玻璃纤维增强聚丙烯复合材料的制备及其性能

以聚丙烯(PP)粒料为原料,玻璃纤维(GF)为增强剂,乙烯-1-辛烯共聚物(POE)为增韧剂,马来酸酐接枝POE(POE-g-MA)为增容剂,采用双螺杆挤出机制备PP/POE/GF复合材料,并分析了复合材料的力学性能。结果表明：POE与PP存在一定相容性,能显著提高复合材料的冲击强度;加入GF,受到弹性POE的削弱作用,GF使复合材料的拉伸强度有一定幅度的提升,冲击强度下降;加入增容剂POE-g-MA,GF与PP/POE间的界面相容性显著改善,复合材料的冲击强度和拉伸强度都得到提升。最优的复合材料组成：PP与POE用量分别为100,25 phr,GF质量分数约为27.9%,POE-g-MA含量为10 phr。与纯PP相比,此条件下制备的复合材料冲击强度提高49%,拉伸强度提高17%。     

高韧性高强度聚丙烯复合材料的研究

研究了自制的马来酸酐接枝聚丙烯(PP-g-MAH)和马来酸酐、苯乙烯接枝聚丙烯(PP-g-MAH-g-St)2种增容剂对聚丙烯/聚烯烃弹性体/玻璃纤维(PP/POE/GF)复合材料力学性能的影响,利用扫描电子显微镜观察了试样断口形貌。结果表明,2种增容剂均显著改善了GF与PP基体的界面粘结强度,从而提高了复合材料的力学性能;就2种增容剂的效果而言,PP-g-MAH-g-St的增容效果远优于PP-g-MAH。当PP-g-MAH-g-St的质量分数为8%时,PP/POE/GF/PP-g-MAH-g-St复合材料的综合性能已接近常用工程塑料的性能。     

高强高韧GF／PP复合材料的研究

通过在短玻(GF)增强聚丙烯(PP)中添加聚烯烃弹性体(POE),并用马来酸酐对PP进行接枝交联的方法, 制备了高冲击韧性GF／PP复合材料。在该材料中,短切玻璃纤维的加入大幅度提高了材料的拉伸、弯曲强度,而POE 则通过产生形变等方式,提高了材料的冲击韧性;在其中加入马来酸酐接枝聚丙烯增加界面结合力,可使GF／PP／POE 复合体系表现出良好的综合力学性能,其拉伸强度为51．9 MPa,弯曲强度为68．1MPa,冲击韧性为44．2 kJ／m2。     

玻璃纤维增强聚丙烯的力学性能研究

研究了玻璃纤维(GF)和马来酸酐接枝聚丙烯(PP-g-MAH)对聚丙烯力学性能的影响。结果表明:随着GF与PP的质量比增加,玻璃纤维增强聚丙烯的拉伸强度增加,冲击强度总体呈下降趋势。当PP与GF的质量比为55∶45时,拉伸强度最高,达到45MPa。当PP与GF的质量比一定时,在玻璃纤维增强聚丙烯复合材料中添加增容剂马来酸酐接枝聚丙烯(PP-g-MAH),可使其拉伸强度得到很大的提高,但是冲击性能却下降。当PP与GF的质量比为75∶25时,随PP-g-MAH与PP/GF复合材料的质量比增加,其拉伸强度先增大后减小,其冲击性能总体呈下降趋势。当PP-g-MAH,PP和GF的质量比为15∶75∶25时,其综合性能最优,拉伸强度为50.5MPa,冲击强度为4.3kJ/m2。     

增容剂对GF增强SAN复合材料性能的影响

玻璃纤维(GF)增强苯乙烯-丙烯腈塑料(SAN)复合材料采用熔体浸渍工艺制备,研究了不同增容剂对GF增强SAN复合材料性能的影响。结果表明,添加增容剂的GF增强SAN复合材料的缺口冲击强度、拉伸强度和弯曲强度均有提高,加入增容剂苯乙烯-丙烯腈接枝甲基丙烯酸缩水甘油酯(SAG)时,复合材料的综合性能最优,其缺口冲击强度、拉伸强度和弯曲强度分别为23.09 k J/m2,103.48 MPa,174.92 MPa;复合材料的储能模量最大,损耗因子峰值最小。加入SAG的GF增强SAN复合材料的相容性比加入苯乙烯接枝马来酸酐(SMA)的复合材料的好。扫描电子显微镜分析表明,GF增强SAN复合材料中的GF没有被拔出,且表面包覆一层基体树脂。     

玻纤增强聚丙烯复合材料性能研究

研究了玻纤(GF)、SEBS和聚丙烯接枝马来酸酐(PP-g-MAH)用量对GF增强聚丙烯复合材料性能的影响,以及PP/GF(65/35)、PP-g-MAH/PP/GF(15/65/35)的微观形态。结果表明:随着GF用量的增加,复合材料的拉伸强度、弯曲强度和弯曲模量增加,断裂伸长率降低,冲击强度先减小后增大,PP/GF复合材料断面呈脆性断裂;在PP/GF中添加增韧剂SEBS可以提高复合材料的冲击强度,但拉伸强度、断裂伸长率、弯曲强度和弯曲模量均减小;在PP/GF中添加增容剂PP-g-MAH,可使其拉伸强度、断裂伸长率、弯曲强度、弯曲模量和冲击强度均得到提高,当PP-g-MAH/PP/GF为15/65/35时,复合材料性能优异,材料断面呈韧性断裂。     

玻璃纤维增强HDPE增容改性研究

为增强高密度聚乙烯(HDPE)的同时保持其良好韧性,采用双螺杆挤出机制备HDPE/玻璃纤维(GF)复合材料,并采用马来酸酐接枝HDPE(HDPE-g-MA)和马来酸酐接枝乙烯-辛烯共聚物(POE-g-MA)作为相容剂进行增容改性,研究了GF用量和相容剂用量对复合材料结晶与熔融行为和力学性能的影响。结果表明:GF对HDPE具有微弱的异相成核作用,当添加量为20%时,复合材料弹性模量显著提高,但拉伸强度和冲击强度下降。不同的相容剂对复合材料影响不同,HDPE-g-MA提高拉伸强度和弹性模量,但冲击强度显著下降;而POE-g-MA可提高复合材料的冲击强度,但对拉伸强度和弹性模量不利。将两种相容剂混合使用,当HDPEg-MA/POE-g-MA用量比为2.5:2.5或者2:3时,可获得综合力学性能优良的复合材料。     

无卤阻燃型聚丙烯的制备及性能研究

利用双螺杆挤出机挤出制备了超细Mg(OH)2改性阻燃聚丙烯(PP)复合材料,研究了Mg(OH)2、复合增容剂的用量对复合材料力学性能、阻燃性能的影响.结果表明,Mg(OH)2经硬脂酸表面改性后,其在PP中的分散性及与PP的界面相容性明显得到改善,当Mg(OH)2用量为90份时,材料的氧指数达到27.5%;(乙烯/辛烯)共聚物接枝马来酸酐/(乙烯/丙烯/二烯)共聚物接枝马来酸酐复合增容剂能明显改善材料的力学性能和阻燃性能,当复合增容剂用量为15份时,材料的断裂伸长率达到141.06%,缺口冲击强度达到22.24 kJ/m2,拉伸强度达到18.51MPa,氧指数增至28.0%.     

接枝物含量对高层建筑用GF/PP复合材料性能的影响

为了提高高层建筑用材料的力学性能,采用熔融共混的方法,在玻璃纤维(GF)增强聚丙烯(PP)复合材料中加入马来酸酐接枝PP(PP-g-MAH)与马来酸酐接枝聚烯烃(POE-g-MAH),分析接枝物含量对复合材料拉伸性能、弯曲性能以及冲击性能的影响。研究表明：当POE-g-MAH或PP-g-MAH的加入量为4 g时,复合材料的流动性明显改善,达到了最大熔体流动速率。当基体中接枝物含量上升后,复合材料的拉伸强度表现为先增大后减小的变化趋势,弯曲强度以及弯曲弹性模量都出现了先增大后减小的变化趋势,并在含有4 g接枝物时达到最大。当复合材料中接枝物含量增大后,含有POE-g-MAH接枝物的复合材料的冲击强度迅速增大。扫描电镜显示,加入接枝物后GF表面上存在明显附着物,GF和PP基体之间形成了良好相容性。     

增容方法对聚丙烯/亚麻纤维性能的影响

研究了NaOH溶液浸泡亚麻纤维(FF)、添加马来酸酐接枝聚烯烃(MAH-g-PO)、2种方法相结合对聚丙烯(PP)/FF复合材料力学性能及微观结构的影响.结果表明,NaOH溶液浸泡FF后PP/FF复合材料的力学性能有所提高.相对分子质量较大且接枝率较高的马来酸酐接枝聚丙烯(MAH-g-PP)增容效果较好;马来酸酐接枝三元乙丙橡胶(MAH-g-EPDM)和马来酸酐接枝乙烯辛烯共聚物(MAH-g-POE)对PP/FF复合材料起到增容和增韧的作用.NaOH溶液浸泡FF和添加MAH-g-PO相结合的PP/FF复合材料的力学性能好于单独采用一种方法的PP/FF复合材料的.     

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.     

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.     

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.     

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.