Synthesis of Integrated Polymers for Soil Stabilization

Abstract

In this work, the synthesis of vinylpyrrolidone- (VP), vinyl acetate- (VA) and acrylamide- (AM) based polymers and copolymers was developed with a view to their application as drilling fluids. P(VP-co-VA), P(AM-co-VA) and P(AM-co-VP) were synthesized with different monomer ratio (87-13%, 75-25% and 50-50%) in water with the aim of obtaining a copolymer which is: (1) water soluble in a ratio of 1 g per liter of water (2) and able to exhibit a viscosity value ≥ 55 s/quart. The material fulfilling these requirements may be applied as (i) a main compound or as (ii) an additive for drilling fluids. All viscosity measurements were performed in a Marsh funnel as preliminary tests to select which was the best candidate polymer for the previous objectives. The chemical composition of all polymers and copolymers was investigated by FTIR-ATR or/and solid state 13C NMR to ensure the success of polymerization. Polymers and copolymers which achieved the previously mentioned requisites (1) and (2) were characterized by scanning electron microscopy (SEM), zeta potential and their molecular weight was determined in an Ubbelohde type I Capillar viscometer. Partially hydrolyzed P(AM-co-VA) with a weight monomer ratio of 75-25% of acrylamide and VP, respectively, and partially hydrolyzed P(AM-co-VP) with a weight monomer ratio of 87-13% of acrylamide and VP, respectively, showed a viscosity of 56 s/quart in water, gathering all needed conditions to be evaluated according to suspension and settling tests with soil. These suspension and settling tests were performed with clay in distilled-deionized and tap water. P(AM-co-VA) were not able to suspend clay neither as main viscosifier nor as additive. P(AM-co-VP) did not reveal suspending clay capacity as main viscosifier, but when 1g of copolymer is added to one liter of PolyMud® solution (1 g/L) comprising distilled-deionized water, 100% of soil suspension was reached over a period of 24 hours. When tap water was used, P(AM-co-VP) exhibited the best performance by keeping in suspension 90% of the total clay present in solution over 24 hours. In addition, PVP was successfully used as additive to a PolyMud® solution (1 g/L), comprising distilled-deionized water, exhibiting in suspension capacity of 90% of the total clay during 24 hours.