New Improved Thermosets Obtained From Diglycidylether of Bisphenol A and a Multiarm Star Copolymer Based on Hyperbranched Poly(glycidol) Core and Poly(methyl methacrylate) Arms

Abstract

A well-defi ned multiarm star copolymer, hyperbranched poly(glycidol)-b -poly(methyl methacrylate) (PGOH-b -PMMA), is used as a modifi er in the curing of diglycidylether of bisphenol A (DGEBA) using 1-methyl imidazole (1MI) as anionic initiator. The effect of the polymer topology on the curing and gelation processes is studied. The addition of the PGOH-b -PMMA to the resin leaves the complex viscosity unaltered. The addition of the modifi er decreases the shrinkage after gelation compared to that measured in the curing of the neat resin. By DMTA a single relaxation process in the pure DGEBA and modifi ed thermoset is found. The addition of the star-like modifi er led to an improvement on the mechanical characteristics such as the impact strength and microhardness in comparison to the neat material.

Influence of end groups in hyperbranched polyesters used as modifiers in the characteristics of epoxy thermosets cured by adipic dihydrazide

“…However, the thermoset containing a 10% of HBP-OH shows a notable improvement in impact strength, quite similar to phase separated materials, but it presents a homogeneous appearance with a patterned roughness. This type of morphology was previously observed by us in materials obtained with 1-methylimidazole, which cured very fast as is also the case here [30]. The T g measured for this thermoset does not indicate plasticization, related to ductility, that dictate its toughness characteristics [31].…”

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

“…Recently, hyperstar polymers (HSPs) have been studied as potential toughening agents in thermosetting formulations . Because of their hyperbranched core, they have a globular structure that makes them still highly advantageous from the processing point of view becaues of their low melt viscosity, which produces a very little increase in the formulation viscosity in comparison with linear polymers, especially with shorter arm lengths .…”

“…Because of their hyperbranched core, they have a globular structure that makes them still highly advantageous from the processing point of view becaues of their low melt viscosity, which produces a very little increase in the formulation viscosity in comparison with linear polymers, especially with shorter arm lengths . Impact strength enhancement of up to 200% has been achieved in cationic epoxy thermosets modified with a HSP consisting of a hyperbranched poly(glycidol) core and poly(methylmethacrylate) arms, and up to 300% in epoxy‐anhydride thermosets with HSP consisting of a hyperbranched poly(ethyleneimine) core and end‐capped poly(ε‐caprolactone) arms . Morell et al synthesized HSPs with hyperbranched poly(glycidol) core and poly(methylmethacrylate) arms and used them successfully as phase‐separating toughening agents for epoxy thermosets cured with tertiary amines .…”

Control of reactions and network structures of epoxy thermosets

“…Early works were performed by Rozenberg and coworkers and are reported in a detailed review [48]. Recently, in a series of papers, Serra and coworkers described studies of the curing of DGEBA initiated by 1-methylimidazole (see section 3.2.1) in the presence of various hydroxyl-ended multiarm polymers [114,[374][375][376][377]. For instance, they used a star polymer based on a poly(styrene) core and poly(ε-caprolactone) arms as a reactive modifier to improve the toughness of final materials [374].…”