Application Of Divinylbenzene-maleic Anhydride Hollow Microspheres In Polyamide And Polyhydroxyalkanoates

Divinylbenzene-maleic anhydride(DM)hollow microspheres have the advantages of small density,small particle size,narrow particle size distribution,good dispersibility,strong chemical stability,micropores on the inner and outer surfaces,and high reactivity.It can be used as a functional particle in a variety of polymers to enhance the basic properties of the matrix,so the application has broad prospects.With the awareness of "energy saving and environmental protection",lightweighting has become a topic of widespread concern.Polyamide is a common engineering plastic,lightweight technology is one of the important directions of its development.In addition,because polyamide is very flammable,a large number of droplets are generated in the combustion process,which is extremely harmful,so the weight and resistance of the polyamide are reduced.Combustion modification is essential.Polyhydroxyalkanoates(PHAs)have attracted more and more attention due to their excellent biocompatibility,biodegradability and hot workability.However,the nucleation rate of PHA is very slow,and there is post-crystallization phenomenon,which will affect the performance of the product,so the promotion of PHA crystallization has great practical application value.In this paper,the use of DM hollow microspheres with low density,large amount of maleic anhydride groups with large surface activity and uniform particle size dispersion is explored.Its application in PA6 light weight,PA6 flame retardant and PHA crystallization is explored.The application value of DM was broadened,and PA6 composites and PHA composites were characterized.The main research work is as follows:(1)DM hollow microspheres and graphene oxide(GO)are ultrasonically dispersed to hybridize the two to obtain DM-GO;hexamethylenediamine and GO were reacted to obtain aminated graphene(HGO),and then DM hollow microspheres were reacted with HGO to obtain DM-HGO,and then DM,DM-GO,DM-HGO were separately mixed into PA6 in a certain ratio,and the PA6 composites material was obtained by melt blending.The results showed that the addition of DM can reduce the density,but there was a gap between the experimental and theoretical values of density reduction.The results showed that when the amount of DM added is 5%,the density can be reduced by 10%.When DM-GO and DM-HGO were added,it was found that the mechanical properties were improved on the basis of keeping the original lightweight.The tensile strength can be increased from 52.7Mpa of the original DM to 55.2MPa,58.4MPa.The impact strength was increased from 4.5 KJ/m2 to 5.2 KJ/m2 and 5.9 KJ/m2.(2)The flame retardant PHDM was successfully synthesized by using DM,hexamethylenediamine and phenylphosphoryl dichloride,and synergistically flame retardant nylon 6 was compounded with ADP,and then PHDM and ADP were added to PA6 in a ratio of 1:2.In the matrix,a PA6/ADP/PHDM composite was prepared.The results show that the two flame retardants are used in combination with the single-addition ADP flame retardant,the UL-94 vertical combustion was increased from the V-1 level to the V-0 level,and the LOI was increased from 30.5%to 33.4%.The amount of carbon residue increased from 2.35%to 6.20%and the heat release rate(HRR)620.5 kW/m2 dropped to 255.31 kW/m2,the tensile strength can be increased from 34.2 MPa to 46.3 MPa.(3)The PHA/DM composites were prepared by solution method from PHA and DM hollow microspheres.It can be found by DSC and XRD that DM can promote the crystallization of PHA to some extent.It is found from the results of non-isothermal crystallization,when the addition amount was at 2%,the melting point can be increased from 148.61? to 169.99?,and the crystallization temperature of PHA was increased from 43.43? to 66.54?.From the isothermal crystallization results,it was found that the addition of DM significantly shortened the crystallization time and accelerated the crystallization rate.When isothermal crystallization at 80?,when the amount of DM added was 2%,the crystallization rate could be increased from 0.125 min-1 to 0.469 min-1.When isothermal crystallization at 85?,when the amount of DM added is 1.5%,the crystallization rate can be increased from 0.105 min-1 to 0.305 min-1.The mechanical properties have also been improved,the tensile strength has been increased from the original 8.17 MPa to 14.62 MPa,the elongation at break has increased from 43.65%to 72.34%,and good processing properties can be maintained.