Dynamic Mechanical and Thermal Analysis

The characterization of viscoelastic properties of polymeric materials on a DMTA (Dynamic, Mechanical and Thermal Analyser), are conducted 

The fractional Maxwell model was used with great success to analyze DMTA data of UHMWPE by Guedes [12]. The creep compliance is given by the following expression. 

Where R is the gas constant, 8.314E-3 kJ/(K mol), AHj, and AH are the relaxation or retardation activation energy and is the reference temperature in °K. Therefore, in this model it is assumed that the elastic modulus, which is time-independent, changes with temperature manifest a vertical shift. Furthermore, vertical shifting also affects the viscoelastic components, which are simultaneously subjected to horizontal shifting (in time). Consequently, this form does comply with the definition given by Delay and Plazek [157] for thermorheologically simple materials. 

In the frequency domain, the storage and loss compliance are given as 

The methodology to determine the elastic-viscoelastic parameters, from DMTA data, is described in detail elsewhere [12]. 

---

Velasco-Santos C, Marty nez-Hema ndez AL, Fisher FT, Ruotf R, Castanlo VM (2003a). Dynamical mechanical and thermal analysis of carbon nanotube-methyl methacrylate nanocomposites. J. Phys. D-Applied Phys. 36 1423-1428. 

C.S. Own, D. Seader, N.A. D Souza, W. Brostow, Cowoven polypropylene/glass composites with polypropylene + polymer liquid crystal interlayers dynamic mechanical and thermal analysis. Polym. Compos. 19(2), 107-115 (1998)... 

The paper by Copley presents a study of two types of silicone pressure-sensitive adhesives, of known composition, by dynamic mechanical and thermal analysis. The materials were prepared from a siloxane resin and two silicone gums poly(dimethylsiloxane) and poly(dimethyl-co-phenylsiloxane). 

Ray D, Sarkar BK, Das S, Rana AK (2002) Dynamic mechanical and thermal analysis of vinylester resin matrix composites reinforced with untreated and alkali-treated jute fibers. Compos Sci Technol 62 911-917... 

E. (2001) A dynamic mechanical and thermal analysis of unplasticized and plasticized poly (vinyl alcohol)/methyl cellulose blends. L Appl. Polym. Sci., 80, 1825-1834. 

Shuying Yang, Jaime Taha-Tijerina, Veronica Serrato-Diaz, KrystalFIernandez, and Karen Lozano. Dynamic mechanical and thermal analysis of aligned vapor grown carbon nanofiber reinforced polyethylene. Composites Part B 38, 228-235 (2007). 

Laaksonen, T.J. and Ross, Y.H. Thermal, dynamic-mechanical, and dielectric analysis of phase and state transitions of frozen wheat dough, /. Cereal Sci, 32, 281,2000. 

MigUaresi, C., Cohn, D., De LoUis, A. and Fambri, L. (1991) Dynamic mechanical and calorimetric analysis of compression-molded PLLA of different molecular weights Effect of thermal treatments. Journal of Applied Polymer Science, 43, 83—95. 

Wurm A, Merzlyakov M, Schick C (1999) Isothermal Crystallisation of PCL Studied by Temperature Modulated Dynamic Mechanical and TMDSC Analysis. J Thermal Anal Cal 56 1155-1161. 

Martinez-Hemandez AL, Velasco-Santos C (2012) Keratin fibers from chicken feathers structure and advances in polymer composites. Nova Publishers, New York, pp 149-211 Martinez-Hemandez AL, Velasco-Santos C, de-Icaza M, Castano VM (2007) D5mamical-mechanical and thermal analysis of polymeric composites reinforced with keratin biofibers from chicken feathers. Compos Part B Eng 38 405 10 Mathew AP, Dufresne A (2002) Morphological investigation of nanocomposites from sorbitol plasticized starch and tunicin whiskers. Biomacromolecules 3 609-617 Md. Islama S, Hamdana S, Talibb ZA, Ahmeda AS, Md. Rahmana R (2012) Tropical wood polymer nanocomposite (WPNC) The impact of nanoclay on dynamic mechanical thermal properties. Compos Sci Technol 72 1995-2001... 

The rheological properties of the material are connected with these physicochemical states. In recent years significant advances have been made in both the theory of viscoelasticity and the related instrumentation. In particular dynamic, mechanical and thermal testing have become quite popular after successful applications to the analysis of polymer systems [26], some elements of which are given in the Appendix A3. 

In a subsequent communication, Elliott and coworkers found that uniaxially oriented membranes swollen with ethanol/water mixtures could relax back to an almost isotropic state. In contrast, morphological relaxation was not observed for membranes swollen in water alone. While this relaxation behavior was attributed to the plasticization effect of ethanol on the fluorocarbon matrix of Nafion, no evidence of interaction between ethanol and the fluorocarbon backbone is presented. In light of the previous thermal relaxation studies of Moore and co-workers, an alternative explanation for this solvent induced relaxation may be that ethanol is more effective than water in weakening the electrostatic interactions and mobilizing the side chain elements. Clearly, a more detailed analysis of this phenomenon involving a dynamic mechanical and/ or spectroscopic analysis is needed to gain a detailed molecular level understanding of this relaxation process. 

The glass transition (Ta) and melting (Tm) temperature of the pure component polymers and their blends were determined on a Perkin-Elmer (DSC-4) differential scanning calorimeter and Thermal Analysis Data Station (TADS). All materials were analyzed at a heating and cooling rate of 20°C min-1 under a purge of dry nitrogen. Dynamic mechanical properties were determined with a Polymer Laboratories, Inc. dynamic mechanical thermal analyzer interfaced to a Hewlett-Packard microcomputer. The... 

Reading, M. and Haines, P.J., Thermomechanical, dynamic mechanical and associated methods, in Thermal Methods of Analysis Principles, Applications and Problems, Haines, P.J., Ed., Blackie Academic and Professional, Glasgow, U.K., 1995. 

Ramamurthy and his colleagues [29] investigated the influence of addition of MWNTs to PANi Aims fabricated by solution processing. The physical characterization of these composites by tensile testing and dynamic thermal mechanical analysis indicated that PANi containing 1% w/w MWNTs is more mechanically and thermally stable than PAni itself. However, only marginal improvements in mechanical properties were reported. 

Dynamic mechanical analysis has also been used to determine the mechanical and thermal properties of low-density polyethylene and ethylene-propylene-diene terpolymer containing jute filler, which had improved flexural and impact properties compared to those of the base polymer [198]. Jeong and coworkers [196] and others [195] investigated the dynamic mechanical properties of a series of polyhexamethyl-ene lerephthalale, poly(l,4-cyclohexylenedimethylene terephthalate), and random copolymers thereof in the amorphous state as a function of temperature and frequency. The effect of copolymer composition on dynamic mechanical properties was examined and the dynamic mechanical properties interpreted in terms of the cooperativity of segmental motions. 

Other thermally based techniques, which have been developed in recent years include thermal volatilisation (Chapter 5), dynamic mechanical analysis (Chapter 8), thermomechanical analysis (Chapter 9), microthermal analysis (Chapter 10) and dielectric thermal analysis (Chapter 12). These have been used in phase transition studies, resin cure, modulus measurement, stress-strain studies, viscoelastic and rheological properties, morphology, topography, mechanical and thermal properties. 

Various workers have reviewed the applications of dynamic mechanical thermal analysis (DMTA) technique to evaluate the mechanical and thermal properties of... 

Addition of hydroxyapatite modified with a silane coupling agent was introduced into PHBV by Tang et al. [255] in an effort to understand the influence of the bioceramic phase on water absorption, solubility, and biodegradation. They concluded that, compared to neat PHBV, diffusion coefficients for the bionanocomposites decreased, whereas the sorption coefficients and the solubility show an opposite tendency. In another work [256], the dynamic mechanical properties, thermal properties, and bioactivity of these bionanocomposite were examined, indicating that better mechanical properties and improved bioactivity were achieved with the introduction of hydroxyapatite. Moreover, thermal analysis revealed that when incorporating hydroxyapatite nanoparticles, the decomposition of PHBV was accelerated at the initial stage but retarded thereafter. 

Because of the link between Tg and the mechanical and thermal properties, the dependence of the glass transition temperature on blend composition is of much interest and has been the subject of many experimental and theoretical papers. The subject is particularly vast since TgS can be determined using various experimental techniques, including differential scanning calorimetry, dynamic mechanical thermal analysis, and dielectric relaxation spectroscopy (DRS). 

---