Search Results

You are looking at 1 - 10 of 67 items for :

  • "Thermomechanical analysis" x
  • Refine by Access: All Content x
Clear All
Journal of Thermal Analysis and Calorimetry
Authors: A. M. Manich, J. Carilla, S. Vilchez, M. D. de Castellar, P. Oller, and P. Erra

Summary  

There is a difference in structure across the wool fibre which is usually referred to as bilateral. The endothermic denaturation doublet of keratins has been observed by different authors for a variety of keratins and measuring conditions and mainly interpreted by different theories. Merino wool yarns have been analyzed by the thermomechanical analysis and at low stress two thermal transitions before melting have been identified. These two thermal transitions are in accordance with the onset temperatures of the denaturation doublet shown by the DSC both at temperatures lower than the thermal degradation temperature determined by TG. The DSC of fibrillated fibres by abrasion showed not a denaturation doublet but just only a denaturation peak. The two transitions of the TMA and the modification of the DSC curve by abrasion seems to confirm that abrasion removes the component which denaturates at lower temperature.

Restricted access

monitoring the sample dimension by means of Thermomechanical Analysis (TMA). The aim of this article is to describe the application of such a method of measurement in the study of crystallization kinetics of Ge 38 S 62 glass that has been previously studied

Restricted access

Abstract  

Two different poly(urethane acrylate) resins (one with a trimer: PUA1, the second with a dimer: PUA2) prepared [1] by photo curing reaction are investigated by means of thermogravimetry and thermomechanical measurements. The lack of mass loss found up to 300C for both systems shows their good thermal stability. Beyond this temperature, two mass losses occur consecutively. This mass loss already studied by TG-FTIR coupled measurements for PUA1 resin has been attributed to the degradation of carbonyl groups [1]. The extension to PUA2 and the comparison between the mass loss magnitude and the relative contain in acrylate of the resins leads to attribute the first degradation to the degradation of the acrylate fraction. The degradation of dimer based resin occurs earlier and with a faster kinetic than the trimer based resin. The variations of linear expansion and penetration coefficients measured by thermomechanical analysis (penetration probe) in the glassy state and in the glass transition temperature domain (the onset glass transition temperatures measured by DSC at 20C min–1 are respectively equal to 111 and 107C for PUA1 and PUA2, the transitions, not well defined, extending over 30C), show that despite of a weaker compactness, the trimer based resin is more rigid than the dimer one.

Restricted access

Abstract  

By employing a ‘modulated-temperature’ heating programme composed of a series of heat-isotherm stages, it is possible to separate the change in dimensions of an oriented material during heating into two contributions: a thermally ‘reversing’ component which is due to linear thermal expansion and a ‘non-reversing’ part arising from relaxation to the disordered state on heating aboveT g. Some preliminary results for biaxially drawn poly(ethylene terephthalate) film are presented.

Restricted access

The purpose of the work was to characterize the thermomechanical behaviour of two well-known and widely-used thermoplastic polymers. Both dynamic and constant load measurements were made for high-density polyethylene (HDPE), low-density polyethylene (LDPE) and amorphous polystyrene (PS). The results of these measurements yield valuable information which can aid in both design applications and material processing.

Restricted access

thermomechanical samples Ann tannins alone and in mixture with different hardeners were tested dynamically by a thermomechanical analysis (TMA) using plies of total dimensions of 21 × 6 × 0.6 mm, and relative humidity of 8–12% were bonded with the resin

Restricted access