Analysis of Water and Hydroxyl Species in Soda Lime Glass Surfaces Using Attenuated Total Reflection (ATR)‐IR Spectroscopy

ATR‐IR spectroscopy is a useful and convenient method for evaluation of local structure and concentration of water and hydroxyl species in glass because it can be more surface sensitive than reflection or transmission IR analysis. In this work, a semiquantitative analysis of the ATR spectra of OH groups and interstitial molecular water species in glass surfaces after various surface treatments is presented. Both hydroxyl groups and interstitial molecular water exist in the hydrated surfaces but the relative water speciation varies with surface treatment. The SiOH and H₂O species in the glass surface showed a wide range of hydrogen bonding interactions and their distributions varied with the SO₂, polishing, acid leaching, thermal tempering, and chemical strengthening treatments. SIMS analysis of the hydrogen concentration — depth profiles for the acid‐leached samples was used to provide independent information to validate and quantify the ATR signal.     

Chemical structure and mechanical properties of soda lime silica glass surfaces treated by thermal poling in inert and reactive ambient gases

This study employed thermal poling at 200°C as a means to modify the surface mechanical properties of soda lime silica (SLS) glass. SLS float glass panels were allowed to react with molecules constituting ambient air (H₂O, O₂, N₂) while sodium ions were depleted from the surface region through diffusion into the bulk under an anodic potential. A sample poled in inert gas (Ar) was used for comparison. Systematic analyses of the chemical composition, thickness, silicate network, trapped molecular species, and hydrous species in the sodium‐depleted layers revealed correlations between subsurface structural changes and mechanical properties such as hardness, elastic modulus, and fracture toughness. A silica‐like structure was created in the inert gas environment through restructuring of Si–O–Si bonds at 200°C in the Na‐depleted zone; this occurred far below T_g. This silica‐like surface also showed enhancement of hardness comparable to that of pure silica glass. The anodic thermal poling condition was found so reactive that O₂ and N₂ species can be incorporated into the glass, which also alters the glass structure and mechanical properties. In the case of the anodic surfaces prepared in a humid environment, the glass showed an improved resistance against crack formation, which implies that abundant hydrous species incorporated during thermal poling could be beneficial to improve the toughness.     

Effects of small molecule plasticizer on the coordination crosslinking reaction between acrylonitrile‐butadiene rubber and copper sulfate

The effects of small molecule plasticizer of liquid acrylonitrile‐butadiene rubber (LNBR) on coordination crosslinking reaction between acrylonitrile‐butadiene rubber (NBR) and copper sulfate (CuSO₄) were investigated. Attenuated total reflectance infrared (ATR‐IR), curing curves analysis, equilibrium swelling method, differential scanning calorimetry (DSC), tensile test, and scanning electron microscope (SEM) were used in this work. The ATR‐IR analysis showed that the peak of restricted  CN is more explicit in NBR/CuSO₄/LNBR system. The curing curve analysis showed that NBR/CuSO₄/LNBR has higher torque. The results of equilibrium swelling method and DSC displayed that NBR/CuSO₄/LNBR has higher crosslink density and glass transition temperature, respectively. And NBR/CuSO₄/LNBR has stronger tensile strength and longer elongation at break from tensile test. SEM revealed the reasons that the NBR/CuSO₄/LNBR has better mechanical properties. All the results showed that addition of an amount of LNBR to NBR/CuSO₄ system could accelerate the coordination crosslinking reaction between NBR and CuSO₄. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Correlation between IR peak position and bond parameter of silica glass: Molecular dynamics study on fictive temperature (cooling rate) effect

The fictive temperature of glass is a consequence of its thermal history (cooling rate, primarily) and has a direct effect on physical and chemical properties of the glass. But, it is not easy to measure. The ability to nondestructively and spectroscopically measure it at room temperature would be of great benefit. Although empirical correlations have been established between fictive temperature and selected absorption peaks in the infrared spectra of silica glass, the fundamental understanding for this correlation has not been reported. Here, we use molecular dynamics simulations to show that the blue shift in the Si–O–Si asymmetric stretching peak of pure silica glass, which is known to correlate with a decrease in fictive temperature, can be attributed to a decrease in the average length of the Si–O bond in the silica network, not changes in the density or the Si–O–Si bond angle. The decrease in density at higher fictive temperatures of silica is associated with a decreased population of 5‐ and 6‐membered rings and broadening of the ring‐size distribution, and an increase in the average Si–O–Si bond angle.     

Determination of Fictive Temperature of Soda-Lime Silicate Glass

Peak positions of silica structural bands, both in infrared absorption and reflection modes, were used earlier to measure the fictive temperature of silica glass. In the present study, the method was applied to determine the fictive temperatures of a soda-lime silicate glass. For the silicate glass, the IR absorption spectra produced a broad structural band which made the precise determination of peak position difficult, and only the IR reflection band was used. Equilibrium peak positions of ∼1056 cm⁻¹ IR band, due to Si-O stretching, were found to be directly correlated with the fictive temperature of the soda-lime silicate glass. The soda-lime glass exhibited an opposite dependence of the IR band position on the glass fictive temperature as compared to silica glass.     

Pressure dependence of density and structural relaxation of glass near the glass transition region

A simplified and effective pressure cell together with an experimental procedure has been developed and applied to compress samples of SCHOTT N‐BK7^® glass under static high pressures in a piston‐cylinder apparatus. Results from the density and volume recovery measurements show that, the glass samples were effectively densified in piston‐cylinder apparatus with the density at room temperature increasing linearly with frozen‐in pressure. To explain the experimental data, we developed a mathematical model based on a suggestion by Gupta (1988) with two internal parameters, named fictive temperature (T_f) and fictive pressure (P_f), which fits the experimental data well.     

Effect of glass composition on the hardness of surface layers on aluminosilicate glasses formed through reaction with strong acid

The effect of glass composition on physico‐chemical properties of surface layers formed through reaction between strong acid and several silicate and aluminosilicate glasses was studied through transmission‐IR, ATR‐IR, XPS, SIMS, and nano‐indentation analyses. It was shown that aluminum is depleted from the surface while molecular water is diffused into the surface layer of glasses with high levels of aluminum. Nano‐indentation experiments indicated that the hardness of the surface layers were decreased compared to that of the bulk region and the degree of the softening was more significant in the high aluminum glass.     

Thermomechanical Modeling of Laser‐Induced Structural Relaxation and Deformation of Glass: Volume Changes in Fused Silica at High Temperatures

A fully coupled thermomechanical model of the nanoscale deformation in amorphous SiO₂ due to laser heating is presented. Direct measurement of the transient, nonuniform temperature profiles was used to first validate a nonlinear thermal transport model. Densification due to structural relaxation above the glass transition point was modeled using the Tool‐Narayanaswamy (TN) formulation for the evolution of structural relaxation times and fictive temperature. TN relaxation parameters were derived from spatially resolved confocal Raman scattering measurements of Si–O–Si stretching mode frequencies. Together, these thermal and microstructural data were used to simulate fictive temperatures which are shown to scale nearly linearly with density, consistent with previous measurements from Shelby et al. Volumetric relaxation coupled with thermal expansion occurring in the liquid‐like and solid‐like glassy states lead to residual stresses and permanent deformation which could be quantified. However, experimental surface deformation profiles between 1700 and 2000 K could only be reconciled with our simulation by assuming a roughly 2 × larger liquid thermal expansion for a‐SiO₂ with a temperature of maximum density ~150 K higher than previously estimated by Bruckner et al. Calculated stress fields agreed well with recent laser‐induced critical fracture measurements, demonstrating accurate material response prediction under processing conditions of practical interest.     

Method to Estimate Thermal Shrinkage Behavior of Glasses

We present a method to estimate the effect of heat treatment on the shrinkage behavior of glasses. As a pre-requisite, sensitivity of the glass density as a function of glass fictive temperature is measured using the sink–float method and the slope of the relationship is used to determine the linear thermal strain proportionality factor. Evolution of the fictive temperature for different temperature–time history is measured using the infrared spectroscopy method and the results are used to estimate the structural relaxation parameters in the temperature range of interest. The overall shrinkage behavior is predicted using the linear thermal strain factor and estimated change in fictive temperature due to the thermal treatment. The predicted shrinkage behavior is observed to be in good agreement with the independent dimensional change measurements performed on large glass sheets that have undergone similar thermal treatments.     

Radiation hardening of silica glass through fictive temperature reduction

The aim of this article was to report the effects of γ-radiation on type-I Infrasil silica glass with different fictive temperatures, T_f, for harsh environment applications. Radiation-induced attenuation in the visible range is found to be much lower in low fictive temperature samples. Photoluminescence experiments show that glasses with higher fictive temperatures have a higher nonbridging oxygen hole centers defect concentration generated by irradiation. In addition, electron paramagnetic resonance studies reveal higher E’ point defects, AlOHC, and hydrogen(II) defects in high T_f samples. In general, we find that the γ-radiation “hardness” of Infrasil301 silica glass becomes significantly higher with decreasing fictive temperature.     

Deterioration in mechanical properties of glass fiber‐reinforced nylon 6,6 composites by aqueous calcium chloride mixture solutions

In this article, nylon 6,6 (NY66) and glass fiber‐(30 wt%) reinforced NY66 (GFNY66) specimens were immersed in various aqueous calcium chloride (aq. CaCl₂) mixture solutions at different thermal conditions for varying intervals of time, and analyzed using attenuated total reflection‐infrared (ATR‐IR) spectroscopy, inductively coupled plasma (ICP), energy dispersive X‐ray (EDX), gel permeation chromatography (GPC), and mechanical studies. ICP data revealed increasing concentration of absorbed Ca²⁺ ions with increasing immersion time resulting in disruption of intra‐ and intermolecular H‐bonding as confirmed using ATR‐IR results. From EDX data, the ratio of Ca²⁺ and Cl⁻ ions absorbed by NY66 was calculated and found to follow its stoichiometric equivalence. GPC data exhibited less reduction in M_n and M_w for aq. CaCl₂‐treated NY66 specimens suggesting the absence of any significant chemical degradation, but the occurrence of only physical changes involving H‐bond breakage and the formation of new CO···Ca²⁺ dative bond in NY66 matrix. The mechanical properties of GFNY66 samples treated with various types of aq. CaCl₂ solutions exhibited pronounced deterioration, possibly due to the interfacial failure between glass fiber and NY66 matrix. The results obtained from this study were quite useful toward understanding the degradation mechanism in NY66 and GFNY66 caused by various aq. CaCl₂ mixture solutions, and will be helpful in improving the mechanical properties of recycled NY66. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Preparation of polystyrene/montmorillonite nanocomposites in supercritical carbon dioxide

The preparation of polystyrene (PS)/montmorillonite (MMT) composites in supercritical carbon dioxide (SC? CO₂) was studied. Lipophilic organically modified MMT can be produced through an ion‐exchange reaction between native hydrophilic MMT and an intercalating agent (alkyl ammonium). PS/clay composites were prepared by free‐radical precipitation polymerization of styrene containing dispersed clay. X‐ray diffraction and transmission electron microscopy indicated that intercalation of MMT was achieved. PS/clay composites have a higher thermal decomposition temperature and lower glass‐transition temperature than pure PS. The IR spectrum analysis showed that the solvent of SC? CO₂ did not change the structures of the PS molecules, but there were some chemical interactions between the PS and the clay in the composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 22–28, 2005     

Inward Migration of Glass‐Modifier Cations During Heat Treatment Under an N2 Atmosphere

An Na⁺/Ca²⁺‐deficient layer is observed to form on the glass surface region up to a depth of hundreds of nanometers when a soda‐lime‐silicate glass is heat treated under an N₂ atmosphere near its glass‐transition temperature. The measurements were performed using X‐ray photoelectron spectroscopy with C₆₀‐ion sputtering (C₆₀‐XPS) and dynamic secondary‐ion mass spectrometry (D‐SIMS) with consideration of the mass and charge balances. The increase in the amount of hydrogen is substantially less than the decrease in the total charge due to the loss of modifier cations in the Na⁺/Ca²⁺‐deficient layer; furthermore, the oxygen concentration in this layer is lower than the bulk value, suggesting that the silanol groups in the surface layer of the glass are dehydrated. A high‐concentration layer of Ca²⁺ is also confirmed in the dehydration layer of the glass heat treated under an N₂ atmosphere, suggesting that Na⁺ and Ca²⁺ ions migrate inward into the glass via an ion‐exchange reaction with protons, which migrate toward the surface from the bulk. We also confirmed that a thicker Na⁺/Ca²⁺‐deficient layer is formed on glass surfaces with higher water content. Our results suggest that the dehydration of the silanol groups is the driving force of the inward migration of Na⁺ and Ca²⁺ ions.     

Microstructure evolution of ammonia‐catalyzed phenolic resin during thermooxidative aging

The thermooxidative aging of ammonia‐catalyzed phenolic resin for 30 days at 60–170°C was investigated in this article. The aging mechanism and thermal properties of the phenolic resin during thermooxidative aging were described by thermogravimetry (TG)–Fourier transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR)–FTIR spectroscopy, and dynamic mechanical thermal analysis. The results show that the C? N bond decomposed into ammonia and the dehydration condensation between the residual hydroxyl groups occurred during the thermooxidative aging. Because of the presence of oxygen, the methylene bridges were oxidized into carbonyl groups. After aging for 30 days, the mass loss ratio reached 4.50%. The results of weight change at high temperatures coincided with the results of TG–FTIR spectroscopy and ATR–FTIR spectroscopy. The glass‐transition temperature (T_g) increased from 240 to 312°C after thermooxidative aging for 30 days, which revealed the postcuring of phenolic resins. In addition, an empirical equation between the weight change ratio and T_g was obtained. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Molecular interactions in poly(methacrylic acid)/poly(N‐isopropyl acrylamide) interpenetrating polymer networks

The molecular interactions between the component networks in poly(methacrylic acid)/poly(N‐isopropyl acrylamide) (PMAA/PNIPAAm) interpenetrating polymer networks (IPNs) were investigated using attenuated total reflectance (ATR)‐Fourier transform IR (FTIR) spectroscopy. Hydrogen‐bond formation was noted between the carboxyl groups of PMAA and the amide groups of PNIPAAm. The ATR‐FTIR results showed shifts in the carboxylic and amide groups, indicating the existence of hydrogen bonding between these two individual networks within the IPNs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1077–1082, 2001     

States of water absorbed in water-borne urethane/epoxy coatings

The water absorption properties of water-borne urethane/epoxy coatings are studied using differential scanning calorimetry (DSC) and attenuated total reflectance Fourier transform IR spectroscopy (ATR FTIR) to estimate the methods of interaction between the water and coating. DSC and ATR FTIR are used to categorize water into states based unique and easily identifiable differences in DSC and ATR FTIR measurements. DSC states (Strong, Weak 1, Weak 2, and Free) and ATR FITR states (S₀, S₁, and S₂) appear to correspond to the relative strength of the interaction and the degree of hydrogen bonding between the water and the polymer network, respectively. The dynamics and relative population of each state are estimated with the most populous states being Strong and S₁ in urethane, and Strong and S₂ in epoxy. Finally six active functional groups within the coating appear to form strong hydrogen bonds with water, and one functional group appears to form weak dipole bonds.     

Thermal and mechanical behavior of flexible polyurethane‐molded plastic films and water‐blown foams with epoxidized soybean oil

Water‐blown flexible polyurethane foams and molded plastic films were made by replacing 0 to 50% of Voranol® 4701 in the B‐side of foam and plastic film formulation by epoxidized soybean oil (ESBO). Physical properties of foams including density, 50% compression force deflection (CFD), 50% constant deflection compression (CDC), and resilience were determined. A dynamic mechanical spectrometer (DMS) and a differential scanning calorimeter (DSC) were used to characterize the hard segment (HS) and soft segment (SS) ratio and thermal properties of plastic. Various functional groups in both flexible polyurethane foam and plastic film were characterized using Fourier transform‐infrared spectroscopy with attenuated total reflectance (FTIR‐ATR). When increasing the ESBO content, both density and 50% CFD of water‐blown polyurethane foams decreased first, then increased. On the other hand, the 50% CDC and resilience of foams showed a sharp increase and decrease, respectively. When increasing the ESBO content, the peak of tan δ in DMS analysis and Δc_p in DSC analysis of plastic films both decreased indicating the hard segment increased and the soft segment decreased in plastic film, respectively. The FTIR‐ATR results also show the hydrogen‐bonded urethane group increased in plastic films with increasing ESBO content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ion‐leaching behaviors and corrosion morphology of glass fiber reinforced vinyl ester composites in sulfuric acid solution

The corrosion mechanism of glass‐fiber reinforced vinyl ester composites was investigated by immersing composite samples in 40 wt% sulfuric acid solution at constant temperature of 35°C, 55°C, 65°C, and 75°C for periods up to 10,500 h. Results were characterized through weight gain tests, inductively coupled plasma analysis, and scanning electron microscope (SEM). Weight gains and ion‐leaching behaviors show that the composite interface has undergone significant changes due to a long corrosive environment, and the interface corrosion of composite increases with increasing the temperature. SEM images of surface and cross‐section of samples indicated that there exit in irreversible degradation reaction on resin matrix and interface in composite, which lead to the increase of weight gain and ion leachability, especially at high temperatures. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Microwave plasma reactions of imidazole on poly(vinyl chloride) surfaces: A spectroscopic study

Although there are various forms of energy available for conducting surface and interfacial reactions, microwave plasma energy is an attractive means for surface modifications because it is fast and it usually does not alter bulk properties. In this study, a closed‐system microwave plasma reactor was used to react imidazole molecules to poly(vinyl chloride) (PVC) surfaces. Newly created surfaces were analyzed using attenuated total reflectance (ATR) Fourier‐transformed infrared (FTIR) spectroscopy. These studies show that surface reactions on PVC are heavily dependent upon a prior thermal history of the PVC substrate. It appears that the plasma reactions on hot‐pressed PVC not only result in the development of CH₂ linkages, but a significant increase of crystallinity in the hot‐pressed PVC inhibits the reactivity of imidazole to the PVC surface. On the other hand, for a solvent‐cast PVC with a significantly lower surface crystalline phase content, imidazole reacts to the PVC surface through CC bond opening. The amount of imidazole reacted to the PVC surface changes with the depth from the surface. Using quantitative ATR FTIR spectroscopy, imidazole content can be quantified, and its concentrations are in the 10⁻⁶ mol/cm² range at about 0.8–1.2 μm for the PVC surface. A mechanism of the PVC–imidazole reactions is also proposed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1–6, 1999     

Pretreatment of polypropylene films for the creation of thin polymer layers,part 1: The use of chemical,electrochemical, and UV methods

The surface of a polypropylene (PP) film was activated with chemical, electrochemical, and physical methods, and the effectiveness of these methods was compared. The effects of PP activation were assessed with attenuated total reflection IR spectroscopy (ATR‐IR), SEM microscopy, and an analysis, based on the liquid contact angle, of the free energy components of the surface. The activation of the PP surface, which was dependent on the oxidizing medium, increased the energy of the PP surface layer and formed new chemical (carbonyl) groups, which were identified by IR (ATR) absorption spectroscopy and confirmed by selective surface dyeing. The treatments were ranked in the following order of increasing effectiveness: UV irradiation < 3M nitric acid < 30% hydrogen peroxide < silver nitrate (electrochemical method) < chromic mixture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011