| As one of the most important thermosetting resins, unsaturated polyester (UP) resins have been well investigated and widely used as coatings and structural adhesives for glass (or carbon)-fiber composites in construction, boat-building and automotive industry because of their low cost, ease of processing and good balance of mechanical and chemical properties. In recent years, many efforts have been paid to improving the toughness and thermostability of UP resins, whereas few reports were regarded to the enhancement of electrical properties of UP resins. With the development of electronic information technology, low dielectric materials are intensively required. Although there have been many polymeric materials with low dielectric constant, including polyimides, poly(aryletherketone), benzocyclobutene resins, SiLK resins, fluorinated polymers, they are usually expensive and sometimes not readily available. Accordingly, developing materials, which show both good electrical properties and low cost, is desirable.In this essay, N-Phenylmaleimides with perfluoroalkyl substituents (-CF3and-C6F13) were firstly synthesized through a direct imidation of the corresponding N-phenylmaleamic acids using an environment-friendly route, in which a Br(?)nsted acidic room temperature ionic liquid and toluene were employed as a catalyst and an azeotropic dehydrating agent, respectively.Secondly, the curing behaviors of neat UP resin and the modified resins were characterized by DSC. The processing properties for the three kinds of modified UP resin were improved efficiently. And the curing temperature was preliminarily determined as references for moulding process.In comparison with neat UP resin and the modified UP resin by fluoro-free N-phenylmaleimide, the fluoromaleimide modified resins showed the decreased dielectric constant and the increased thermostability. The best result was obtained when the substituent was-CF3, which gave a dielectric constant of3.63and5wt%loss temperature of336℃under N2. |
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