Preparation And Performance Of Hydrophobically Modified Ethoxylated Urethanes Thickener With Different Terminal Chains

As a class of novel enviromental thickener, hydrophobic ethoxylated urethanes(HEUR) can significantly increase the viscosity of whole system and improve other performance. Due to its unique thickening mechanism, it has been widely used in many industrial fields. How to optimize its structure and performance plays a key role in research and development.This thesis aimed at study the effect of terminal hydrophobic chain numbers/lengths on the HEUR’s aggregation propertites and rheological behavior in soultion, and their relationship between thickening effect.Three novel HEUR polymers(HEUR-3C8, HEUR-2C12, HEUR-C24) end- functionalized by dendritic substituted benzene alcohol with different terminal hydrophobic chains were prepared, their structure, molecular weight and end-capping ratio(ECR) were characterized by fourier transform infrared spectroscop y(FT-IR), gel permeation chromatography(GPC) and nuclear magnetic resonance(1H-NMR) respectively.Critical micelle concentration(CMC), aggreation number(N) and particle size of HEUR solution were characeterizd by surface tension, fluorescence spectrum(FR) and dynamic light scattering(DLS) respepectively. It was found that HEUR-3C8’s more hydrophobic chains led to lower CMC, less N and smaller micelle size, indicating the hydrophobic segment is the dominant factor for the aggregation property.HEUR’s steady state and oscillatary shear results showed that HEUR-3C8 act as Newtonian fluid at low shear rate while HEUR-2C12 and HEUR-C24 showed shear thinning over the whole shear rate. Due to its shorter hydrophobic tail and relaxtion time, HEUR-3C8 behave as viscoelastic fluid, while HEUR-2C12 and HEUR-C24 formed elastic body. When temperature rises, the viscosity of HEUR-3C8 drops significantly compared with HEUR-C24 and accompanied with shear-thickening.The amount of HEUR polymers required for the formation of a complete association network in latexes decreases in the order of terminal hydrophobic chain number, i.e., HEUR-C24(0.6 wt%), HEUR-2C12(0.4 wt%), HEUR-3C8(0.2 wt%).