Synthetic Biodegradable Aliphatic Polyester/Montmorillonite Nanocomposites

Abstract

Biodegradable aliphatic polyesters (BAPs), synthesized from diols and dicarboxylic acids, and organophilic montmorillonite (OMMT) were intercalated by a solvent-casting method using chloroform as a cosolvent to produce nanocomposite (BAP/OMMT). The d spacings of both BAP and BAP/OMMT were examined by X-ray diffraction analysis, and the microstructure of BAP/OMMT was examined by transmission electron microscopy. Melting temperature changes and residuals were measured by thermal gravimetric analysis. Tensile strength and elongation were also examined with a universal testing machine. Increases in both the thermal stability and the mechanical strength of BAP/OMMT were observed for several different OMMT loadings. The rheological properties of the BAP/OMMTs were also examined with a rotational rheometer having a parallel-plate geometry. The shear viscosity at low shear rate exhibited a Newtonian plateau even at high loading and showed a higher degree of shear thinning at higher shear rate. Both the Newtonian plateau and the enhanced power-law behavior were correlated with a scaling function.

Rheological properties of a new rubbery nanocomposite: Polyepichlorohydrin/organoclay nanocomposites

“…On the other hand, at high shear rates, the nanocomposites display a rapid shear-thinning behavior that is comparable to that of the pure polymer because the entanglement of polymer chain and the arrangement of clay particles are not permanent and they can be altered under flow and during relaxation processes. 33,34 Similar steady shear rheological behavior has been also investigated for a series of intercalated poly(dimethyl-diphenyl siloxane)-layered silicate (dimethyl-ditallow MMT) nanocomposites with varying silicate loadings. 35 To investigate the dependence of the shear viscosity () on the shear rate (␥ ), we fitted the measured shear viscosity to the Carreau model 36 given in the following equation: …”

Crystallization behavior and properties of exfoliated isotactic polypropylene/organoclay nanocomposites

“…[1][2][3][4][5][6][7][8][9][10][11] A classification of nanocomposites based on the dimensions of the dispersed particles, divides them into three classes: (a) isodimensional nanofillers, such as spherical silica nanoparticles 12 and calcium carbonate (CaCO 3 ) [13][14][15] ; (b) bidimensional fillers when two dimensions are in the nanometer scale and the third is larger, forming an elongated structure, the fillers are generally known as whiskers, such as carbon nanotubes 16 or cellulose whiskers 17,18 ; (c) nanocomposites of the third type containing reinforcing particles that have only one lateral dimension in the nanometer range, such as smectite-clay minerals. These fillers are platelets that are a few nanometers thick while the linear planar dimensions are the order of few microns.…”

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

“…Scheme 2), was used to reinforce the matrix polymer by forming polymer + clay nanocomposites. Cationic exchange capacity (CEC) of the OMMT is 95 meq/100 g. The gallery height of its interlayer is estimated to be 2.18 nm, which is 1.01 nm higher than that of pristine Na + MMT (1.17 nm [8].…”

“…We embedded an inexpensive and light inorganic filler (montmorillonite) into the BAP matrix and prepared BAP + organoclay nanocomposites via solvent casting. Enhanced mechanical and thermal properties were previously observed [8][9][10][11][12]. However, structural changes were not yet fully characterized and understood by rheological measurements, especially in dynamic oscillatory shear mode [13,14].…”