Fiber Reinforced Modified Benzoxazine Resin-based Laminated Composite

Resin matrix composite is a kind of fiber reinforced resin matrix composites based on organic macromolecule resin materials,such as phenolic resin,epoxy resin,polybenzoxazine resin,glass fiber,carbon fiber and other organic fibers.In particular,as a new flunctional material,resin matrix composites have been widely used because of their simple preparation process and many properties that metal sheets do not have,such as light weight,shock absorption,corrosion resistance,such as construction,aviation,anti-corrosion,subway escape materials and other fields.As a new type of thermosetting resin,Benzoxazine Resin is the best choice for the preparation of composite materials because of its simple synthesis steps,flexible molecular design,excellent properties and low cost.Therefore,the laminated composites of glass fiber reinforced phenolic resin benzoxazine were prepared according to the characteristics of high strength of glass fiber cloth.Furthermore,the laminated composites of carbon fiber reinforced benzoxazine with high heat resistance were developed from glass cloth to carbon fiber cloth as reinforcing material.In addition,based on the flexibility of benzoxazine molecular design,a novel hybrid material containing Si-O-B structure was prepared by introducing boron at the molecular level.The specific research contents and results of this paper are as follows:1.A phenolic resin was synthesized from phenol and polyformaldehyde,and benzoxazine with phenolic structure was synthesized as a phenolic source.The glass fiber reinforced phenolic benzoxazine laminated composites were prepared by using this benzoxazine as matrix resin and glass fiber cloth as reinforcing material.The synthesized benzoxazine and its curing process were characterized by FTIR.The thermal properties of the resin and composite were tested by TGA and DMA.The mechanical properties of the composite were tested by universal tension machine.The results show that 944cm-1 corresponds to the characteristic peak of oxazine ring and its curing temperature is 150 C;the residual char rates of phenolic resin-based benzoxazine(PRBZ)curing resin at 5%weight loss are 310 C,370 C and 10%weight loss Td10,respectively,and 44%at 800 C,which have good thermal stability;the glass transition temperature Tg is 180 C,which has good heat resistance;impact strength and bending strength.The average bending strength is 88KJ · m-2 and 576MPa,respectively,showing good mechanical properties.2.Carbon fiber reinforced benzoxazine/bismaleimide composites were prepared by using cyanide-containing benzoxazine(CNBZ)and bismaleimide(BMI)blends as matrix resins and carbon fiber cloth as reinforcing materials.The effects of carbon fibers treated with hydrogen peroxide on the mechanical properties of the composites were studied.The CNBZ/BMI monomer and cured resin were characterized by FTIR,The heat resistance,thermal stability and mechanical properties of the composites were tested by DMA,TGA and universal testing machine.The cross section of the composites was characterized by SEM.The results show that the initial temperature of 170 is the best curing operation;the Tg of CNBZ/BM cured at 257? has excellent heat resistance;the Td5 and Td10 of composites are 381 and 472? respectively,which have excellent thermal stability;the residual carbon rate is 82.7%at 800 and the flexural strength and impact strength of laminated composites prepared with 5%hydrogen peroxide water treatment are 1340 MPa and 167 KJ ·m-2 respectively,compared with the laminated composites prepared by untreated carbon fiber cloth,increased by 21%and 64%respectively.3.The siloxane group-containing benzoxazine monomer SBZ was synthesized by chemical design of benzoxazine,and then SBZ was polycondensed with phenylboronic acid Pa to form borosiloxane prepolymerized with benzoxazine side group.The(BSB)hybrid material was finally subjected to thermal ring-opening polymerization to obtain a thermosetting polybenzoxazine PBSB containing a Si-O-B structure.The effects of reaction temperature,reaction time and presence or absence of catalyst on the molecular weight of the polymer were studied.The BSB polymer prepared under the optimal conditions was selected.The synthesized product BSB was characterized by infrared FTIR and nuclear magnetic spectroscopy.The water resistance of the material was studied.Finally,TGA and DMA were used to test the thermal stability and dynamic mechanical properties of the cured resin.The results showed that the benzoxazine hybrid material containing Si-OB structure was successfully prepared.The reaction condition was 5h in the absence of catalyst and 120?.The water resistance test showed that there was no water absorption in seven days.at room temperature,water resistance is excellent;The TGA test results showed that PBSB had a Tas of 5%weight loss of 320?,weight loss of 10%of Td1o was 360 ?,and a carbon residue rate of 59.2%at 800?.The DMA test showed that the glass transition temperature of PBSB was around 220 ?;the mechanical properties test results show that the impact strength and flexural strength of the composites are 158KJ · m-2 and 1099MPa,respectively,showing excellent mechanical properties.