Relaxation peak broadening and polymer chain dynamics in aramid‐fiber‐reinforced nylon‐66 microcomposites

Abstract

The relationship between the parameter of symmetric broadening of the glass‐transition relaxation process and the structure of aramid‐fiber‐reinforced nylon‐66 microcomposites is investigated in this article. The approach is based on a previously derived model that sets a quantitative interrelation between the Cole–Cole parameter α, the relaxation time, and the fractal dimension of a mobile polymer segment. The microcomposite, the dielectric response of which reflects the transcrystallinity effects, indeed exhibits significantly different values, such as higher Kirkwood correlation factor and α exponent values, in comparison with the control materials, and this indicates its different crystalline morphology and perhaps lower order in the amorphous phase. However, at this stage, it is still difficult to establish a quantitative relationship with the polymer chain dynamics. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 217–223, 2003

The Significance of Dielectric Spectroscopy in the Study of Transition Dynamics and Morphology of Transcrystallinity in Polymeric Composites

“…Then, according to Equation (3) and by using Á" that is obtained from the fitting routine, one can retrieve the temperature dependence of the Kirkwood correlation factor g, and in turn, assess the mutual orientation of neighboring dipoles. For example, in the case of aramid fiber-reinforced nylon 66 composites a tendency of antiparallel orientation of neighbouring dipoles as presented in Figure 6 is evident [17]. This observation is in good agreement with the results of [25] in which the majority of the investigated polymers exhibited values in the range 0<g<1.…”

“…With regard to this process, the dielectric properties of three sets of composites are considered, namely, aramid fiber-reinforced nylon 66 [12,17], aramid fiberreinforced poly(ether ether ketone) (PEEK) [16] and ultrahigh-molecular weight polyethylene (UHMWPE) fiber-reinforced high-density polyethylene (HDPE) [14]. In each set the specific contribution of the tc The Significance of Dielectric Spectroscopy 465 layer was evaluated against a control either without or with a different tc layer.…”

Cole-Cole Broadening in Dielectric Relaxation and Strange Kinetics

“…The normalization factor Q is the maximum value of the right-hand part of Eq. (7). The correspondence of these expressions in temperature range is very good, lending credence to the derivations of Eqs.…”

“…This approach was successfully applied to water polymer solutions [6], where dipolar water molecules interact with the polymer molecules, and to microcomposite polymer materials [7]. However, an attempt to apply this model to other systems that manifested CC behavior (water in porous glasses [8] or porous silicon [9]) was unsuccessful due to the limitations of the model.…”

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

“…For amorphous polymers, a non-symmetric distribution of times is expected for the α relaxation, associated with macromolecular segmental motion, at temperatures immediately above the glass transition. But for semi-crystalline polymers and more generally for heterogeneous systems, published data by Boyd [55], Laredo [56], Cebe [57], Noda [58], Ryabov [59], Janik [60], Feldman [61], Ortiz-Serna [29][30] etc., show that symmetrical distributions are observed for the α relaxation processes. However, the temperature dependence of a for the β process differs from that observed for the glass rubber relaxation since it decreases with temperature.…”