Macromolecules Article the ORCID tha tha Songqi Ma:000-0002.9652-1016 H ■ACKNOWLEDGMENTS cial s EP2 theP-DM the highe mobility of the chain seg bio-hased kthahofDGEBA-DDM.EP2-DDM has ■REFERENCES den P-DDM.wing to strong a A-DDM he. al stre oduced from the ess fo H rk,K H;Kim,B.H;Choi,Y.W;Jun,G.H.;Le D B.S.;P Aa,AMt.2013,25S,7 much lowe 230 the t ture (230 C) 5)M EP2-DDM.A EP2-DDM high stress leading to the comp aratively low tensile strength ■CONCLUSIONS gPom5a.2010,35(4),487-s09 nd Low (2)555-S the h (8)Fh nation and the additio hite,followed by the DGEBA The c dyl ether.Po 620 ed b 201l,52(16,3611 ith no UL. 94 rating low L0Iof24.6% ased epoxy 200 49 1g9 803MP and t resin 270 her than those 13 igid le.the two bic perties he ed that lin ba M:P ate,V.Caillol,Habas,J.P. epoxy divers n,J.J.A esin hom veget ng PP A Pol Chem 201.( ■AUTHOR INFORMATION ding authors (S.M.)E-mail mas mte.ac.cni Tel 86-0574. able oil amine.Eur..Lipid Sci Technol 2015,117(11) *0Z)E T86-057487619806Fax 86-0574-86685186. 2011,22（0.139-150. sug 90 Obviously, the moduli of EP1-DDM and EP2-DDM were much higher than that of the cured DGEBA. As Tg, modulus of thermoset also has a close tie with its cross-link density and rigidity of chain segment structure,49,50 and the higher moduli of EP1-DDM and EP2-DDM were ascribed to their higher rigidity from the more rigid aromatic rings and strongly polar N−H originated intramolecular hydrogen bonds52 than the cured DGEBA. Owing to the higher cross-link density and more N−H of EP2-DDM than those of EP1-DDM and EP2- DDM presented higher modulus than EP1-DDM. The higher rigidity of the EP1-DDM and EP2-DDM led to the lower mobility of the chain segments of the networks, corresponding to the lower elongation at break of the two bio-based epoxy networks than that of DGEBA-DDM. EP2-DDM has higher cross-link density and more N−H originated intramolecular hydrogen bonds than EP1-DDM, resulting in its lower elongation at break than EP1-DDM. Owing to its more strong aromatic rings and N−H originated intramolecular hydrogen bonds, EP1-DDM showed higher tensile strength than DGEBA-DDM. While for the EP2-DDM, it exhibited lower tensile strength than DGEBA-DDM. This is probably due to the more internal stress produced from the curing process for EP2-DDM. The internal stress is related to Tg. When the curing temperature is higher than Tg, the internal stress will be low. When the curing temperature is lower than Tg, the internal stress will be high.53 For EP1-DDM and DGEBA-DDM, their Tgs are much lower than the curing temperature (230 °C), while the temperature 230 °C locates in the glass transition range of EP2-DDM. As a result, EP2-DDM has high internal stress, leading to the comparatively low tensile strength. ■ CONCLUSIONS Two novel bio-based epoxy resins with excellent flame retardancy and thermal and mechanical properties were prepared from the lignin derivative. The epoxy resins were synthesized by the one-pot reaction of Schiff-base structure formation and the phosphorus−hydrogen addition between vanillin, diamines, and diethyl phosphite, followed by the reaction with epichlorohydrin. The bio-based epoxies demon￾strated similar curing reactivity to DGEBA. The cured bio￾based epoxies presented excellent flame retardancy with UL-94 V0 rating and high LOI of 31.4% and 32.8%, which was due to the outstanding intumescent and dense char formation ability. While the commonly used epoxy resin DGEBA was flammable with no UL-94 rating and low LOI of 24.6%. More interestingly, high Tg of ∼214 °C and outstanding mechanical properties with tensile strength of ∼80.3 MPa and tensile modulus of ∼2709 MPa, much higher than those of the DGEBA system, were achieved for the bio-based epoxies due to their high rigid structures. Meanwhile, the two bio-based epoxy resins showed different properties due to their different “coupling” structure, which suggested that vanillin-based flame retardant epoxy resins with diverse performance could be easily obtained by adjusting diamines during the synthesis. ■ AUTHOR INFORMATION Corresponding Authors *(S.M.) E-mail masongqi@nimte.ac.cn; Tel 86-0574- 87619806; Fax 86-0574-86685186. *(J.Z.) E-mail jzhu@nimte.ac.cn; Tel 86-0574-87619806; Fax 86-0574-86685186. ORCID Songqi Ma: 0000-0002-9652-1016 Notes The authors declare no competing financial interest. ■ ACKNOWLEDGMENTS The authors are grateful for the financial support from Project 51473180 supported by the National Natural Science Foundation of China, Natural Science Foundation of Zhejiang Province (LY15E030004), and the Ministry for Industry and Information of the People’s Republic of China under grant agreement no. [2016] 92. ■ REFERENCES (1) Zhang, Q.; Molenda, M.; Reineke, T. M. 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