The varying mass ratios of soft and hard segments in waterborne polyurethane films: Performances of thermal conductivity and adhesive properties

Abstract

Waterborne polyurethanes (WPUs) with different mass ratios of soft and hard segments were synthesized by toluene diisocyanate, polypropylene glycol (PPG) and ethylene glycol (EG). It was shown that the PPG-based WPU with a mass ratio of soft and hard segments of 3:2 expressed a highest thermal conductivity (∼0.374 W/ m•K), but showed a lowest T-peel strength (21.55 N/25 mm). As the mass ratio of soft and hard segments increased to 4:1, the T-peel strength was increased to 136.14 N/25 mm and thermal conductivity was decreased to a lowest value (∼0.306 W/m•K). To gain more understandings a number of analytic were carried out, such as FTIR, TG, DSC, DMA, AFM and XRD. Furthermore, mechanical properties of the PPG-based WPU coatings were tested as well. A possible explanation for the change in properties is due to the degree of phase separation and crystallinity, which was increased with the increasing of hard segment content. As a result, the hard and soft segments formed orderly oriented stacked structures by owing to the increasing of phase separation.

Green Synthesis of Waterborne Polyurethane for High Damping Capacity

“…Bright domains indicate the aggregation of hard segments, while dark domains correspond to soft segments. [ 51,52 ] WPU3 and WPU4 films have smooth surfaces with evenly distributed columnar protrusions, indicating a low degree of hard segment aggression. WPU5, WPU6, and WPU7 display obvious columnar protrusions and surface roughness caused by the hard segments’ aggregation.…”

Study on structure-induced heat transfer capabilities of waterborne polyurethane membranes

“…a) 3D morphology of WPU membranes with ratio of soft segment to hard segment of 3:2, 7:3, 3:1 and 4:1 respectively, among the membrane with 40 % of hard segment content showed a significant distribution of hard segment and soft segment. And phase separation degree decreased with the decreasing of hard segment content; b) XRD analysis showed two diffraction peaks at 2θ of 20°and 45°respectively in XRD spectra, and the amplification of 2θ of 45°and corresponding calculation of crystal size of lattice showed a higher value in WPU membrane (0.146 Å) with 40 % of hard segment content, while the crystalline sizes of 30 %, 25 % and 20 % of hard segment content are 0.074 Å, 0.065 Å and 0.064 Å respectively; c) DSC analysis showed a higher enthalpy in WPU membrane with 40 % of hard segment content during the whole heating process, and enthalpy was decreased with decreasing of hard segment content; d) TCC measurement of WPU membranes 21 . Copyright 2019.…”

“…In this study, series of WPU emulsions were synthesized to select optimal prepolymer components by referring to optimization orthogonal arrays, then based on the fixed prepolymer components a further analysis of varying hard segment content and hydrophilic fragments on structural features were carried out afterwards [13,16,[20][21][22]. Finally, thermal annealing treatment on WPU membranes was conducted as well.…”

Revised Manuscript with Corrections: Polyurethane-Based Conductive Composites: From Synthesis to Applications

“…They have outstanding properties, including excellent elasticity, elongation, high impact, tensile strength, high abrasion resistance, good weathering resistance, excellent gloss, color retention, and corrosion resistance properties [ 2 ]. The aforementioned properties allow them to find applications in a variety of industries, including leather [ 3 ], foams [ 4 , 5 , 6 ], furniture, fibers [ 7 , 8 , 9 ], elastomers [ 10 ], adhesives [ 11 ], paints [ 12 , 13 ], coatings [ 14 ], sensors [ 7 ], electronic components [ 15 ], biomedical [ 16 , 17 ], and others [ 18 , 19 ]. In spite of versatile applications, the use of standalone PU often cannot ensure that sufficient thermal and mechanical performances are attained.…”