title: Grafting of polyethylenimine onto cellulose nanofibers for interfacial enhancement in their epoxy nanocomposites.
abstract: Cellulose nanofibers (CNFs) were surface-modified with polyethyleneimine (PEI), which brought plentiful amine groups on the surface of CNFs, leading to a reduced hydrogen bond density between CNFs and consequently less CNFs agglomerates. The amine groups could also react with the epoxy as an effective curing agent that could increase the interfacial crosslinking density and strengthen interfacial adhesion. The tensile strength and Young's modulus of CNFs-PEI/Epoxy nanocomposites were 88.1% and 237.6% higher than those of neat epoxy, respectively. The tensile storage modulus of the nanocomposites also increased significantly at the temperature either below or above the Tg. The coefficient of thermal expansion for the CNFs-PEI/Epoxy nanocomposites was 22.2ppmK-1, much lower than that of the neat epoxy (88.6ppmK-1). In addition, the thermal conductivity of the nanocomposites was observed to increase as well. The exceptional and balanced properties may provide the nanocomposites promising applications in automotive, construction and electronic devices.
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China.
authors.forename: Jiangqi
authors.initials: J
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China.
authors.forename: Qingye
authors.initials: Q
authors.lastname: Li
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China.
authors.forename: Meijie
authors.initials: M
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China. Electronic address: weizhang@scu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China. Electronic address: canhuilu@263.net.
authors.forename: Canhui
authors.initials: C
authors.lastname: Lu
keywords: Cellulose nanofibers (CNFs); Coefficients of thermal expansion (CTE); Epoxy resin; Interfacial enhancement; Nanocomposites; Polyethylenimine (PEI)