PP-g-MAH对玻璃纤维增强PP的影响

研究了聚丙烯接枝马来酸酐(PP-g-MAH)和剪切场强度等对玻璃纤维增强聚丙烯(GFRPP)性能的影响。加入PP-g-MAH后,GFRPP的拉伸强度持续增加,最大达82.5 MPa;弯曲性能大幅度提高;缺口冲击强度明显增大,最大达160.3 J/m;热变形温度基本维持不变。PP-g-MAH的加入可改善玻璃纤维与聚丙烯间的界面作用,从而有利于提高GFRPP的性能。在极高剪切场强度的条件下,GFRPP的力学性能和热性能有所下降。     

剪切作用下POE-g-MAH和PP-g-MAH对PA1010/PP共混物的增容作用

采用熔融共混的方法制备了聚酰胺1010/聚丙烯（PA1010/PP）共混物,通过扫描电镜、力学性能和差示扫描量热等方法研究了剪切作用下马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH）和马来酸酐接枝聚丙烯（PP-g-MAH）对PA1010/PP共混物的增容作用。结果表明,同样条件下,PP-g-MAH增容体系的相区尺寸较小,相界面更模糊,PP相的结晶温度和结晶度明显提高,共混物的拉伸强度和冲击强度均高于非增容体系。而POE-g-MAH增容体系的相区尺寸相对较大,PP相的结晶温度和结晶度明显降低,共混物只有冲击强度明显高于非增容体系,拉伸强度略低于非增容体系。     

聚乙烯接枝马来酸酐共聚物粘接性能的研究

介绍了聚乙烯接枝马来酸酐共聚物与金属的粘接强度，并对接枝率与粘接强度的关系进行了研究。结果发现，接枝共聚物的粘接强度明显优于聚乙烯，它与金属的１８０°剥离强度可达１４０Ｎ／ｃｍ，剪切强度可达１０ＭＰａ，而且，随着接枝共聚物接枝率的增加，其粘接强度缓慢增加，最终达到最大值。     

马来酸酐接枝聚丙烯增容聚丙烯/碳酸钙复合物力学性能与增容机理

用在50L固相接枝反应器中合成的马来酸酐接枝聚丙烯(PP-g-MAH)作界面改性剂，制备了马来酸酐接枝聚丙烯／聚丙烯／碳酸钙(i-PP／PP-g-MAH／CaCO3)复合材料。研究了i-PP／PP-g-MAH／CaCO3复合材料的力学性能和增容机理。结果表明，PP-g-MAH对i-PP／CaCO3复合物的缺口冲击强度、弯曲强度和拉伸强度均有提高；PP-g-MAH与CaCO3反应形成PP-g-MAH的钙盐，实现反应性增容。     

不同接枝率相容剂对PP/POE/nano-CaCO_3复合材料性能的影响

研究了不同接枝率的马来酸酐接枝聚丙烯(PP-g-MAH)对聚丙烯(PP)/乙烯-辛烯共聚物(POE)/nanoCaCO_3复合材料性能的影响,并对复合材料的微观形貌、流变性能和力学性能进行表征。结果表明,PP-g-MAH的加入改善了nano-CaCO_3与基体之间的相容性,促进了nano-CaCO_3的分散,提高了复合材料的力学性能。高接枝率PP-gMAH对材料的冲击强度提升幅度更高,且拉伸强度和弯曲强度保持稳定。当其添加量为5%时,复合材料的冲击强度和拉伸强度分别提高76.4%和14.7%。     

PTT/PP共混物的性能研究

通过熔融共混制备了聚对苯二甲酸丙二酯/聚丙烯(PTT/PP=75/25)及其马来酸酐接枝PP(PP-g-MAH)增容共混物,研究了PTT/PP及其增容共混物的结晶性能、力学性能、流变性能和结晶形态。研究结果表明,PTT与PP共混能提高PP、PTT组分的结晶温度;对于增容共混物,随PP-g-MAH用量的增加,PP和PTT的结晶温度基本不变。加入PP使PTT拉伸强度降低,冲击强度提高;PP-g-MAH增容使共混物的拉伸和冲击强度都提高。增容共混物的熔体粘度明显降低,存在明显的剪切变稀现象,但熔体粘度与PP-g-MAH用量无关。在一定用量范围内,随PP-g-MAH用量的增加,PP分散相的尺寸变小。     

PP／POE／nan0-CaC03三元复合体系性能的研究

用纳米碳酸钙（nano-CaC03）填充改性聚丙烯，乙烯-辛烯共聚物（PP／POE）共混体系，研究了三元复合体系的力学性能和流动性随nano-CaC03用量变化的规律，发现nano--CaCO。的添加量存在最佳值，加入适量的马来酸酐接枝聚丙烯（PP-g-MAH）能提高接枝共聚物三元复合体系的强度。     

增容剂对PP/PA66共混物力学性能和结晶行为的影响

采用熔融共混法制备了聚丙烯(PP)/聚酰胺66(PA66)共混物,研究了聚丙烯接枝马来酸酐(PP-g-MAH)和乙烯-辛烯共聚物接枝马来酸酐(POE-g-MAH)作为增容剂对PP/PA66共混物力学性能和非等温结晶行为的影响。结果表明:PP-g-MAH提高了共混体系的拉伸强度,加入5份POE-g-MAH能显著提高共混物的断裂伸长率;PA66可起到异相成核作用,使PP的结晶峰温度升高;加入PP-g-MAH进一步提高了PP的结晶峰温度;PA66使PP的结晶活化能增大,增容剂的加入则使共混体系中PP的结晶活化能降低。     

相容剂对稻糠/聚丙烯复合材料加工性能和尺寸稳定性的影响

通过反应挤出法制备了马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)相容剂,研究了POE-g-MAH对稻糠/聚丙烯(PP)复合材料力学性能、加工性能和尺寸稳定性的影响。结果表明:POE-g-MAH增容效果优于马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH)和马来酸酐接枝聚丙烯(PP-g-MAH),能显著提高复合材料的拉伸强度、冲击强度、弯曲强度和尺寸稳定性;EPDM-g-MAH和PP-g-MAH对复合材料加工性能影响不大,而POE-g-MAH使稻糠/PP复合材料的最大转矩和平衡转矩明显降低,加工性能得到改善。     

聚丙烯接枝马来酸酐热稳定性能的研究

采用热失重方法研究了聚丙烯接枝马来酸酐(PP-g-MAH)的热分解行为,考察了MAH接枝率、PP降解程度和残余MAH单体对PP-g-MAH热稳定性能的影响。结果表明,MAH的接枝可以提高PP的热稳定性能。与PP相比,接枝率为0.72 %的PP-g-MAH起始分解温度升高28 ℃,420 ℃时的热分解速率常数下降57.6 %;接枝过程中PP分子链的降解对PP-g-MAH热稳定性能有不利影响。与降解程度最小的PP-g-MAH相比,降解程度最大的PP-g-MAH起始分解温度降低了20 ℃,420 ℃时的热分解速率常数增加了115 %;PP-g-MAH中残留的MAH使其起始分解温度降低了4.3 ℃。     

Effects of different compatilizers on mechanical,crystallization and thermal properties of polypropylene/magensium oxysulfate whisker composites

Two kinds of compatilizers, maleic anhydride grafted polyolefin elastomer (POE-g-MAH) and maleic anhydride grafted polypropylene (PP-g-MAH), were incorporated into a polypropylene/magnesium oxysulfate whisker (PP/MOSw) composite. Scanning electron microscopy pictures presented a clear interface between MOSw and the PP matrix in the PP/MOSw composite, while vague interfaces appeared in the PP/iPOE-g-MAH/5MOSw and PP/iPP-g-MAH/5MOSw composites. Dynamic mechanical thermal analysis results indicated that PP-g-MAH was highly compatible with the PP matrix while POE-g-MAH was not. Impact strength results showed that POE-g-MAH had a superior toughening effect on PP/MOSw composites, since the proper interfacial interaction and appearance of β-crystal PP. However, incorporating PP-g-MAH seemed to be conducive to increasing strength and modulus (both for tensile and flexural tests), as evidenced by the greatly raised interfacial adhesion between the PP matrix and MOSw. Quantitative characterization carried out by Turcsányi equation for ternary composites also confirmed that PP-g-MAH efficiently enhanced interfacial interaction, by the proof of higher B values. Therefore, the thermal stability of PP-g-MAH treated composites was far superior to that of PP/iPOE-g-MAH/5MOSw composites. Differential scanning calorimetery and polarized light microscopy results showed that POE-g-MAH promoted PP nucleation, with effects further enhanced with the presence of PP-g-MAH.     

增容剂对动态硫化氯化丁基橡胶/尼龙12热塑性弹性体性能的影响

分别以聚丙烯接枝马来酸酐( PP -g - MAH)、苯乙烯-乙烯-丁二烯-苯乙烯共聚物接枝马来酸酐(SEBS-g- MAH)以及新型改性剂苯乙烯-共轭二烯烃嵌段共聚物选择加氢物(SEPS)作为增容剂,考察了不同增容剂对动态硫化氯化丁基橡胶/尼龙12热塑性弹性体(PA 12/CIIR TPV)物理机械性能的影响,并研...     

Antioxidant Activity of Amaranth Protein Hydrolysate Against Thermal Oxidation of Vegetable Oils

The antioxidant capacity of amaranth protein hydrolysate (AH) during the thermally induced oxidation of two different vegetable oils, sunflower oil (SO) and canola oil (CO), was assessed by differential scanning calorimetry by means of isothermal and non‐isothermal assays. Interactions between AH and tocopherols were also analyzed. In both oils, AH (10 % w/w) produced an increase in the induction period in isothermal assays, presenting a synergistic effect with tocopherols. In the case of non‐isothermal assays, thermograms of oils with AH showed a significant diminution in the second exothermic peak, suggesting an inhibition of the decomposition of primary to secondary oxidation products. In addition, AH produced an increase in the oxidation rate constant (k) value at low temperatures being more evident in the case of canola oil. However, this effect decreased as a function of the temperature increase, which suggests that AH would have a pro‐oxidant effect at low temperatures but a heat stabilizing effect at high temperatures (above 210 °C for SO and 190 °C for CO).     

Separation of chalcopyrite and pyrite from a copper tailing by ammonium humate

Copper tailings constitute a large proportion of mine wastes. Some of the copper tailings can be recycled to recover valuable minerals. In this paper, a copper tailing was studied through the chemical analysis method, X-ray diffraction and scanning electron microscope-energy dispersive spectrum. It turned out that chalcopyrite (Cu) and pyrite (S) were the main recoverable minerals in the tailing. In order to separate chalcopyrite from pyrite in low pulp pH, ammonium humate (AH) was singled out as the effective regulator. The depression mechanism of AH on the flotation of pyrite was proved by FTIR spectrum and XPS spectrum, demonstrating that there was a chemical adsorption between AH and pyrite. By Response Surface Methodology (RSM), the interaction between AH, pulp pH and iso-butyl ethionine (Z200) was discussed. It was illustrated that the optimal dosage of AH was 1678 g·t^-1 involving both the recovery of Cu and S. The point prediction by RSM and the closed-circuit flotation displayed that the qualified Cu concentrate and S concentrate could be obtained from the copper tailing. The study indicated that AH was a promising pyrite depressor in the low pulp pH from copper tailings.     

碱联合超高压预处理对笋壳酶解效率的影响

以竹笋壳（BS）为原料,采用单独超高压（UHP）、单独碱加热（AH）、超高压后碱加热（UHP+AT）和碱加热后超高压（AT+UHP）4种方法进行预处理,并对比分析了样品预处理前后的化学组成、扫描电镜（SEM）、晶体结构（XRD）、红外光谱（FTIR）、比表面积和孔结构及酶水解效率的变化规律。结果表明：与其他处理方法相比,AT+UHP在450MPa压强下处理效果最好。预处理后样品中木质素的脱除率为86.87%,微观表面结构松散和粗糙,结晶指数有所上升,比表面积和孔体积分别为2.590m²/g、0.010cm³/g,酶水解效率高达97.89%。UHP+AT与AT+UHP预处理效果差异不明显,其酶解效率达到96.94%。因此,碱联合超高压处理是生物燃料生产中生物质预处理的一种潜在选择。     

竹炭对铜（Ⅱ）吸附的热力学和动力学参数的研究

研究了竹炭对水相中铜（Ⅱ）吸附的动力学和热力学参数。动力学研究表明：竹炭对铜（Ⅱ）的吸附拟用准一级动力学处理,动力学方程可表示为-1n（1-F）=k1,弗测定不同粒径、不同温度下竹炭对铜（Ⅱ）吸附的表观速率常数及活化能。热力学研究表明：竹炭对铜（Ⅱ）的吸附的焓变△H=-22．6kJ／mol,说明竹炭吸附过程为放热过程,且△H〈40kJ／mol,表明吸附过程主要为物理吸附。同时测得吉布斯自由能△G〈0,且受温度的影响不大,表明吸附质从溶液到吸附剂表面的吸附过程是自发过程。     

Rheological properties of endodontic sealers: the effect of time, temperature, and composition

This study was aimed to investigate the effect of different parameters such as shear rate, temperature, and time on the viscosity of four endodontic sealers. Furthermore, the effect of variations in powder to liquid ratio of two powder/liquid sealers upon their viscosity was evaluated. The tested sealers were AH Plus, Endofill, AH 26, and Epiphany self-etch (SE) sealer. As all of the tested sealers contain particles of resinous composites; shear thinning and some time-dependency of viscosity are expected. Therefore, steady shear viscosity and thixotropy behavior were assessed. The samples were examined at 25 and 37?°C with the shear rate ranged from 0.0001 to 100?s^?1. All sealers almost exhibited shear thinning behavior. At both temperatures of 25 and 37?°C, the viscosities of sealers were at the same order and ranked from the highest to the lowest as follows: Epiphany SE, AH Plus, AH 26, and Endofill. The samples with higher powder to liquid ratio of 3:1 exhibited higher viscosity compared to 2:1 ratio in both tested temperatures. With the exception of Epiphany SE and AH 26 (at shear rate less than 1?s^?1), viscosity of all sealers decreased with increasing temperature from 25 to 37?°C. All sealers exhibited time-dependent viscosity characteristics at the two examined temperatures.     

Thermal degradation behavior of polypropylene base wood plastic composites hybridized with metal (aluminum,magnesium) hydroxides

The effect of hybridization of wood fibers and metal hydroxides on the thermal stability of polypropylene (PP) based plastic composites is studied through thermo gravimetric analysis (TGA). The wood fiber increases thermal stability of the metal hydroxide hybridized WPC including aluminum hydroxide (AH) and magnesium hydroxide (MH). Hybridization with the AH increases decomposition temperature of the maximum loss rate (T_max) of the PP due to reinforcement of residue, but the onset‐temperature of the PP decomposition is nearly shifted. However, hybridization with the MH increases both the onset‐temperature and the T_max of the PP thermal degradation. Both AH and MH fillers increase the T_max of the PP matrix decomposition with increment of their contents. Besides, the MH case shows higher thermal stability of the PP resin in WPC decomposition than the AH case at the same loading level. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40120.     

Airborne Virus Survivability During Long-Term Sampling Using a Non-Viable Andersen Cascade Impactor in an Environmental Chamber

In order to evaluate the survivability of airborne viruses and the sampling performance of an eight-stage non-viable Andersen impactor in typical indoor environments featuring low viral aerosol concentrations, aerosols of a male-specific bacteriophage (MS2), human adenovirus type 1 (HAdV-1), and avian influenza virus (AIV) were sampled size-selectively using the impactor in an environmental chamber. Live virus titer, total virus RNA or DNA concentration, and intensity of a fluorescein tracer were measured to calculate relative virus recovery and virus survival. Viral aerosols were first sampled for 1 and 6 h at 25°C and 50% relative humidity (RH). Virus inactivation and plate overloading were found to be significant in the impactor. Viral aerosols were then sampled at different temperature and humidity levels. MS2 and AIV showed higher survival at lower temperature. Absolute humidity (AH) was found to be a better predictor of virus survival than RH, and the interaction between AH and temperature was not significant. For the tested AH range of 8.8 to 15.2 g/m³, MS2 and HAdV-1 had the highest survival at the lowest AH while AIV had the highest survival at the highest AH. More than 95% of mass collected was for particles smaller than 4.7 m, with the mass median diameter of 1.5 m. In the nebulizer, virus inactivation was not significant at 10 psi (69 kPa) compressed air pressure for up to 6 h of nebulization. Nebulizer analysis also reveals that the use of fluorescein tracer may not always accurately predict the physical loss of virus.

Copyright 2014 American Association for Aerosol Research     

Preparation of ion-exchange celluloses. I. Anion exchange celluloses

Cellulose–poly(glycidyl methacrylate) graft copolymer (CPGMA) was treated with ammonia (AH), ethylamine (EA), diethylamine (DEA), and triethylamine (TEA). Factors affecting the reaction, such as reaction duration, temperature, liquor ratio, pH, and aminating agent/epoxide molar ratio were studied. A mechanism of the reaction was suggested. The anion exchange celluloses were characterized by studying its capacity, potentiometric titration, and durability to use. Potentiometric titration of the produced anion exchangers has been studied and pK_b values were found to be 6.1, 7.6, and 8.9 for DEA–CPGMA, EA–CPGMA, and AH–CPGMA, respectively.