Preparation And Properties Of Inorganic Particleboard With A Mixture Of Wheat Straw And Wood

In recent years,in order to solve the problem of low utilization rate of rich straw resources in our country,as the crops straw stalk comprehensive high value-utilization new technologies,wheat straw particleboard is widely researched.However,it has defects of low bonding strength,formaldehyde pollution and easily causes a fire.With wheat straw,wood and inorganic adhesive as major raw materials,inorganic particleboard with a mixture of wheat straw and wood was manufactured by hot-pressing technology and single factor test.Homogenous particleboard was made by the way of mixing wheat straw and wood uniformly.Three-layered particleboard was made by layered mixture.The effects of wheat straw-wood ratio,adhesive consumption,hot-pressing time,hot-pressing temperature and curing time on physical and mechanical properties of the board were studied.Optimal process of two kinds of particleboard was got,and flame retardancy of them was studied.Then physical and mechanical properties and flame retardancy of homogenous particleboard and three-layered particleboard with same preparation conditions were contrastively analysed.We hope to obtain fine performance straw particleboard of high strength,low cost,fire prevention,smoke suppression and no artificial formaldehyde release.(1)In the optimization experiment of adhesive consumption,wood inorganic particleboard was made with adhesive consumption of 51%,55%,59%and 63%;Wheat straw inorganic particleboard was made with adhesive consumption of 62%,66%,70%and 74%.Optimum adhesive consumption of wood and wheat straw were 59%and 70%respectively by mechanical testing.(2)The preparation of inorganic particleboard with a uniform mixture of wheat straw and wood was studied.Results showed that modulus of rupture(MOR),modulus of elasticity(MOE)and internal bond strength(IB)of the board gradually increased while thickness swelling(TS)of that gradually decreased with declining wheat straw-wood ratio;optimal wheat straw-wood mass ratio was 4:6.As adhesive consumption increased from 57%to 66%,MOR and MOE firstly increased and then decreased,meanwhile,IB increased gradually and TS decreased gradually;MOR and MOE reached the maximum when adhesive consumption was 63%.As board's density increased from 0.9 g/cm3 to 1.2 g/cm3,MOR,MOE and IB gradually increased while TS gradually decreased.As hot-pressing time extended from 15min to 30min,MOR,MOE and IB first increased sharply and then slowly,TS first decreased sharply and then slowly.As hot-pressing temperature rose from 70? to 110?,MOR,MOE and IB firstly gradually increased and then decreased,meanwhile,TS firstly gradually decreased and then increased;MOR,MOE and IB reached the maximum as 16.8MPa,3350MPa and 0.56MPa,while the TS reached the minimum as 3.5%with hot-pressing temperature of 100?.As curing time extended from 7 days to 16 days,MOR,MOE and IB first gradually increased and then trended to balance,TS first gradually decreased and then trended to balance.Optimal process was as follows:wheat straw-wood ratio of 4:6,adhesive consumption of 63%,density of 1.2g/cm3,hot-pressing time of 30 min,hot-pressing temperature of 100 ? and curing time of 13 days.(3)The preparation of inorganic particleboard with a layered mixture of wheat straw and wood was studied.Results show that MOR and MOE of the board gradually decreased with increasing wheat straw-wood ratio,meanwhile,IB gradually increased and TS gradually decreased;optimal wheat straw-wood mass ratio was 5:5,in order to improve the bonding strength.As board's density increased from 0.9g/cm3 to 1.2g/cm3,MOR,MOE and IB gradually increased while TS gradually decreased-As hot-pressing time extended from 15min to 30 min,MOR,MOE and IB first increased sharply and then trended to balance,TS was in contrast.As hot-pressing temperature rose from 70? to 110?,MOR,MOE and IB firstly gradually increased and then decreased,meanwhile,TS firstly gradually decreased and then increased;MOR,MOE and IB reached the maximum as 17.1 MPa,3400MPa and 0.5MPa,while the TS reached the minimum as 4%with hot-pressing temperature of 100?.As curing time extended from 7 days to 16 days,MOR,MOE and IB first increased sharply and then slowly,TS first decreased sharply and then slowly.Optimal process was as follows:wheat straw-wood ratio of 5:5,density of 1.2g/cm3,hot-pressing time of 30 min,hot-pressing temperature of 100? and curing time of 13 days.(4)Flame retardancy of inorganic particleboard with a uniform mixture of wheat straw and wood was studied by comparing with wheat straw inorganic particleboard,wood inorganic particleboard and ordinary organic wheat straw particleboard.Results show that compared with ordinary organic wheat straw particleboard,inorganic adhesive can significantly reduce the heat release and smoke release.Flame retardancy and smoke suppression of inorganic particleboard with a uniform mixture of wheat straw and wood was better than wood inorganic particleboard,and poorer than wheat straw inorganic particleboard.Flame retardancy of inorganic particleboard with a layered mixture of wheat straw and wood was studied by comparing with wheat straw inorganic particleboard,wood inorganic particleboard and ordinary organic wheat straw particleboard.Results showed that heat release and smoke release of three-layered particleboard were significantly lower than ordinary organic wheat straw particleboard,and flame retardancy and smoke suppression of three-layered particleboard was better than wood inorganic particleboard,and poorer than wheat straw inorganic particleboard.Inorganic particleboard with a mixture of wheat straw and wood was an ideal indoor and outdoor decoration,funiture and building wall materials in terms of fire retardancy and smoke suppression.(5)Physical and mechanical properties and flame retardancy of homogenous particleboard and three-layered particleboard with same preparation conditions were contrastively analysed.Results showed that MOR and MOE of three-layered particleboard were higher than homogenous particleboard,while IB was lower,and TS was higher.HRR,THR,SPR,TSP and MLR of three-layered particleboard were lower than homogenous particleboard,and time to ignition of that extended for 25s,indicating that flame retardancy of three-layered particleboard was better than homogenous particleboard.In conclusion,the better mat structure is three-layered particleboard with wheat straw as surface layer and wood as center ply,but the problem of poor IB of three-layered particleboard still needed to be further explored...