General H2O Outgassing Model Applicable to Silica-Filled Silicones

• Published in: Industrial & engineering chemistry research 2020-11, Vol.59 (44), p.19510-19521
• Main Authors: Sharma, Hom N, Dinh, Long N, Leckey, J. H, Maxwell, Robert S, McLean, William
• Format: Article
• Language: English
• Subjects: INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; kinetic modeling; kinetic parameters; Kinetics, Catalysis, and Reaction Engineering; MATERIALS SCIENCE; moisture; silica; silicones
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.0c03370

Moisture-induced aging and degradation are continuing concerns in long-term storage and use of silicone materials. The silica fillers frequently used to provide mechanical reinforcement in silicone formulations have a high affinity for H2O and act as a source of moisture outgassing later when placed in dry or vacuum applications. Accurate kinetic measurements and analyses are needed for reliable predictions of long-term outgassing behavior from silica-filled silicones. Here, we present a mechanistic and heuristic approach to developing a general kinetic model with a set of kinetic parameters that is appropriate for moisture outgassing from a wide range of silica-filled silicones. Data from temperature-programmed desorption and dynamic vapor sorption experiments on many different silica-filled silicones are utilized in conjunction with isoconversional and constrained iterative regression analyses to develop the general outgassing kinetic model over a wide range of temperatures. This work provides a single set of outgassing kinetic parameters to predict long-term H2O outgassing from all silica-filled silicones.