Effect of neat and reinforced polyacrylonitrile nanofibers incorporation on interlaminar fracture toughness of carbon/epoxy composite

This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, the paper focuses on the effect of adding Al2O3 nanopartiles in PAN nanofibers, which were incorporated in unidirectional （UD） laminates. The effectiveness of adding a thin film made of Al2O3-PAN on the fracture behavior of the carbon fiber reinforced polymer （CFRP） has been addressed by comparing the energy release rates, obtained by testing double cantilever beam （DCB） samples under mode I loading condition. A general improvement in interlaminar fracture energy of the CFRP is observed when the both neat PAN nanofibers and Al2O3-PAN nanofibers are interleaved. However, higher interlaminar strength has been observed for the samples with a thin film of Al2O3-PAN nanofibers, suggesting a better stress distribution and stress transformation from resin-rich area to reinforcement phase of hybrid composites.

Analysis of Nanof luids as Cutting Fluid in Grinding EN-31 Steel

Grinding requires high specific energy which develops high temperatures at wheel work piece interface. High temperatures impair work piece quality by inducing tensile residual stress, burn, and micro cracks. Control of grinding temperature is achieved by providing effective cooling and lubrication. Conventional flood cooling is often ineffective due to enormous heat generation and improper heat dissipation. This paper deals with an investigation on using TRIM E709 emulsifier with Al_2O_3 nanoparticles to reduce the heat generated at grinding zone. An experimental setup has been developed for this and detailed comparison has been done with dry, TRIM E709 emulsifier and TRIM E709 emulsifier with Al_2O_3 nanoparticles in grinding EN-31 steel in terms of temperature distribution and surface finish. Results shows that surface roughness and heat penetration were decreased with addition of Al_2O_3 nanoparticles.

Preparation and characterization of Pd/Fe bimetallic nanoparticles immobilized on Al_2O_3/PVDF membrane:Parameter optimization and dechlorination of dichloroacetic acid

Using a liquid-solid phase inversion method, a hybrid matrix poly（vinylidene fluoride）（PVDF） membrane was prepared with alumina（Al2O3） nanoparticle addition. Pd/Fe nanoparticles（NPs） were successfully immobilized on the Al2O3/PVDF membrane, which was characterized by Scanning Electron Microscopy（SEM） and Transmission Electron Microscopy（TEM）. The micrographs showed that the Pd/Fe NPs were dispersed homogeneously. Several important experimental parameters were optimized, including the mechanical properties, contact angle and surface area of Al2O3/PVDF composite membranes with different Al2O3 contents. At the same time, the ferrous ion concentration and the effect of hydrophilization were studied. The results showed that the modified Al2O3/PVDF membrane functioned well as a support. The Al2O3/PVDF membrane with immobilized Pd/Fe NPs exhibited high efficiency in terms of dichloroacetic acid（DCAA） dechlorination. Additionally, a reaction pathway for DCAA dechlorination by Pd/Fe NPs immobilized on the Al2O3/PVDF membrane system was proposed.

一种基于辐射制冷和太阳能制热的温度自适应双层薄膜

传统的制冷、制热技术能源消耗量巨大,而利用太空和太阳作为天然冷源和热源的辐射制冷和太阳能制热技术由于零能耗、低碳排的特点受到了研究者们的广泛关注,然而,目前被动式制冷/制热器件通常只能实现单一功能、无法满足动态环境条件下多变的制冷/制热需求,本文提出了一种温度自适应的智能控温双层薄膜(STG),以辐射制冷技术和太阳能制热技术为基础,可以随温度响应实现不同环境条件下制冷/制热模式的智能切换,当温度低于其境界温度时,STG膜在太阳光波段从高反射切换为高吸收(反射率由0.962变为0.059),而中红外发射率始终保持在0.95.该光谱特性使得STG膜在夏季直射阳光(辐射峰值>900Wm)下能够实现比环境温度低5°C的亚环境日间辐射冷却,而在冬季则能实现550Wm²的太阳光加热功率。作者同时通过理论模拟验证当STG膜被大规模应用时,这种可智能切换的制冷/制热装置在节能方面展现出了巨大的应用潜力该设计策略能够为零能耗的热响应控温器件提供新的思路,并为实现能源的可持续发展提供新的途径。