scholarly journals Facile Synthesis of Graphene from Waste Tire/Silica Hybrid Additives and Optimization Study for the Fabrication of Thermally Enhanced Cement Grouts

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 886 ◽  
Author(s):  
Ilayda Berktas ◽  
Ali Nejad Ghafar ◽  
Patrick Fontana ◽  
Ayten Caputcu ◽  
Yusuf Menceloglu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silica Surface ◽  
Hybrid Structure ◽  
Functionalized Silica ◽  
Facile Synthesis ◽  
Waste Tire ◽  
Optimization Study ◽  
Thermal Enhancement ◽  
The Cost ◽  
Silica Hybrid

This work evaluates the effects of newly designed graphene/silica hybrid additives on the properties of cementitious grout. In the hybrid structure, graphene nanoplatelet (GNP) obtained from waste tire was used to improve the thermal conductivity and reduce the cost and environmental impacts by using recyclable sources. Additionally, functionalized silica nanoparticles were utilized to enhance the dispersion and solubility of carbon material and thus the hydrolyzable groups of silane coupling agent were attached to the silica surface. Then, the hybridization of GNP and functionalized silica was conducted to make proper bridges and develop hybrid structures by tailoring carbon/silica ratios. Afterwards, special grout formulations were studied by incorporating these hybrid additives at different loadings. As the amount of hybrid additive incorporated into grout suspension increased from 3 to 5 wt%, water uptake increased from 660 to 725 g resulting in the reduction of thermal conductivity by 20.6%. On the other hand, as the concentration of GNP in hybrid structure increased, water demand was reduced, and thus the enhancement in thermal conductivity was improved by approximately 29% at the same loading ratios of hybrids in the prepared grout mixes. Therefore, these developed hybrid additives showed noticeable potential as a thermal enhancement material in cement-based grouts.

Polyimide-Silica Hybrid Aerogels with High Mechanical Strength for Thermal Insulation Applications

2011 ◽  
Vol 1306 ◽  
Author(s):  
Wenting Dong ◽  
Wendell Rhine ◽  
Shannon White
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Ambient Conditions ◽  
Separation Membranes ◽  
Low Dielectric ◽  
Aging Conditions ◽  
Hybrid Aerogels ◽  
Mechanical Strengths ◽  
The Relationship ◽  
Silica Hybrid

ABSTRACTHigh performance polyimides have been widely investigated as materials with excellent thermal, mechanical, and electronic properties due to their highly rigid structures. Aspen has developed an approach to prepare polyimide aerogels which have applications as low dielectric constant materials, separation membranes, catalyst supports and insulation materials. In this paper, we will discuss the preparation of polyimide-silica hybrid aerogel materials with good mechanical strengths and low thermal conductivities. The polyimide-silica hybrid aerogels were made by a two-step process and the materials were characterized to determine thermal conductivity and compressive strength. Results show that compressive moduli of the polyimide-silica hybrid aerogels increase dramatically with density (power law relationship). Thermal conductivity of the aerogels is dependent on the aging conditions and density, with the lowest value achieved so far being ~12 mW/m-K at ambient conditions. The relationship between aerogel density and surface area, thermal stability, porosity and morphology of the nanostructure of the polyimide-silica hybrid aerogels are also described in this paper.

scholarly journals Removal of Cu(II) from wastewater by waste tire rubber ash

2010 ◽  
Vol 75 (6) ◽  
pp. 845-853 ◽  
Author(s):  
Hassan Mousavi ◽  
Abdorrahman Hosseinifar ◽  
Vahdat Jahed
Keyword(s):  
Copper Ions ◽  
Low Cost ◽  
Batch Adsorption ◽  
Tire Rubber ◽  
Freundlich Isotherms ◽  
Waste Tire ◽  
Waste Tire Rubber ◽  
Wastewater Samples ◽  
The Cost ◽  
Influence Of Ph

The influence of pH, adsorbent dose, initial Cu(II) concentration and contact time on the removal of Cu(II) from aqueous solution by the batch adsorption technique using waste tire rubber ash as a low-cost adsorbent was investigated. The adsorption equilibrium was achieved after 2 h at pH 4-6, the optimum for the adsorption of Cu(II) ions. A dose of 1.5 g/L of adsorbent was sufficient for the optimum removal of copper ions. The experimental data were analyzed by the Langmuir and Freundlich isotherms and the corresponding sorption constants were evaluated. The adsorption kinetics data were fitted by a first-order equation. The cost of removal is expected to be quite low, as the adsorbent is cheap and easily available in large quantities. The present study showed that waste tire rubber ash was capable of removing copper ions from industrial wastewater samples.

Development of Animal Fibres Composites for Construction Applications

2022 ◽  
Author(s):  
Anna Alfocea-Roig ◽  
Sergio Huete-Hernandez ◽  
Alex Maldonado-Alameda ◽  
Jessica Giro-Paloma ◽  
Josep Maria Chimenos-Ribera ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raw Materials ◽  
Industrial Process ◽  
Economic Cost ◽  
Low Grade ◽  
Environmental Consequences ◽  
Potential Applications ◽  
Competitive Prices ◽  
New Material ◽  
The Cost

Climate change has become one of the world’s leading threats. Currently, the construction industry has a high environmental footprint. For this reason, the scientific and technological sector is looking for new materials to reduce the environmental consequences of this division. It is well known that the valorisation of different by-products can contribute to the reduction of the energy global consumption and CO2 emissions. Magnesium Phosphate Cement (MPC) can be obtained by using Low Grade Magnesium Oxide (LG-MgO) as a by-product from the industrial process of magnesite calcination. In this research, a Sustainable MPC (Sust-MPC) for different construction purposes is developed by using LG-MgO along with monopotassium phosphate KH2PO4 (MKP) as raw materials. The increasing use of synthetic fibres in clothing, as well as China’s competitive prices on Animal Fibres (AF) market, have led to a commercial interest fibre decrease for wool-like AF in Spain. This study aims to formulate a Sust-MPC cement with Animal Fibre (AF) to reduce the cost of the new material (Sust-MPC-AF) and to increase the thermal insulation, allowing the use of Sust-MPC-AF in several potential applications. Besides, it should be emphasized that the final pH of Sust-MPC is neutral, which allows containing natural fibres. To develop Sust-MPC-AF, some properties such as thermal conductivity, density, Modulus of Elasticity (MoE), flexural strength, and economic cost were evaluated using the Design of Experiments (DoE). The DoE studies allowed obtaining a model for further optimization considering minimum thermal conductivity and cost dosages. The formulation 30L-25EW presents the minimum conductivity (λ=0.140 W·m-1·K-1). Therefore, two optimal dosages (36L-25EW and 24L-22EW) are obtained by considering mixing variables such as AF/Cement ratio (AF/C) and AF/Extra Water ratio (AF/EW).

scholarly journals Dispersed-Monolayer Graphene-Doped Polymer/Silica Hybrid Mach-Zehnder interferometer (MZI) Thermal Optical Switch with Low-Power Consumption and Fast Response

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1898 ◽  
Author(s):  
Yue Cao ◽  
Daming Zhang ◽  
Yue Yang ◽  
Baizhu Lin ◽  
Jiawen Lv ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Consumption ◽  
Low Power ◽  
Optical Switch ◽  
Fast Response ◽  
Zehnder Interferometer ◽  
Low Power Consumption ◽  
Monolayer Graphene ◽  
Doped Polymer ◽  
Silica Hybrid

This article demonstrates a dispersed-monolayer graphene-doped polymer/silica hybrid Mach–Zehnder interferometer (MZI) thermal optical switch with low-power consumption and fast response. The polymer/silica hybrid MZI structure reduces the power consumption of the device as a result of the large thermal optical coefficient of the polymer material. To further decrease the response time of the thermal optical switch device, a polymethyl methacrylate, doped with monolayer graphene as a cladding material, has been synthesized. Our study theoretically analyzed the thermal conductivity of composites using the Lewis–Nielsen model. The predicted thermal conductivity of the composites increased by 133.16% at a graphene volume fraction of 0.263 vol %, due to the large thermal conductivity of graphene. Measurements taken of the fabricated thermal optical switch exhibited a power consumption of 7.68 mW, a rise time of 40 μs, and a fall time of 80 μs at a wavelength of 1550 nm.

Vinyl functionalized silica hybrid monolith-based trypsin microreactor for on line digestion and separation via thiol-ene “click” strategy

2011 ◽  
Vol 1218 (44) ◽  
pp. 7982-7988 ◽  
Author(s):  
Yingzhuang Chen ◽  
Minghuo Wu ◽  
Keyi Wang ◽  
Bo Chen ◽  
Shouzhuo Yao ◽  
...  
Keyword(s):  
Functionalized Silica ◽  
On Line ◽  
Silica Hybrid

Thermomechanical properties of silica–epoxy nanocomposite modified by hyperbranched polyester: A molecular dynamics simulation

2021 ◽  
pp. 095400832110323
Author(s):  
Jianwen Zhang ◽  
Dongwei Wang ◽  
Lujia Wang ◽  
Wanwan Zuo ◽  
Xiaohua Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Glass Transition ◽  
Epoxy Resin ◽  
Silica Surface ◽  
Thermomechanical Properties ◽  
Dynamics Simulation ◽  
Hyperbranched Polyester ◽  
Pure Epoxy ◽  
Epoxy Nanocomposite

In this article, pure epoxy resin and silica–epoxy nanocomposite models were established to investigate the effects of hyperbranched polyester on microstructure and thermomechanical properties of epoxy resin through molecular dynamics simulation. Results revealed that the composite of silica can improve the thermomechanical properties of nanocomposites, including the glass transition temperature, thermal conductivity, and elastic modulus. Moreover, the thermomechanical properties were further enhanced through chemical modification on the silica surface, where the effectiveness was the best through grafting hyperbranched polyester on the silica surface. Compared with pure epoxy resin, the glass transition temperature of silica–epoxy composite modified by silica grafted with hyperbranched polyester increased by 38 K. The thermal conductivity increased with the increase of temperature and thermal conductivity at room temperature increased to 0.4171 W/(m·K)−1 with an increase ratio of 94.3%. Young’s modulus, volume modulus, and shear modulus all fluctuated as temperature rise with a down overall trend. They increased by 44.68%, 29.52%, and 36.65%, respectively, when compared with pure epoxy resin. At the same time, the thermomechanical properties were closely related to the microstructure such as fractional free volume (FFV), mean square displacement (MSD), and binding energy. Silica surface modification by grafting hyperbranched polyester reduced the FFV value and MSD value most and strengthened the combination of silica and epoxy resin matrix the best, resulting in the best thermomechanical properties.

FUNCTIONALIZED SILICA AS AN ECO-FRIENDLY VULCANIZATION ACCELERATOR TO ENHANCE THE INTERFACIAL INTERACTION IN NR/SILICA COMPOSITES

2020 ◽  
pp. 000-000
Author(s):  
Kaizheng Zhu ◽  
Yang Pan ◽  
Jie Wu ◽  
Kuncai Li ◽  
Xiwei Guo ◽  
...  
Keyword(s):  
Silica Surface ◽  
Decomposition Temperature ◽  
Interfacial Interaction ◽  
Rubber Matrix ◽  
Functionalized Silica ◽  
Rubber Industry ◽  
Degradation Temperature ◽  
Technological Opportunities ◽  
Vulcanization Accelerator

ABSTRACT Xanthate is a class of non-toxic, rapid, and eco-friendly rubber vulcanization accelerator, but it is seldom used in the rubber industry because of its poor thermostability and ease of decomposition. To overcome these drawbacks, silica supported sodium isobutyl xanthate (silica-s-SIBX) was prepared by chemically bonding SIBX onto the silica surface. After loading, the initial degradation temperature (T0), maximum degradation temperature (Tp), and final decomposition temperature (Tf) of silica-s-SIBX were increased by 85.8, 118.9, and 146.9 °C, respectively. Meanwhile, silica-s-SIBX could not only improve the dispersion of fillers in the rubber but also enhance the interfacial interaction between silica and the rubber matrix. Therefore, it may offer new scientific and technological opportunities for preparation of green additives in the rubber industry.

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