Lignopolymers as viscosity-reducing additives in magnesium oxide suspensions.
Lignopolymers are a new class of polymer additives with the capability to be used as dispersants in cementitious pastes. Made with kraft lignin cores and grafted polymer side-chains, the custom-synthesized lignopolymers were examined in terms of the molecular architecture for viscosity reducing potential in inert model suspensions. Lignin-poly(acrylic acid) (LPAA) and lignin-polyacrylamide (LPAm) have been found to vary the rheology of magnesium oxide (MgO) suspensions based on differences in chain architecture and particle-polymer interactions. A commercial comb-polymer polycarboxylate ester was compared to LPAA and LPAm at 2.7 mg/mL, a typical dosage for cement admixtures, as well as 0.25mg/mL. It was found that LPAm was a more effective viscosity reducer than both LPAA and the commercial additive at low concentrations, which was attributed to greater adsorption on the MgO particle surface and increased steric dispersion from PAm side-chain extension. The influence of chain adsorption and grafted side-chain molecular weight on rheology was also tested.
School of Materials Engineering, Purdue University, 701 West Stadium Ave., West Lafayette, IN 47907, USA. Electronic address: lnielse@purdue.edu.
Lisa R
LR
Murray
Department of Materials Science & Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA. Electronic address: cgupta@andrew.cmu.edu.
Chetali
C
Gupta
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave., Pittsburgh, PA 15213, USA; Department of Biomedical Engineering, Carnegie Mellon University, 4400 Fifth Ave., Pittsburgh, PA 15213, USA. Electronic address: washburn@andrew.cmu.edu.
Newell R
NR
Washburn
School of Materials Engineering, Purdue University, 701 West Stadium Ave., West Lafayette, IN 47907, USA. Electronic address: erk@purdue.edu.
Kendra A
KA
Erk
D000180:Acrylic Resins / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D013535:Suspensions / Q000737:chemistry; D014783:Viscosity; D000099166:Polyacrylamides
D000180:Acrylic Resins; D008031:Lignin; D008277:Magnesium Oxide; D013535:Suspensions; D000099166:Polyacrylamides; C006903:carbopol 940
Cement; Colloids; Comb-polymer adsorption; Lignin; Rheology; Structure–property relationships; Superplasticizer