Hybrid cords of two different polyamide yarns, poly(p-phenylene terephthalamide; aramid) and poly(hexamethylene adipamide; nylon 6.6) have been investigated. Aramid is a high-tenacity, high-modulus, low-elongation, and thermally stable yarn material. Nylon 6.6 is a high-elongation, low-modulus, high-fatigue-resistant, and good adhering synthetic yarn. The combination of these two different synthetic yarns enables hybrid cords with a diversified range of mechanical properties. The hybrid cord product property diversification is achieved by proper combination of different cord-forming properties of individual plies, such as linear densities, twist levels, ply numbers, treating conditions, and so forth. The effect of linear densities, twist level of plies, and twist level of cabled cord and ply number on the cord properties and also cord performance have been summarized. Aramid yarn having an 1100 linear density has been combined with nylon 6.6 yarn with a different linear density, ranging from 940 to 2100, to form hybrid cord structures. Twisting of aramid and nylon 6.6 yarns has been kept between 150 and 450 twists per meter, while the ply number of aramid and nylon 6.6 yarns has been varied as one and two plies by keeping the total ply number of the cord as three.
In this study, the possibility of enhancing heat insulation performance of hollow bricks by filling the cavities with perlite is investigated. A conjugate heat transfer by conduction, convection and radiation in different hollow bricks are analyzed numerically to assess their thermal performance. Calculations are performed for three scenarios for each type of hollow brick: (i) cavities are filled with air, (ii) half of the cavities are filled with perlite while the other half is filled with air, (iii) all cavities are filled with perlite. The benefit of filling cavities with perlite is justified quantitatively for each investigated hollow brick type. It is concluded that the enhancement in insulation performance can be up to 15.6% and 27.5% for half-perlite and full-perlite cases, respectively, depending on the brick type.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.