Thermal Degradation Studies of Terpolymer Derived from 2-Aminothiophenol, Hexamethylenediamine, and Formaldehyde

Terpolymer (2-ATPHMDAF-I) has been synthesized by the condensation of 2-aminothiophenol and hexamethylenediamine with formaldehyde in the presence of 2 M hydrochloric acid as a catalyst with 1 : 1 : 2 molar proportion of reacting monomers. The structure of newly synthesized terpolymer has been elucidated and confirmed on the basis of elemental analysis and various spectral techniques, that is, UV-visible, FT-IR, and 1H-NMR spectroscopy. Number average molecular weight (Mn¯) has been determined by conductometric titration in nonaqueous medium. The viscosity measurements in dimethyl sulfoxide (DMSO) have been carried out to ascertain the characteristic functions and constants. The studies have been further extended to nonisothermal thermogravimetric analysis for determination of their mode of decomposition and relative thermal stability. Activation energy Ea, order of reaction (n), and frequency factor (z) were calculated by Friedman, Chang, Sharp-Wentworth and Freeman-Carroll methods. Activation energy calculated by Friedman and Chang methods are in close agreement with each other while the results obtained from Freeman-Carroll and Sharp-Wentworth’s methods are found to be in a similar order.

High Throughput Screening of the Thermal Stability of Colorants in a Polycarbonate Matrix

ABSTRACTThe relative thermal stability of 44 colorants of interest to GE Plastics as polymer colorants was determined. The effects of common (non-colorant) additives on the thermal stability in a polymer matrix were also determined. The measurements were carried out by reflectance spectrometry on thin films of polymers that had been subjected to heating cycles. The change in the visible spectrum was used as an indicator of thermal stability. This paper discusses the method and overall results for the experiments.

Implant Isolation of Device Structures Containing Buried, Highly-Doped Layers

ABSTRACTThe formation of high resistivity (> 107 Ω□) regions in GaAs-AlGaAs HBT and SEED structures by oxygen and hydrogen ion implantation is described. Multiple energy implants in the dose range 1013 cm−3 (for O+) and 1015 cm−2 (for H+), followed by annealing around 500°C are necessary to isolate structures ∼2 μm thick. In each case, the evolution of the sheet resistance of the implanted material with annealing is consistent with a reduction in hopping probabilities of trapped carriers between deep level states for temperatures up to ∼600°C, followed by significant annealing of these deep levels. A comparison of the relative thermal stability of O+ or H+ ion implantisolated p+ material is given. Small geometry (2 × 9 μm2) HBTs exhibiting current gain of 44 and cut-off frequency fT as high as 45 GHz are demonstrated using implant isolation.