Preparation And Performence Of Rigid Polyurethane Reinforced By Hollow Glass Bead-palygorskite

Rigid polyurethane foam(RPUF)is widely used in the construction industry and other fields due to its excellent thermal and acoustic insulation,light weight and chemical stability.However,the RPUF currently prepared suffers from irregular bubble structure,poor mechanical properties and insufficient thermal stability,which greatly limit the safe use of RPUF.To solve these problems,RPUF is usually reinforced with various inorganic fillers.In this paper,RPUF is reinforced with inorganic rigid particles and natural clay,and the RPUF composites are analysed by XRD,FTIR,SEM,differential thermal analysis,mechanical properties and thermal insulation effect tests to determine the best preparation process and reinforcement mechanism.HGB/RPUF and Pal/RPUF composites were prepared using hollow glass beads(HGB)and palygorskite(Pal)as fillers,respectively.In order to improve the interfacial compatibility between the fillers and RPUF,the hydrophobic modification of the fillers was carried out and characterized using the silane coupling agent KH570.The results show that the optimum coupling agent additional contents for modified HGB and Pal were 1 wt.%and 2 wt.%,respectively.RPUF was reinforced with HGB and Pal under optimal modification conditions,respectively,and the results show that the mechanical properties of RPUF were positively correlated with its apparent density within a certain threshold,and the best mechanical properties of the prepared RPUF composites were obtained when the additional contents of HGB and Pal were 3 wt.% and 8 wt.%,respectively.On the basis of this,HGB and Pal as nucleating agents not only reduced the average cell size of RPUF,but also improved the uniformity of the cell structure.Meanwhile,the thermal barrier effect between the nucleating agent and RPUF also increased the initial decomposition temperature and average insulation temperature difference of the material.Further analysis shows that HGB strengthened the cell pillars of RPUF,Pal strengthened the cell matrix,and Pal had a better effect on optimizing the cell structure of RPUF than HGB due to its nano-effect and abundant hydroxyl groups.In order to give play to the synergistic effect of HGB and Pal,RPUF was reinforced with them as dual-phase filler to maximize the comprehensive performance of RPUF.The results of the research show that the HGB/Pal/RPUF ternary composite has the best compressive strength(0.31 MPa)and modulus of elasticity(4.86 MPa)at 3 wt.% and 7 wt.%of HGB and Pal addtional content,respectively.Compared with pure RPUF,these two performances are improved by 114% and 140%,respectively.The cell structure of the best sample(HPR3-7)become more compact and dense compared with pure RPUF.The average cell size of HPR3-7 is about 257 μm,which is 23% less than that of pure RPUF.The residual rate of HPR3-7 at 800°C is 28 wt.%,while that of pure RPUF is only 16 wt.%.The dual-phase filler greatly enhances the thermal stability of RPUF.In addition,HGB and Pal act as thermal barrier to inhibit the conduction of heat in the cells,which makes a better thermal insulation effect of the reinforced RPUF.The comparison results show that the effect of dual-phase filler composite reinforcement RPUF is better than the single reinforcement.This work provides specific ideas for improving the comprehensive properties of RPUF,and the prepared RPUF composites have broad development prospects.