Novel flame-resistant UV-curable epoxy (EP) composites were prepared using the organophosphorous flame retardant dimethyl methylphosphonate (DMMP) which was loaded into halloysite nanotubes (HNTs).

The halloysite nanotubes (HNTs) were loaded with pentaerythritol (PER). The as‐prepared composite (HNT‐P) and ammonium polyphosphate (APP) was subsequently added to the UV‐curable epoxy resins, giving a new flame‐resistant system. Loading of the hydrophilic PER into HNT can reduce the moisture absorption in the UV‐curable epoxy resins. The flame retardancy was evaluated by means of the cone calorimeter and limit oxygen index test. The results showed that the flame retardancy of the modified epoxy resin was greatly improved with an obvious decrease in both the heat release and smoke release. Moreover, it was revealed that HNT could catalyze the reaction of APP and PER, and the burning surface of the epoxy resin should be covered by the polyphosphoric‐HNT intumescent char layer. We have measured the moisture sorption and dynamic mechanical properties of the UV‐cured epoxy resins. As compared to the use of the simple mixture of PER and HNT, the use of the HNT‐P nearly kept the storage modulus at about 1809 Mpa and reduced the moisture absorption by 58.2 wt % at 40 °C. The results proved that the addition of the HNT‐P obtained lower moisture absorption and higher stability of the mechanical properties than adding the simple mixture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45045.

No abstract

We prepared a new size-stable UV-cured material by loading a radical scavenger, 4-methoxyphenol (MEHQ), into halloysite nanotubes (HNTs) to improve the size-stability of UV-cured products. Loading the MEHQ into halloysite nanotubes was intended to protect the curing reaction from the typical inhibitive influence of a radical scavenger. After the curing process, heating treatment was performed on the cured products to accelerate the release of MEHQ from the halloysite lumen. The Brunauer-Emmett-Teller tests and transmission electron micrographs showed that MEHQ was successfully loaded into the halloysite lumen. The photopolymerization kinetic curves of composites revealed that adding the MEHQ-loaded halloysite nanotubes (HNTs-M) into UV-cured materials enabled faster photopolymerization rate than adding a simple mixture of HNTs and MEHQ. With MEHQ loaded in HNTs, the inhibition influence of MEHQ could be reduced. The results of the size-stability test showed that composites with HNTs-M underwent lower deformation during daily use than neat cured materials. In particular, the volume shrinkage of the composites with 8 wt% HNTs-M in daily use was decreased by 51.3%. The results of the release experiment showed that the release rate of MEHQ could be increased through heating treatment. This method may be used to improve the size-stability of UV-curable materials in the future.