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Study On Structure And Properties Of Carboxyl Nitrile Butadiene Rubber/Polyamide 12 Thermoplastic Elastomer

Posted on:2022-12-06Degree:MasterType:Thesis
Country:ChinaCandidate:Z Y LiFull Text:PDF
GTID:2491306782451384Subject:Organic Chemical Industry
Abstract/Summary:PDF Full Text Request
In this thesis,peroxide-crosslinked XNBR/PA12 thermoplastic elastomer(TPV)was prepared by dynamic curing XNBR/PA12.The effects of different carboxylation rates and rubber-plastic ratio on the TPV properties of XNBR/PA12 were studied.In XNBR/PA12with 7%XNBR carboxylation rate and 50/50 rubber-plastic ratio,ZnO was added to introduce Zn2+ion crosslinking,and the effect of ionic crosslinking on the performance of XNBR/PA12 was studied.The vulcanization characteristics show that the vulcanization rate of two XNBR blends with different carboxylation rates can be promoted by increasing the temperature in the range of 180℃to 190℃.The MH-MLdifference between the highest torque and the lowest torque of the low carboxylation compound(XB)was the highest at 185℃,while the curing temperature had little effect on the MH-MLvalue of the high carboxylation compound(NXB).DSC results show that the amount of XNBR has little effect on the glass transition temperature of XNBR/PA12 TPV.Under the same rubber-plastic ratio,the glass transition temperature of TPV rubber phase was significantly higher than that of the sample without peroxide.For XNBR/PA12 with XNBR carboxylation rate of 7%and rubber/plastic ratio of 50/50,the glass transition temperature of rubber phase increased after adding ZnO.With the increase of the rubber blending ratio,the melting temperature of PA12 phase increased.The crystallization temperature of PA12 phase in TPV is higher than that of pure PA12.The change of carboxylation rate and peroxide have little effect on the crystallization capacity of XNBR/PA12 elastomer,while the increase of ZnO content is beneficial to the increase of crystallization rate.With the increase of the ratio of rubber to plastic,the comprehensive mechanical properties of all samples decreased.Under the same ratio of rubber to plastic,the tensile strength,elongation at break,tear strength and tensile permanent deformation of TPV with high carboxylation rate were superior to those of TPV with low carboxylation rate and uncrosslinked blend.The tensile resilience of TPV prepared with high carboxylation rate XNBR was stronger than that of TPV with low carboxylation rate XNBR.For XNBR/PA12 elastomers with 7%XNBR carboxylation rate and 50/50 rubber/plastic ratio,the mechanical properties of XNBR/PA12 elastomer improved with the increase of ZnO content.The mechanical properties of ZnO/peroxide crosslinking samples improved more than that of peroxide crosslinking alone.The Mullins effect was observed in all TPV samples during the cyclic stretching process.The cyclic stretching at constant elongation showed that the increase of rubber content was beneficial to the improvement of TPV elasticity.After the addition of ZnO,the TPV hysteresis loop of XNBR/PA12 increased.The reversible energy of all samples decreased while the loss energy increased with the increase of the ZnO conten.The reversible energy of TPV crosslinked by ZnO/peroxide is larger than that of ZnO only,and the progressive cycles of the former are smaller than that of the latter,indicating that the composite crosslinked by ZnO/peroxide is beneficial to tensile resilience.The vulcanization of ZnO alone is beneficial to the circulation elongation.The rheological results show that the increase of rubber content increases the modulus and viscosity of the sample,and the modulus and viscosity of TPV with high carboxylation rate are higher than those of TPV with low carboxylation rate.The relaxation modulus of TPV decreased with the increase of rubber/plastic ratio.When the rubber-plastic ratio was the same,the stress relaxation modulus of TPV was higher than that of uncrosslinked blend,and the anti-relaxation ability of TPV with high carboxylation rate was higher than that of TPV with low carboxylation rate.Dynamic frequency scanning results show that the energy storage modulus platform of TPV is higher than that of the uncrosslinked blend,and the strain corresponding to the nonlinear decline of the energy storage modulus of the uncrosslinked blend decreases with the increase of the rubber/plastic ratio.With the addition of ZnO,the energy storage modulus of all samples increases with the increase of ZnO content.The storage modulus and relaxation modulus of ZnO/peroxide co-vulcanized samples are larger than those of ZnO only vulcanized samples.The heat oil resistant and hot air aging properties of TPV are stronger than those of uncrosslinked blends.The high carboxylation rate is beneficial to improve the aging resistance and heat oil resistant properties of TPV.Under the same carboxylation rate,the aging resistance of TPV decreased with the increase of rubber/plastic ratio.The swelling rate of all samples increased with the increase of rubber content.Under the same ratio of rubber to plastic,the swelling resistance of TPV is better than that of uncrosslinked blend,and TPV(PNXB)with high carboxylation rate has better swelling resistance than TPV(PXB)with low carboxylation rate.The ZnO/peroxide co-vulcanization has better swelling resistance,thermal stability,heat resistance to oil and air aging than that of ZnO only.The increase of ZnO content is beneficial to improve the swelling resistance,thermal stability and aging resistance of TPV.
Keywords/Search Tags:carboxyl nitrile butadiene rubber, polyamide 12, thermoplastic elastomer, rheological property, oil resistance
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