Carboxymethyl Starch/Montmorillonite Aqueous Dispersions: The Effect of Components and Mixing Method on Rheoviscometric Characteristics

Abstract

ABSTRACT:The rheoviscometric properties of low and high substituted carboxymethyl starch (CMS) 2 wt% aqueous solutions and their dispersions with sodium, calcium, and organomodified montmorillonite (MMT) have been investigated. The influence of MMT type and content on viscosity of CMS (degree of substitution, DS, 0.90)/sodium MMT aqueous dispersions, their stability, and transparency during storage up to 18 months has been investigated. Moreover, the methods of MMT dispergation in low substituted CMS solutions (DS 0.15), that is, mechanical stirring or mechanical and ultrasonication stirring on viscosity have been compared. It resulted in higher viscosity when using the latter mixing procedure (7000 and 9250 mPa·s, respectively, at 1 rpm for CMS (DS 0.15)/7 phr calcium MMT). In addition, thermal resistance of native starch and both CMS with different DS values has been investigated. The results are important as far as commercial applications of CMS solutions or dispersions with MMTs are concerned. C

Viscosity changes of aqueous carboxymethyl starch by partial crosslinking and montmorillonite addition

“…The strong peaks at 1595, 1415, and 1315 cm −1 were assigned to carbonyl CO asymmetric and symmetric COO – groups, CH 2 scissoring and OH bending vibrations, respectively. These bands confirmed the carboxymethylation modification …”

Carboxymethyl Starch/Medium Chain Fatty Acid Compositions: Rheological Changes During Storage and Selected Film Properties

“…Comparing viscosity after storage time, as it was mentioned earlier, viscosity of CMS solution dropped sharply ( Figure 1A) and this phenomenon, caused mainly by polysaccharide chain hydrolysis, [ 13 ] was also observed in other works. [ 13,15,24 ] On the other side viscosity of CMS/C8‐10 and CMS/C9‐10 systems decreased to a substantially lower extent through 2 months (Table S1, Supporting Information and Figure 1B,C). Similar relationships were observed by Wilpiszewska et al.…”

“…Interestingly, when CMC was used as additive in low concentration for oil emulsions [26] or aqueous bentonite suspension [27] relevant viscosities increased. Similarly, the difference between CMS and CMC solutions with clay presence was noticeable, that is, viscosity of CMS solution increased [13,15] and CMC decreased [28] when small, comparable amount of clay was introduced. Table S1, Supporting Information and Figure 3, show that CMC neat solution and CMC/C9-10 samples reached the highest viscosity after one month storage (9000 mPas for CMC and 4000 mPas for CMC/C9-10 at initial 1 rpm) but CMC/C8-10 exhibited a maximum after two months.…”

“…[9,10] Viscosity of CMS solutions is a very important factor in many applications and it can be regulated by, for example, optimization of starch etherification parameters, [11,12] slight crosslinking [13,14] or additive incorporation, for example clays, into solutions. [13,15] CMS is safe and non-toxic, so it can be used for cosmetics or medicine. It is listed on United States and British Pharmacopoeia.…”

Synthesis, Characterization and Application of Carboxymethyl Potato Starch Obtained From Waste

“…As seen in Figure 7, the weight loss in the temperature range from 50 to 120 °C, which is the first step of degradation, was related to moisture (or free water) evaporation, while the second one corresponded to decomposition. 51 Comparing with WPS, which decomposed at 300 °C, the decomposition of CMPSs (DS = 0.25 and 0.88) started at 200 and 250 °C, respectively. The waste potato starch showed the fastest rate of decomposition as the temperature increased.…”