Study on structure and performance of reactive silicate reinforced polyurethane composite

Abstract

Polyurethane (PU)/silicate composite for grouting is prepared using toluene 2,4‐diisocyanate (TDI), polyoxypropylene glycol (PPG), and sodium silicate. The reaction temperature change, mechanical properties, flame resistance, thermal performance, chemical structure, and section morphology of PU/silicate composite are investigated by thermometer, mechanical test, LOI and vertical combustion tester, thermogravimetric analysis (TGA), FTIR, and scanning electron microscopy (SEM). The addition of sodium silicate reduced the maximum reaction temperature and improved the mechanical properties and flame resistance of PU composite dramatically. The best comprehensive performance can be achieved when the silicate fraction is 25 wt%, tensile strength is 19.3 MPa, bonding strength is 4.1 MPa, compression strength is 47.2 MPa, the value of LOI is 34.1% and reaches UL 94 V‐0 rating. Porous structures with microspheres and spherical crevices are observed in the section of PU/silicate composite, which contributes to the low reaction temperature and higher mechanical performance, the reaction equations and possible formation mechanism of the special microspheres reinforced structure are put forward finally. POLYM. ENG. SCI., 55:2322–2327, 2015. © 2015 Society of Plastics Engineers

Effects of different catalysts on the structure and properties of polyurethane/water glass grouting materials

“…Thus, the positively charged carbon atoms of isocyanate species are more active and susceptible to the interactions with the hydroxyl groups of polyols. Owing to the presence of empty orbitals, the organotin catalyst can produce binary or ternary complexes with polyols and isocyanates and thus undergo polymerization, leading to the formation of a network structure (its reaction is described in detail in parts (a) and (b) of Scheme ).The other specific reactions of the PU/WG grouting system are also shown in Scheme . The isocyanate groups of PU interact mainly with water in the whole system (c) and then undergo the diol (d) or silanol (e) formation reaction followed by the decomposition of polysilicic acid (f). The WG hydrolysis reaction is described by equation (e).After the addition of the tertiary amine catalyst, isocyanates react first with water and then with polyols.…”

“…Thus, the positively charged carbon atoms of isocyanate species are more active and susceptible to the interactions with the hydroxyl groups of polyols. Owing to the presence of empty orbitals, the organotin catalyst can produce binary or ternary complexes with polyols and isocyanates and thus undergo polymerization, leading to the formation of a network structure (its reaction is described in detail in parts (a) and (b) of Scheme ).…”

“…studied the adhesion between PU/WG materials and coal and showed that the former possessed excellent mechanical properties. Hong et al . prepared inorganic microsphere‐reinforced PU composites by a one‐step mixing process.…”

Experimental Study on Mix Proportion Parameter Optimization of Cement Anchoring Material

“…When sodium silicate was added, it immediately reacted with the Ca(OH) 2 produced during cement hydration to form a large amount of calcium silicate gels. As the reaction progressed, more and more colloids were formed, which helped to improve the adhesion stress between the contact faces [27]. Figure 11c shows that the adhesion stress increased as a result of the increase in the ettringite content.…”

“…This was because sodium silicate can generate a gel reaction with metals or metal oxides. The alkali in the sodium silicate is seized by the metal ions, which causes the sodium silicate to lose water to form silica gel, thereby increasing the strength of the bond stress between the anchor and the paste [27]. Figure 10c shows that the size of the bond stress changed little with the increase in ettringite.…”