Chemically stable polyphenylene ether (PPO) microcapsules (MCs) filled with epoxy resins (PPO-EP MCs) were prepared using low-molecular-weight PPO with vinyl end-groups as shell wall and epoxy resins as core material using an oil-in-water emulsion solvent evaporation method. This method for synthesizing MCs with PPO shell walls is simple, convenient and novel, which can avoid the influence of processing parameters on the chemical stability of the epoxy resin core material. The resulting PPO-EP MCs exhibit good chemical stability below 255 °C mainly owing to the absence of a polymerization catalyst of the epoxy resins. The initial thermal decomposition temperature of the MCs is about 275 °C. The MCs were embedded in a 4,4′-bismaleimidodiphenylmethane/O,O′-diallylbisphenol A (BMI/BA) thermosetting resin system. When processed at high temperature (up to 220 °C), the microencapsulated epoxy resins could be released from the fractured MCs to matrix crack surfaces and bond the crack surfaces. An amount of 8 wt% MCs restored 91 and 112% of the original fracture toughness of the BMI/BA matrix when heated at 220 °C/2 h and 80 °C/1 h + 220 °C/2 h, respectively. The MCs only slightly decreased the thermal property of the matrix. © 2016 Society of Chemical Industry

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 15 wt.% 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 15 wt.% PPO after heating to 220°C for 1 h exhibited a recovery of 73% in toughness and 81% in microtensile strength. Copyright © 2014 John Wiley & Sons, Ltd.

Novel polyphenylene oxide (PPO) microcapsules filled with epoxy resins (PPOMCs) were synthesized by in situ polymerization technology with 2, 6-dimethy phenol as shell materials and diglycidyl ether of bisphenol A epoxy resins as core materials. The structures and morphologies of PPOMCs were characterized using Fourier-transform infrared spectroscopy, micro-confocal Raman microscope, laser scanning confocal microscopy, scanning electron microscopy and optical microscopy, respectively. The thermal properties of PPOMCs were investigated using differential scanning calorimetry and thermogravimetric analysis. The influences of different processing parameters such as the weight ratio of shell material to core material, kind of surfactant and reaction temperature on the morphologies and sizes of PPOMCs were investigated. Preliminary investigation on application of PPOMCs to thermosetting resins 4,4′-bismaleimidodiphenylmethane/O,O′-diallylbisphenol A (BMI/BA) system was conducted. Results indicate that PPOMCs can be synthesized successfully. The sizes and surface morphologies of PPOMCs may be significantly affected by different processing parameters. PPOMCs can be well prepared at about 30°C, and they depend strongly on the kind of surfactant and the weight ratio of shell material to core material. PPOMCs basically exhibit high thermal stability when the temperature is below 258°C. The addition of PPOMCs can improve the mechanical properties and maintain the thermal properties of BMI/BA system. The released core materials from PPOMCs may repair the matrix cracks through the polymerization of epoxy resins initiated by curing agent. Copyright © 2012 John Wiley & Sons, Ltd.

Novel high performance self-healing 4,4′-bismaleimidodiphenylmethane (BDM)/diallylbisphenol A(BA)/poly(phenylene oxide) microcapsules filled with epoxy resin (PPOMCs) systems with low temperature processability were developed. The effects of PPOMCs on the reactivity of BDM/BA resin system were investigated; the properties of cured BDM/BA/PPOMCs systems such as fracture toughness, dynamic mechanical property, dielectric property, and self-healing ability were discussed. The morphologies of the cured resin systems were characterized using scanning electronic microscope and light microscopy. Results reveal that the addition of PPOMCs can catalyze the polymerization reaction of BDM/BA resins. BDM/BA systems with appropriate PPOMCs content cured at low temperature possess excellent fracture toughness, high glass transition temperature (T_g), and low dielectric property. The self-healing ability of BDM/BA can be realized by the introduction of PPOMCs owing to the polymerization of the released core materials from PPOMCs. The self-healing efficiency of healed BDM/BA/PPOMCs systems can be influenced by the size and content of PPOMCs and the contact areas between the crack surfaces. © 2013 Society of Plastics Engineers

The encapsulated catalyst can be released under stimulation conditions to control the polymerization reaction. In this study, poly(urea-formaldehyde) (PUF) microcapsules (MCs) filled with dibutyltin dilaurate (DBTDL) catalyst (PUF/DBTDL MCs) were applied to bisphenol A dicyanate ester (BADCy) resins to develop a novel low temperature cure high performance BADCy/MCs systems. The effect of PUF/DBTDL MCs on the reactivity of BADCy was investigated. The mechanical property, the thermal property, the water uptake, and the dielectric property of cured BADCy/MCs resin systems were discussed in detail. Results indicate that roughly varying the content of the encapsulated DBTDL can easily and safely adjust the polymerization temperature. The BADCy systems with proper content of MCs cured at low temperature show excellent mechanical property, good thermal property, low water uptake, and low dielectric property. When the content of MCs is 0.125 wt%, the cured BADCy/MCs system has the optimal integrated properties owing to the formation of more uniform crosslinked structure and high conversion of cyanate ester (OCN) groups resulting from the slow release of DBTDL catalyst through the wall shell under heating condition. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

Organic rectorite (OREC) was applied to bisphenol A dicyanate ester (BADCy) resin to develop a novel BADCy/OREC system. The influence of OREC on the reactivity of BADCy was discussed. The morphologies of cured BADCy/OREC systems were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The static and dynamic mechanical properties as well as the hot water resistance of cured BADCy/OREC systems were evaluated. Results indicate that the addition of OREC can catalyze the reaction of BDACy resin. The intercalated structure and exfoliated structure of silicate platelets may be formed in the cured BADCy/OREC composites. The suitable amount of OREC canimprove the flexural strength, the impact resistance and the hot water resistance of cured BADCy. OREC can maintain the glass transition temperature (T_g) and have slight influence on the dielectric property of cured BADCy. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Poly(urea-formaldehyde) microcapsules filled with epoxy resins(MCEs) were applied to bisphenol A dicyanate ester (BADCy) resin to develop a novel BADCy/MCEs system. The effects of MCEs on the viscosity and the reactivity of BADCy were investigated. The mechanical properties and the hot water resistance of cured BADCy/MCEs systems were evaluated. The morphologies of the cured systems were characterized using a scanning electron microscope. The thermal property of cured systems was investigated using thermogravimetric analysis. The results indicate that MCEs may influence the reaction of BDACy. The proper addition of MCEs can significantly improve the mechanical property and the hot water resistance of cured BADCy resin. MCEs have a negative influence on the initial thermal decomposition temperature (T_d) of cured BADCy resin. POLYM. COMPOS., 2010. © 2008 Society of Plastics Engineers.