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Application of azodiisobutyronitrile and azobisisoheptonitrile in low‐density unsaturated polyester resin manufacturing
Author(s) -
Guo LiangZhi,
Wang XiaoJun,
Zhang YiFan,
Wang XiaoYao
Publication year - 2014
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.40238
Subject(s) - unsaturated polyester , polyester , materials science , polymer science , composite material , polyester resin , polymer chemistry
Low‐density unsaturated polyester resin (LDUPR) is an extended application of unsaturated polyester resin (UPR) material. In this study, azodiisobutyronitrile (AIBN) and azobisisoheptonitrile (ABVN) were presented as composite foaming agents and as initiators in LDUPR manufacturing. On the basis of the kinetics of AIBN and ABVN, their optimum half‐lives ( t 1/2 's) for LDUPR were both 1.0 h. In this study, the mass ratio of AIBN and ABVN was chosen at 7:3, and the preferred amount of the composite foaming agent was 2 wt % resin. They were treated at a molding temperature of 78.7 ± 1.0°C. The obtained LDUPR had an apparent density of 0.37 ± 0.01 g/cm 3 and a specific compression strength of 35.58 ± 1.50 MPa·g −1 ·cm −3 ; it approached the highest specific compression strength value of rigid polyurethane foam (28–35 MPa g −1 cm −3 ). A dual‐initiation and dual‐foaming mechanism based on the dual‐exothermic decomposition properties of the composite foaming agent was proposed with the support of the differential scanning calorimetry and scanning electron microscopy results. In the first stage, ABVN decomposed, released bubble nuclei, and initiated UPR cross‐polymerization. The bubble nuclei spread in the resin glue and grew. In the second stage, the gas in resin glue was enriched by the AIBN decomposition. The gelation time of the resin glue was influenced by AIBN and delayed. With the curing of resin, more bubbles grew up, took shape, and were retained in the UPR matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40238.