Use of Microscopic FT-IR/DSC Combined System for the Study of Glass Transition Temperatures of Polymers

Abstract

KEY WORDSGlass Transition / Differential Scanning Calorimetry / Microscopic FT-IR/ DSC System/ Polymers/ Polymers exhibit significantly different physical and mechanical properties near glass transition (Tg) temperature. 1 • 2 Since glass transition is related to change in the molecular motion of polymers, the infrared (IR) spectrum in the transition regions probably provides certain information on vibrational motion in relation to polymer transition. Hannon et al. suggest that IR spectroscopy is a sensitive and unique means for determining transition behavior in polymers, but sample preparation and the sample cell designed for Tg determination seem to be complicate~. 3 Lin et al. recently used newly-developed microscopic Fourier transform infrared (FT-JR) spectroscopy equipped with differential scanning calorimetry (DSC) to study simultaneously the thermal behavior and structural changes of samples such as drug polymorphs, porcine stratum corneum, silicone elastomer, and encapsulated squil oil. 4 -8 This newly-designed system is a simple, quick, and powerful apparatus, in which the sample is only sealed within a KBr disc and set on a DSC microscopy cell. Since chain motion is the major mechanism in the transition state, Tg of a sample may be easily predicted by this microscopic FT-IR/DSC system. The purpose of this

Characterization of Pulsed-Plasma-Polymerized Aromatic Films

“…F. Differential Scanning Calorimetry. Differential scanning calorimetry (DSC), a sensitive means of determining material thermochemical properties, , was performed on films deposited from pulsed benzene, TFB, and HFB plasmas and on a polystyrene standard (MW 975 000) between 40 and 500 °C. The polystyrene standard shows an endothermic structural change at 112 °C indicative of the glass transition temperature ( T g ) for this polymer.…”

Deposition of Highly Ordered CF2-Rich Films Using Continuous Wave and Pulsed Hexafluoropropylene Oxide Plasmas

“…As the duty cycle increases, however, the CF 2 content decreases and the orientation of film chains becomes less distinct in materials deposited at position C (Table and Figure ). Pulsed plasma dynamics studies show that during the on-time period radicals and charged species are created, followed by the rapid decay of short-lived ionic fragments during the off time of the pulse sequence. , The effect of energetic species on film composition and structure is significantly reduced at all reactor positions because the plasma is pulsed. With a constant on time, lower pulse duty cycles (longer off times) provide a longer time for deposition to occur unhindered by charged species effects.…”

Thermal stability of methacrylic acid copolymers of Eudragits L, S, and L30D and the acrylic acid polymer of carbopol

“…On the other hand, two endothermic peaks, at 155 and 228°C, appeared on the DSC thermogram of the film of Eudragit L. The first might be due to the glass transition temperature (T g ) of Eudragit L film, which was consistent with the T g value of 157°C in our previous study. 16 The second was also attributed to the anhydride formation, which was higher than that of the endothermic peak at 213°C of the pulverized powder of Eudragit L. Since the kinetics by intra-or/and interpolymer condensation are different in film and powder, the film or powder type polymer might have a different degree of condensation from intra-or/and intermolecular reaction, which might be the reason for the different endothermic peak at 228 or 213°C. The endothermic peak at 228°C might be mainly attributable to the loss of water by condensation.…”