Grafting of polyethylenimine onto cellulose nanofibers for interfacial enhancement in their epoxy nanocomposites

Jiangqi Zhao; Qingye Li; Xiaofang Zhang; Meijie Xiao; Wei Zhang; Canhui Lu

doi:10.1016/j.carbpol.2016.11.025

Grafting of polyethylenimine onto cellulose nanofibers for interfacial enhancement in their epoxy nanocomposites

Carbohydr Polym. 2017 Feb 10:157:1419-1425. doi: 10.1016/j.carbpol.2016.11.025. Epub 2016 Nov 10.

Authors

Jiangqi Zhao¹, Qingye Li¹, Xiaofang Zhang¹, Meijie Xiao¹, Wei Zhang², Canhui Lu³

Affiliations

¹ State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China.
² State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China. Electronic address: weizhang@scu.edu.cn.
³ State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute at Sichuan University, Chengdu 610065, China. Electronic address: canhuilu@263.net.

PMID: 27987851
DOI: 10.1016/j.carbpol.2016.11.025

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.

Keywords: Cellulose nanofibers (CNFs); Coefficients of thermal expansion (CTE); Epoxy resin; Interfacial enhancement; Nanocomposites; Polyethylenimine (PEI).