New anhydride/epoxy thermosets based on diglycidyl ether of bisphenol A and 10-undecenoyl modified poly(ethyleneimine) with improved impact resistance

Abstract

New dendritic modifiers have been synthesized by amidation of hyperbranched poly(ethylenimine) (PEIs) with 10-undecenoic acid to obtain hyperbranched polymers (HBPs) with different degree of modification. These HBPs have been used as toughness modifiers in a proportion of 10 and 20% in reference to the epoxy resin in diglycidyl ether of Bisphenol A (DGEBA) / methyltetrahydrophthalic anhydride (MTHPA) formulations. The curing process has been studied by dynamic scanning calorimetry and by rheometry, which allow the kinetic constants and the gel and vitrification times to be evaluated. The materials obtained have been thermally characterized and their mechanical properties have been evaluated. An increase in impact resistance has been achieved and the Tg of all thermosets prepared was higher than 100ºC in spite of the flexible structure of the PEI modifiers. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 We thank the reviewers for their task and I would like to tell that we have corrected all the failures detailed by the reviewer 2. ProfWe have also improved a little the grammar and we have shortened some sentences to make them more understandable. Response to ReviewersGraphical Abstract (for review) Highlights 10-unedecenoyl derivative of polyethyleneimine was obtained.  This polymer was used as modifier in epoxy/anhydride formulations.  The final materials were characterized thermally and mechanically.  Impact strength was notably increased in the modified materials. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 formulations. The curing process has been studied by dynamic scanning calorimetry and by rheometry, which allow the kinetic constants and the gel and vitrification times to be evaluated. The materials obtained have been thermally characterized and their mechanical properties have been evaluated. An increase in impact resistance has been achieved and the T g of all thermosets prepared was higher than 100ºC in spite of the flexible structure of the PEI modifiers. Research Highlights

Hyperbranched‐modified epoxy thermosets: Enhancement of thermomechanical and shape‐memory performances

“…In order to improve the impact resistance of a material, it is important to introduce mechanisms that can contribute to energy dissipation, thereby impeding crack propagation. It has been demonstrated that the use of HBPs can effectively enhance the impact strength of epoxy materials . However, the addition of LP decreases the impact strength in comparison to the neat epoxy‐D400 formulation (100D400).…”

“…reported values of impact strength lower than 4 kJ/m 2 in epoxy thermosets modified with hyperbranched poly(ester‐amide)s. Flores et al . and Acebo et al . reported values lower than 10 and 4 kJ/m 2 , respectively, in epoxy networks modified with undecenoyl‐modified hyperbranched polymers.…”

Improved epoxy thermosets by the use of poly(ethyleneimine) derivatives

“…The synthetic process is carried out in one pot and two steps: first, the activation of 10-undecenoic acid by reaction with CDI and then the nucleophilic substitution of imidazole group in the CDI derivative by amines of the PEI structure. On changing the proportion of CDI and 10-undecenoic acid to NH reactive groups, different modification percentages could be obtained [165].…”

Preparation and Properties of Toluene-Diisocyanate-Trimer-Modified Epoxy Resin

“…Epoxy resin (EP) is a kind of polymer which contains two or more epoxy groups in its molecular chain and forms thermosetting products through various reactions between epoxy groups. It has the advantages of high mechanical strength [1], high bonding strength [2], low shrinkage [3], high stability [4,5], and easy deployment and construction. However, epoxy resin has the disadvantages of poor toughness, brittle quality, easy cracking, and low impact strength, which results in limitations to its application to repairing concrete cracks.…”