| Epoxy resins are important thermosetting resinsdue to so much of excellent properties of the resin,e.g.,high mechanical properties,excellent thermal stability and good processing characteristics,good bonding properties,good wear resistance,electrical insulation and anti-corrosion performance,low curing shrinkage rate,and low cost.Epoxy resins are widely used in adhesives,anti-corrosion coatings,electronic electrical insulation materials,and advanced composite materials.However,typically epoxy resin cured with a high crosslinking density that lead to a brittle and poor flexibility,low impact and anti-stripping performance.At the same time,high temperature and long molding cycle are generally required in epoxy curing process,which lead to a low efficiency of production and limit the applications of epoxy resin in extensives technology fields.Therefore it is vital important to find a way to improve the fracture toughness of epoxy resin without sacrificing its process ability and pristine properties.In this paper,a toughening epoxy resin was established.The effective of a"ladybug" mechanism was proposed for explaining the synergistic toughening effects;a rapid curing UV curable epoxy resin system was prepared for the low visicosity process,and a UV curing shape memory epoxy polymer was established.Those provided theoretical and experimental basis for the preparation of high toughness and rapid epoxy system and the expansion of its functional research.1.Different kinds and sizes of core-shell particles(CSPs)toughening epoxy resin matrix via two-step dispersed method to obtain a CSPuniform dispersion in situ toughening resin system.The rheological properties,mechanical properties,thermal stability and microstructure of resin system were studied.The CSP can significantly improved the fracture toughness,tensile strength,flexual strength and other mechanical properties of resin matrix with the premise of unchanged the thermal stability.2.A high performance epoxy system modified by a hybrid of toughening agents,block copolymer particle(BCP)and core-shell particle(CSP),was successfully prepared via a two-step processing method.The viscosity,thermal stability and mechanical property of the resulting modified epoxy,BCP\CSP\epoxy,were studied.The results showed that the BCP\CSP\epoxy maintained the viscosity and thermal stability of the epoxy resin,while its flexural strength and fracture toughness(KIc)were significantly increased in comparison with the neat epoxy,BCP\epoxy and CSP\epoxy.Based on the morphology analysis,a "ladybug mechanism responsible for these impressive synergistic enhancement effects was proposed.It is believed that this study provides a new pathway for the toughening of epoxy matrix materials for making advanced composites.3.A kind of fast curing and high toughness UV curing system with a certain process time was established by adding monomer to the epoxy resin.The viscosity,reaction speed,monomer conversion,thermal stability,mechanical properties of resin system were studied.A Curing time delay mechanism responsible for these systems was proposed.The results showed that the system showed low viscosity time range(less than 0.6 Pa s)more than 160s,which can meet the requirement of the system viscosity.The thichness limited of the UV curing process was solve by pre-initiation and post-injection process.This process provides a new way to improve the efficiency of epoxy curing.4.A UV curable shape-memory epoxy(SUE)system with excellent shape-memory performance and good toughness.The SME was designed based on cross-linking epoxy resin diglycidyl ether of bisphenolF(DGEBF)("hard"segments)and toughening agent 3-ethyl-3-oxetanemethanol(TMPO)("soft"segments)to create a three-dimensional network with TMPO-co-DGEBF structures.The fold-deploy tests showed that the shape fixity ratio(Rf)and the shape recovery ratio(Rr)of the SME sample with 50 wt%TMPO after 20 cycles were above 97%and 99%,respectively.The brittleness of the epoxy system has been overcome by incorporating TMPO segments in the crosslinking structure.In addition,the good mechanical properties and thermal stability of the material make it very promising for applications in industry. |
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