粉的活化处理、不同种类相容剂对回收高密度聚乙烯/废胶粉(RHDPE/WRP)共混体系的增容效果.结果表明,WRP活化处理对提高WRP界面活性有效果.不同相容剂对提升共混体系性能的影响不同,其中添加10份马来酸酐接枝聚乙烯(PE-g-MAH)相容剂对提升RHDPE/活化WRP体系整体性能最有效,可使RHDPE/WRP共混材料的拉伸强度从简单共混物的18.8 MPa提高到22.5 MPa,缺口冲击强度从37.5 kJ/m2提高到60.9 kJ/m2;热变形温度从55.8℃提高到63.6℃.     

胶粉/LLDPE弹性体合金的研制

系统研究了废胶粉（GRT）／线型低密度聚乙烯（LLDPE）弹性体合金（GRT／LLDPE）的配方，以及粒径，GRT含量，相容剂和硫化剂（DCP）用量对共混物力学性能的影响，结果表明，采用两阶共混法，当GRT／LLDPE共混比为：60：40，DCP用量为2份，相容剂马来酸酐三单体接枝物用量为3－5份时，所得弹性体合金力学性能最佳，弹性体合金的拉伸强度从简单共混物的5．8Mpa上升到11．1MPa，撕裂强度从39．4kN/m，上升到63．4kN/m，断裂伸长率从180％增加到260％。     

胶粉/聚苯乙烯共混物的性能研究

研究胶粉／聚苯乙烯(PS)共混物的物理性能、流动性能及热性能。添加胶粉可改善PS材料的抗冲击性能，且胶粉粒径越小改善效果越好，但会使共混物的拉伸强度下降。当胶粉质量分数为0．05～0．15时，共混物的综合性能较好。共混物的流动性能随着胶粉粒径的减小而提高，随着胶粉用量的增大而下降。添加硅烷偶联剂或钛酸醋偶联剂，可提高共混物的热变形温度。     

废旧轮胎胶粉/聚苯乙烯共混物性能研究

研究废旧轮胎胶粉( GTR)粒径和用量以及相容剂种类和用量对GTR/聚苯乙烯(PS)共混物性能的影响.结果表明:GTR可以改善PS的脆性,提高PS的抗冲击性能,但会使拉伸性能降低;GTR粒径越小,GTR/PS共混物的抗冲击性能越好;相容剂乙烯-丙烯酸酯-甲基丙烯酸缩水甘油酯和苯乙烯-丁二烯-苯乙烯嵌段共聚物( SBS)能大幅改善GTR/PS共混物的抗冲击性能,相容剂马来酸酐接枝聚丙烯以及甲基丙烯酸甲酯、丁二烯和苯乙烯的三元共聚物对GTR/PS共混物的抗冲击性能改善不大;GTR(粒径为75 μm)/PS/相容剂SBS用量比为40/100/10时,GTR/PS共混物的综合性能较好,缺口冲击强度达到4.87 kJ·m-2.     

橡胶再生剂与相容剂并用在废轮胎胶粉增韧废PP复合材料中的应用研究

进行了橡胶再生剂与相容剂并用在废轮胎胶粉(GRT)增韧废PP复合材料中的应用研究.结果表明,采用橡胶再生剂De-link/相容剂CA并用改性GRT/废PP复合材料的冲击强度可达22.6KJ@m-2,比简单GRT/废PP共混体系提高了2.4倍,比废PP体系提高了2倍;拉伸强度则比简单GRT/废PP共混体系提高了30%,为废PP体系的87%;再生剂通过改变胶粉的交联度来提高复合材料的韧性,相容剂主要通过改善界面性能和提高相容性来提高复合材料的力学性能.     

硫化胶粉/PP共混材料的研究

研究了硫化胶粉/PP共混体系的力学性能、流动性能和热变温度等.结果表明,利用硫化胶粉可以明显改善PP的冲击性能,而且胶粉粒径越小,改善的效果越显著,但共混体系的拉伸强度有所下降.胶粉含量在5%-15%时,共混体系的综合性能较好.     

PP/EVA/胶粉热塑性弹性体的制备及性能研究

制备聚丙烯(PP)/乙烯-醋酸乙烯共聚物(EVA)/胶粉热塑性弹性体(TPV),研究胶粉改性剂201酚醛树脂、松香、橡胶活化剂450、橡胶再生剂RV,相容剂聚丙烯接枝马来酸酐(PP-g-MAH)用量,以及EVA/胶粉共混比对TPV性能的影响。结果表明:与采用未改性胶粉相比,采用改性胶粉制得的TPV拉伸强度、拉断伸长率和撕裂强度增大;当PP-g-MAH用量为5份、EVA/胶粉共混比为15/45时,TPV的综合性能较好。     

多单体反应挤出PP/胶粉共混材料的研究

按一定的次序将单体马来酸酐(MAH)、苯乙烯(St)、引发剂过氧化二异丙苯(DCP)、聚丙烯(PP)、废胶粉等在高速混合机中混合均匀后,在双螺杆挤出机中就地反应增容制备 PP/胶粉共混材料。讨论了 MAh/St/DCP 三者的含量对 PP/胶粉共混材料力学性能的影响;红外光谱(FTIR)分析证明双单体成功接枝于 PP 大分子链中。通过扫描电镜分析了一步法反应增容对 PP/胶粉共混物界面的影响。结果表明,一步法反应增容改善了共混物的界面相容性,当 PP、胶粉、DCP、MAH、St 的配比为70/30/0.1/1.5/1.5时,PP/胶粉共混物的拉伸强度和悬臂梁缺口冲击强度达到最佳。     

废胶粉与POE改性二次回收聚丙烯的研究

采用废胶粉和乙烯/辛烯共聚物(POE)对二次回收聚丙烯(RPP)进行增韧改性,制成RPP/废胶粉和RPP/POE共混材料,研究了两种共混材料力学性能、热性能与流变性能等.结果表明,当废胶粉加入80份时,缺口冲击强度提高约67%.RPP/废胶粉改性体系有较好的耐热性、较高的硬度与耐磨性,属于非牛顿性假塑性流体,废胶粉可以部分替代POE作为某些制品的增韧剂.     

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.