Toward a Better Understanding of B72 Acrylic Resin/Methyltrimethoxysilane Stone Consolidants

Abstract

B72 acrylic resin/methyltrimethoxysilane (YMTMOS) mixtures are frequently employed as consolidants for deteriorated limestones, sandstones and marbles- The addition of B72 to MTMOS imparts adhesive properties to the consolidant but it is not known to what degree the B72 affects the reactions which MTMOS must undergo to form a solid polymer network. This paper examines the following chemical, physical, and mechanical properties in order to better understand B72/MTMOS systems: 1. viscosity 2. vapor pressure 3. reaction mechanism and kinetics 4. chemical nature of polymer solids 5. rupture moduli of polymer solids and 6. rupture moduli of stone/consolidant composites.

Multi-nuclear liquid state NMR investigation of the effects of pH and addition of polyethyleneglycol on the long-term hydrolysis and condensation of tetraethoxysilane

“…3d shows that the alcohol was not found in the pre-solution added with PEG 2000 at pH 9 even with the aging time of 81 h. Overall, the presence of PEG increases the degree of hydrolysis and condensation of the TEOS pre-solutions at pH 3 and pH 9 (except pre-solution with addition of PEG 2000 at pH 9). These results are similar to that reported by Wheeler et al [29]. They found that polyacrylate could promote the degree of condensation of TEOS.…”

“…Heteronuclear decoupling was not employed in order to retain proton multiplets for better presenting the evolution of the spectral pattern. In addition, the liquid 13 C and 29 Si NMR measurements were performed on a Bruker 300 MHz NMR spectrometer with the resonance frequency of 75.47 MHz for 13 C and 59.63 MHz for 29 Si, respectively. To obtain sufficient signal intensity, 128 scans were acquired for each 13 C NMR spectrum with a 2 s recycle delay using a 30°pulse angle and 9000 scans were acquired for each 29 Si NMR spectrum with a 5 s recycle delay using a 30°pulse.…”

“…The hydrolysis and condensation reactions of the sol-gel process are characterized by 1 H, 13 C and 29 Si multi-nuclear liquid NMR spectroscopy. In most of the previous studies, liquid 29 Si NMR spectroscopy was used to measure the hydrolysis and condensation reaction of the sol-gel process of TEOS [18,20,21]. However, the sensitivity of the NMR spectroscopy of the nucleus with low natural abundance is low (the natural abundances of 1 H, 13 C, and 29 Si are 99.8%, 1.11%, and 13%, respectively.)…”

“…In most of the previous studies, liquid 29 Si NMR spectroscopy was used to measure the hydrolysis and condensation reaction of the sol-gel process of TEOS [18,20,21]. However, the sensitivity of the NMR spectroscopy of the nucleus with low natural abundance is low (the natural abundances of 1 H, 13 C, and 29 Si are 99.8%, 1.11%, and 13%, respectively.) Because the focus of this work is on the long time stages, high resolution 1 H NMR spectroscopy can be employed instead of 29 Si NMR to measure the time evolution of the functional group concentrations in the TEOS sol-gel system.…”

“…However, the sensitivity of the NMR spectroscopy of the nucleus with low natural abundance is low (the natural abundances of 1 H, 13 C, and 29 Si are 99.8%, 1.11%, and 13%, respectively.) Because the focus of this work is on the long time stages, high resolution 1 H NMR spectroscopy can be employed instead of 29 Si NMR to measure the time evolution of the functional group concentrations in the TEOS sol-gel system. Specifically, this research involves a series of investigations regarding the effects of pH and aging time on TEOS sol with and without addition of PEG.…”