Constructing Cellulose Diacetate Aerogels with Pearl-Necklace-Like Skeleton Networking Structure

Cellulose and its derivative aerogels have attracted much attention due to their renewable and biodegradable properties. However, the significant shrinkage in the supercritical drying process causes the relatively high thermal conductivity and low mechanical property of cellulose and its derivatives aerogels. Considering the pearl-necklace-like skeleton network of silica aerogels, which can improve thermal insulation property and mechanical property. Herein, we propose a new strategy for fabricating cellulose diacetate aerogels (CDAAs) with pearl-necklace-like skeletons by using tert-butanol (TBA) as exchange solvent after experiencing the freezing-drying course. CDAAs obtained have the low density of 0.09 g cm−3, the nanopore size in the range of 10–40 nm, the low thermal conductivity of 0.024 W m−1 K−1 at ambient conditions, and the excellent mechanical properties (0.18 MPa at 3% strain, 0.38 MPa at 5% strain). Ultimately, CDAAs with moderate mechanical property paralleled to cellulose-derived aerogels obtained from supercritical drying process are produced, only simultaneously owning the radial shrinkage of 6.2%. The facile method for fabricating CDAAs could provide a new reference for constructing cellulose/cellulose-derived aerogels and other biomass aerogels.

Analysis and Optimization of Hybrid Soil Properties for Gel Based Roof Tiles

Our current 21st century has seen more drastic changes in terms of environmental conditions due to global warming, climate change and deforestation. This has shown a great rise in the global temperature throughout the world. Normally, the roof top of a building is provided with tiles to protect the structural components and to create a comfortable environment. The tiles can be made of materials like clay, concrete, fly ash, lime etc. Due to the prevailing environmental challenges, there is a need for the tiles to be made as with more energy efficient material that supports thermal insulation and cost effectiveness. Aerogel and hydrogel are the gel based product that are used in our current work to enhance the thermal insulation property of the tiles. Various tests such as water absorption test, wet and dry cycle test, bending strength test, thermal conductivity test, wear and tear test are carried out on the tile to quantify its characteristics. All the above shows better value than the normal commercial tile product.

Analysis and Optimization of Hybrid Soil Properties for Gel Based Roof Tiles

Our current 21st century has seen more drastic changes in terms of environmental conditions due to global warming, climate change and deforestation. This has shown a great rise in the global temperature throughout the world. Normally, the roof top of a building is provided with tiles to protect the structural components and to create a comfortable environment. The tiles can be made of materials like clay, concrete, fly ash, lime etc. Due to the prevailing environmental challenges, there is a need for the tiles to be made as with more energy efficient material that supports thermal insulation and cost effectiveness. Aerogel and hydrogel are the gel based product that are used in our current work to enhance the thermal insulation property of the tiles. Various tests such as water absorption test, wet and dry cycle test, bending strength test, thermal conductivity test, wear and tear test are carried out on the tile to quantify its characteristics. All the above shows better value than the normal commercial tile product.

Thermal insulation property of graphene/polymer coated textile based multi-layer fabric heating element with aramid fabric

This study investigated the thermal insulation properties based on electrical heating test of graphene-based multi-layer fabric heating elements to confirm the possibility of application for fabric heating element for protective clothing. Four layers were designed as layers of outer, filler, electrical heating textile, and lining. The outer fabrics used two different densities of aramid woven fabrics (LD_ARW and HD_ARW), an aramid knit (AR_KT), and nonwoven (AR_NW). Fabricated graphene/polymer coated electrical heating textile (GR) exhibits a surface temperature of about 85 °C, a current of 0.12 A, and a power of 3 W when 30 V is applied. As composed with 4-layer, the surface temperature of LD_ARW and HD_ARW used as the outer for sample indicated less than 50 °C, due to their excellent heat resistance property; whereas, when AR_KT and AR_NW were used, the temperature was about 50 °C. This is because their fine fibers form high porosity that can entrap air. As a result of the thermal insulation properties, the temperature difference of each layer was in the order ΔT(GR-N3) < ΔT(GR-Lining) < ΔT(GR-Outer). In particular, when AR_NW was used as the outer fabric, ΔT(GR-Outer) was decreased by about 10 °C, compared with that of the other outer fabric. By the effect of relative humidity under dry 25% RH and comfortable 55% RH, the temperature difference was decreased under 55% RH; thus, the thermal insulation property was improved under comfortable humidity condition. Therefore, the best thermal insulation performance was exhibited when AR_NW was used as outer under 55% RH, and it is expected to expand its application to fabric heating element for protective clothing.

Preparation of Ultrafine Fly Ash-Based Superhydrophobic Composite Coating and Its Application to Foam Concrete

The waterproof and thermal insulation property of foamed concrete is very important. In this study, the ultrafine fly ash (UFA)-based superhydrophobic composite coating was applied onto foam concrete. The UFA-based base coating that closely adhered to the concrete initially improved the waterproofness of the test block, and the silane coupling agent-modified UFA-based surface coating further achieved superhydrophobicity. The UFA on the coating surface and the asperities on the surface jointly formed a lotus leaf-like rough micro–nanostructure. The 154.34° water drop contact angle and 2.41° sliding angle on No. 5 coating were reached, indicating that it was a superhydrophobic surface. The water absorption ratios of the composite coating block were 1.87% and 16.6% at 4 h and 7 days, which were reduced by 97% and 75% in comparison with the original foam concrete. The compressive strength and heat conductivity coefficient after soaking for 4 h of the composite coating block were higher than 4.0 MPa and 0.225 W·m−1·K−1, respectively. The UFA-based superhydrophobic composite coating proposed in this study and applied onto foam concrete is simple and cheap, requires no precise instrument, and can be applied in a large area.

Carbon particulate and controlled-hydrolysis assisted extrusion foaming of semi-crystalline polyethylene terephthalate for the enhanced thermal insulation property

This work presents a facile method to produce low-density PET foams using pristine semi-crystalline resin by moisture-induced controlled-hydrolysis in a tight processing window (moisture content ∼ 0.12 wt.%). We investigated the effect of moisture and moisture containing activated carbon (AC) on the foam expansion ratio, cell morphology, and PET resin degradation and crystallization properties. Controlled-hydrolysis increased the melt-flow rate of PET resin (intrinsic viscosity: 0.52 to 0.54 dL/g) without losing crystallinity, and thus the PET foams possess better tensile properties (∼2 MPa stress and ∼100% strain) and higher thermal stability (>200°C) than chemically modified PET foams. The foam density could be made as low as ∼ 0.15 g/cm3 using a lab scale twin-screw extruder. A strand array die was also designed to produce plate-shaped foam samples. AC allowed easier control of the moisture content and delayed resin degradation in extrusion. Both AC and micrographite (mGr) could stabilize the PET foam morphology in extrusion and serve as good infrared attenuation agents (IAAs) in a simulated housing thermal insulation experiment.