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Yuan L.,Soochow University of China | Yuan L.,Jiangsu Yingxiang Chemical Fiber Stock Co. | Yuan L.,University of Southern California | Huang S.,University of Southern California | And 7 more authors.
Polymers for Advanced Technologies | Year: 2014

Self-healing cyanate ester resins (CE) were developed by adding low molecular weight poly(phenylene oxide) (PPO) resin, yielding a high performance CE/PPO system via a low-temperature process. The addition of PPO improved the flexural strength and fracture toughness of the CE matrix without sacrificing thermal properties. CE/PPO formulations with 5, 10, and 15wt.% PPO showed 43%, 65%, and 105% increase in fracture toughness due to a combination of crack deflection, crack pinning, and matrix cavitation around second-phase particles. When PPO was introduced into the CE, dielectric properties were either unchanged or declined. During thermal treatment to heal damaged CE, liquid PPO flowed into cracks, and during subsequent cooling, solidified to bond the crack surfaces. The self-healing efficiency for CE with 15wt.% PPO after heating to 220°C for 1h exhibited a recovery of 73% in toughness and 81% in microtensile strength. © 2014 John Wiley & Sons, Ltd. Source


Yuan L.,Soochow University of China | Yuan L.,Jiangsu Yingxiang Chemical Fiber Stock Co. | Yuan L.,University of Southern California | Chen F.,Soochow University of China | And 9 more authors.
Polymer Bulletin | Year: 2014

Polymeric microcapsules (MCs) filled with catalyst can be controlled to release the catalyst to initiate the polymerization reaction. In the present work, poly(urea-formaldehyde) (PUF) MCs filled with DBTDL (PUF/DBTDL MCs) were prepared using urea (U) and formaldehyde (F) as the wall shell materials by in situ polymerization. The U-F resins could easily polymerize in the presence of the core material DBTDL to produce PUF polymers, then they deposited on the surface of the DBTDL droplets, forming PUF/DBTDL MCs. The decomposition temperature (T d) at 5 % weight loss of PUF/DBTDL MCs was about 245 C. The application of PUF/DBTDL MCs to cyanate ester resins preliminarily showed the reaction control capability of the MCs due to the slow release of DBTDL through the wall shell. © 2013 Springer-Verlag Berlin Heidelberg. Source

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