Viscoelastic linear dynamic

The linear viscoelastic properties in the melt state of highly grafted polymers on spherical silica nanoparticles are probed using linear dynamic oscillatory measurements and linear stress relaxation measurements. While the pure silica tethered polymer nanocomposite exhibits solid-like response, the addition of a matched molecular weight free matrix homopolymer chains to this hybrid material, initially lowers the modulus and later changes the viscoelastic response to that of a liquid. These results are consistent with the breakdown of the ordered mesoscale structure, characteristic of the pure hybrid and the high hybrid concentration blends, by the addition of homopolymers with matched molecular weights. 

K-factor See coefficient of thermal conductivity, kieselguhr See diatomaceous earth, kinematic viscosity See viscosity, kinematic, kinetic A branch of dynamics that is concerned with the relations between the movement of bodies and the forces acting on them. See Avogadro s law reactor technology thermogravimetric analysis viscoelasticity, linear viscoelasticity, nonlinear. 

Starch nanocrystals were used to reinforce a non-vulcanised NR matrix. The NR was not vulcanised to enhance biodegradability of the total biocomposite. Non-linear dynamic mechanical experiments demonstrated a strong reinforcement by starch nanocrystals, with the presence of Mullins and Payne effects. The Payne effect was able to be predicted using a filler-filler model (Kraus model) and a matrix-filler model (Maier and Goritz model). The Maier and Goritz model showed that adsorption-desorption of NR onto the starch surface contributed the non-linear viscoelasticity. The Kraus model confirmed presence of a percolation network. ... 

Two manifestations of linear viscoelasticity are creep and stress relaxation-, the respective two testing methods are known as transient tests. One can also apply sinusoidal load, an increasingly more used method of study of viscoelasticity by dynamic mechanical analysis (qv) (DMA). We shall now briefly discuss each of these three approaches. 

In this chapter, we outline the principle, measurement, and application of dynamic viscoelasticity for solid and liquid polymers. In Section II, a basic treatment of the dynamic viscoelasticity is described. Section III deals with the various dynamic viscoelastic measurements of solid and liquid polymers. Section IV reviews in detail the results of linear dynamic viscoelasticity as a function of frequency and temperature. The dynamic mechanical studies have... 

Edelstein, W. S., Gurtin, M.E. (1964) Uniqueness theorems in the linear dynamic theory of anistropic viscoelastic solids. Arch. Rat. Mech. Anal. 17, 47-60 Efimov, A.B. (1966a) Axisymmetric contact problem for linear viscoelastic bodies. Vest. Moskov. Univ., Ser. 1, Mat. Mek. 21, 120-127... 

Caughey TK, O Kelly MEJ (1965) Classical normal modes in damped linear dynamic systems. Trans ASME J Appl Mech 32 583-588 McTavish DJ, Hughes PC (1993) Modeling of linear viscoelastic space structures. Tran ASME J Vib Acoust 115 103-110... 

Temperature-Independent Correlations for the Linear Dynamic Viscoelastic Properties of Linear Flexible Homopolymers... 

Graessley and Stmglinski (1986) developed a theory, that predicts the linear dynamic viscoelastic properties of binary blends of monodisperse flexible homopolymers, based on the tube model, by incorporating constraint release and path fluctuations into the reptation motion (see Chapter 4). They assumed that the stress relaxation modulus of a binary blend, Gb(0, may be represented by... 

Here, we consider the rheological behavior of PS/PaMS blends exhibiting UCST. The miscibility and phase behavior of PS/PaMS blends have been studied (Cowies and McEwen 1985 Lau et al. 1982 Lin and Roe 1987, 1988 Rameau et al. 1989 Saeki et al. 1983 Schneider andDilger 1989 Wimpier and Maynard 1987) and the miscibility window of PS/PaMS blends has been found to be very sensitive to the molecular weights of the constituent components. We next consider the phase behavior and linear dynamic viscoelastic properties of three pairs of PS/PaMS blends, each having different molecular weights, as summarized in Table 7.1. 

In this section, we present the molecular theory for the linear dynamic viscoelasticity of miscible polymer blends by Han and Kim (1989a, 1989b), which is based on the concept of the tube model presented in Chapter 4. Specifically, the reptation of two primitive chains of dissimilar chemical structures under an external potential will be considered, and the expressions for the linear viscoelastic properties of miscible polymer blends will be presented. We will first present the expressions for zero-shear viscosity ob. dynamic storage and loss moduli G co) and G " co), and steady-state compliance J° for binary miscible blends of monodisperse, entangled flexible homopolymers and then consider the effect of polydispersity. There are a few other molecular theories reported... 

PMMA/PSAN blends at temperatures below LCST. Here, we present the linear dynamic viscoelastic properties of PMMA/PSAN blends and compare them with theoretical predictions from the molecular theory presented in the preceding section. 

Effect of Block Length Ratio on the Linear Dynamic Viscoelasticity of Disordered Block Copolymers... 

In this section, we present the effect of block composition (block length ratio) on the linear dynamic viscoelasticity of disordered PS- /ocfc-poly(a-methylstyrene) (PaMS) copolymers and also SI diblock copolymers in the disordered state. Table 8.3 gives a summary of the molecular characteristics for seven PS- tocA -PaMS copolymers, and Figure 8.38 gives thermograms of differential scanning calorimetry (DSC) for the seven... 

Stockmayer and Kennedy (1975) conducted a seminal smdy on the chain dynamics of Rouse chains of AB-type diblock or ABA-type triblock copolymers by modifying the bead—spring model of Rouse for linear flexible homopofymers (see Chapter 4). They calculated the spectrum of relaxation times ftp biodc) block copolymer in terms of the terminal relaxation times for the Rouse chains for the A and B blocks. Once the values of are determined, one can calculate linear dynamic viscoelastic... 

We have presented experimental observations for the linear dynamic viscoelasticity of low-molecular-weight SI diblock copolymers in the disordered state. We have shown that the log G versus log G" plot is very useful for investigating the effects of molecular weight and block length ratio on the linear dynamic viscoelasticity of block copolymers. The experimental results were compared with currently held theory for disordered, unentangled AB-type and ABA-type block copolymers. 

Lee and Han (2003b) investigated linear dynamic viscoelastic properties of organoclay nanocomposites based on both SI diblock copolymer and SIOH diblock copolymer. An SIOH diblock copolymer (referred to as SI-14/3-OH) was obtained by hydroxylation of the polyisoprene (PI) block of a highly asymmetric SI diblock copolymer (SI-14/3, with Af = 1.7 x 10" and = 1.08). SI-14/3 was a... 

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