Mechanical Properties of Single-Layer Diamond Reinforced Poly(vinyl alcohol) Nanocomposites through Atomistic Simulation

Low-dimensional carbon nanostructures are ideal nanofillers to reinforce the mechanical performance of polymer nanocomposites due to their excellent mechanical properties. Through molecular dynamics simulations, the mechanical performance of poly(vinyl alchohol) (PVA) nanocomposites reinforced with a single-layer diamond – diamane is investigated. It is found the PVA/diamane exhibits similar interfacial strengths and pull-out characteristics with the PVA/bilayer-graphene counterpart. Specifically, when the nanofiller is fully embedded in the nanocomposite, it is unable to deform simultaneously with the PVA matrix due to the weak interfacial load transfer efficiency, thus the enhancement effect is not significant. In comparison, diamane can effectively promote the tensile properties of the nanocomposite when it has a laminated structure as it deforms simultaneously with the matrix. With this configuration, the interlayer sp³ bonds endows diamane with a much higher resistance under compression and shear tests, thus the nanocomposite can reach very high compressive and shear stress. Overall, enhancement on the mechanical interlocking at the interface as triggered by surface functionalization is only effective for the fully embedded nanofiller. This work provides a fundamental understanding of the mechanical properties of PVA nanocomposites reinforced by diamane, which can shed lights on the design and preparation of next generation high-performance nanocomposites.     

Effects of interphase on tensile strength of polymer/CNT nanocomposites by Kelly–Tyson theory

The micromechanics models for composites usually underpredict the tensile strength of polymer nanocomposites. This paper establishes a simple model based on Kelly–Tyson theory for tensile strength of polymer/CNT nanocomposites assuming the effect of interphase between polymer and CNT. In addition, Pukanszky model is joined with the suggested model to calculate the interfacial shear strength (τ), interphase strength (σ_i) and critical length of CNT (L_c).The proposed approach is applied to calculate τ, σ_i and L_c for various samples from recent literature. It is revealed that the experimental data are well fitted to calculations by new model which confirm the important effect of interphase on the properties of nanocomposites. Moreover, the derived equations demonstrate that dissimilar correlations are found between τ and B (from Pukanszky model) as well as L_c and B. It is shown that a large B value obtained by strong interfacial adhesion between polymer and CNT is adequate to reduce L_c in polymer/CNT nanocomposites.     

Fabrication of core–shell nanocomposites with enhanced photocatalytic efficacy

The current study establishes the unprecedented involvement in the evolution and production of novel core–shell nanocomposites composed of nanosized titanium dioxide and aniline‐o‐phenylenediamine copolymer. TiO₂@copoly(aniline and o‐phenylenediamine) (TiO₂@PANI‐o‐PDA) core–shell nanocomposites were chemically synthesized in a molar ratio of 5:1 of the particular monomers and several weights of nano‐TiO₂ via oxidative copolymerization. The construction of the TiO₂@PANI‐o‐PDA core–shell nanocomposites was ascertained from Fourier transform IR spectroscopy, UV–visible spectroscopy and XRD. A reasonable thermal behavior for the original copolymer and the TiO₂@PANI‐o‐PDA core–shell nanocomposites was investigated. The bare PANI‐o‐PDA copolymer was thermally less stable than the TiO₂@PANI‐o‐PDA nanocomposites. The core–shell feature of the nanocomposites was found to have core and shell sizes of 17 nm and 19–26 nm, respectively. In addition, it was found that the addition of a high ratio of TiO₂ nanoparticles increases the electrical conductivity and consequently lowers the electrical resistivity of the TiO₂@PANI‐o‐PDA core–shell nanocomposites. The hybrid photocatalysts exhibit a dramatic photocatalytic efficacy of methylene blue degradation under solar light irradiation. A plausible interpretation of the photocatalytic degradation results of methylene blue is also demonstrated. Our setup introduces a facile, inexpensive, unique and efficient technique for developing new core–shell nanomaterials with various required functionalities and colloidal stabilities. © 2018 Society of Chemical Industry     

Stability and cytotoxicity study of NiFe2O4 nanocomposites synthesized by co-precipitation and subsequent thermal annealing

In this article, NiFe₂O₄ nanoparticles (NPs) were prepared by co-precipitation method with subsequent thermal annealing leading to obtainment NPs with average sizes of 78 nm. Structure and magnetic analysis were performed by X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and vibrating sample magnetometry techniques. Stability of NiFe₂O₄ NPs was evaluated in PBS solution during 20 days. The toxicity of prepared NPs was evaluated in vitro using different cancer cell lines: HeLa (cervical cancer cell), PC-3 (prostate cancer cell). Fibroblasts like cells of L929 obtained from subcutaneous adipose tissue of mouse were used as normal cells. Results indicate successful synthesis of NiFe₂O₄ NPs that exhibit low cytotoxicity in concentration range from 1 to 100 μg/ml. Presented physical and biological results indicate the possibility of application investigated magnetic nanoparticles in hyperthermia, targeted drug delivery, magnetic resonance imaging or cell separation.     

EVA和BSC的比较与分析研究

文章介绍了EVA和BSC两种业绩评价方法,通过对其相关概念的引入、EVA和BSC各自适合的企业以及整合的相关性、可行性的分析。     

Single chamber Solid Oxide Fuel Cells selective electrodes: A real chance with brownmillerite-based nanocomposites

In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca₂FeAl_0.95Mg_0.05O₅) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeO_x/CGO/CFA + FeO_x) and complete cells (CFA + FeO_x/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeO_x is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated.     

1 000 t/a书籍装订热熔胶技术经济分析

介绍了书籍装订热熔胶生产工艺及产品的技术指标，对1000t/a生产装置的投资与产品成本进行了核算。分析结果表明，总投资110万元，年利润达266万元。     

聚丙烯酰胺/氧化石墨纳米复合材料的研究

氧化石墨具有良好的层状结构，其层间具有丰富的官能团，能与有机聚合物形成插层纳米复合材料进而改善材料的性能．采用层离吸收-原位聚合法制备了聚丙烯酰胺／氧化石墨纳米复合材料，并采用XRD、HREM及DSC等对其结构和性能进行了表征。结果表明，聚丙烯酰胺与氧化石墨两者之间存在着较强的相互作用，材料的玻璃化转变温度得到提高，层离吸收-原位聚合法是获得聚丙烯酰胺／氧化石墨层纳米复合材料的有效途径，聚丙烯酰胺在氧化石墨中存在着多种排列方式，不同层间距(1．6nm和2．8nm)的聚丙烯酰胺／氧化石墨纳米复合结构同时存在。     

EVA基质PTC特性材料制备与导电机理分析

本文简述了以EVA为基质材料制备有机PTC特性材料的实验,实测了样品有关特性,并用非线性回归方法讨论了其导电机理.这对指导温度传感器的设计有一定帮助.