Spectroscopic characterization of molecular interdiffusion at a poly(vinyl pyrrolidone)/vinyl ester interface

Abstract

Mechanical properties of (woven carbon fiber / vinyl ester matrix) composites can be greatly improved if the interphase between the reinforcing high-strength low-weight fiber and the thermoset resin is made more compliant. In order to improve the adhesion of the vinyl ester matrix to the carbon fiber, a thermoplastic coating such as poly(vinyl pyrrolidone) (PVP) can be used as an intermediate between the matrix and the fiber. The extent of mutual diffusion at the (sizing material / polymer matrix) interphase plays a critical role in determining the mechanical properties of the composite.In this research, the molecular interdiffusion across a poly(vinyl pyrrolidone))/vinyl ester monomer (PVP/VE) interface is being investigated by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy. The ATR method which can be used to characterize the transport phenomena, offers several advantages, such as the ability to monitor the diffusion in situ or to observe chemical reactions. In order to separate the effects of the vinyl ester monomer diffusion and the crosslinking reaction, ATR experiments were carried out at temperatures below the normal curing temperature. Diffusion coefficients were determined by following variations in infrared bands as a function of time, and fitting this data to a Fickian model. The values of the diffusion coefficients calculated were consistent with values found in the literature for diffusion of small molecules in polymers. The dependence of diffusion coefficients on temperature followed the Arrhenius equation. Hydrogen bonding interactions were also characterized. The diffusion model used in this study, however, does not seem to be appropriate for the particular (PVP/VE) system.Because the glass transition temperature of the PVP changed as diffusion proceeded, one would expect that the mutual diffusion coefficient did not stay constant. In fact, it was shown that the T g can drop by 140 o C during the diffusion process. A more suitable model of the (PVP/VE) system should take into account plasticization, hydrogen bonding, and especially a concentration dependent diffusion coefficient. Further analysis is therefore needed.iv ACKNOWLEDGMENTS

Assessment of in situ-Prepared Polyvinylpyrrolidone-Silver Nanocomposite for Antimicrobial Applications

“…A medium peak and a weak shoulder appeared at 2955 cm −1 and 2893 cm −1 , respectively, which are corresponding to symmetric and asymmetric stretching vibrations of CH 2 , respectively [40,41]. A strong sharp peak ascribed to C=O stretching vibration appeared at 1663 cm −1 [42,43], followed by four medium peaks at 1495, 1462, 1439, and 1423 cm −1 which could be assigned to scissoring vibration of CH 2 group. CH 2 wagging vibrations and C-N stretching appeared at 1318 cm −1 and 1290 cm −1 , respectively [44,45].…”

Correlation between Structures and Antioxidant Activities of Polyvinylpyrrolidone/Garcinia mangostana L. Extract Composite Nanofiber Mats Prepared Using Electrospinning

“…The characteristic peaks of PVP appeared at 1649 cm −1 , which belongs to C=O stretching of pyrrolidone rings, along with 1288 and 577 cm −1 , which represent their C-N stretching and in-plane N-C=O bending, respectively [20,30]. Asymmetric stretching of CH 2 and C-H deformations was indicated by the peaks at 2953 and 1423 cm −1 , respectively [20,31]. The PM10, PM7, and PM5 composite nanofiber mats had the O-H stretching peaks at 3393, 3391, and 3377 cm −1 , respectively, which are higher than that of the GME at 3273 cm −1 .…”

Dielectric investigation of interphase formation in composite materials. I. Ionic conductivity and permittivity exploration

“…This phenomenology was introduced a few years ago, 19,20 but recent studies aim at characterizing in detail such a phase. 21,22 As mentioned by Drzal, 23 composite properties depend strongly on interfacial properties and interphase nature.…”

“…This value is around the values reported in the literature. 24,25 To try to understand the effects of vacuum on the value of IFSS (Fig. 1), ionic conductivity measurements were performed for the low-pressure process.…”