Preparation And Properties Of HTBN Modified Bio-based Waterborne Polyurethane

The synthesis of waterborne polyurethane(WPU)from polyols converted from cashew shell oil is sustainable and more environmentally friendly.At the same time,this natural extract gives WPU comprehensive properties such as water resistance and solvent resistance.Liquid hydroxyl terminated butadiene nitrile rubber(HTBN)is made by copolymerization of butadiene and acrylonitrile,which can give WPU oil resistance,water resistance,aging resistance and bonding properties,so that it can be applied to polar surfaces such as plastics.HTBN was modified by 4-fluorophenol(FBLF)to obtain fluorinated hydroxy-terminated polybutadiene acrylonitrile(FHTBN),and then used to modify WPU is expected to further enhance its hydrophobicity and improve the compatibility of the system.Firstly,the WPU was prepared by acetone method using cashew shell oil diphenyl alcohol(CNSL)as soft segment.The effects of DMPA dosage,R value(isocyanate root index)and neutralization degree on the emulsion stability and mechanical properties of the film were investigated.The appearance,particle size,storage stability and mechanical properties of the emulsion were tested.The results showed that the stability and comprehensive properties of the WPU emulsion were better when the DMPA content was 5%,the R value was 1.4 and the neutralization degree was 1.Secondly,this paper modified the bio-based WPU by adding hydroxyl-terminated polybutadiene acrylonitrile(HTBN)to the soft segment,and synthesized HTBN-CNSL modified WPU with excellent performance.Its structure was characterized by infrared spectrum,which proved that HTBN has been successfully connected to the WPU backbone.The quality fraction of HTBN in the soft segment was changed to explore the influence of the addition amount of HTBN on WPU performance.The particle size of WPU increased with the increase of HTBN addition amount,but the WPU remained stable at 50wt%.The glass transition temperature of WPU shows an increasing trend.The introduction of HTBN on TG test surface can improve the heat resistance of WPU.The tensile strength and elongation at break of the WPU film increased at first and then decreased.The best mechanical properties of the film were obtained at 40 wt%,with the tensile strength of 19.8MPa and elongation at break of 565.4%.The modified WPU has better adhesion on the surface of polar substrate and better water resistance.Finally,HTBN and 4-fluorophenol(FBLF)with fluorobenzene side chain were synthesized by mercapto-ene click reaction in this paper.Then,FHTBN was used for modification of bio-based WPU,which gave it hydrophobicity and further improved its heat resistance.Besides,the non-polarity of butadiene chain segment in HTBN was changed to improve the compatibility of the whole system.The results of IR and HNMR analysis show that the double bond of butadiene segment in HTBN has been opened and the fluorobenzene side chain has been connected successfully.The quality fraction of FHTBN in soft segment was changed to explore the influence of FHTBN addition amount on FWPU performance.The particle size of FWPU also increased with the increase of the addition amount of FHTBN,but the particle size showed a downward trend compared with that of the previous year,indicating a better stability of the system.TG test found that the heat resistance was further improved.The tensile strength and elongation at break of FWPU film also increased first and then decreased with the increase of FHTBN content.The best mechanical properties of FWPU film were obtained when the amount of FHTBN was 40 wt%,the tensile strength was17.3 MPa and the elongation at break was 480%.The adhesion and water resistance of FWPU are improved to a certain extent.The contact Angle test showed that the hydrophobicity of the film was greatly improved,and the contact Angle increased slowly with the increase of the amount of FHTBN.It can be seen from the SEM figure that there are particles on the surface of the modified FWPU film.At the same time,in addition to C,O,N,S and F in EDS element analysis,the introduction of element F is further explained.