Authors:Sarfaraz Alam, L. D. Kandpal, and I. K. Varma
The paper describes the co-curing studies of ethynyl and ethenyl end-capped imide resins. The effect of composition and chemical structure of ethenyl end-capped resins (nadicimides) on thermal behavior of ethynyl end-capped resins was evaluated using DSC and thermogravimetric analysis. An increase in char yield was observed on co-curing of few resin formulations. A mechanism has been proposed to account for this observation.
Authors:M. Saraf, Sarfaraz Alam, R. Gupta, K. Surekha, and G. Mathur
Polyimides have aromatic moieties in the backbone structure which are responsible for their increased thermal stability. If
phosphorus is introduced in the main chain structure of polyimides, there is further improvement in the thermal stability.
This has been proved by the work carried out in our group. The polyimide having amine termination can be used for crosslinking
of epoxy resins.
In the present study amine terminated phosphorus containing nadicimide were taken as curing agent for DGEBA resins. The curing
characteristics of DGEBA resin were studied by DSC using different amounts of nadic endcapped phosphorylated amines. DSC thermogram
showed the heat of polymerization was lower as compared to system cured with aromatic amines.
Authors:C. A. Gracia-Fernández, P. Davies, S. Gómez-Barreiro, Beceiro J. López, J. Tarrío-Saavedra, and R. Artiaga
The development of photopolymers was helped by the development of photocalorimetry, which is now a basic technique for the study of these materials. This work shows how to obtain vitrification times in single isothermal curing experiments by monitoring the reversing heat capacity along time in modulated temperature DSC–photocuring systems, overcoming the time-consuming problem of standard DSC. The effects of the light intensity and the isothermal curing temperature on the vitrification time of a photocurable system were evaluated. The results obtained at a given curing temperature with different light intensities indicate that the UV-light affects the molecular mobility hindering the vitrification process. The effects of the curing temperature on the vitrification time, the conversion at the vitrification time and the maximum conversion were also evaluated.
Authors:B. Gaur, B. Lochab, V. Choudhary, and I. Varma
The paper describes the synthesis of low molecular mass poly(allyl chloride) (PAC) (Mn= 856-3834 g mol-1) using Lewis acid (ALCL3, FeCL3, TiCL4) and al powder. Branching in PAC was indicated on the basis of elemental analysis and 1H-NMR spectroscopy. azidation of pac could be carried out at 100°C by using NaN3 and DMSO as solvent. Curing of poly(allyl azide) (PAA) by cyclic dipolar addition reaction with EGDMA (ethylene glycol dimethacrylate,
5-45 phr) was investigated by differential scanning calorimetry and structure of cured polymer was confirmed by FTIR. A two-step
mass loss was exhibited by uncured and cured PAA in nitrogen atmosphere. A mass loss of 20-28% (155-274°C) and 50-61% (330-550°C)
Authors:Vikram Singh, Lalit Kumar, Vinay Kumar, A. K. Narula, and Gagan Deep
TA 2100 thermal analyzer having 910 DSC module was used for recording DSC traces at heating rates of 5, 10, 15 and 20 °C min −1 in nitrogen atmosphere. 5 ± 2 mg of samples in sealed pan were used in each experiment. For curingstudies
Authors:Subrata Pradhan, Priyanka Brahmbhatt, Janardhanan Devaki Sudha, and Jisha Unnikrishnan
by performing the curingstudies in the presence and absence of the catalyst. Typical DSC curves of 60:40 blend systems studied under nonisothermal condition with heating rate of 0.5 °C min −1 in the absence and presence of catalyst is given in Fig