Structure thermomechanical analysis

Network properties and microscopic structures of various epoxy resins cross-linked by phenolic novolacs were investigated by Suzuki et al.97 Positron annihilation spectroscopy (PAS) was utilized to characterize intermolecular spacing of networks and the results were compared to bulk polymer properties. The lifetimes (t3) and intensities (/3) of the active species (positronium ions) correspond to volume and number of holes which constitute the free volume in the network. Networks cured with flexible epoxies had more holes throughout the temperature range, and the space increased with temperature increases. Glass transition temperatures and thermal expansion coefficients (a) were calculated from plots of t3 versus temperature. The Tgs and thermal expansion coefficients obtained from PAS were lower titan those obtained from thermomechanical analysis. These differences were attributed to micro-Brownian motions determined by PAS versus macroscopic polymer properties determined by thermomechanical analysis. 

First-order phase transitions can be detected by various thermoanalytical techniques, such as DSC, thermogravimetric analysis (TGA), and thermomechanical analysis (TMA) [31]. Phase transitions leading to visual changes can be detected by optical methods such as microscopy [3], Solid-solid transitions involving a change in the crystal structure can be detected by X-ray diffraction [32] or infrared spectroscopy [33], A combination of these techniques is usually employed to study the phase transitions in organic solids such as drugs. 

X-ray diffraction and thermomechanical analysis are used, respectively, to examine structural order and shrinkage behaviour for oriented samples of rigid and flexible PVC. Results are compared with previously measured tensile... 

In some attempted syntheses of block copolymers, random copolymers may result during the secondary processes of chain reshuffling. Thus, NMR methods, particularly 13C-NMR spectroscopy, should be used to determine the presence of the heterodyads. In addition, DSC, light scattering, electron microscopy, small angle X-ray scattering, and thermomechanical analysis can also be used to distinguish between block and random structures. 

Static and dynamic thermomechanical analysis of the commercial polymer separators (PP and PE) were made to understand their properties (Love, 2011). Anisotropic separators manufactured from a dry process showed limited tensile performance in the transverse direction. The separators prepared from a wet process displayed a uniform and biaxial structure and nearly showed identical mechanical strength on both directions. It was also found that small losses in mechanical integrity were observed after the separators were exposed to various electrolytes. 

Information on physical parameters of the molecular structure of polyamide fibers are usually obtained by x-ray diffraction methods, electron and light microscopies, infrared spectroscopy, thermal analyses such as differential thermal analysis, differential scanning calorimetry, and thermomechanical analysis, electron spin resonance, and nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction provides detailed information on the molecular and fine structures of polyamide fibers. Although the diffraction patterns of polyamide fibers show wide variation, they exhibit usually three distinct regions ... 

The joint use of several thermal techniques enables us to solve more complex problems, e.g. to correlate through the study of TG, DTA and thermomechanical analysis (TMA) dehydration traces of zeolite Linde A and some of its cation-exchanged forms, the single recorded thermal eflFect with the removal of water molecules from a specific structural site [11, 12], or to find, through TG, DTA and thermodilatometry (TD) measurements, the structural relationships between cymrite (BaAl2Si208.H20) and hexagonal barium feldspar [13]. 

Guzatto R., Da Roza M. B., Denardin E. L. G., Samios D. (2009). Dynamical, morphological and mechanical properties of poly (ethylene terephthalate) deformed by plane strain compression. Polymer Testing, Vol. 28, pp. 24-29, ISSN 0142-9418 Karagiannidis P. G., Stergiou A. C., Karayannidis G. P. (2008). Study of crystallinity and thermomechanical analysis of annealed poly (ethylene terephthalate) films. European Polymer Journal, Vol. 44, pp. 1475-1486, ISSN 0014-3057 Keum J. K, Song H. H. (2005). Thermal deformations of oriented noncrystalline poly(ethylene terephthalate) fibers in the presence of mesophases structure. Polymer, 46, pp. 939-945, ISSN 0032-3861... 

DSC analysis was used for glass temperature and melting point of PAO determination and presented values were in a good agreement with those obtained by thermomechanical and dielectrical methods. It is essential to note, that the regions of structural transitions predicted by increment modeling coincide within the limits of 5 % with DSC and thermomechanical analysis data. 

Thermomechanical analysis (TMA) was used to investigate the curing behavior of resorcinol-formaldehyde (RF) and phenol-resorcinol-formaldheyde (PRF) adhesive resins used for structural glued laminated timber and veneer lumber, Samples were heated from room temperature... 

PAS-8 were greater than those on SILASTIC 500-1, PAS-41, and 71. Although the surfaces of PASs and SILASTIC 500-1 were hydrophobic, the contact angle for PAS-8 was slightly lower than those for SILASTIC 500-1, PAS-41, and 71 (see Table 9). It was thought that the PAS-8 surface might have an influence on the aramid block. The phenomenon of the cell adhesion onto PAS-41 and 71 could not be explained by hydrophobicity alone. In former sections, the results of the gas-permeability measurement and the dynamic thermomechanical analysis of PAS implied the presence of a microphase-separated structure between PDMS and aramid phases in the PASs containing over 26 wt% of PDMS [14]. Moreover, a TEM study indicated that PAS films possessed microdomain structures in their bulk phases. That is, not only the hydrophobicity of the surfaces, but also the presence of a microphase-separated structure in the PASs may influence cell adhesion. 

A new method based on thermomechanical analysis of solid (not dissolved) polymer was used to study the topology and molecular structure of different kinds of sulphur (mineral and two polymeric types), commonly used as vulcanising agents for diene rubbers. It was found that a significant difference existed in their MWDs and in their degrees of crystallinity. Both mineral and polymeric sulphurs had a polymeric nature. 9 refs. EASTERN EUROPE POLAND RUSSIA Accession no. 645667... 

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