氟橡胶的红外光谱研究

采用红外(IR)光谱,包括一维红外光谱、二阶导数红外光谱、四阶导数红外光谱和去卷积红外光谱对氟橡胶(FKM)的分子结构进行了研究。试验发现:氟橡胶的红外吸收模式主要包括CH2不对称伸缩振动模式(νasCH2-FKM)、CH2对称伸缩振动模式(νsCH2-FKM)、CH2弯曲伸缩振动模式(δCH2-FKM)、CF2不对称伸缩振动模式(νasCF2-FKM)、CF2对称伸缩振动模式(νsCF2-FKM)和CFCl伸缩振动模式(νCFCl-FKM)等。研究发现:氟橡胶的去卷积IR光谱的谱图分辨能力要优于相应的一维IR光谱、二阶导数IR光谱和四阶导数IR光谱。此研究拓展了IR光谱在氟橡胶结构及应用研究的范围。     

全自动集装箱码头装卸系统质量管理

全自动集装箱码头装卸系统集成了当今世界各项先进技术,在研发、制造、调试过程中,都要坚持质量第一、安全第一的原则,确保各项技术参数可靠,设备运行稳定。在总结国内几个全自动码头装卸系统的质量管理方法与经验的基础上,结合自动化码头自身特点,给出全自动集装箱码头装卸系统主要质量管理方法,进一步丰富发展自动化码头装卸系统建造过程中的“不欠债离岸”质量管理理念。     

风电高速轴制动器温度场及热力耦合分析

型风电制动器紧急制动涉及摩擦、流体、热弹性、高能量密度摩擦副等多物理场耦合，为了进一步揭示其摩擦功传热原理，基于传热性能分析理论，推导风电高速轴制动器热-机耦合三维有限元数学模型，利用有限元分析软件Abaqua瞬态完全热力耦合法，研究风电高速轴刹车盘热应力特性。结果表明，风电制动器对偶件由于接触不均匀，导致温度在盘圆周方向推移的时效性及不对称性特征。解释了由于换热和热流输入的循环交替变化引起温度在半径方向上的温升及应力变化规律，并针对热应力集中区产生热裂纹萌生及扩展情形进行推理论证，对大型风电机高速轴刹车盘转速过高状态下的高热能摩擦作用机制研究具参考作用。     

Developing conductive immiscible polystyrene/polypropylene blends with a percolated conducting polyaniline/polyamide filler by tuning its specific interactions with the styrene-based triblock compatibilizer grafted with maleic anhydride

An approach to induce conductivity in immiscible polystyrene/polypropylene (PS/PP) blends is described using a percolated conducting polyaniline/polyamide (PANI/PA) filler combined with a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride compatibilizer. The approach is based on the ability of the compatibilizer to concomitantly stabilize the cocontinuous morphology and to improve the state of dispersion of the PANI/PA filler. Selective localization of PANI/PA in the PS phase with improved filler dispersion is achieved with the optimal master batch (MB) preparation technique followed by its optimized sequence addition to the blend components. This results in an increase in the dc conductivity by six decades as compared with that of the neat compatibilized blend at an effective 4.8-wt % PANI concentration. An investigation of the effect of functionality and concentration of the filler and the compatibilizer on the filler connectivity in the blend is performed. The prevailing specific interactions are analyzed by Fourier transform infrared spectroscopy and thermogravimetric analysis of the MBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48433.     

Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

The coal and biomass coupling power generation technology is considered as a promising technology for energy conservation and emission reduction. In this paper, a novel coal and biomass indirect coupling system is proposed based on the technology of biomass gasification and co-combustion of coal and gasification gas. For the sake of comparison, a coal and biomass direct coupling system is also introduced based on the technology of co-combustion of coal and biomass. The process of the direct and the indirect coupling system is simulated. The thermodynamic and economic performances of two systems are analyzed and compared. The simulation indicates that the thermodynamic performance of the indirect coupling system is slightly worse, but the economic performance is better than that of the direct coupling system. When the blending ratio of biomass is 20%, the energy and exergy efficiencies of the indirect coupling system are 42.70% and 41.14%, the internal rate of return (IRR) and discounted payback period (DPP) of the system are 25.68% and 8.56 years. The price fluctuation of fuels and products has a great influence on the economic performance of the indirect coupling system. The environmental impact analysis indicates that the indirect coupling system can inhibit the propagation of NO_x and reduce the environmental cost.     

载荷对PTFE/AlSi10Mg复合材料摩擦磨损行为的影响

采用选区激光熔化(SLM)、浸渗和真空烧结工艺制备了以AlSi10Mg为基体的多孔骨架填充聚四氟乙烯(PTFE)的自润滑复合材料。采用往复式Bruker UMT-3摩擦试验机研究了速度为5mm/s、不同载荷下复合材料的摩擦磨损性能,并采用SEM、EDS等对其成分、结构以及摩擦学行为进行了研究。结果表明,复合材料的平均摩擦因数和磨损率随着载荷的增加呈现先增大后减小的趋势;复合材料的摩擦稳定性主要由存储在骨架中的PTFE决定。其摩擦机制主要是在载荷的作用下,当磨擦表面发生磨损时,骨架中的PTFE将磨屑捕获,形成完整的PTFE润滑层,并且发生膜的转移,从而增加了复合材料的摩擦学稳定性。     

冷轧预变形对新型铝锂合金的时效析出与力学性能影响

采用大气熔炼铸造及热变形方法制备了Al-4.5Cu-1Li-0.7Mg-1Zn-0.3Ag-0.3Mn-0.2Zr新型铝锂合金板材。通过维氏硬度、拉伸性能、扫描电镜、透射电镜等方法，研究了固溶后不同冷轧预变形量对显微组织和力学性能影响。结果表明，时效前的冷轧预变形量有效促进了新型铝锂基体合金中T1(Al2CuLi)相的析出与均匀分布，减少了θ′(Al2Cu)相的体积分数。冷轧预变形量的增加，缩短了峰时效时间，晶界析出相由连续析出变为非连续析出，无沉淀析出区宽度变小。当冷轧预变形量为15%时，时效态合金的屈服强度与抗拉强度分别达到了668 MPa、690 MPa，延伸率保持在7.9%。     

Preparation of Docosahexaenoic Acid-Rich Diacylglycerol-Rich Oil by Lipase-Catalyzed Glycerolysis of Microbial Oil from Schizochytrium sp. in a Solvent-Free System

Docosahexaenoic acid (DHA)-rich diacylglycerol (DAG)-rich oil was prepared by lipase-catalyzed glycerolysis of microbial oil from Schizochytrium sp. in a solvent-free system. The reaction parameters including lipase type, substrate molar ratio, temperature, lipase concentration, and reaction time were screened. The selected conditions were determined as follows: Novozym® 435 (Novozymes A/S, Bagsvaerd, Denmark) as biocatalyst at 8 wt%, substrate ratio (DHA-rich microbial TAG/glycerol) of 1:1 mol/mol, temperature of 50 °C, and reaction time of 12 hours. Under these conditions, the triacylglycerol (TAG), DAG, and monoacylglycerol (MAG) contents in the product were 36.4%, 48.2%, and 15.4%, respectively. The lipase was reused successively for 18 cycles without significant loss of activity under the conditions given above. Fatty acid composition analysis of the final product showed that the contents of DHA in TAG, DAG, and MAG were 53.9%, 44.9%, and 34.8%, respectively. DHA-rich DAG has the potential to be used as an ingredient in infant formula to increase the bioavailability of DHA.     

High molecular weight poly(butylene terephthalate-co-butylene 2,5-furan dicarboxylate) copolyesters: From synthesis to thermomechanical and barrier properties

Poly(butylene terephthalate-co-butylene 2,5-furandicarboxylate) copolyesters (PBTFs) were synthesized from 1,4-butanediol, dimethyl terephthalate (DMT), and 2,5-furandicarboxylic acid (FDCA) by a two-step polymerization method. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon nuclear magnetic resonance before thermal properties were explored with differential scanning calorimeter and thermogravimetric analyzer. Results showed that PBTFs changed from semi-crystalline to completely amorphous when the content of FDCA unit was increased to 45 mol% at first, and then became crystallographic again with the further increment of FDCA unit to 75 mol%. For their mechanical properties, the tensile modulus and strength showed the similar trend, decreasing firstly and then increasing later. Their barrier to carbon dioxide and oxygen became better with the increasing of furan content due to the rigidity and higher polarity of furan ring. The performance of PBTFs copolyesters was investigated clearly, and the relative content of FDCA and DMT can be adjusted to satisfy different performance requirements.     

In-line characterization of dispersion uniformity evolution during a twin-screw blending extrusion based on near-infrared spectroscopy

Properties of an immiscible polymer blend have been proved to be closely related to dispersion uniformity of the minor phase. At present, dispersion uniformity is difficult to evaluate during the blending process, resulting in hysteretic feedback. Aiming at this problem, this work utilized near-infrared (NIR) spectroscopy to in-line characterize dispersion uniformity evolution during a twin-screw extrusion. A multichannel NIR measurement system was set up and applied to evaluate the blending process of polypropylene and polyolefin elastomer (POE). Based on the NIR spectra collected at different positions of the extruder, five prediction models of POE content were established using the light gradient boosting machine algorithm. Dispersion uniformity was characterized through the fluctuation of the predicted content. The evolution of dispersion under such processing parameters was consistent with scanning electron microscopy.