Effects on the Mechanical and Thermal Behaviors of an Alternative Mortar when Adding Modified Silica Aerogel with Aminopropyl Triethoxysilane and PEG-PPG-PEG Triblock Copolymer Additives

• Published in: SILICON 2023-08, Vol.15 (12), p.5353-5366
• Main Authors: Valdez-Cano, R., González-López, J. R., Guerra-Cossío, M. A.
• Format: Article
• Language: English
• Subjects: Additives; Block copolymers; Calcium compounds; Chemistry; Chemistry and Materials Science; Conductivity; Dosage; Environmental Chemistry; Heat conductivity; Inorganic Chemistry; Insulation; Lasers; Materials Science; Mechanical properties; Mortars (material); Optical Devices; Optics; Particle size; Photonics; Polymer Sciences; Separation; Silica aerogels; Thermodynamic properties
• ISSN: 1876-990X; 1876-9918
• DOI: 10.1007/s12633-023-02445-z

The incorporation of silica aerogel (SA) aggregates with different granulometry and surface modifications with two additives are evaluated to determine the effects that occur on the mechanical and thermal properties of an alternative mortar (MC). The results are obtained through physical, mechanical, thermal and microstructural analyses, demonstrating that the incorporation of small SA and high-density A3100 favors thermal and mechanical behaviors, reaching a conductivity of 0.111 W/mK in paste and 0.312 W/mK in mortar. Thus, reductions of 31% relative to the sample composed of only MC and of 26% relative to the sample with the largest A1000 particle size are achieved. The superficial modification of the SA with the two additives benefits the resistance of the compound, increasing adherence and minimizing the cracking and separation caused by the poor compatibility of the aerogel surrounding the particles in the interfaces between materials. The copolymer (COP) in a 5% dosage with the SA A3100 aggregate in a proportion of 80% increases the calcium and silicon contents, producing a homogeneous, large and dense compound with few cavities and fissures. The dosage increases the resistance relative to the samples without SA; the strength values reach 13.35 MPa at 56 days, becoming the most viable option for modifying the SA surface and improving the behaviors in the MC. This sample differs from triethoxysilane (S), which generates surfaces with macropores and separation distances reaching 5 µm improving its ability to conduct heat.