Crosslinking polydopamine/cellulose nanofibril composite aerogels by metal coordination bonds for significantly improved thermal stability, flame resistance, and thermal insulation properties

Abstract Cellulose nanofibril (CNF) aerogels have attracted great interests in recent years due to the low cost, sustainability and biocompatibility of raw CNFs. However, the poor thermal stability and flammable feature of CNF aerogels have limited their wider applications. In this paper, polydopamine/CNF composite aerogels with good comprehensive properties are fabricated by modification of CNF with polydopamine and metal coordination bonds crosslinking. The microstructure and properties of composite aerogels are thoroughly characterized by a variety of tests. It is found that the microstructure of aerogels are more regular and the compressive strength of aerogels are enhanced by the incorporation of polydopamine and Fe3+ crosslinking. Importantly, the thermal stability and flame resistance of aerogels are significantly improved, which permit the application of composite aerogels in high-temperature thermal insulation. In addition, the reversible characteristic of metal coordination bonds allows the water induced healing of fractured composite aerogels. This study is expected to provide information for future development of green and high-performance aerogels.

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Fire-resistant, ultralight, superelastic and thermally insulated polybenzazole aerogels

Journal of Materials Chemistry A ◽

10.1039/c8ta07204c ◽

2018 ◽

Vol 6 (42) ◽

pp. 20769-20777 ◽

Cited By ~ 13

Author(s):

Zhenchao Qian ◽

Meng Yang ◽

Rui Li ◽

Dongdong Li ◽

Jianling Zhang ◽

...

Keyword(s):

Thermal Insulation ◽

Energy Efficient ◽

Flame Resistance ◽

Composite Aerogels

The polybenzazole aerogels exhibit superelasticity and flame resistance without additives. High thermal insulation and resistance to a 1000 °C flame has been achieved for the composite aerogels, showing potential in energy efficient areas.

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Cryogenic thermal insulating and mechanical properties of rigid polyurethane foams blown with hydrofluoroolefin: Effect of perfluoroalkane

Journal of Cellular Plastics ◽

10.1177/0021955x211062633 ◽

2021 ◽

pp. 0021955X2110626

Author(s):

Tae Seok Kim ◽

Yeongbeom Lee ◽

Chul Hyun Hwang ◽

Kwang Ho Song ◽

Woo Nyon Kim

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Thermal Stability ◽

Cell Size ◽

Thermal Insulation ◽

Coefficient Of Thermal Expansion ◽

Lower Surface ◽

Polyurethane Foams ◽

Insulation Material ◽

Pu Foams

The effect of perfluoroalkane (PFA) on the morphology, thermal conductivity, mechanical properties and thermal stability of rigid polyurethane (PU) foams was investigated under ambient and cryogenic conditions. The PU foams were blown with hydrofluorolefin. Morphological results showed that the minimum cell size (153 μm) was observed when the PFA content was 1.0 part per hundred polyols by weight (php). This was due to the lower surface tension of the mixed polyol solution when the PFA content was 1.0 php. The thermal conductivity of PU foams measured under ambient (0.0215 W/mK) and cryogenic (0.0179 W/mK at −100°C) conditions reached a minimum when the PFA content was 1.0 php. The low value of thermal conductivity was a result of the small cell size of the foams. The above results suggest that PFA acted as a nucleating agent to enhanced the thermal insulation properties of PU foams. The compressive and shear strengths of the PU foams did not appreciably change with PFA content at either −170°C or 20°C. However, it shows that the mechanical strengths at −170°C and 20°C for the PU foams meet the specification. Coefficient of thermal expansion, and thermal shock tests of the PU foams showed enough thermal stability for the LNG carrier’s operation temperature. Therefore, it is suggested that the PU foams blown by HFO with the PFA addition can be used as a thermal insulation material for a conventional LNG carrier.

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Rigid Polyurethane Foams Modified with Biochar

Materials ◽

10.3390/ma14195616 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5616

Author(s):

Katarzyna Uram ◽

Maria Kurańska ◽

Jacek Andrzejewski ◽

Aleksander Prociak

Keyword(s):

Thermal Conductivity ◽

Thermal Stability ◽

Thermal Insulation ◽

Foam Cells ◽

Polyurethane Foams ◽

Cross Sectional ◽

Rigid Polyurethane Foams ◽

Insulation Materials

This paper presents results of research on the preparation of biochar-modified rigid polyurethane foams that could be successfully used as thermal insulation materials. The biochar was introduced into polyurethane systems in an amount of up to 20 wt.%. As a result, foam cells became elongated in the direction of foam growth and their cross-sectional areas decreased. The filler-containing systems exhibited a reduction in their apparent densities of up to 20% compared to the unfilled system while maintaining a thermal conductivity of 25 mW/m·K. Biochar in rigid polyurethane foams improved their dimensional and thermal stability.

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Novel GO/silica composite aerogels with enhanced mechanical and thermal insulation properties prepared at ambient pressure

Ferroelectrics ◽

10.1080/00150193.2018.1448192 ◽

2018 ◽

Vol 528 (1) ◽

pp. 15-21 ◽

Cited By ~ 3

Author(s):

Liu Hong-li ◽

He Xiang ◽

Li Hong-yan ◽

Li Jing ◽

Li Ya-jing

Keyword(s):

Thermal Insulation ◽

Ambient Pressure ◽

Silica Composite ◽

Composite Aerogels

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Cellulose Aerogels for Thermal Insulation in Buildings: Trends and Challenges

Coatings ◽

10.3390/coatings8100345 ◽

2018 ◽

Vol 8 (10) ◽

pp. 345 ◽

Cited By ~ 14

Author(s):

Danny Illera ◽

Jaime Mesa ◽

Humberto Gomez ◽

Heriberto Maury

Keyword(s):

Thermal Stability ◽

Thermal Insulation ◽

Gaseous Phase ◽

Energy Demand ◽

Cost Effective ◽

Silica Aerogels ◽

Moisture Sensitivity ◽

Knudsen Effect ◽

Cellulose Aerogel ◽

Current Trends

Cellulose-based aerogels hold the potential to become a cost-effective bio-based solution for thermal insulation in buildings. Low thermal conductivities (<0.025 W·m−1·K−1) are achieved through a decrease in gaseous phase contribution, exploiting the Knudsen effect. However, several challenges need to be overcome: production energy demand and cost, moisture sensitivity, flammability, and thermal stability. Herein, a description and discussion of current trends and challenges in cellulose aerogel research for thermal insulation are presented, gathered from studies reported within the last five years. The text is divided into three main sections: (i) an overview of thermal performance of cellulose aerogels, (ii) an identification of challenges and possible solutions for cellulose aerogel thermal insulation, and (iii) a brief description of cellulose/silica aerogels.

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