UV-curable epoxy materials are widely used in coatings, electronics industry and 3D printing technology. However, high flammability is one of the main problems of materials. During the combustion process, the photoinitiator remaining in the UV curing material can generate active free radicals, which accelerates the combustion degradation process of the polymer. Intumescent flame retardants are often used for the flame retardant properties of UV-cured epoxy materials, but the disadvantage is that the polyol used as a carbon source is too water-absorbing, which affects the mechanical properties of epoxy materials.

　　 In response, Professor Ni Xiuyuan from Fudan University and Dr. Zheng Tiancheng from his research group used polyols to be loaded into clay nanotubes, which effectively improved the hygroscopicity of polyols and successfully prepared environmentally stable UV-curable epoxy materials. .

　　 Halloysite nanotubes (HNTs) have good compatibility in polar polymers and are often used as nanocarriers, and HNTs can form a network during the combustion process The structure is conducive to the improvement of flame retardant performance. In this study, the researchers first prepared a modified halloysite tube (HNT-P) by a vacuum adsorption method, that is, the air in the lumen of the HNT was replaced by a pentaerythritol (PER) solution by ultrasonic treatment, and the HNT was loaded with PER . Then add APP and HNT-P in different proportions to UV curable epoxy resin (EP). Through continuous stirring to prepare a homogeneous mixture, namely EP / HNT-P composite material. In addition, the researchers also prepared EP / HNT / PER composites by adding PER and HNT; in order to make HNT-P composites and HNT and PER directly added to the composites for moisture resistance.

　　researchers test and analyze the combustion performance and moisture absorption of composite materials:

The composition and LOI test results of pure EP, EP / HNT-P and EP / HNT / PER composite materials are listed in Table III. The LOI value of pure EP is only 18, which has high flammability; APP / HNT-P (EP / HNT-P) UV curing epoxy resin, with the increase of APP / HNT-P addition, the LOI value increases significantly. When 35wt% APP/HNT-P is added, the LOI value of EP/HNT-P can reach 28.2. However, the LOI of simple blended EP/HNT/PER composites is only about 20. The results show that the two components in HNT-P have a good synergistic flame retardant effect.

　　 In addition, the CC test results showed that compared with pure EP, the TTI of 25wt% EP2 increased from 24s to 33s, and the pHRR and THR decreased from 1002.4 kM/m2 and 104.1 MJ/m2 to 562 kM/m2, respectively. And 51.8 MJ/m2, showing lower flammability. APP / HNT-P may have the following reactions during the combustion process, leading to the improvement of combustion performance.

　　 The maximum moisture absorption rate (Mmax-m) of the test material represents the moisture absorption of the material (Figure 5). Compared with EP / HNT / PER, EP / The Mmax-m of HNT-P decreased from 2.08wt% to 0.87wt%, a decrease of 58.2%. When the temperature is raised to 85°C, it drops from 5.68wt% to 2.90wt%, a drop of 48.9%. In addition, the water absorption rate (Mmax-w) was reduced from 7.83wt% of EP/HNT/PER to 6.42wt% of EP/HNT-P when tested for water absorption at 85℃ (Figure 6). The results show that EP/HNT-P composites have better moisture resistance and water resistance than EP/HNT/PER composites.

　　 Finally, the researchers tested the storage modulus of EP / HNT / PER and EP / HNT-P with the addition of two composite materials through DMA. The former caused the resin to soften due to the hydrophilicity of PER, and the latter was already due to the hydrophilicity of PER. It is loaded into HNT, so the softening effect is reduced. The results show that the use of HNT-P can effectively inhibit the water absorption of PER.

　　 Generally speaking, this study on loading PER with HNT and synergistically modifying the flame retardant and water resistance of UV-curable epoxy resin with APP is still very successful. By loading PER in hollow nanotubes to form a new structure, it effectively alleviates the humidity sensitivity of polyols and other issues.