Novel silicon-modified phenolic novolacs and their biofiber-reinforced composites: Preparation, characterization and performance

4,4′-(1,3-Dipropyl-tetramethyldisiloxane)bis-2-methoxyphenol (SIE), a novel silicone-contained biphenol type monomer, is synthesized from eugenol and 1,1,3,3-tetramethyldisiloxane, and used to modify phenolic novolac through copolymerization with phenol and formaldehyde to yield SIE-modified resins (SPNs). Then, the SPNs are used as resin matrix, while surface-treated chopped sisal fiber is used as the reinforced filler to produce the novel phenolic molding composites. Eugenol and sisal are biobased renewable materials. Due to modification of SIE, the ultimate composites expressed excellent electrical resistance, low water absorption and high thermal stability compared to the normal composites. Our work provides a facile and effective way to prepare the silicone modified, biofiber-reinforced phenolic composites with improved water resistance and electric property.