STUDIES ON DAMPING PROPERTIES OF POLYURETHANE/VINYL ESTER RESIN COMPOSITE ELASTOMER
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A series of polyurethane/vinyl ester resin (PU/VER) composite elastomers were prepared by precursors polymerization. The damping properties of PU/VER samples, with different composition, different isocyanate index and hydroxyl groups in VER metered or not, were studied by dynamic mechanical analysis (DMA). The results demonstrated that PU/VER composite elastomers show better damping properties at PU/VER=60/40 and isocyanate index at close range 1. When hydroxyl groups in VER were not metered, the elastomers presented two glass-transition temperatures. Furthermore, the damping temperature range of PU/VER cross-linking copolymer with better tan δ within normal temperature range was beyond 100 ℃, when VER acted as cross-linking agent of PU.Keywords:
Isocyanate
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Firstly isocyanate group-terminated polyurethane prepolymer was synthesized by a re-action of a N210with Toluene-2,4-diisocyanate(TDI)and then extended with PDMS and dimethlopropionic acid(DMPA),hydroxyl group-terminated PDMS-modified polyurethane oligomers containing carboxyl groups were obtained.Subsequently,a noveltype of PU/EP IPN was prepared by reaction the oligomers with the epoxy resin,cured by methyl tetrahydrophthalic anhydride(MeTHPA).The kinetics of IPN formation and behavior of microphase separation were analyzed by FTIR and SEM.The mechnical properties with varied PU/EP ratio IPN were investigated by DMA and Izod Impact Strength,heat resistance was also studied by TGA.The experimental results show that at a certain ratio of PU/EP,the synergism of IPN occurred,accordingly the composite ma-terials obtained exhibited excellent compositive properties.
Prepolymer
Isocyanate
Toughening
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The polyurethane modified by epoxy resin are prepared using isocyanate(TDI),polyether(N210),(1,4-)butanediol(BDO),trimethylolpropane(TMP) and epoxy resin as main raw materials.The effects of total mole ratio of NCO/OH,the kinds and amount of epoxy resin,the amount of BDO and TMP on the performance of PU and PUE coating films are investigated.The structure and thermal stability were characterized by FTIR and TG respectively.The results show that the hardness,tensile strength of PUE coating film are better than that of PU when the total mole ratio of NCO/OH is 1.3～1.4,the amount of E44 is 6%～7%,the BDO is 6%～8%,the TMP is 2.5%～3%.Also,the main performance of PUE coating films is accorded with the standard of GB/T19250-2003.
Trimethylolpropane
Thermal Stability
Isocyanate
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With polyurethane(PU)modification of the epoxy resin(EP)blend of phenol-based epoxy propane(E-51)and diglycidyl-4,5-epoxycyclohexane-1,2-dicarboxylate(TDE-85),the modified epoxy resin system(PU/EP)was formed using mixed aromatic amine as curing agent.The structure characteristics of the PU/EP system were analyzed by IR and SEM.The mechanical properties of the modified material were tested,and the thermal stability of the modified EP blend was also investigated by TG.The results indicate that the graft copolymerization between PU and EP effectly inforces the miscibility of the PU/EP system.Compared with the properties of pure EP,the impact strength and tensile strength of the PU/EP with high thermal stability are markedly enhanced,and the fracture surface of the PU/EP system displays tough fracture features.
Thermal Stability
Miscibility
Diglycidyl ether
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In order to improve the mechanical and chemical properties,especially the solvent resistance of the cast films formed from normal waterborne polyurethane(PU) dispersions,a novel ultraviolet(UV)-curable epoxy and acrylate-modified waterborne polyurethane dispersion(UV-EP-AC-WPUD) and its film with high crosslinking density and excellent film properties were prepared and studied.4% epoxy resin E-20 was introduced in PU chain by grafting reaction between epoxy resin and polyurethane prepolymer terminated with the -N=C=O group.The C=C bond was introduced in PU chain by the chain-extending reaction of —NCO in polyurethane prepolymer with two hydroxyl vinyl monomers PEDA and single-hydroxyl vinyl monomers PETA,and the obtained maximum C=C content was up to 4.65 meq·g-1.3% photoinitiator Irgacure 2959 was used to initiate the polymerization of C=C bond in cast films,and the gel content of the UV-EP-AC-WPUD films could reach up to 91% after 12 s UV-radiation,which meant the polymerization rate and crosslinking rate of C=C bond was high,and the obtained UV-EP-AC-WPUD film was highly-crosslinked and insoluble in solvent.The water absorption,solvent resistance,gel content,pendulum hardness and tensile strength of the cured film were studied,and Fourier transform infrared spectroscopy(FTIR) analysis and film study results showed that the UV-cured EP-AC-WPUD films including epoxy resins and hydroxyl-containing vinyl monomers had excellent mechanical and chemical properties.Thermo gravimetric analysis(TGA) also indicated that the thermal stability of the film was improved significantly.
Prepolymer
Thermal Stability
Chemical resistance
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Four polyester polyols with different molecular weight and di-or tri-functional group were synthesized,and isocyanate-and hydroxy-terminated polyurethane(PU)prepolymers were also synthesized using MDI and the trifunctional polyester polyol.The synthesized polyester polyols and PU-prepolymers were examined by FTIR.A series of PU adhesive component based on the polyester polyols,the PU-prepolymer,PAPI and MDI were prepared and their adhesion properties,thermal-aging and thermal weight loss were determined.The results showed that the shear strengths at room temperature,80 ℃,100 ℃ and 200 ℃ were 35～40 MPa,12～16 MPa,6～8 MPa and 3～5 MPa,peel strengths were 5～7 kN/m,and T5 was 286 ℃.The shear strengths at high temperature and thermal-aging properties were improved by adding asbestos.It can be used as structure adhesive.
Prepolymer
Isocyanate
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Cellular polyurethane elastomer was prepared by means of quasi prepolymerization method with polyester(POL 2016),polyether(PPG 330N), isocyanate(MT/MDI 100LL),EG and TMP as raw materials The effects of the types and mass ratio of polylol, the mass fraction of free NCO group, the mass ratio of crosslinking agent/curing agent, and the mass ratio of isocyanate on the mechanical properties of the cellular polyurethane elastomers were studied The results showed the elastomer had good property when m (POL2016)/ m (PPG 330N)=60/40 and the mass fraction of NCO was 6%～6 5%
Isocyanate
Mass fraction
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Epoxy resin grafted and modified with polyurethane(PU)was prepared by reaction of-NCO-ter- minated PU prepolymer with epoxy resin.The effects of content of PU prepolymer and reactive diluter,the diiso- cyanate structure etc.on viscosity and adhesion properties of modified epoxy resin were emphatically investigated. The results showed that the viscosity of the modified epoxy resin increased with increasing content of PU prepoly- mer and decreased with increasing content of reactive diluter.The sequence of viscosity of epoxy resin modified by different diisocyanate was IPDIMDITDI in the same condition.The shear strength of modified epoxy resin with 20% PU prepolymer on aluminum/aluminum sheets reached 7.82 MPa and the shear strength of modified epoxy resin with 10% PU prepolymer on iron/iron plates reached 11.70 MPa.The adhesion properties of epoxy resin modified with TDI or IPDI on metals were better than that with MDI.
Prepolymer
Cyanate ester
Shear Strength
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Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)-modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one-shot method. Two types of PU-modified epoxy: PU-crosslinked epoxy and PU-dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU-modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU-modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU-modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU-dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU-crosslinked epoxy/PU IPNs with 20 wt % of PU-crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999
Interpenetrating polymer network
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A series of polyurethane elastomers were prepared by pre-polymerization method using hydroxyl-terminated polybutadiene(HTPB),N,N-bis(2-hydroxylpropylene)anitin(BHA)and toluene diisocyanate(TDI)as materials,and using 4,4′-methylene bis(2-chloroaniline)(MOCA)as chain extender.The influences on the mechanical properties of polyurethane elastomers were studied,including the synthetic method,polyol,reaction temperature,reaction time,the content of —NCO in polyurethane prepolymer and curing technology.Through FTIR spectroscopy of different curing temperature polyurethane elastomer research shows elastomer micro phase separation degree gradually increasing.
Prepolymer
Hydroxyl-terminated polybutadiene
Toluene diisocyanate
Isocyanate
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