Hyperbranched polyester modified nanoparticles can greatly enhance impregnating varnish  performance.
Using Al2O3 nano-particles modiffied by aliphatic hyperbranched polydihydroxytoluene propi-onate(HMPA) as filler, using insulating impregnating varnish as matrix to prepare thermal conductivity impregnating varnish to study its performance. Get the following conclusions: (a) hyperfunctional Al2O3 nanoparticles can effectively improve the dispersion performance and interface compatibility of the particles in the varnish, when the particles filling amount is 20%, hyperfunctional Al2O3 nanoparticles can still evenly dispersed in the varnish, almost invisible agglomeration, while the particles without modification have serious agglomeration. (2) varnish filled with hyperfunctional Al2O3 nanoparticles, its impact strength, thermal conductivity is significantly improved. When the filling amount is 20%, varnish filled with hyperfunctional Al2O3 nanoparticles reaches maximum impact properties which are 4.96 times than non filled. When the filler content is 25% and filled with hyperfunctional Al2O3 nanoparticles, impregnating varnish thermal conductivity reaches the maximum which is 1.82 times than non filled. (3)composite volume resistivity is increased if filling with hyperfunctional Al2O3 nanoparticles , but increased slightly, keep within an order of magnitude, the varnish is still able to maintain good electrical insulation. Weihai CY Dendrimer Technology Co. Ltd forwards from “Study of Impregnating Varnish Modified with Hyperbranched Al2O3 Nanoparticles” Fu JiFang a, b, Xiao Yinglin a, Chen Yi a, b, Shi Liyi a, b, Chen Liya a, Zhong Qingdong a, b (a. Nano-Science and Technology Research Center of Shanghai University ; b. School of Materials Science and Engineering, Shanghai University, Shanghai 200072) Insulation Materials, 2011, 44 (2), 4-8