Preparation And Properties Of Castor Oil Modified Waterborne Polyurethane

Waterborne polyurethane as a new eco-friendly material with high performance and low volatile organic compound(VOC)content has attracted extensive concerns.It has been widely used in building coating,wood coating,leather,textile and adhesive,etc.As a potential application in damping coating,waterborne polyurethane has its inherent disadvantages such as poor water resistance,mechanical properties and low-temperature damping properties.In this study,waterborne polyurethane hybrid emulsions were synthesized by the reaction of isophorone diisocyanate and polytetramethylene ether glycol as main raw materials.Series of WPUs with different structure and cross-linked network were obtained by introduction of castor oil and chain-extender.The water resistance,mechanical and damping properties of WPU films were investigated.The effect of chain extension manner on the properties of WPU were investigated.It was found that with the increment of proportion post-chain extension,the particle size of WPU increased while the emulsion viscosity decreased.The water resistance of WPU film was improved.A dynamic effectively enhances in mechanical properties with an over 340% increase,gave the maximum tensile strength of 47.42 MPa while a slight decrease of damping properties and thermostability.Then,the introduction of CO on the properties of WPU were studied.Stable emulsions with particle size ranging from 110 nm to 180 nm,viscosity ranging from 14.47-22.98 mPa.s and solid content about 34% were obtained.With the increase of CO content,a decrease of water resistance and transparency of WPU films was found.While an improvement of tensile elongation at break about 1626.25% and improved thermostability were obtained.As to the damping properties of WPU,a decrease of effective Initial damping temperature from 0.68? down to-42.30? were observed.The study on the effect of the cross-linked network on the properties of WPU showed that uniformity of cross-linked network has effective improvement of mechanical and damping properties.The tensile strength of WPU film can obtain an increase over 25%.An effective Initial damping temperature moved to a lower temperature-43.25?,which have potential application prospects in low-temperature damping coating.