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Simultaneous enhancement in strength and elongation of waterborne polyurethane and role of star‐like network with lignin core
Author(s) -
Cui Guojuan,
Fan Honglei,
Xia Wenbing,
Ai Fujin,
Huang Jin
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.28052
Subject(s) - elongation , polyurethane , materials science , composite material , ultimate tensile strength , lignin , star (game theory) , modulus , izod impact strength test , chemistry , organic chemistry , mathematics , mathematical analysis
We have reported that a star‐like network structure with lignin as center in polyurethane resulted in the simultaneous enhancement in mechanical strength and elongation. In this study, we aimed to enhance the mechanical properties of waterborne polyurethane by adding nitro‐lignin (NL) to form analogical star‐like network. It was found that the resultant material has optimal mechanical performances when the NL content is 3.0 wt %, i.e., its apparent mechanical strength and elongation increased by about 80% at one time. Especially, its real mechanical strength reaches 71.3 MPa at this time, which is 3.6‐fold over that of neat waterborne polyurethane material. The simultaneous enhancements in strength and elongation are attributed to the forming of star‐like network in the composites. The stiffness of lignin improved the mechanical strength, while the entangling and crosslinking in polyurethane component increased the elongation. However, higher NL loading and lower grafting level induced the forming of supramolecular NL aggregates, and hence greatly inhibited star‐like network, resulting in lower mechanical strength and elongation. However, the Young's modulus of the material is enhanced with an increase of rigid supramolecular aggregates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008