General H₂O Outgassing Model Applicable to Silica-Filled Silicones

Abstract

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.

Gamma Radiation Chemistry of Polydimethylsiloxane Foam in Radiation-Thermal Environments: Experiments and Simulations

“…Some free H 2 O molecules are absorbed onto the polar silica surface due to the hydrogen bonding interaction (Figure d*). The absorbed H 2 O is reported to manifest quite different outgassing behavior …”

Polymer degradation through chemical change: a quantum-based test of inferred reactions in irradiated polydimethylsiloxane

“…Despite these characteristics, PDMS is not impervious to chemical damage and it can interact with other materials. Common vectors for degradation arise from the ready uptake of environmental water [4][5][6][7] or absorption of radiation. [7][8][9][10][11][12] Understanding the degradation responses of PDMS has enormous practical applications, ranging from assessing environmental impacts [13][14][15] to establishing models for the aging and lifetime prediction of silicone components.…”

“…[7][8][9][10][11][12] Understanding the degradation responses of PDMS has enormous practical applications, ranging from assessing environmental impacts [13][14][15] to establishing models for the aging and lifetime prediction of silicone components. [4][5][6][7][8][9][10][11][12]16,17 Ionizing radiation is a common cause for polymer degradation that can arise during component sterilization, 1,18,19 as a consequence of planned operation conditions, and as a driver in accelerated aging studies. [7][8][9][10][11][12] In 1955, Charlesby proposed 20 a set of reaction schemes for crosslinking in irradiated PDMS that were quickly refined by others 21,22 and were based on IR vibrational spectroscopy, titration, mass spectra of off-gassing species, and chromatography (see Fig.…”

Polymer Degradation through Chemical Change: A Quantum-based Test of Inferred Reactions in Irradiated Polydimethylsiloxane

“…Despite these characteristics, PDMS is not impervious to chemical damage and it can interact with other materials. Common vectors for degradation arise from the ready uptake of environmental water [4][5][6][7] or absorption of radiation. [7][8][9][10][11][12] Understanding the degradation responses of PDMS has enormous practical applications, ranging from assessing environmental ima Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States; E-mail: kroonblawd1@llnl.gov pacts [13][14][15] to establishing models for the aging and lifetime prediction of silicone components.…”

“…[7][8][9][10][11][12] Understanding the degradation responses of PDMS has enormous practical applications, ranging from assessing environmental ima Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States; E-mail: kroonblawd1@llnl.gov pacts [13][14][15] to establishing models for the aging and lifetime prediction of silicone components. [4][5][6][7][8][9][10][11][12]16,17 Ionizing radiation is a common cause for polymer degradation that can arise during component sterilization, 1,18,19 as a consequence of planned operation conditions, and as a driver in accelerated aging studies. [7][8][9][10][11][12] In 1955, Charlesby proposed 20 a set of reaction schemes for crosslinking in irradiated PDMS that were quickly refined by others 21,22 and were based on IR vibrational spectroscopy, titration, mass spectra of off-gassing species, and chromatography (see Figure 1).…”