Dynamic mechanical thermal analysis polymers

Chateauminois, A., Vincent, L, Chabert, B., Soulier, J.P. (1994). Study of the interfacial degradation of a glass-epoxy composite during hygrothermal ageing using water diffusion measurements and dynamic mechanical thermal analysis. Polymer, 35, 4766 774. doi 10.1016/0032-3861(94)90730-7 Colin, X., Verdu, J. (2003). Plastics rubber and composites, Macromolecular Engineering, 32(8/9), 349-356. 

Viscoelastic phenomena always involve the change of properties with time and, therefore, the measurements of viscoelastic properties of solid polymers may be called dynamic mechanical. Dynamic mechanical thermal analysis (DMTA) is a very useful tool for studying... 

This second group of tests is designed to measure the mechanical response of a substance to applied vibrational loads or strains. Both temperature and frequency can be varied, and thus contribute to the information that these tests can provide. There are a number of such tests, of which the major ones are probably the torsion pendulum and dynamic mechanical thermal analysis (DMTA). The underlying principles of these dynamic tests have been covered earlier. Such tests are used as relatively rapid methods of characterisation and evaluation of viscoelastic polymers, including the measurement of T, the study of the curing characteristics of thermosets, and the study of polymer blends and their compatibility. They can be used in essentially non-destructive modes and, unlike the majority of measurements made in non-dynamic tests, they yield data on continuous properties of polymeric materials, rather than discontinuous ones, as are any of the types of strength which are measured routinely. 

Differential Scanning Calorimeter (DSC) thermograms were obtained on a Perkin Elmer DSC-2 run at 10°C per minutes. Dynamic Mechanical Thermal Analysis (DMTA) spectra were obtained on a Polymer Labs DMTA at a frequency of 1Hz with a temperature range from -150°C to +150°C at a scan rate of 5°C per minute. 

The physical properties of the acid- and ion-containing polymers are quite interesting. The storage moduli vs. temperature behavior (Figure 8) was determined by dynamic mechanical thermal analysis (DMTA) for the PS-PIBMA diblock precursor, the polystyrene diblock ionomer and the poly(styrene)-b-poly(isobutyl methacrylate-co-methacrylic acid) diblock. The last two samples were obtained by the KC>2 hydrolysis approach. It is important to note that these three curves are offset for clarity, i.e. the modulus of the precursor is not necessarily higher than the ionomer. In particular, one should note the same Tg of the polystyrene block before and after ionomer formation, and the extension of the rubbery plateau past 200°C. In contrast, flow occurred in... 

An instrument designed to follow hysteresis losses in polymers by measuring the resistance to the rolling of small balls over the surface of the test piece it can investigate transitions in polymers to as low a temperature as -120 °C. Superseded by modem dynamic mechanical thermal analysis equipment. 

Polymer films of approximately 1000 microns wet film thickness were laid down with a bar applicator on PTFE coated glass panels and the solvent allowed to evaporate at ambient temperature for a standard period of seven days. A typical plot of solvent weight loss with time is shown in Figure 2. The thickness of the wet film was dictated by the need to have adequate mechanical strength in the dry films in order that they might be suitable for subsequent mechanical test procedures. Dry film thicknesses were approximately 300 microns as measured by micrometer. The dried polymer films were examined by dynamic mechanical thermal analysis (DMTA) (Polymer Laboratories Ltd.). Typical DMTA data for a polymer and paint are... 

The styrene content affects the crystallinity of ESI (131) for >50% styrene the copolymers are amorphous. As the styrene content is increased from 50 to 70% styrene the Tg increases from -15 °C to 20 °C. Low density foams were made (8) from a blend of 50% of various ESI polymers, 33% of EVA and 17% of azodicarbonamide blowing agent. Thermal analysis showed that the blends, with an ESI having approximately 70% styrene, had a Tg in the range 22 to 30 °C. Dynamic mechanical thermal analysis (DMTA) traces (see Section 5.1) show that these blends... 

Dynamic mechanical analysis (DMA) or dynamic mechanical thermal analysis (DMTA) provides a method for determining elastic and loss moduli of polymers as a function of temperature, frequency or time, or both [1-13]. Viscoelasticity describes the time-dependent mechanical properties of polymers, which in limiting cases can behave as either elastic solids or viscous liquids (Fig. 23.2). Knowledge of the viscoelastic behavior of polymers and its relation to molecular structure is essential in the understanding of both processing and end-use properties. 

Most of the physical properties of the polymer (heat capacity, expansion coefficient, storage modulus, gas permeability, refractive index, etc.) undergo a discontinuous variation at the glass transition. The most frequently used methods to determine Tg are differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical thermal analysis (DMTA). But several other techniques may be also employed, such as the measurement of the complex dielectric permittivity as a function of temperature. The shape of variation of corresponding properties is shown in Fig. 4.1. 

After following the microhardness behaviour during the stress-induced polymorphic transition of homo-PBT and its multiblock copolymers attention is now focused on the deformation behaviour of a blend of PBT and a PEE thermoplastic elastomer, the latter being a copolymer of PBT and PEO. This system is attractive not only because the two polymers have the same crystallizable component but also because the copolymer, being an elastomer, strongly affects the mechanical properties of the blend. It should be mentioned that these blends have been well characterized by differential scanning calorimetry, SAXS, dynamic mechanical thermal analysis and static mechanical measurements (Apostolov et al, 1994). 

Lafferty SV, Newton JM, Podczeck F. Dynamic mechanical thermal analysis studies of polymer films prepared from aqueous dispersion, frit J Pharm 2002 235 107-111. 

Wetton, R. (1986) Dynamic mechanical thermal analysis of polymers and related materials, in Dawkins, J. (Ed.) Developments in Polymer Characterization, London Elsevier. 

The relaxation methods employed are Dynamic Mechanical Thermal Analysis (DMTA) and Dielectric Thermal Analysis (DETA). Generally in both cases a single excitation frequency is used and the temperature is varied, typically over a range between — 100 °C and +200 °C. Changes in molecular motion, and hence 7, are detected by both techniques, but in the case of DETA the process has to involve movement of dipoles or fully developed electrical charges on the polymer in order to be detected. Thus the two techniques can be used to complement each other, since transitions can be detected on DMTA and assigned as due to dipoles according to whether or not they also occur with DETA. 

DSC, and dynamical mechanical thermal analysis (DMTA) have emerged as powerful thermoanalytical techniques to monitor physical and chemical changes in both natural and synthetic polymers. 

Dynamic mechanical thermal analysis of several of the norbornene functional organic resins and the silicone resins gave relatively unremarkable results. The maximum for tan 5 peaks were in good agreement with Tg detamiined by DSC. The silicone elastomer (with 35% fumed silica as reinforcing filler) exhibited a Tg of ca. -90°C and a Tm at ca. -30 C which is typical for this type of polymer. 

The polymers were prepared by reacting five glycidyl ethers with 4, 4 -diisocyanatodiphenylmethane in the presence of 2-ethyl-4-methylimidazole. The degree of cure of the resins was followed by IR spectroscopy and DSC. The rates of the isocyanurate to oxazolidone linkages were determined quantitatively by an infrared method and the glass transition temperatures of the polymers were measured by DSC and dynamic mechanical thermal analysis. 16 refs. 

Figure 9.32 Isothermal (173°C) variation of the storage modulus G with time. The blend contains 75% COP, obtained from solution by acetone precipitation and kept under compression at 210-220 C and 4.0 MPa for Imin. Dynamic-mechanical thermal analysis (DMTA) Polymer Labs MKII (8.0 mm X 8.0 cm x 1.5 mm samples) with cantilever clamps [125] and [128]. Reproduced with permission of Elsevier Science Ltd. For explanation see text.

DDM = Diamino diphenyl methane For the mixtures of epoxy monomers, 1 1 mol ratio was used. Stoichiometric amounts were used in all cases. From differential scanning calorimetry method measurements (10 °C/min). Maximum of the loss modulus from dynamic mechanical thermal analysis measurements. a relaxation peak of the loss factor. Reproduced with permission from M. Sponton, L.A. Mercado, J.C. Ronda, M. Galia and V. Cadiz, Polymer Degradation and Stability, 2008, 93, 2025. 2008, Elsevier [22] ... 

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