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A Facile Strategy for Preparing Self‐Healing Polymer Composites by Incorporation of Cationic Catalyst‐Loaded Vegetable Fibers
Author(s) -
Xiao Ding Shu,
Yuan Yan Chao,
Rong Min Zhi,
Zhang Ming Qiu
Publication year - 2009
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200801827
Subject(s) - epoxy , materials science , cationic polymerization , monomer , composite material , catalysis , polymerization , polymer , polystyrene , composite number , polymer chemistry , organic chemistry , chemistry
A two‐component healing agent, consisting of epoxy‐loaded microcapsules and an extremely active catalyst (boron trifluoride diethyl etherate, (C 2 H 5 ) 2 O · BF 3 )), is incorporated into epoxy composites to provide the latter with rapid self‐healing capability. To avoid deactivation of the catalyst during composite manufacturing, (C 2 H 5 ) 2 O · BF 3 is firstly absorbed by fibrous carriers (i.e., short sisal fibers), and then the fibers are coated with polystyrene and embedded in the epoxy matrix together with the encapsulated epoxy monomer. Because of gradual diffusion of the absorbed (C 2 H 5 ) 2 O · BF 3 from the sisal into the surrounding matrix, the catalyst is eventually distributed throughout the composites and acts as a latent hardener. Upon cracking of the composites, the epoxy monomer is released from the broken capsules, spreading over the cracked planes. As a result, polymerization, triggered by the dispersed (C 2 H 5 ) 2 O · BF 3 , takes place and the damaged sites are rebonded. Since the epoxy–BF 3 cure belongs to a cationic chain polymerization, the exact stoichiometric ratio of the reaction components required by other healing chemistries is no longer necessary. Only a small amount of (C 2 H 5 ) 2 O · BF 3 is sufficient to initiate very fast healing (e.g., a 76% recovery of impact strength is observed within 30 min at 20 °C).