Development of Tg-less epoxy thermosets by introducing crosslinking points into rigid mesogenic moiety via Schiff base-derived self-polymerization

被引:8
作者
Ota, Saki [1 ]
Michishio, Koji [2 ]
Harada, Miyuki [1 ]
机构
[1] Kansai Univ, Fac Chem Mat & Bioengn, 3-3-35 Yamate Cho, Suita, Osaka 5648680, Japan
[2] Natl Inst Adv Ind Sci & Technol, 1-1-1 Umezono, Tsukuba, Ibaraki 3058568, Japan
关键词
Epoxy resin; Mesogenic epoxy; Thermal property; Self-polymerization; T-g-less; Free volume; LIQUID-CRYSTALLINE EPOXY; CURED POLYMER; THERMAL-CONDUCTIVITY; THERMOMECHANICAL PROPERTIES; MECHANICAL-PROPERTIES; RESIN; COMPOSITE; KINETICS; MONOMER; CTE;
D O I
10.1016/j.mtcomm.2022.103501
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Novel glass-transition-temperature-less (T-g-less) epoxy thermosets were prepared by a Schiff base (CH=N)-derived self-polymerization of mesogenic epoxy. The self-polymerization mechanism was verified by differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The epoxy-CH=N addition reaction formed a new tertiary amine, introducing a crosslinking point into the rigid mesogenic moiety. Dynamic mechanical analysis of the cured system showed a slight alpha-relaxation in tan delta, and a high storage modulus was maintained at > 250 C. Also, no drastic increase in the coefficient of thermal expansion related to the glass-transition behavior was observed. The results suggested that the crosslinking point formed in the rigid mesogenic moiety effectively suppressed the thermal motion of networked chains, resulting in T-g-less behavior. An imidazole catalyst was used to enhance the self-polymerization reactivity. The imidazole content effect on the temperature-dependency of the mean free volume in the network structure was investigated by positron annihilation lifetime spectrometry.
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页数:14
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