Preparation And Properties Of High Performance Eucommia Ulmoides Composite Latex

Eucommia ulmoides gum(EUG)and natural rubber(NR)are isomers of each other.As a unique strategic resource in China,EUG is used in many fields for its good performance.Unlike natural rubber latex(NRL)and synthetic latex,Eucommia ulmoides latex(EUL)cannot be obtained by tapping or chemical emulsion polymerization,and there are few studies on emulsification of EUG,so EUG has not yet been applied to latex products.In this paper,the preparation method of EUL was explored,and the prepared EUL was blended respectively with NRL and nitrile-butadiene rubber latex(NBRL),preparation of NR/EUG composite film and NBR/EUG composite film,the influencing factors of EUG on the properties of composite films were studied,which was helpful for expanding the application field of EUG and improving the properties of the existing latex products.Three main sections are included in this paper.In the first part,EUL was prepared by emulsion solvent evaporation technology,and the influences of factors on the EUL such as the type and amount of emulsifier,the mass fraction of EUG in the oil phase,and the shear force of the emulsifier were explored.The best formula and process conditions are as follows: using dichloromethane as solvent,using Polyvinyl alcohol(PVA)/Sodium dodecyl benzene sulfonate(SDBS)/Polyoxyethylene glycol monocetyl ether(POE)as emulsifier.In the oil phase,the mass fraction of EUG is 5%,the mass fraction of POE is 1.2%.In the water phase,the mass fraction of PVA is 1%,the mass fraction of SDBS is 1.5%.The speed of the high-speed shearing emulsifier during emulsification is 8000 r/min.The appearance of the EUL prepared under this formula and process conditions is similar to that of NRL,it is a milky white liquid,and its viscosity is higher than that of NRL and NBRL under the same solid content.The EUL particles are regular spherical,their surfaces are covered with a layer of emulsifier,and the average particle size is 405 nm,EUG in the form of latex particles still maintains the crystals of α-form and β-form.In the second part,NR/EUG composite films were prepared,and the effects of EUG content on the crosslinking density,crystallinity,two-phase structure,mechanical properties and dynamic thermomechanical properties of the composite films were investigated.It was found that with the increase of EUG content,the crosslinking density and crystallinity of the film gradually increased.The EUG are dispersed in the film as the morphology of the latex particles.When the content of EUG is low,the two phases of NR and EUG present a "sea-island" structure.As the content of EUG increases,the latex particles begin to aggregate to form a continuous phase.The addition of EUG improves the modulus,tensile stress,hardness and the slope of the stress-strain curve,thereby enhancing the dimensional stability of the composite latex film under stress.With the increase of EUG content,the tear strength of the composite film first increased and then decreased.EUG can also affect the dynamic thermomechanical properties of the composite film.When the temperature is greater than the glass transition temperature(Tg)of the film,the addition of EUG will increase the storage modulus and decrease the loss factor of the composite film.In the third part,NBR/EUG composite latex films were prepared,and the effects of EUG content on the crosslinking density,crystallinity,two-phase structure,mechanical properties and dynamic thermomechanical properties of the films were investigated.It was found that the addition of EUG can increase the crystallinity and cross-linking density of the film.The EUG keeps the morphology of latex particles in the film,as the content increases,the EUG gradually changes from a dispersed phase to a continuous phase.Increasing the EUG content can increase the modulus,tensile stress,hardness and slope of the stress-strain curve of the film,resulting in enhanced dimensional stability under stress.The addition of EUG can also improve the tensile strength and tear strength of the film,and the elongation at break remains basically unchanged.When the temperature is higher than the Tg of the nitrile rubber,the addition of the EUG component can increase the storage modulus and decrease the loss factor of the NBR/EUG composite film.