Durability and free volume in polymeric coatings studied by positron annihilation spectroscopy

被引:21
作者
Chen, H
Zhang, R
Li, Y
Zhang, JJ
Wu, YC
Sandreczki, TC
Mallon, PE
Suzuki, R
Ohdaira, T
Gu, X
Nguyen, T
Jean, YC [1 ]
机构
[1] Univ Missouri, Dept Chem, Kansas City, MO 64110 USA
[2] Univ Stellenbosch, Div Polymer Sci, Dept Chem, ZA-7602 Matieland, South Africa
[3] Natl Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki, Japan
[4] NIST, Gaithersburg, MD 20899 USA
来源
POSITRON ANNIHILATION, ICPA-13, PROCEEDINGS | 2004年 / 445-6卷
关键词
coatings; durability; lifetime spectroscopy; photo-degradation; polymers; slow positron beam;
D O I
10.4028/www.scientific.net/MSF.445-446.274
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
A simple positron annihilation lifetime (PAL) spectrometer using secondary electrons as the starting signal has been constructed inside the existing slow positron beam at the University of Missouri-Kansas City (UMKC). This instrument has been employed for investigating photo-degradation of amine-cured epoxy coatings exposed to UV radiation. The lifetime results are compared with the S-parameter changes obtained from positron annihilation spectroscopy (PAS). A significant decrease of the S-parameter and of ortho-positronium (o-Ps) intensity in polymers is observed as a function of exposure time and of depth from the bulk to the surface. This is interpreted as due to a loss of free volume and holes resulting from photo-degradation in the samples. UV irradiation in epoxy produces a "dead layer" near the surface up to a thickness of 0.3 mum, where a substantial change in the o-Ps intensity and the S-parameter is observed.
引用
收藏
页码:274 / 276
页数:3
相关论文
共 8 条
[1]   Free-volume hole model for positronium formation in polymers: surface studies [J].
Cao, H ;
Zhang, R ;
Yuan, JP ;
Huang, CM ;
Jean, YC ;
Suzuki, R ;
Ohdaira, T ;
Nielsen, B .
JOURNAL OF PHYSICS-CONDENSED MATTER, 1998, 10 (46) :10429-10442
[2]   Degradation of polymer coating systems studied by positron annihilation spectroscopy. 1. UV irradiation effect [J].
Cao, H ;
Zhang, RW ;
Sundar, CS ;
Yuan, JP ;
He, Y ;
Sandreczki, TC ;
Jean, YC ;
Nielsen, B .
MACROMOLECULES, 1998, 31 (19) :6627-6635
[3]  
Jean Y.C., 2003, PRINCIPLES APPL POSI, P282
[4]   Glass transition of polystyrene near the surface studied by slow-positron-annihilation spectroscopy [J].
Jean, YC ;
Zhang, RW ;
Cao, H ;
Yuan, JP ;
Huang, CM ;
Nielsen, B ;
AsokaKumar, P .
PHYSICAL REVIEW B, 1997, 56 (14) :R8459-R8462
[5]   PRECISION-MEASUREMENT OF THE ORTHOPOSITRONIUM DECAY-RATE USING THE VACUUM TECHNIQUE [J].
NICO, JS ;
GIDLEY, DW ;
RICH, A ;
ZITZEWITZ, PW .
PHYSICAL REVIEW LETTERS, 1990, 65 (11) :1344-1347
[6]   GENERATION OF AN INTENSE PULSED POSITRON BEAM FOR POSITRON LIFETIME AND TOF EXPERIMENTS [J].
SUZUKI, R ;
MIKADO, T ;
CHIWAKI, M ;
OHGAKI, H ;
YAMAZAKI, T .
APPLIED SURFACE SCIENCE, 1995, 85 (1-4) :87-91
[7]   A simple positron lifetime spectrometer for a magnetically guided low-energy beam [J].
Szpala, S ;
Petkov, MP ;
Lynn, KG .
REVIEW OF SCIENTIFIC INSTRUMENTS, 2002, 73 (01) :147-155
[8]   Development of positron annihilation spectroscopy to test accelerated weathering of protective polymer coatings [J].
Zhang, R ;
Cao, H ;
Chen, HM ;
Mallon, P ;
Sandreczki, T ;
Richardson, JR ;
Jean, YC ;
Nielsen, B ;
Suzuki, R ;
Ohdaira, T .
RADIATION PHYSICS AND CHEMISTRY, 2000, 58 (5-6) :639-644