TY - JOUR
T1 - Environmental degradation of epoxy-organoclay nanocomposites due to UV exposure. Part I
T2 - Photo-degradation
AU - Woo, Ricky S.C.
AU - Chen, Yanghai
AU - Zhu, Honggang
AU - Li, Jing
AU - Kim, Jang Kyo
AU - Leung, Christopher K.Y.
N1 - Funding Information:
This project was supported by the Research Grant Council of Hong Kong Special Administration Region (Project Number HKUST6184/03E). Technical assistance from the Advanced Engineering Materials Facility (AEMF) and the Materials Characterization and Preparation Facilities (MCPF), HKUST is much appreciated. Part of the paper was presented at SAMPE ’06 at Long Beach, CA, USA in May 2006.
PY - 2007/12
Y1 - 2007/12
N2 - The environmental degradation mechanisms of epoxy-organoclay nanocomposites due to accelerated UV and moisture exposure are studied. Various characterisation tools, including FTIR, SEM, XRD and XRF analyses, were used to evaluate the effects of clay content on the progressive changes in chemical element, topography and colour of the nanocomposite. It is found that microcracks started to appear on both the neat epoxy and nanocomposite surface after about 300 h of UV exposure. The nanocomposite exhibited thicker and shallower cracks with a less degree of discoloration than the neat epoxy due to the diffusion barrier characteristics of organoclay with high aspect ratio. The presence of transition metal ions along with low-molecular-weight organic modifiers in organoclay, however, accelerated the degradation of polymer, counterbalancing the above ameliorating barrier properties of clay. FTIR analysis indicated that photo-degradation generated carbonyl groups by chain scission and the rate was slightly higher for the nanocomposites than for the neat epoxy. While moisture further accelerated the photo-degradation process through the enhanced mobility of free radicals and ions, the organoclay could limit the deteriorating effect of moisture, resulting in much better overall resistance to photo-degradation in the presence of moisture for the nanocomposite than the neat epoxy.
AB - The environmental degradation mechanisms of epoxy-organoclay nanocomposites due to accelerated UV and moisture exposure are studied. Various characterisation tools, including FTIR, SEM, XRD and XRF analyses, were used to evaluate the effects of clay content on the progressive changes in chemical element, topography and colour of the nanocomposite. It is found that microcracks started to appear on both the neat epoxy and nanocomposite surface after about 300 h of UV exposure. The nanocomposite exhibited thicker and shallower cracks with a less degree of discoloration than the neat epoxy due to the diffusion barrier characteristics of organoclay with high aspect ratio. The presence of transition metal ions along with low-molecular-weight organic modifiers in organoclay, however, accelerated the degradation of polymer, counterbalancing the above ameliorating barrier properties of clay. FTIR analysis indicated that photo-degradation generated carbonyl groups by chain scission and the rate was slightly higher for the nanocomposites than for the neat epoxy. While moisture further accelerated the photo-degradation process through the enhanced mobility of free radicals and ions, the organoclay could limit the deteriorating effect of moisture, resulting in much better overall resistance to photo-degradation in the presence of moisture for the nanocomposite than the neat epoxy.
KW - A. Epoxy/Clay Nanocomposite
KW - A. Nano-structures
KW - A. Polymer-matrix composites (PMCs)
KW - B. Environmental degradation
KW - D. Chemical analysis
UR - http://www.scopus.com/inward/record.url?scp=35248819150&partnerID=8YFLogxK
U2 - 10.1016/j.compscitech.2007.03.004
DO - 10.1016/j.compscitech.2007.03.004
M3 - Article
AN - SCOPUS:35248819150
SN - 0266-3538
VL - 67
SP - 3448
EP - 3456
JO - Composites Science and Technology
JF - Composites Science and Technology
IS - 15-16
ER -