Preparation And Properties Of High Strength Phenolic Cloth Laminated Board

Phenolic cloth laminated board has high mechanical strength and good fatresistance properties, commonly used as mechanical insulation parts. The biggestdrawback of phenolic resin is brittle as a binder after curing, resulting in poorperformance of impact resistance property of phenolic cloth laminated board.Enhancing and toughening the phenolic cloth laminated board help improve itsusing performance and expand its application ranges. In this paper, we chosetung oil and PBT (polyethylene terephthalate) to enhance and toughen thephenolic cloth laminated board as a representative of two modified methodsinclude inner toughing and outer toughing, and examined the impact on thermalstability of phenolic resin of these two methods. Using the enhancement andtoughening technique of rigid inorganic particles, the needle wollastonitepowders was applied to the preparation of high strength phenolic cloth laminatedboard, and a preliminary study on compound modification of PBT/needlewollastonite powder was conducted.Results showed that the transverse impact strength of phenolic clothlaminated board increased from23.2KJ/m2to34.4KJ/m2, while the longitudinalimpact strength increased from30.3KJ/m2to63.8KJ/m2, the flexural strengthdecreased gradually, with the the mass fraction of tung oil modified phenolicresin increased; Thermal stability of tung oil modified phenolic resin decreasedcompared to unmodified phenolic resin in the high-temperature region higherthan350℃. As the blending mass fraction increased from0%to15%, theflexural strength of phenolic cloth laminated board first increased and thenstabilized later, the impact strength began to improve slightly later reduced, bothin two directions; The SEM image of fracture surface showed that the fracturesurface was flat and the structure of the phenolic cloth laminated board could bedivided as continuous phase and dispersed phase; Thermal stability of PBT blending modified phenolic resin had a little decreased in the high-temperatureregion higher than375℃, when compared to that of the unmodified phenolicresin. With the increase in filling amount of needle wollastonite powder, theimpact strength of phenolic cloth laminated board gradually improved and theflexural strength began to increase first then reduced in both directions; Theimpact strength of phenolic cloth laminated board improved when the particlesize of needle wollastonite powder increased from6.5μm to23μm, while theflexural strength almost unchanged; The transverse impact strength of phenoliccloth laminated board increased from28.6KJ/m2to35.3KJ/m2, the longitudinalimpact strength increased from36.1KJ/m2to52.8KJ/m2, the flexural strengthalmost unchanged, when the surface of needle wollastonite powder was modifiedby coupling agents. The SEM images of fracture surface showed that the needlewollastonite powder dispersed more evenly and reunion reduced if the surface ofneedle wollastonite powder was modified. The method of compoundmodification of PBT/needle wollastonite powder could further enhance thetoughening effect contrast to single modification way of PBT, the transverseimpact strength of phenolic cloth laminated board increased from25.3KJ/m2to31KJ/m2, as well as, the longitudinal impact strength increased from34.5KJ/m2to43.6KJ/m2, the transverse flexural strength of phenolic cloth laminated boardincreased from164.8MPa to172.6MPa, the longitudinal flexural strengthincreased from131.8MPa to136MPa.