Thermoplastic polyurethane (TPU) modifier to develop bimodal cell structure in polypropylene/TPU microcellular foam in presence of supercritical CO2

Currently, the fabrication of microcell and bimodal cell structures (BCS) in polymer foams by using supercritical fluids has become a hot as well as a challenging research area worldwide. In this work, an environmentally friendly, effective, facile, and CO₂-based foaming technique was presented to fabricate microcellular polypropylene (PP) foams with BCS via blending with thermoplastic polyurethane (TPU). The toughness, thermal properties, rheological properties, and foamability of PP were systematically investigated with gradual incorporation of TPU. Representative sea-island structure was observed in the scanning electron microscopy (SEM) images for the fracture surface of various PP/TPU samples. Rheological measurement results demonstrated that the viscoelasticity of various PP/TPU samples was improved remarkably compared with that of pure PP and pure TPU. The impact strength of various PP/TPU samples possessed the highest value as 12.4 kJ/m² with the TPU content of 15 wt%. After the addition of TPU, an ameliorative cellular morphology was observed in the SEM micrographs of various PP/TPU samples and their volume expansion ratio was enhanced significantly thanks to their improved melt elasticity. Moreover, it is worth noting that BCS appeared in various PP/TPU foams when the TPU content exceeded 5 wt%.     

Role of Macrophages and RhoA Pathway in Atherosclerosis

The development, progression, or stabilization of the atherosclerotic plaque depends on the pro-inflammatory and anti-inflammatory macrophages. The influx of the macrophages and the regulation of macrophage phenotype, inflammatory or anti-inflammatory, are controlled by the small GTPase RhoA and its downstream effectors. Therefore, macrophages and the components of the RhoA pathway are attractive targets for anti-atherosclerotic therapies, which would inhibit macrophage influx and inflammatory phenotype, maintain an anti-inflammatory environment, and promote tissue remodeling and repair. Here, we discuss the recent findings on the role of macrophages and RhoA pathway in the atherosclerotic plaque formation and resolution and the novel therapeutic approaches.     

珠粒和工艺因素对消失模铸造模质量的影响

从珠粒因素和工艺因素两方面分别介绍了其对消失模铸造模质量的影响情况及在中国的研究现状,对其原因进行了分析,得出了珠粒粒度和发泡剂含量、发泡工艺和模密度、发泡工艺和成型工艺等都相互制约的结论,并提出,可以通过对以上关键因素正交优化达到控制模质量的目的.     

微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术。前者利用表面活性剂形成油-水微乳液提高增溶能力,降低油水界面张力和毛细管阻力,从而提高驱替效率和微观采收率;后者利用泡沫剂将气体稳定地分散在水相中,在油藏孔隙中形成泡沫,封堵优势通道和已驱替区域,从而扩大波及体积并提高宏观采收率。通过综述两个技术的国内外发展历史和研究进展,阐明了其优势和局限性。近年来提出的微乳液泡沫驱油技术,又称为低张力泡沫驱,其既可以保留两个独立技术的优势,又可以克服他们的缺点,最终同时提高微观和宏观采收率。但是在实际研究中,微乳液泡沫驱技术却面临理论和应用上的双重挑战。通过调查国内外相关研究进展,详细阐述了微乳液泡沫驱技术目前面临的挑战、研发思路和研究建议。     

Degradable Superhydrophilic Iron-Pillared Bentonite Doped with Polybutylene Adipate/Terephthalate Open-Cell Foam: Its Application in Dye Degradation,Removal of Heavy Metal Ions,and Oil–Water Separation

Development of industrialization has brought convenience to people's lives; however, it has also brought serious harm to the environment, where, water pollution is the most obvious. Here, a polybutylene adipate terephthalate (PBAT) open-cell foam doped with iron-pillared bentonite (IPB) is prepared by using sugar as a pore-forming agent and solution phase separation, and then combined with a solution dipping method to coat the foam surface with a polyacrylamide/SiO₂, which makes the PBAT foam superhydrophilic. The static adsorption effect of superhydrophilic IPB-doped PBAT open-cell foam on methylene blue (MB) and Cu²⁺ is studied. The adsorption isotherm fitting shows that the adsorption conforms to the Langmuir model and it has biased toward monolayer adsorption. The adsorption kinetics fitting confirms that the adsorption process is in line with the pseudo-second-order adsorption model, which is dominated by chemical adsorption. The modified PBAT open-cell foam has an adsorption effect on Cu²⁺; however, it has weak cyclic adsorption capacity. It shows a good cyclic adsorption ability for the cationic dye MB and it has >95% photodegradation efficiency of the MB after five time's cyclic adsorption. The superhydrophilicity makes the foam to have better applications in oil–water separation.     

Effect of high temperature on the mechanical properties of hierarchical porous cenosphere/geopolymer composite foams

A hierarchical porous cenosphere/geopolymer composite foam (FHCs/KGP) was fabricated by the simultaneous incorporation of O₂ pore from hydrogen peroxide and cenosphere filler addition. Effects of both H₂O₂ content and high-temperature treatment on the microstructure, porosity and strength of porous FHCs/KGP foams were investigated systematically. The obtained FHCs/KGP foams showed typical amorphous structure and desirable porosity from 65 to 82%. The composites could crystallize in situ to FHCs/leucite foams above 1000℃. Compression strength of the FHCs/leucite foams showed a maximum value of 5 ± 0.3 MPa when treated at 1000°C. The improvement of mechanical properties for the composite foams was attributed to crack deflection, fractured microspheres and the good bond between the FHCs and matrix. This study could open opportunities to employ cellular foams as alternatives in structure and filtration applications.     

平板类气体辅助注射成型产品的CAE模拟研究

通过建立具有代表性的平板类气体辅助注射成型产品模型,借助注塑成型CAE软件Moldflow对该模型进行了一系列分析模拟。通过对模拟结果数据的综合分析和数学处理,得到了气体注射参数对气道穿透长度的影响规律、气体注射参数设置及气道穿透长度预测公式。     

应变速率对闭孔泡沫铝力学性能和能量吸收性能的影响

采用分离式霍普金森压杆 (SHPB)技术 ,研究了应变速率 (1× 10 - 3s- 1 ～ 2 5 0 0s- 1 )对泡沫铝力学性能和能量吸收性能的影响。结果表明 :泡沫铝有较高的应变速率敏感性 ,随应变速率的增加 ,泡沫铝的屈服强度和吸能能力增加 ,泡沫铝的应变速率敏感性随应变、应变速率变化幅度的增加而增加。     

真空渗流法制备泡沫铝及其动态力学性能的研究

以真空渗流法制备陶瓷中空球泡沫铝,研究了应变率对吸能量和吸能效率的影响、相对密度对屈服强度的影响,并与普通泡沫铝进行比较。结果表明,工艺简单可行,所制备的泡沫铝的动态压缩应力-应变曲线只有弹性变形区和塑性变形区;随应变率的增大,屈服强度和吸能效率变化规律不明显,吸能量增大;随相对密度的增大,屈服强度增大,吸能量增大,吸能效率也增大;动态压缩时两种泡沫铝的吸能效率均较高,最大吸能效率大于0.9,是良好的吸能材料。     

基于消失模铸造的AZ91镁合金组织改性研究

研究了机械振动处理技术对AZ91合金在消失模铸造条件下的组织形貌的影响,以及该铸态组织在半固态等温热处理过程中的组织演变,并探讨了振动细化机理和组织演变机理。结果表明:机械振动能显著地细化AZ91合金的铸态组织;在液固相区570℃等温处理时,其铸态组织都能由枝晶转变为球状晶组织,而且振动处理可获得更加细小并且均匀的球状组织。等温处理时间过长时,两种组织都会发生合并长大。