Dynamic Mechanical Spectroscopy polymer

Huang, Y. Q., Jiang, S. L., Wu, L. B., and Hua, Y. Q. 2004. Characterization of LLDPE/nano-Si02 composites by solid-state dynamic mechanical spectroscopy. Polymer Testing 23 9-15. 

Roudaut et al. (1999a) used low-frequency pulsed-proton NMR and dielectric dynamic mechanical spectroscopies to study molecular mobility in glassy bread (<9%) as a function of temperature. Based on NMR results, they reported that some (if not all) of the water molecules were much more mobile than the polymer matrix whose relaxation time could not be measured within the 20-p,s dead time of the RF probe. 

R Musto, M. Abbate, G. Ragosta and G. Scarinzi, A smdy by Raman, near-infrared and dynamic-mechanical spectroscopies on the curing behaviour, molecular structure and viscoelastic properties of epoxy/anhydride networks, Polymer, 48, 3703-3716 (2007). 

The first data on polymer systems were collected via (laser-) light-scattering techniques [1] and turbidity measurements, further developed by Derham et al. [2,3]. Techniques based on the glass-transition of the polymer-blend constituents were also tested, such as DSC, Dynamic Mechanical Spectroscopy, and Dielectric relaxation [4]. Films made from solutions of... 

The latexes were cleaned by ion exchange and serum replacement, and the number and type of surface groups were determined by conductometric titration. The molecular weight distributions of the polymers were determined by gel permeation chromatography. The stability of the latexes to added electrolyte was determined by spectrophotometry. The compositional distribution was determined by dynamic mechanical spectroscopy (Rheovibron) and differential scanning calorimetry, and the sequence distribution by C13 nuclear magnetic resonance. 

Abbreviations y x AFM AIBN BuMA Ca DCP DMA DMS DSC EGDMA EMA EPDM FT-IR HDPE HTV IPN LDPE LLDPE MA MAA MDI MMA PA PAC PB PBT PBuMA PDMS PDMS-NH2 interfacial tension viscosity ratio atomic force microscopy 2,2 -azobis(isobutyronitrile) butyl methacrylate capillary number dicumyl peroxide dynamic mechanical analysis dynamic mechanical spectroscopy differential scanning calorimetry ethylene glycol dimethacrylate ethyl methacrylate ethylene-propylene-diene rubber Fourier transform-infra-red high density polyethylene high temperature vulcanization interpenetrating polymer network low density polyethylene linear low density polyethylene maleic anhydride methacrylic acid 4,4 -diphenylmethanediisocyanate methyl methacrylate poly( amide) poly( acrylate) poly(butadiene) poly(butylene terephtalate) poly(butyl methacrylate) poly(dimethylsiloxane) amino-terminated poly(dimethylsiloxane)... 

Figure 1. Dynamic mechanical spectroscopy of formula B This material, containing 70% EA comonomer between polymer networks I and II, displays a mechanical spectrum only slightly broader than would be expected of the corresponding random copolymer.

Comprehensive texts on dynamic mechanical spectroscopy in relation to the molecular structure of polymers are given in Refs 1-3. 

This chapter discusses the dynamic mechanical properties of polystyrene, styrene copolymers, rubber-modified polystyrene and rubber-modified styrene copolymers. In polystyrene, the experimental relaxation spectrum and its probable molecular origins are reviewed further the effects on the relaxations caused by polymer structure (e.g. tacticity, molecular weight, substituents and crosslinking) and additives (e.g. plasticizers, antioxidants, UV stabilizers, flame retardants and colorants) are assessed. The main relaxation behaviour of styrene copolymers is presented and some of the effects of random copolymerization on secondary mechanical relaxation processes are illustrated on styrene-co-acrylonitrile and styrene-co-methacrylic acid. Finally, in rubber-modified polystyrene and styrene copolymers, it is shown how dynamic mechanical spectroscopy can help in the characterization of rubber phase morphology through the analysis of its main relaxation loss peak. 

EFFECT OF POLYMER STRUCTURE AND ADDITIVES ON THE DYNAMIC MECHANICAL SPECTROSCOPY OF POLYSTYRENE... 

Some cellulose derivatives and P(3HB) and P(3HB-co-3HV) have been found to show good compatibility [114-116]. These are chemically modified natural and natural biodegradable polymer blend systems. Blends obtained by melts compounding P(3HB) with cellulose acetate butyrate (CAB, degrees of butyrate and acetate substitution are 2.50 and 0.18, respectively) have been found to be miscible over the whole composition range by DSC and dynamic mechanical spectroscopy [116]. 

Secondary relaxations are usually measured either by mechanical methods such as dynamic mechanical spectroscopy or (somewhat less often) by electrical methods such as dielectric relaxation spectroscopy [159], The existence of Tp is generally ascribed to the onset of a significant amount of some kind of motion of the polymer chains and/or the side groups attached to them, on a much smaller and more localized scale than the large-scale cooperative motions of chain segments associated with Ta. These motions are usually inferred from the results of measurements using methods such as nuclear magnetic resonance spectroscopy. See... 

Figure 6.12. Dynamic mechanical spectroscopy results for blend of separate core/shell latex film 1/1 A/C and 1/1 B/C at a 1/1 blend ratio A = P(Bd/S), B = P(EHMA/S), and C = SAN. More distinctive glass transitions are shown here, particularly for polymer B.

Mijovic, J., Lee, H. K., Kenny, J., and Mays, J., Dynamics in polymer-silicate nanocomposites as smdied by dielectric relaxation spectroscopy and dynamic mechanical spectroscopy, Macrvmolecules, 39, 2172—2182 (2006). 

In the majority of cases the compatibility of the polymers is characterized by the glass-transition temperature Tg, determined by methods such as dilatometry, differential scanning calorimetry (DSC), reversed-phase gas chromatography (RGC), radiation thermal luminescence (RTL), dynamic mechanical spectroscopy (DMS), nuclear magnetic resonance (NMR), or dielectric loss. The existence of two... 

Considerable information about elastic and viscoelastic parameters may be derived by measuring the response of a polymer to a small-amplitude cyclic deformation. Molecules perturbed in this way store a portion of the imparted energy elastically, and dissipate a portion in the form of heat (Ferry, 1970 Meares, 1965 Miller, M. L., 1966, pp. 243-253 Nielsen, 1962, Chapter 7 Rosen, 1971 Schultz, 1974, pp. 67-71 Williams, D. J., 1971), the ratio of dissipation to storage depending on the temperature and frequency. In dynamic mechanical spectroscopy experiments, a cyclic stress is applied to a specimen, and two fundamental parameters are measured the storage modulus E a measure of the energy stored elastically, and the loss modulus a measure of the energy dissipated. The loss modulus E" may be calculated as follows ... 

The mechanical properties and glass transition behavior of these polymer alloys were compared. The kinetics of polymerization of the component pol3rmers were measured and varied by changing the concentration of catalysts in order to determine the effect of polymerization rates on the morphology of the IPN s. Electron microscopy and dynamic mechanical spectroscopy were also carried out. Several theoretical models predicting the modulus of... 

The dielectric relaxation spectroscopy can effectively measure the relaxation processes of dipoles in the polymers. Like the dynamic mechanical spectroscopy, the sinusoidal electric field is the imposing stimulation, and again in a complex form. 

The a relaxation peak in dynamic mechanical spectroscopy and dielectric relaxation spectroscopy of non-crystalUne polymers also reflect the glass transition phenomenon ... 

The mechanical properties of a series of main-chain and side-chain LC elastomers that possessed Sc, Sc, N, cholesteric, and isotropic phases were studied using dynamic mechanic spectroscopy [25], Around Tg, the polymers exhibit value s variation for storage modulus above and below the transition. In the nematic state, G is below the value observed in the isotropic state. In the smectic phase, the layered organization produces a kind of network that causes a G plateau. A summary of this behavior is shown in Figure 9.9. 

The morphology of IPNs has been widely investigated via electron microscopy and dynamical mechanical spectroscopy. Many IPNs have dual-phase continuity, with phase domain sizes of the order of several hundred angstroms. For sound and vibration damping over broad temperature ranges, the two polymers are mixed in different extents in different parts of the material, usually in the submicron range. 

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