聚丙烯/木粉复合材料的制备及其力学性能的研究

以聚丙烯为基体,木粉为填料,采用机械共混、二次挤出共混和注塑成型方法制备不同木粉含量的PP/木粉复合材料,并且测定了PP/木粉复合材料的力学性能。实验结果表明:随着木粉用量的增加,复合材料拉伸强度逐渐增大;木粉用量为60%时,复合材料拉伸强度达到最大值36.04 MPa;木粉用量为80%时,复合材料拉伸强度降低到34.60 MPa。木粉的含量由20%增加到80%,复合材料弹性模量由579.12 MPa增加到869.80MPa,断裂伸长率从18.92%降低到7.39%,冲击强度由9.33 kJ/m2降低到7.76 kJ/m2。这是因为PP/木粉复合材料体系中随着木粉含量的增加,木粉起到了应力集中的作用,使材料变脆,冲击强度降低。     

聚丙烯基木塑复合材料力学性能的研究

研究了聚丙烯(PP)基木塑复合材料的界面形态,采用两种不同的偶联剂对木粉进行表面处理,考察了混炼时间和木粉用量对复合材料力学性能的影响,并通过扫描电子显微镜(SEM)对试样的断口形貌进行了观察。结果表明:在木粉用量相同的情况下,钛酸酯偶联剂对木粉的处理效果要优于铝酸酯偶联剂,偶联剂处理使木粉与PP的界面相容性得到了改善,复合材料的性能得到提高;在偶联剂不变的情况下,随着木粉含量的增加,木塑复合材料的冲击强度和拉伸强度均下降;随着混炼时间的增加,木塑复合材料的冲击强度和拉伸强度呈先升后降的趋势。     

几种加工助剂在聚丙烯基木塑复合材料中的应用对比

研究了3种加工助剂对聚丙烯(PP)基木塑复合材料物理力学性能和加工性能的影响,并利用扫描电子显微镜对复合材料的冲击断面进行了分析。结果表明,在一定用量范围内,芳香族碳氢化合物(S-105)和改性烷基酚醛树脂(TKM-M80)能够提高木粉在PP基体中的分散性,改善基体与木粉之间的相容性,从而提高PP基木塑复合材料的拉伸强度、冲击强度、弯曲强度、弯曲弹性模量和加工性能;脂肪醇和脂肪酸酯的混合物(Deoflow A)能够明显提高木粉在PP基体中的分散性和复合材料的加工性能,但用量较大时对复合材料的拉伸强度、弯曲强度和弯曲弹性模量有不利影响。     

建筑用聚丙烯基木塑复合材料耐水性能研究

制备了聚丙烯(PP)基木塑复合材料(WPC),研究了马来酸酐(MAH)、木粉用量以及木粉粒径对WPC性能的影响,并考察了浸泡及擦干放置后WPC的性能变化和恢复情况。结果表明:随着增容剂MAH用量的增加,WPC的拉伸强度和冲击强度均先增大后减小,吸水率则呈下降趋势;当浸水1天后,WPC浸水试样的拉伸强度下降,冲击强度则有所提升,并且随着MAH用量的增加,材料拉伸强度的下降趋于显著,冲击强度的提升幅度则逐渐减小;当MAH用量超过8份后,干燥后的WPC浸水试样(擦干放置1天),力学性能基本恢复。随着木粉用量的增加,WPC的拉伸强度先增大后减小,冲击强度不断减小,而吸水率则有所增大,其中当木粉含量超过10份时,干燥后的WPC浸水试样,其拉伸强度仅能得到部分恢复。另外随着木粉粒径的减小,WPC的吸水率明显增大,冲击强度有所提高;而木粉粒径对干燥后WPC浸水试样的拉伸强度恢复情况影响不大,其中当木粉粒度为60目时,试样的冲击强度比浸水前有所提升。     

再生PP/沙柳复合材料成型及力学性能研究

以沙柳和再生聚丙烯(PP)为原料,采用模压法制备木塑复合材料(WPC),研究了沙柳木粉和硅烷偶联剂KH550对WPC成型及力学性能的影响。结果表明:随着沙柳木粉用量的增加,WPC的熔体流动速率(MFR)显著下降,成型性能变差,弹性模量呈上升趋势,静曲强度、拉伸强度和冲击强度随之降低;随着KH550用量的增加,WPC的MFR小幅上升,静曲强度和拉伸强度逐渐提高,弹性模量呈先升后降趋势,冲击强度变化不明显;沙柳木粉用量50份、KH550用量3份时,WPC的成型和力学性能相对较佳。     

聚丙烯／木粉复合材料的加工成型及其力学性能研究

采用混炼工艺制备了聚丙烯／木粉复合材料（WPC）。研究了木粉、界面增溶剂-马来酸酐接枝聚丙烯（MAPP）的用量对WPC力学性能的影响。采用红外光谱仪对PP、MAPP、木粉及WPC的结构进行了表征和分析。结果表明，聚丙烯中加入木粉后，复合材料的拉伸强度及弯曲强度均比纯PP的要低，拉伸模量和弯曲模量逐渐升高，但复合材料的拉伸断裂伸长率随木粉用量的增加而逐渐下降。随着MAPP用量的增加，木粉用量较低（10％、20％）的WPC的拉伸强度和弯曲强度均先增加，然后逐渐减少，而木粉用量较高的WPC的强度值却在不断增高。当MAPP的质量分数为2％-4％时，复合材料的冲击强度值一般达到最高。红外谱图研究表明，偶联剂的加入可以把木纤维中的羟基酯化，改善木塑界面之间的相容性。     

聚丙烯/木粉/纳米凹凸棒土复合材料性能研究

采用双螺杆挤出机制备了一系列聚丙烯(PP)/木粉/纳米凹凸棒土(AT)木塑复合材料(WPC.研究了AT用量对复合材料力学性能、热性能、加工性能的影响.结果表明,随着AT用量的增加,复合材料拉伸强度逐渐增加、冲击强度逐渐减小,硬度先增加后减小,AT用量为5份时复合材料硬度最大;复合材料维卡软化点不断提高;熔体流动速率(M...     

稻糠粉/木粉并用对PVC基木塑复合材料的性能影响

采用稻糠粉和木粉填充聚氯乙烯(PVC)基木塑复合材料,研究并比对了复合体系的力学性能、耐水性、使用温度和加工性能的影响。结果表明:稻糠粉/木粉并用比增加,可以提高复合材料的拉伸强度、冲击强度和使用温度,改善其耐水性和加工流动性;当稻糠粉/木粉用量比为50/50时,复合材料的综合性能最佳,拉伸强度、冲击强度和维卡软化点温度分别达到最大值44.3MPa、15.2kJ/m2和117℃。     

相容剂对PP/木粉复合材料力学性能的影响

通过亚临界流体辅助反应挤出技术制备了木塑复合材料,对相容剂的种类及用量进行了筛选,同时对聚丙烯(PP)/木粉复合材料的组分进行了优化,并对PP/木粉复合材料进行了扫描电子显微镜(SEM)和傅里叶转换红外光谱分析(FTIR)。结果表明:在亚临界乙醇作用下,添加质量分数10%的马来酸酐接枝PP的PP/木粉复合材料综合力学性能最佳,PP与木粉间结合较好。在乙醇中加入质量分数2%硅烷偶联剂(KH550)时,PP/木粉复合材料力学性能进一步提高,其拉伸强度、弯曲强度、弯曲模量、冲击强度分别达到44.32 MPa,88.44 MPa,6 579.36 MPa和7.12kJ/m2。     

马来酸酐/1-十烯共聚物在聚丙烯木塑复合材料中的应用

采用红外光谱、核磁共振氢谱和凝胶渗透色谱表征了自行合成的马来酸酐(MAH)/1-十烯共聚物,探讨了该共聚物作为相容剂在聚丙烯(PP)基木塑复合材料中的应用。结果表明:MAH/1-十烯共聚物可改善木粉在PP中的分散性和相容性,提高PP与木粉间的界面黏合力,进而改善复合材料的力学性能;当相容剂用量为5份时,复合材料的拉伸强度提高了59.3%,弯曲强度提高了44.6%,冲击强度提高了82.6%。     

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.