Solidlike transition of melt‐intercalated biodegradable polymer/clay nanocomposites

Abstract

Synthetic biodegradable aliphatic polyester (BAP) intercalated into organoclay was prepared by melt compounding, and its solidlike characteristics were investigated via several rheological test modes: steady shear rotation, oscillation, and creep testing. Structural investigations with X‐ray diffraction and transmission electron spectroscopy were also performed for a better understanding of the characteristic rheological behaviors. The creep, recovery, and stress modulus exhibited a solidlike transition of BAP/clay nanocomposites that depended on the clay content. An increase in the zero shear rate viscosity and a shifting of the crossover point (storage modulus vs loss modulus) to a lower frequency were also observed with increasing clay contents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2052–2061, 2003

Relationship between structural evolution and rheological measurements for polymer + organoclay nanocomposites

“…From these results, we conjugate the existence of a critical concentration at which a remarkable increase in the modulus is achieved. Similar results were reported for BAP/OMMT nanocomposites prepared via melt intercalation, showing a significant increase in storage modulus and elastic recovery at a clay content of 3 wt.-% [18]. Furthermore, a plot of G′ versus G″ for different temperatures can be used as an effective method to elucidate structural changes [19], analogous to Cole-Cole plots in dielectric spectroscopy [20].…”

Effect of shear processing on the linear viscoelastic behaviour and microstructure of bitumen/montmorillonite/MDI ternary composites

“…As widely reported for composite materials [10,[12][13][14][15][16][17][22][23][24][27][28][29], a better nanoclay dispersion yields an increase in interfacial area, allowing for optimal mechanical stress transfer between the filler and the matrix and, therefore, an enhancement in mechanical behaviour. In this regard, as discussed in previous works [15,16], the disappearance of the rubbery plateau region in the 24 h-bitumen/C20A/MDI composite has been attributed to the effects of MDI-related reactions under low shear processing, which, in fact, may promote the agglomeration/re-aggregation of C20A tactoids/platelets through interactions between hydroxyl groups located on the edges of the clay platelets [10,12,[15][16][17].…”

“…In general, the observed rheological behaviour hints at the development of a complex, clay-based micro-and nano-structured continuum that reinforces the system structure and derives from the intercalation/exfoliation of clay tactoids in the bituminous matrix [14][15][16]23,24].…”

“…The optimization of formulation/processing of nanocomposites with tailored properties requires a feedback process which includes their comprehensive rheological characterization [10,14]. In general, addition of clay to bitumen has yielded nanocomposites characterized by shear thinning behaviour at low shear rates, with noticeably increased viscosities with respect to their parent bitumen [3,11,13,15,16].…”

Use of unnatural amino acids for design of novel organomodified clays as components of nanocomposite biomaterials

“…PCNs show significant improvement in properties when compared with neat polymer and polymers containing micron-sized fillers. Several studies have reported that PCNs show improvement in mechanical properties (Okada et al 1990;Giannelis 1996;Chen et al 2002;Maity et al 2002;Lim et al 2003;Ma et al 2003;Park et al 2003;Pramanik et al 2003;Pramoda et al 2003), a decrease in gas permeability (Yano et al 1993;Messersmith & Giannelis 1995;Bharadwaj 2001;Xu et al 2001) and flammability (Gilman et al 1997(Gilman et al , 2000Gilman 1999) and also affect the biodegradability of biodegradable polymers (Ray et al 2002). There has also been considerable interest in modelling and in the simulation and development of new theories for PCNs.…”