Rheological properties of pectin, poly(vinyl alcohol) and their blends in aqueous solutions

Abstract

The new blends composed of natural polysaccharide -pectin and synthetic water soluble polymer -poly(vinyl alcohol) (PVA) are attractive materials due to their biocompatibility, non-toxicity and biodegradability. In this work the rheological properties of aqueous solutions of pectin (PEC), poly(vinyl alcohol) and their mixtures at various weight ratios (70/30, 50/50, 30/70) have been investigated. Flow measurements were carried out using a rotary viscometer with concentric cylinder at different temperatures (20-70 ºC) and shear rates (24-1234 s -1 ). The flow parameters and energy of activation have been calculated from the flow curves and Arrhenius plots, respectively. It was found that studied polymer solutions exhibited non-Newtonian behavior, moreover, the flow properties were dependent on the blend composition. The result show that practically there was no thixotropy in studied system but some interactions between PVA and pectin in water occurred.

Influence of molecular weight on structure and rheological properties of microcrystalline chitosan mixtures

“…It is in accordance with previously reported data for the solutions of PAM [19,20]. The decrease of apparent shear viscosity with the shear rate is mainly related to the orientation of macromolecules along the streamline of flow and to the disentanglement of macromolecules with the increasing shear force [19][20][21][22]. However aqueous solutions of mixtures at w MCCh ≤ 0.5 exhibit the higher apparent viscosity than the apparent viscosity of native polymers.…”

“…For the solutions of MCCh I and MCCh I/PAM mixtures, the shear-thickening behavior is observed. The shear-thickening behavior may be related to the change of macromolecular conformation induced by flow [19][20][21][22]. In the case of the mixture solutions, the intermolecular interaction participates in the shear thickening phenomenon.…”

“…The shear dependence of the viscosity was analyzed by using the well-know power law relationship [19][20][21][22]. The obtained values of rheological parameters are listed in Table 1.…”

“…Flow properties of the used polymers and their mixtures solutions obey the power law relationship of the Ostwald de Waele model [15][16][17][18][19][20][21][22]:…”

Ultrasound-Assisted Extraction of Pectin from Malus domestica ‘Fălticeni’ Apple Pomace

“…0.2 Pa•s) [57] and viscosity obtained for 5% pectin solutions of cacao pod husks [58] and apple pomace [59], which was lower than 0.2 Pa•s. Figure 4 presents the flow curves of the three pectin samples; all curves present a shear thinning behaviour of a non-Newtonian fluid due to the weakness of the pectin intermolecular forces with increasing shear rate [55,56]. It can be observed that the origin of pectin had no influence on the thinning behaviour of the solutions, as all of them had the same behaviour, showing viscosity decrease with the increasing of shear rate.…”