| Gypsum board has the advantages of light weight,high strength,convenient processing,sound insulation,heat insulation and fire protection.Synthetic fibers were commonly used as reinforcement fiber for gypsum board,such as glass fiber,carbon fiber,polypropylene fiber,etc.However,these synthetic fibers have problems of high cost and environmental pollution.In the present study,wood fiber,sisal fiber and bamboo fiber these three kinds of biomass fibers were used as reinforcements to reinforce gypsum matrix.The effects of fiber content,length,and surface treatment on the performance of the gypsum composite board were investigated emphatically.The one-time molding preparation method of the poplar veneer gypsum board was developed based on the preparation technology of plasterboard.The scanning electron microscope(SEM)and fourier transform infrared spectroscopy(FTIR)were used to investigate the modification mechanism.The change of the crystallinity of gypsum was analyzed by X-ray diffraction(XRD).The results of the study provide reliable technological parameters and theoretical basis for the preparation of biomass fiber reinforced gypsum board.The main research contents and results are divided into the following parts:1.Using wood fibers to reinforce gypsum board.The effects of fiber size,fiber dosage and silane coupling agent surface treatment on the performance of gypsum board were studied.The results showed that the wood fiber with the particle size of 10?40 mesh had the best reinforcing effect.When the added amount of the fibers was 3%,the elastic modulus,the static bending strength and the internal bonding strength of the composite board were the highest,which were 14.24%,35.73%and 57.41%higher,respectively,than that of the pure gypsum board.The polarity of the surface of wood fiber was weakened,the interface between wood fiber and the gypsum was improved,and the crystallinity of the gypsum was improved after the wood fiber was treated with silane coupling agent.The elastic modulus,static bending strength and internal bonding strength of the gypsum board filled with 3%modified wood fiber increased by 25.75%,92.22%and 100.67%,respectively,compared with the pure gypsum board.In addition,proper addition of wood fibers also reduced the brittleness of the gypsum board.2.Using sisal fibers to reinforce gypsum board.The effects of fiber length,fiber dosage and different chemical reagents(NaOH,H2O2,silane coupling agent KH550)treatments on the performance of gypsum board were studied.The results showed that when the length of the sisal fiber is 20 mm and the addition amount is 3%,the sisal fiber had the best reinforcing effect for gypsum board.Compared with the untreated sisal fiber reinforced gypsum board,the elastic modulus,static bending strength and internal bonding strength of the gypsum board filled with sisal fiber treated with NaOH+H2O2 increased by 14.05%,43.90%and 104.23%,respectively.Compared with the pure gypsum board,the elastic modulus,static bending strength and internal bonding strength of the gypsum board filled with sisal fiber treated with NaOH+H2O2 increased by 15.90%,70.03%and 168.52%,respectively.3.Using bamboo fibers to reinforce gypsum board.The effects of different treatment methods(water wetting,NaOH treatment,NaOH+H2O2 treatment,KH550 treatment)on the performance of gypsum board were studied.The results showed that the NaOH treatment was optimum.When the length of the bamboo fiber is 20 mm and the addition amount is 3%,The elastic modulus,static bending strength and internal bonding strength of the gypsum board filled with bamboo fibers treated with NaOH increased by 9.36%,77.81%and 229.63%,respectively,compared with the pure gypsum board.By comparison,it was found that among wood fiber,sisal fiber and bamboo fiber these three kinds of biomass fibers,the elastic modulus and static bending strength of gypsum board reinforced with wood fiber treated with silane coupling agent KH550 were the highest.The internal bonding strength of gypsum board reinforced with bamboo fibers treated with NaOH+H2O2 was the highest,reaching 1.78 MPa.4.Using poplar veneer to decorate gypsum board.The effects of mixing time of slurry and veneered methods on the performance of gypsum board were studied.The results showed that the elastic modulus,static bending strength,maximum load and surface bonding strength of gypsum board prepared by mixing 10 min were significantly higher than that of gypsum board prepared by mixing 5 min and 15 min.For different types of biomass fibers,the mechanical properties of the bamboo fiber gypsum board veneered via poplar veneer were the best.The elastic modulus,static bending strength,maximum load and surface bonding strength of plates were up to 5318.93 MPa,21.93 MPa and 438.61 N,0.57 MPa,respectively.For different veneered methods,poplar veneer/jute cloth composite veneered method was better than poplar veneer veneered method.The elastic modulus,static bending strength,maximum load and surface bonding strength of bamboo fibers reinforced gypsum board prepared by poplar veneer/jute cloth composite veneered method were 7220.75 MPa,23.77 MPa,742.78 N and 0.63 MPa,respectively,which were 35.76%,8.39%,69.35%and 10.53%higher,respectively,than that of the bamboo fibers reinforced gypsum board prepared by poplar veneer veneered method. |
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