Synthesis Of Acrylamide Copolymer Thickener Based On Aqueous/Isoamyl Caprylate-White Oil Inverse Emulsion System And Its Application

Acrylamide copolymer thickener is a kind of functional polymer materials with good water solubility,which can improve the viscosity of aqueous solution system.It is widely used in coat printing,oil exploitation and other fields.In the synthesis process of this kind of thickener,saturated paraffin white oil is often used as the dispersion medium.However,white oil is environmentally polluting,necessitating the urgent need for a greener alternative.Additionally,temperature and salt resistance are crucial properties for the thickener.In this study,the biodegradable compound isoamyl caprylate was proposed to replace part of the white oil as the dispersion medium.Anionic(P(AM-AA-AMPS))and cationic(P(AM-DAC))acrylamide copolymer thickeners were designed and synthesized using the inverted emulsion polymerization method.These thickeners were employed in coat printing and oil and gas field fracturing applications.The properties of P(AM-AA-AMPS)and P(AM-DAC)were compared with anionic polyacrylamide thickeners(P(AM-AA-AMPS)-W),cationic polyacrylamide thickeners(P(AM-DAC)-W)prepared using white oil as the dispersion medium,and commercially available products.The specific research work conducted is outlined as follows:(1)The effects of dispersion medium type,emulsifier type,dosage,and oil-water ratio on the stability of the pre-emulsion were investigated.The results showed that the highest stability of the pre-emulsion was achieved when 50wt%of the 3#white oil was substituted with isoamyl caprylate,with a dosage of 10wt%for Span 80/Tween 80,and the ratio of oil to water was 5 to 3.(2)P(AM-AA-AMPS)was synthesized from acrylamide(AM),acrylic acid(AA)and 2-acrylamide-2-methylpropanesulfonic acid(AMPS).The structure was characterized by hydrogen nuclear magnetic resonance spectroscopy(1HNMR),fourier infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM).The effects of initiator type,initiator dosage,reaction pH,AA dosage,reaction temperature and AMPS dosage on the properties of P(AM-AA-AMPS)were investigated.The results showed that:The viscosity of P(AM-AA-AMPS)aqueous solution was the highest which was 138 mPa·s,when the initiator was redox initiation system(NH4)2S2O8/NaHSO3 combined with azodiisobutanitrile and azodiisobulimidazoline hydrochloride at 0.12wt%,the pH was 7,the dosage of AA was 35wt%,the reaction temperature was 38℃ and the dosage of AMPS was 7wt%.The results showed that the viscosity retention rates of P(AM-AA-AMPS)and P(AM-AA-AMPS)-W solutions at 0.4wt%Na+concentration were 74.67%and 75.81%,respectively,when the thickener was used in coat printing process,and the concentration was 5wt%.After a constant temperature of 85℃ for 5 h,the viscosity was 60249 mPa·s and 61357 mPa·s,respectively.The K/S values of the calico samples were 12.17 and 12.31,respectively.After dry and wet wipe,the rating of the printed fabric samples was above grade 4.When the applied in oil and gas field fracturing,the viscosity of P(AM-AA-AMPS)and P(AM-AA-AMPS)-W solution at 3000 mg/L Na+concentration was 63 mPa·s and 65 mPa·s,respectively,when the thickener concentration was 1t%.After continuous shear at 90℃ and 170 s-1 for 45 min,the viscosity was 51.9 mPa·s and 54.5 mPa·s,respectively.The substitution of isoamyl capylate instead of white oil had no effect on the structure and properties of P(AM-AA-AMPS).(3)P(AM-DAC)was synthesized from AM and acryloxyethyl trimethylammonium chloride(DAC).The structure was characterized by 1HNMR,FT-IR and SEM.The effects of initiator dosage,reaction temperature and DAC dosage on the properties of P(AM-DAC)were investigated.The results showed that when the initiator dosage was 0.18wt%,the reaction temperature was 38℃,and the DAC dosage was 30wt%,the viscosity of P(AM-DAC)aqueous solution was the highest,which was 132 mPa·s.The application results showed that the viscosity retention rates of P(AM-DAC)and P(AM-DAC)-W solutions at 0.4wt%Na+ concentration were 51%and 53.3%,respectively,when the thickener was used in coat printing process,and the concentration was 5wt%.After a constant temperature of 85℃ for 5 h,the viscosity was 30858 mPa·s and 32586 mPa·s,respectively.The K/S values of the calico samples were 12.17 and 12.31,respectively.After dry and wet wipe,the rating of the printed fabric samples was above grade 4.When the applied in oil and gas field fracturing,the viscosity of P(AM-DAC)and P(AM-DAC)-W solution under 3000 mg/L Na+concentration was 58 mPa·s and 67 mPa·s,respectively,when the thickener concentration was 1wt%.After continuous shear at 90℃ and 170 s-1 for 45 min,the viscosity was 36.9 mPa·s and 43.1 mPa·s,respectively.The subsitution of isoamyl caprylate instead of white oil had no effect on the structure and properties of P(AM-DAC).(4)The performance of P(AM-AA-AMPS)and P(AM-DAC)was compared with that of commercially available PTF thickeners for coat printing and VSW thickeners for oil and gas field fracturing.The results showed that the viscosity retention rates of P(AM-AA-AMPS)and PTF thickener solutions were 70.53%and 35.8%,respectively,when the dosage wad 3wt%and the concentration of Na+ was 0.4wt%.After constant temperature at 85℃ for 5 h,the viscosity was 24663 mPa·s and 8765 mPa·s,respectively.The K/S values of the printed fabric samples were 12.17 and 12.823 respectively.After dry and wet wipe,the rating of the printed fabric samples was above grade 4.Compared with PTF thickener,the salt resistance of P(AM-AA-AMPS)was increased by 34.73%,and the heat stability was increased by 54%.The K/S value and friction fastness of the calicloth samples were similar to those of PTF thickener.The fracturing test results showed that the viscosity of P(AM-AA-AMPS)and VSW was 65 mPa·s and 63 mPa·s,respectively,when the dosage was 1wt%and the concentration of Na+ was 3000 mg/L.The viscosity of aqueous solution was 51.9 mPa·s and 64.1 mPa·s,respectively,after continuous shear at 90℃ and 170 s-1 for 45 min.The salt resistance and temperature and shear resistance of P(AM-AA-AMPS)were similar to that of commercially available VSW thickeners.The anionic thickener designed and synthesized in this study could meet the needs of coat printing and oil and gas field fracturing.