Curing and Characterization of Oxazolidone-Isocyanurate-Ether Networks

10.1002/app.3550

New chemically reworkable epoxy coatings obtained by the addition of polyesters with star topologies to diglycidyl ether of bisphenol A resins

10.1016/j.porgcoat.2013.07.01

Enhanced chemical reworkability of DGEBA thermosets cured with rare earth triflates using aromatic hyperbranched polyesters (HBP) and multiarm star HBP-b-poly(e-caprolactone) as modifiers

10.1002/pat.317

Cure kinetics modelling and thermomechanical properties of cycloaliphatic epoxy-anhydride thermosets modified with hyperstar polymers

10.1002/polb.23555Hyperstar polymers (HSPs) with hyperbranched aromatic polyester core and arms consisting of block copolymers of poly(methyl methacrylate) and poly(hydroxyethyl methacrylate) have been used as polymeric modifiers in cycloaliphatic epoxy-anhydride formulations catalyzed with tertiary amines, with the purpose of enhancing the impact strength of the resulting materials without compromising other thermal and mechanical properties.> In this work, the effect of these polymeric modifiers on the curing kinetics, processing, thermal-mechanical properties and thermal stability has been studied using thermal analysis techniques such as DSC, TMA, DMA, and TGA. The morphology of the cured materials has been analyzed with SEM. The curing kinetics has been analyzed by isoconversional procedures and phenomenological kinetic models taking into account the vitrification during curing, and the degradation kinetics has been analyzed by means of isoconversional procedures, summarizing the results in a time-temperature-transformation (TTT) diagram. The results show that HSPs participate in the crosslinking process due to the presence of reactive groups, without compromising significantly their thermal-mechanical properties. The modified materials show a potential toughness enhancement produced by the formation of a nano-grained morphology. The TTT diagram is shown to be a useful tool for the optimization of the curing schedule in terms of curing completion and safe processing window, as well as for defining storage stability conditions

Multiarm Star with Poly(ethyleneimine) core and poly(e-caprolactone) arms as Modifiers of Diglycidyl Ether of Bisphenol A Thermosets cured by 1-methylimidazole

10.1016/j.reactfunctpolym.2012.11.007Well-defined multiarm star copolymers, with hyperbranched poly(ethyleneimine) (PEI) as the core and poly(e-caprolactone) (PCL) arms with different degree of polymerization were synthesized by cationic ring-opening polymerization of e-caprolactone from a hyperbranched poly(ethyleneimine) core and used to modify diglycidylether of bisphenol A formulations cured with 1-methylimidazole as anionic initiator. The curing process was studied by dynamic scanning calorimetry (DSC) and FTIR. By rheometry the complex viscosity of the multiarm stars synthesized and the influence of their addition to the reactive mixture was analyzed in detail. The resulting materials were characterized by thermal and mechanical tests. The addition of the multiarm star to the formulation led to homogeneous materials with a slightly toughened fracture in comparison to neat DGEBA thermosets without compromising thermal characteristics

Modification of Epoxy-Anhydride Thermosets with a Hyperbranched Poly(ester amide). II. Thermal, Dynamic Mechanical, and Dielectric Properties and Thermal Reworkability

10.1002/APP.3845

Thermal curing and photocuring of a DGEBA modified with multiarm star poly(glycidol)-b-poly(e-caprolactone) polymers of different arm lengths

10.1007/s10973-012-2919-

New epoxy thermosets modified with amphiphilic multiarm star polymers as toughness enhancer

10.1016/j.reactfunctpolym.2014.07.022The synthesis and characterization of two novel amphiphilic multiarm star polymers with linear polyethylene glycol (PEG) and poly(e-caprolactone) (PCL) arms and their use as toughening modifiers of epoxy anhydride thermosets are reported. The new star polymers were obtained by partial pegylation of a hyperbranched polyester and subsequent growth of PCL arms. The curing process was studied by calorimetry and thermomechanical analysis, demonstrating the accelerating effect and the influence on gelation of the hydroxyl terminal groups. The curing kinetics was analyzed by model-free and model-fitting methods. The final properties of the resulting materials were determined by thermal and mechanical tests. The addition of the star-like modifiers led only to notable improvement on impact strength in the material containing a 10% of the star with PCL and PEG arms, without compromising glass transition temperature and thermal stability. The morphology of the resulting materials depended on the structure of the toughness modifier used, as demonstrated by electron microscopy, but all modified thermosets obtained showed phase-separated morphologies with nanosized particle