Toward a Better Understanding of B72 Acrylic Resin/Methyltrimethoxysilane Stone Consolidants
- PDF / 2,582,862 Bytes
- 18 Pages / 420.48 x 639 pts Page_size
- 27 Downloads / 152 Views
TOWARD A BETTER UNDERSTANDING OF B72 ACRYLIC RESIN/METHYLTRIMETHOXYSILANE STONE CONSOLIDANTS G.S. WHEELER,* G.L. SHEARER,* S. FLEMING,** L.W. KELTS,*** A. VEGA,**** R.J. KOESTLER* *The Metropolitan Museum of Art, New York, NY **AT&T Bell Laboratories, Murray Hill, NJ ***E.I. Dupont de Nemours, Wilmington, DE ****Eastman Kodak, Rochester, NY
AND
ABSTRACT B72 acrylic resin/methyltrimethoxysilane (YMTMOS) mixtures are frequently employed as consolidants for deteriorated limestones, sandstones and marblesThe 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. INTRODUCTION Advancing the front of stone consolidation has proved difficult in recent years. Since the development of WACKER OH and H [1] and the Lewin method (2] in the 1960s, BRETHANE, [3] the "Bologna Cocktail," (4] and acrylic resins dissolved in methyltrimethoxysilane (or just neat MTMOS) [5] in the 1970s, there has been no evolution in stone consolidation. This fact was lamented in the closing remarks by V. Furlan at the Fifth International "Stone Conference" in 1985. [6] What was not pointed out at that time was how little is known about the chemical, physical, and mechanical properties of many of the above-mentioned consolidation systems. This paper purports to elucidate some of these properties for B72/MTMOS mixtures as they pertain to the usage of these mixtures as stone consolidants. BACKGROUND Acrylic resins hold important positions in the conservation repertoire as adhesives and consolidants for many materials. However, subsequent to the work of Larson acrylic resin/MTMOS mixtures attained near regal status for the consolidation of limestones and marbles in museums. [7] One reason Larson employed these resins was to impart adhesive properties to the consolidated stone. His experience indicated that it was difficult to cohere pieces of stone previously treated with MTMOS and that the addition of i-i0ý w/v of the acrylic resin overcame the problem. Other workers found that alkoxysilanes in general could not consolidate stones with large grains - on the order of 3 mis or greater. [8] These kinds of stones can also be more successfully consolidated by adding B72 to MTMOS, again, presumably, relying on the adhesive properties of B72. It is not known to what degree B72 affects the physical properties of MTMOS such as viscosity and vapor pressure, the kinetics and mechanisms of the complex set of reactions which produce the solid network of MTMOS-derived polymers, or the mechanical properties of this solid network. Each is important to the successful consolidation of stone:
Mat. Res. Soc. Symp. Pr
Data Loading...
