Properties Of Epoxy-Based Composite Foam Based On Sizing Agent Modified Hollow Glass Microsphere

The 21st century is the century of the ocean,and the rich resources stored in the ocean can not only meet the production activities of human society,but also promote the development and progress of human industry.Currently,humans are exploring ocean resources in various aspects.As exploration of deeper ocean areas with more complex environments increases,the demands for performance of exploration equipment also increases.Composite foam materials,as lightweight materials composed of resin as the matrix and hollow microspheres as the filler,are mainly used to reduce weight in various ocean exploration equipment.Compared with traditional foam materials,composite foam materials have the advantages of designability,easy processing and forming,and no internal defects caused by chemical foaming,while also maintaining their lightweight and high-strength characteristics.Currently,epoxy resin is commonly used as the matrix of composite foam materials,while hollow glass microspheres are often chosen as the lightweight filler.However,epoxy resin and hollow glass microspheres not only have significant differences in physical properties such as shape,density,melting point,and thermal expansion coefficient,but also have significant differences in chemical properties such as surface polarity and reaction activity.Mixing hollow glass microspheres into the resin slurry will result in numerous adverse interface effects,which can affect the overall performance of composite foam materials.This article proposes a feasible method,Specifically,a flexible polymer with long PBA molecular chains(without rigid groups)is grafted onto the surface of hollow glass microspheres,which has good compatibility with the matrix(PBA molecular chain segment contains 1%epoxy groups,which is similar to the matrix resin structure)and has a certain molecular weight.This method can effectively improve the interfacial properties of composite foam materials,and has a certain degree of environmental friendliness.”Therefore,this article uses a water-based sizing agent to modify and pre-treat hollow glass microspheres,and then fill them into the matrix resin to prepare epoxy-based composite foam materials.The curing process of the solidification system before and after modification was explored;the surface modification of hollow glass microspheres was analyzed;the general rules of the influence of different variable parameters on the interface performance and mechanical properties of composite foam materials were investigated:(1)The large amount of filling of 32P and the surface modification of PBA will have an impact on the curing process of composite foam materials.The non-isothermal DSC method was used to calculate and analyze the curing process of various curing systems,investigate the influence of fillers on the curing reaction,and determine parameters such as curing temperature and curing time.The apparent activation energies of the three curing systems were 53.96 k J/mol,52.38 k J/mol,and 55.12 k J/mol,respectively,with low reaction activation energies and easily occurring reactions.With the increase of curing conversion rate,the apparent activation energy of the curing system gradually increases.This paper sets the curing process of the composite foam material as 70℃,1 h;110℃,1 h;150℃,11 h.Under this curing condition,the three curing systems are fully reacted and cured,and the curing process has a certain rationality.(2)Using polybutyl acrylate(PBA)as the sizing agent,effective modification of the surface of hollow glass microspheres(32P)was carried out,and the feasibility of the modification treatment was characterized by microscopic analysis of the molecular structure and morphology of the 32P surface.The mechanical properties of the prepared composite material were analyzed by macroscopic testing.With increasing sizing concentration,the content of PBA aggregated on the surface of 32P also significantly increased,and the optimal coverage of PBA was 5.11%.After modification,the surface energy of 32P could be reduced to55.29 J·m~2,which improved the wettability of the modified microsphere surface by the resin.When 32P was highly filled(50%),the strength of the composite foam material decreased to55.48 MPa.When the sizing concentration was 30%,the compressive strength of the composite foam material reached its peak value of 82.35 MPa,which was 48.4%higher than that of the unmodified sample.After introducing 2%of KH570,the compressive strength of the composite foam material reached a peak value of 96.30 MPa,which was 16.9%higher than that of the PBA single-modified sample,and the interfacial adhesion coefficient reached the ideal bonding state.(3)Analysis and testing of the dynamic mechanical properties of the prepared composite foam materials were carried out to investigate the effects of temperature and frequency on various dynamic mechanical parameters.As the amount of 32P added increased,the tanδ,storage modulus and loss modulus of the composite foam material decreased,while the glass transition temperature of the composite foam material increased overall.The addition of PBA enhanced the interfacial compatibility of the composite foam material,improving its resistance and damping capabilities against dynamic loads.Introducing a structurally similar silane coupling agent into the PBA resulted in better bonding of 32P-PBA-E51,further enhancing the interfacial compatibility of the composite foam material and improving its damping and vibration reduction properties.Additionally,the molecular chain segments of the composite foam material became more complex,resulting in an increase in both the glass transition temperature and molecular chain movement.