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P
olyurethane (PUR) is a synthetic polymer with unique properties.1-4 It is widely used in adhesives and coatings. Waterborne PUR
(WPUR) is environmentally friendly be- cause only water evaporates during dry- QVO 1\ Q[ VWV\W`QK VWVÆIUUIJTM IVL nonpolluting.5-7
It has poor solvent, heat,
water, and mechanical properties, thus inhibiting its extensive application.8-10 To improve the performance of
WPUR, physical blending and chemical UWLQÅKI\QWV IZM ][ML 11-12
Blending with
water-based resins yields better perfor- mance and is widely used because it is convenient, low-cost, and easy to imple- UMV\ +PMUQKIT UWLQÅKI\QWV QV^WT^M[ \PM introduction of other components such as polylactic acid or epoxy resin to form chemical bonds with polymer chains. It leads to better stability of the chemical bond.13-14 Microcrystalline cellulose (MCC) par-
\QKTM[ IZM ÅJZW][ ZWL[ KWV[Q[\QVO WN IV IOOZMOI\M WN QV\MZTQVSML UQKZW ÅJZQT[ IVL MIKP UQKZW ÅJZQT KWV\IQV[ KPIQV[ WN TQVMIZ G (1-4) d-glucopyranose polymer units.15 It is a colorless, tasteless, short, rod-like XIZ\QKTM WN ÅJZW][ KMTT]TW[M UIQVTa _WWL pulp), which is lightweight, low cost, and can be recycled. The size of the particle is from 20 to 80 µm and the degree of polymerization is from 15 to 375.16-18 In this work, MCC was added as a
modifier into the synthesis process of WPUR while changing the order of add- ing MCC and the hydrophilic cross- linking time. Finally, some properties _MZM KWUXIZML JM\_MMV \PM UWLQÅML ?8=: ÅTU[ IVL IV ]VUWLQÅML WVM
Experimental Procedures Materials
All of the chemical reagents used in
this work were of analytical grade. Isophorone diisocyanate (IPDI) was used I[ ZMKMQ^ML _Q\PW]\ N]Z\PMZ X]ZQÅKI\QWV
NACE International, Vol. 51, No. 4 April 2012 MATERIALS PERFORMANCE 35
Microcrystalline Cellulose 5WLQÅML
Waterborne Polyurethane
SIGANG ZHANG, QIANG GUO, ZHENGPING ZHAO, JINLIANG SUN, AND ZHIJUN NIE, Shanghai University, Shanghai, China
Waterborne polyurethane (WPUR) was
synthesized. Microcrystalline cellulose was used to prepare a series of modified WPUR. Te
mechanical properties of modified WPUR films showed higher tensile strength and elongation than the unmodified one. Te water resistance of films was also greatly enhanced after modification.