The Preparation And Properties Of HTBN/PTMG Polyurethane Elastomer Composite Materials

PTMG type polyurethane prone to orientation of crystallization under stress,having excellent mechanical properties,because of the regular structured of PTMG.But PTMG type polyurethane elastomer(PUE)was easy to break at heteroatoms at high temperature.HTBN was pure carbon chain polyols,free of other hetero atoms,making it had good heat resistance.But HTBN type PUE had poor physical properties.HTBN/PTMG type PUE could combine the advantages of both effectively,to prepare PUE with excellent comprehensive properties.This paper designed from the polyurethane molecular main chain.The soft segment intermolecular respectively introduced small molecular crosslinks composed of N,N-metabenzyl bimaleimide(HVA-2)and ionic polymer crosslinks composed of P-HZMMA formed by polymerization of hydroxyl zinc mono-methacrylate(HZMMA),and the hard segment intermolecular introduced inorganic nano layered graphene oxide(GO).The chemical crosslinking network and the physical crosslinking network formed respectively in the matrix,greatly improved the temperature resistance of materials,and enhanced the tensile strength.The preparation and properties of HVA-2 adjacency cross-linked PUE was explored in detail.Adjacency cross-linked polyurethane-urea elastomers(PUU)were prepared by using hydroxyl-terminated liquid butadiene-nitrile(HTBN),polytetrahydrofuran glycol(PTMG),toluene diisocyanate(TDI),chain extender 3,5-dimethyl thio-toluene diamine(DMTDA)and HVA-2 as the crosslinking agent.The effects of hard segment content,crosslinking density and temperature on the mechanical properties were studied,and influences of the crosslinking density on low temperature thermal performance and thermal stability were deeply studied.The mechanical properties,crosslinking density and thermal properties were characterized by equilibrium swelling method,hign and low temperature mechanic test,TGA,DSC.It was found that when the content of hard segment was 39%,the mechanical properties of PUU achieved optimal performance.The crosslinking density of PUU was enhanced by HVA-2.When the crosslinking density was 0.947×10-3 mol·cm-3,the tensile strength,Tg and the maximum decomposition temperature of the cross-linked PUU increased by 17.3%,20.1 ℃ and 5 ℃ respectively than those of the linear PUU.Cross-linked network improved the thermal and mechanical properties of the materials.The preparation and properties of ionic polymer adjacency cross-linked PUU were explored in detail.Prepolymer was synthesized by reaction between TDI,HTBN and PTMG,and then reacted with chain extender DMTDA,which mixed with initiator DCP and crosslinking reagent hydroxyl zinc mono-methacrylate(HZMMA).Herein,the ionic polymer was formed in PUU by the free radicals polymerization of HZMMA in the presence of DCP initiators during postcure process,at the same time,the adjacency crosslinking bond were formed by the reaction of the free radical active chains of ionic polymer and the unsaturated double bond in the soft segment of polyurethane,then ionic polymer adjacency polyurethane was prepared.The influences of the ionic polymer on mechanical properties,hydrogen bonding interaction,low temperature thermal performance and thermal stability were studied.It was found that when the content of HZMMA was 0.2%,the tensile strength and elongation at break of PUU achieved optimal performance.The cross-linked PU showed a higher mechanical properties retention rate at high temperature.Variable temperature FT-IR showed that the cross-linking structure slowed down the damage of temperature to hydrogen bonding.Thermogravimetric analysis showed that maximum decomposition temperature of the cross-linked PUU increased from 401.3 ℃ to 423.3 ℃ than the linear PUU.The crosslinked network formed by the ionic polymer not only improved the tensile strength but also increased the elongation at break,while the temperature resistance improved significantly.The preparation and properties of GO/PUU were explored in detail.GO was synthesized from oxidation of graphite powders by Hummers’ method,grafting GO to the hard segment of polyurethane by in situ polymerization,then the GO/PU composite material was prepared.The influence of GO on mechanical properties and thermal performance were studied.The structure and performance of GO and GO/PU were characterized by FTIR,XRD,mechanics test,SEM,DSC,TGA.It was found that the graphite interlayer spacing increased from 0.337 nm to 1.055 nm.The GO characteristic peak was not present in the XRD spectra,indicating that the GO was dispersed evenly by single layer state in the PUU matrix.It was also showed the same results in SEM.The tensile strength of the composites increased from 38.3 MPa to 44.9 MPa,and the maximum decomposition temperature increased from 401.3 ℃ to 450 ℃.The GO was well-dispersed in the PUU matrix,the tensile strength and thermal stability greatly improved.