| The C8 fraction of petroleum cracking by-product contains a large amount of olefin monomers,which can be used to synthesize polymer resins.However,due to the large difference in monomer activity in the C8 fraction and containing a large amount of polymerization inhibitors,the conventional polymerization method has complicated processes,low yields,and severe limitations comprehensive utilization of the C8 fraction.In this thesis,maleic anhydride(MAH)is used as a comonomer.The high copolymerization activity of olefin monomer and maleic anhydride and the selection of appropriate initiators were used to successfully prepare C8-MAH copolymers at high temperature.The composition of the reaction medium,effects of comonomer ratio,initiator amount,reaction temperature and other conditions on the copolymer yield,structure composition and molecular weight was studied..The synthesized C8-MAH random copolymers with different molecular weights and different structures were modified with epoxy soybean oil(ESO).The optimal modification conditions were determined based on the analysis of the structure and properties of the modified product.ESO-based thermosetting resins with better comprehensive properties were prepared under optimized conditions.The specific research content is as follows:1.Using low molecular weight styrene-maleic anhydride random copolymer(R-SMA)as a model compound,R-SMA modified ESO was prepared under the catalysis of tertiary amine accelerators.The results of dynamic thermomechanical tests showed that Amine(DABCO)as the accelerator,the amount is 1 wt%of the total mass of acid anhydride and epoxy group,and the molar ratio of acid anhydride to epoxy group ?1,the temperature range of high storage modulus of the modified product is widened,shows best performance;the relationship between reaction heat and temperature was measured by differential scanning calorimetry,and the change curve of reaction activation energy with conversion rate was calculated by FWO method.It was found that the activation energy decreased rapidly when the conversion rate was>60%,and increased with the conversion rate.The hydroxyl content generated by epoxy ring-opening in the system increased,and the self-acceleration phenomenon may be related to the autocatalysis of the hydroxyl group;the infrared spectrum showed that the R-SMA modified ESO mainly formed the ester bond structure,and there were still a small amount of acid anhydride groups in the product and epoxy groups.2.The C8 fraction is used as a raw material without isolation and purification.It is directly copolymerized with MAH of different molar ratios.Xylene is used as a reaction medium.A random copolymer was prepared by using dicumyl peroxide as an initiator(1 wt%of monomer mass)at a temperature of 100? by adding a comonomer dropwise.When the molar ratio of olefin monomer to MAH in C8 is 65/35,the mass fraction of the anhydride in the prepared C8-MAH copolymer is 45%.As the molar ratio of olefin to MAH increases,the mass fraction of anhydride in C8-MAH copolymer is gradually reduced to 23%,and the molecular weight of the product is in the range of 6000-10000.3.Keep the monomer concentration and molar ratio unchanged.By introducing non-polar n-heptane into the reaction solvent,the yield of the copolymer can be effectively improved,but the anhydride content in the copolymer will increase slightly;otherwise,the polar solvent is added.Cyclohexanone(50%,V/V)can obtain a C8-MAH random copolymer with a low anhydride content(close to the feed ratio);as the amount of initiator increases,the number average molecular weight of the copolymer decreases from 8,000 to 2500,However,it has no significant effect on the anhydride content of the copolymer;the reaction temperature is further increased to 120?,and a low acid anhydride content C8-MAH random copolymer close to the monomer feed ratio can be obtained without adding a polar solvent;The glass transition temperature of the random copolymer is gradually reduced from 130 ?(33%anhydride content)to 110 ?(18%anhydride content).4.Reaction conditions of C8-MAH random copolymer with epoxy soybean oil which content the optimal reactant molar ratio,the amount of accelerator the reaction time,and the temperature,are same as the reaction when using the above R-SMA as the model compound,The experimental results show that when the C8-MAH random copolymer has a number average molecular weight of less than 5000 and an acid anhydride content of less than 30%,the storage modulus of the ESO modified product is the highest,that is due to the internal toughening of epoxy soybean oil.As a result,the glass transition temperature of the modified product is reduced to about 70?.As a bio-based material with excellent properties,C8-MAH modified ESO has broad application prospects in the field of thermosetting resins. |
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