A comparative thermoacoustic insulation study of silica aerogels reinforced with reclaimed textile fibres: cotton, polyester and wool

Silica aerogels are highly porous materials with exceptional thermal insulation performance. They become even more attractive if combined thermal and acoustic insulation is achieved. Silica aerogel composites reinforced with fibres are an ingenious way to surpass the fragility stemmed from the aerogel’s intrinsic porosity, and textile fibres are good sound absorption materials. Reclaimed fibres are a relatively low-cost feedstock and were obtained in this work exclusively through mechanical processes from textile wastes, thus promoting the concept of circular economy, namely for cotton, polyester and wool fibres. These reclaimed fibres were used as reinforcement matrices for silica aerogel composites obtained from sol–gel transformation of tetraethyl orthosilicate and isobutyltriethoxysilane/or vinyltrimethoxysilane precursors and dried at ambient pressure after silylation. Silica aerogel composites reinforced with reclaimed cotton fibres had the best sound absorption coefficient (a peak value of 0.89), while the polyester-reinforced composite exhibited the lowest thermal conductivity (k = ~24 mW m−1 K−1, Hot Disk). The better combined results on thermal and acoustic insulation were achieved by the wool-reinforced composites. The thermal conductivity values were less than 27 mW m−1 K−1, and the sound absorption coefficient achieved a peak value of 0.85. Therefore, the aerogel composites developed here can be selected for thermal or/and acoustic barriers by choosing a suitable type of fibre. Their design and preparation protocol followed environmental-friendly and cost-effective approaches.Teresa Linhares acknowledges the PhD grant Ref. SFRH/BD/131819/2017, attributed by Fundação para a Ciência e Tecnologia, I.P. (FCT, Portugal), funded by national funds from MCTES (Ministério da Ciência, Tecnologia e Ensino Superior) and, when appropriate, co-funded by the European Commission through the European Social Fund. Consumables for the syntheses and characterizations performed at CIEPQPF and 2C2T research units were funded by the European Regional Development Fund (ERDF), through COMPETE 2020 Operational Programme for Competitiveness and Internationalization, combined with Portuguese National Funds, through FCT, I.P. under the projects POCI-01-0145-FEDER-006910 and POCI-01-0145-FEDER-007136 (FCT Refs. UIDB/EQU/00102/2020 and UID/CTM/00264/2020, respectively)

Enzymatically enhanced adhesion of cellulosic woven fabrics composites

This work intended to study the production of composite using enzymatic modified woven cellulosic fabrics made up from fibres of cotton, linen and bamboo viscose. The adhesion of the fabric will be promoted using different mixture of cellulase enzymes. The properties of the woven fabrics and produced composites were characterized using several physical tests. The cotton & viscose composite appear to be the best combination exhibiting improved breaking force (0.5% of Xylanase PLUSTM) and percentage of elongation at maximum force (0.1% of Xylanase PLUSTM), as well as on the peel adhesion test (0.5% of AlternaFuel® MAXTM). The linen & cotton combination did not show any improvement for all the tested properties. Linen & viscose combination despite did not show peel strength improvement, exhibit remarkable elongation and breaking force (0.5% of Xylanase PLUSTM). Since there is no emission of volatile products it is expected a great public acceptance. However, higher enzymatic concentrations should be studied to clarify the contribution of this parameter on the surface modification and adhesion promotion.This work is financed by FEDER funds through the Competivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136

Enzymatic enhanced adhesion of cellulosic woven fabrics composites

The purpose of this work was to produce and characterize enzymatically treated fabric composites using different mixture of two commercial cellulase enzyme solutions in dosages of 0.1% and 0.5% in order to improve fabric’s adhesion. Three cellulosic taffeta plain weave fabrics of 100% flax, cotton and bamboo viscose were used in different combinations. The properties of the woven fabrics and produced composites were characterized using several mechanical tests. The cotton & viscose composite appears to be the best materials combination exhibiting improved breaking force (0.5% of Xylanase PLUSTM) and percentage of elongation at maximum force (0.1% of Xylanase PLUSTM), as well as better results on the peel adhesion test (0.5% of AlternaFuel® MAXTM). The flax & cotton combination did not show any improvement for all the tested properties. Flax & viscose combination despite did not show pell strength improvement, exhibit remarkable elongation and breaking force (0.5% of Xylanase PLUSTM). Since there is no posterior emission of volatile products one can expect a great public acceptance. However, higher enzymatic concentrations should be studied to clarify the contribution of this parameter on the surface modification and adhesion promotion.This work is also funded by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136