The Effect Of Macromolecule Sequence Structure And Soft Segments On Properties Of Polyurethane

Because of the diversity of raw material of preparation of polyurethane and complexity of polyurethane structure, many factors affects properties of polyurethane, such as polymer polyol, diisocyanate, chain extender, other polymers added and process conditions. Since properties of polyurethane are closely related to structure, macromolecular structure sequence has a direct impact on polyurethane molecular arrangement and micro-phase separation, thereby affecting its performance, so it is necessary to study the effect of macromolecule sequence on the properties of polyurethane. And different soft segment structures also have impacts on properties of polyurethane, so the effects of soft segment structures on properties of polyurethane were also investigated.In this paper, polyether polyurethanes, polycaprolactone polyurethanes and polyether-polycaprolactone polyurethanes developed from Polytetramethylene glycol (PTMG), Polycaprolactone diol (PCL), Polyethylene glycol adipate (PEA), toluene2,4-diisocyanate (TDI-100) and3,5-dimethyl mercapto toluenediamine (E-300) were prepared by molecular design. Mechanical properties, solvent resistance and Dynamic mechanical analysis(DMA) were tested to investigate the effects of macromolecular structure sequence on properties of polyurethanes(PUs). Meanwhile, properties of PUs developed from Polytetramethylene glycol (PTMG) and Polycaprolactone diol (PCL) as mixed soft segments and PUs developed from Polyethylene glycol adipate (PEA) and Polycaprolactone diol (PCL) as mixed soft segments were also investigated.(In this paper, Polytetramethylene glycol (PTMG) was denoted as A, Polycaprolactone diol (PCL) was denoted as B, toluene2,4-diisocyanate (TDI-100) was denoted as C,3,5-dimethyl mercapto toluenediamine (E-300) was denoted as D)The results showed that:(1) Poly ether polyurethane PU1with-D-CAC-as a unit has higher hard segment content, hardness, tensile strength, tear resistance and solvent resistance, but lower elongation at break compared to polyether polyurethane PU2with-D-CAC-ACA-CAC-as a unit. In addition, PU2has a lower glass transition temperature, but gradually loses its elasticity with increasing temperatures, due to large molecular weights between crosslinking points.(2) If macromolecule sequence structure is different, properties of polycaprolactone polyurethane are also different. But the effects of sequence structure on polycaprolactone polyurethane performance are different from polyether polyurethane. Polycaprolactone polyurethane PU3with-D-CBC-as a unit has higher hard segment content, hardness, tensile strength, tear resistance and solvent resistance, but lower elongation at break compared to polycaprolactone polyurethane PU4with-D-CBC-BCB-CBC-as a unit. But all these properties change little. In addition, hardness of PU2and PU4are more than ShoreA80at room temperature, while hardness of PU4is about ShoreA20at100℃. Besides, the two sequence structure has little effect on the dynamic mechanical properties of polycaprolactone polyurethane. The glass transition temperature of PU4with-D-CBC-BCB-CBC-as a unit is lower than the glass transition temperature of PU3with-D-CBC-as a unit, but decreases slightly.(3) The effects of sequence structure on properties of polyether-polycaprolactone polyurethanes are between polyether polyurethane and polycaprolactone polyurethane. Polyether-polycaprolactone polyurethanes with-D-CXC-(X was denoted A or B) as a unit has higher hard segment content, hardness,tensile strength, tear resistance and solvent resistance compared with PU6with-D-CBC-ACA-CBC-as a unit and PU7with-D-CAC-BCB-CAC-as a unit. In addition, PU6and PU7have similar properties, and they have lower glass transition temperatures than PU5, but gradually lose their elasticity with increasing temperatures.(4) For polyurethanes (PUs) developed from polytetramethylene glycol (PTMG), tensile strength change little, tear resistance and elongation at break have greatly improved when adding polycaprolactone diol (PCL). But micro-phase separation is worse when adding polycaprolactone diol (PCL). For polyurethanes (PUs) developed from polyethylene glycol adipate (PEA), tensile strength is enhanced, while tear resistance and elongation at break decreases. But adding polycaprolactone diol (PCL) to polyurethane with polyethylene glycol adipate (PEA) as soft segment, micro-phase separation is improved. In addition, PU with polycaprolactone diol (PCL) has better damping properties.