Preparation And Study Of High Activity Nitrile Oxide And Its Room Temperature Curing Properties

As a new type of curing agent,nitrile oxide has a wide range of applications in polymer binders.Nitrile oxides allow the polymeric binders cured at room temperature.In this work,three curing agent precursors were synthesized from m-phthalaldehyde and terephthalaldehyde.They were:1,3-benzenedichlorocarboxaldehyde oxime,1,4-benzenedichloroformaldehyde oxime and 5-nitro-1,3-benzenedichloroformaldehyde oxime.Polybutadiene and hydroxyl-terminated polybutadiene were used as curing matrix to prepare meta-elastomer,para-elastomer and nitro-containing elastomer at room temperature.The elastomers were characterized by mechanical testing,shore hardness testing,FT-IR spectra analysis,thermogravimetric analysis(TGA),glass transition temperature analyisis(T_g),contact angle analysis,field emission scanning electron microscopy(FESEM)and kinetics analysis.In this project,the room-temperature curing of polybutadiene and hydroxyl-terminated polybutadiene was achieved by continuously improving the curing process,which corrected the shortcomings in isocyanate curing technology.The performance of the meta-curing system and the para-curing system was compared and analyzed.The performance of the nitro-containing curing system at different curing ratios was analyzed.(1)Comparing the mechanical properties and shore hardness of meta-elastomer and para-elastomer,we can see that with the increase of chloroaldoxime content the tensile strength,modulus and shore hardness of both elastomers increase,and the elongation at break decreases.The tensile strength of the meta-elastomers increased from 0.17 MPa to0.33 MPa,the modulus increased from 0.13 kPa to 0.47 kPa,the Shore hardness increased from 17.6 Ha to 32.9 Ha,and the elongation at break decreased from 135%to73%with the increase of chloroaldoxime content;With the increase of chloroaldoxime content,the tensile strength of the para-elastomer increased from 0.21 MPa to 0.45 MPa,the modulus increased from 0.26 kPa to 0.88 kPa,the Shore hardness increased from22.3 Ha to 37.8 Ha,and the elongation at break decreased from 83%to 51%.It can be concluded that the tensile strength of the para-elastomer was greater than that of the meta-elastomer,but the elongation of the meta-elastomer was significantly better than that of the para-elastomer.when the content of 1,3-benzenedichlorocarboxaldehyde oxime was 11%,the meta-elastomer had the best hydrophobicity;when the content of1,4-benzenedichloroformaldehyde oxime was 10%,the para-elastomer had the best hydrophobicity.(2)In the nitro-containing curing system,the mechanical properties and Shore hardness of the prepared elastomers were analyzed.As the content of 5-nitro-1,3-benzenedichloroformaldehyde oxime increased from 10%to 18%,the tensile strength of each elastomer increased from 0.14 MPa to 0.65 MPa,and the modulus increased from 0.04 kPa to 0.75 kPa,the shore hardness increased from 5.6 Ha to 25.8 Ha,and the elongation at break decreased from 346%to 87%,which means that the solidification network of the elastomer gradually completes with the curing agent increases.The analysis of the thermal weight loss process of the elastomer shown that the residual C=C double bond in the elastomer had a certain effect on the thermal stability of the elastomer.The more double bonds remain at the low temperature,the elastomer was more stable;The network integrity of the cured system determines the thermal stability of the elastomer when the system temperature was sufficiently high(above 480?).The contact angle of the nitro-containing elastomer was analyzed.When the content of5-nitro-1,3-benzenedichloroformaldehyde oxime reached 14%,the hydrophobic effect of the elastomer was the strongest.(3)The analysis of the kinetics of meta-cure system,para-cure system,and nitro-containing curing system shown that three different curing systems were first-order reactions;The apparent activation energy of the meta-curing system was 8.62kJ/mol;the apparent activation energy of the para-elastomer was 10.23 kJ/mol;the apparent activation energy of the nitro-containing curing system was 8.94 kJ/mol.The three cure systems had a small apparent activation energy,so room temperature curing of the polymer binder can be achieved.