Preparation and Aqueous Properties of Starch‐grafted Polyacrylamide Copolymers

Abstract

In the present work, starch-grafted polyacrylamide copolymers were prepared and their rheological properties, either in water or in water-based muds, were investigated. The advantages in using starches as substrates to prepare additives which are suited for improving stability and the rheological properties of water-based muds, lie in their low cost, and their lower biodegradability than native starches. Thus, various copolymer series were prepared by free-radically grafting acrylamide (AM) onto starch using ceric ammonium sulphate (CAS) as initiator. It is shown that the intrinsic viscosity and the molecular weight of the grafted starches are controlled by the initiator and monomer concentrations. Furthermore, to predict the behaviour of the samples under oilwell conditions, the aqueous solution properties of the copolymers such as water solubility, viscosity, shear rate, were determined as function of temperature, salt concentration and type, and aging time. The knowledge of these properties is a prerequisite for the use of the copolymers in drilling fluids. The data indicate that starchgrafted polyacrylamide copolymers as compared to the non-modified starch, behave as shear-thinning, are salt resistant, and their rheological properties are stable with time. The grafted starches as prepared above were also added to water-based mud and the rheological properties of the resulting muds were determined under oil-well conditions. Grafted starches, having high AM contents, are more efficient in decreasing the filtrate volume, and increasing the plastic viscosity of the muds, when compared to PAC-L, a modified cellulosic polymer used in the filtration control of most water-based muds. Such improvements in the rheological properties of the muds were found to result from the behaviour and/or properties of the grafted starches in water.

A novel photo-grafting of acrylamide onto carboxymethyl starch. 1. Utilization of CMS-g-PAAm in easy care finishing of cotton fabrics

“…Different chemical initiation systems such as potassium persulfate (Lu et al, 2003;Nakason et al, 2010), ammonium persulfate (Li et al, 2005;Zhang et al, 2006b), ceric ammonium sulfate (Eutamene et al, 2009) and ceric ammonium nitrate (Hao et al, 2007) were used. Physical initiation systems such as γ irradiation (Kaur et al, 1993) and microwave (Singh et al, 2006) were also utilized.…”

Cassava starch‐graft‐polymethacrylamide copolymers as flocculants and textile sizing agents

“…The nitrogen content in the graft copolymers ( N f ) was determined with a Vario EL III CHNS elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). The monomer conversion ( X MAM ) was calculated as follows: …”

Influence of modified starches composition on their performance as fluid loss additives in invert-emulsion drilling fluids

“…Finally, yield point (YP) was calculated by L 300 À PV. Table 3 summarizes the rheological properties evaluated directly or indirectly by the viscosity readings as well as the units of measurement [21,33,34]. Tables 4 and 5 show the means of the results obtained for the filtrate volumes collected in the HTHP filtration tests, the rheological properties and electrical stability of the non-aged and aged fluids, respectively, formulated with 8.5 kg/m 3 of filtrate control additive.…”

“…Tables 6 and 7 show the means of the same parameters for the non-aged and aged fluids, respectively, formulated with 14.2 kg/m 3 of filtrate control additive. The concentrations of these additives were selected based on the values found in the literature [6,27,[33][34][35][36][37].…”