Six‐arm star‐shaped polymer with cyclophosphazene core and poly(ε‐caprolactone) arms as modifier of epoxy thermosets

Abstract

A six‐arm star‐shaped poly(ε‐caprolactone) (s‐PCL) based on cyclophosphazene core was obtained by presynthesis of a hydroxy‐teminated cyclophosphazene derivative and subsequent initiation of the ring‐opening polymerization of ε‐caprolactone, and its use in different proportions as toughening modifier of diglycidylether of bisphenol A/anhydride thermosets was studied. The star‐shaped polymer was characterized to have approximately 30 caprolactone units per arm. Differential scanning calorimetry revealed a nonsignificant influence on the curing process of the epoxy‐anhydride formulation by the addition of s‐PCL. The s‐PCL‐modified epoxy thermosets exhibited a great improvement in both toughness and strength compared with the neat resin, as the result of a joint effort by the internal rigid core and the external ductile polyester chains of s‐PCL. When the addition of the modifier was 3 wt %, an optimal mechanical and thermomechanical performance was achieved. The impact resistance and tensile strength of the cured epoxy resin were enhanced by 150% and 30%, respectively. The glass transition temperature was also increased slightly. Moreover, the addition of the star‐shaped modifier had little harmful effect on the thermal stability of the material. Thus s‐PCL was proved to be a superior toughening agent without sacrificing thermal and mechanical properties of the thermosets. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44384.

A One-Component, Fast-Cure, and Economical Epoxy Resin System Suitable for Liquid Molding of Automotive Composite Parts

“…Owing to the high strength-to-weight ratio and specific stiffness, carbon fiber-reinforced plastics (CFRPs) are increasingly used in a variety of applications that require high-performance and light weight [ 1 , 2 , 3 , 4 , 5 , 6 ]. CFRPs are regarded as ideal substitutes for metals for the manufacturing of new-generation electric or hybrid car body and parts [ 7 , 8 ].…”

Curing kinetics and mechanical properties of fast curing epoxy resins with isophorone diamine and N‐(3‐aminopropyl)‐imidazole

“…The comparison of the T g of the cured epoxy resins with different IPD mass ratios was measured by the DSC, as shown in Figure . The T g of thermosetting resin is mainly influenced by the crosslink density, internal molecular rigidity, steric hindrance effect, and so on . It can be seen that the T g of the system increases gradually with the increase of IPD level, suggesting more adequate crosslink density.…”

Thermal latent curing agent for epoxy resins from neutralization of 2‐methylimidazole with a phosphazene‐containing polyfunctional carboxylic acid

“…N 3 P 3 ‐PHBA was first synthesized by a nucleophilic substitution between HCCP and PHBA using TEA as an acid acceptor . The N 3 P 3 ‐PHBA was then oxidized using KMnO 4 under alkaline condition to obtain N 3 P 3 ‐COOH .…”

“…Hexachlorocyclotriphosphazene (HCCP) is an inorganic‐organic hybrid molecule with six active chlorine atoms, which endow its versatility to be the core in the synthesis of functional star‐shaped compounds/polymers, because covalent linkages can be easily formed between nucleophiles and phosphorus atoms with chloride as the leaving group . The chemical incorporation of cyclotriphosphazene units may invariably ensure the composites excellent rigidity owing to the extraordinary ring structure composed of alternating phosphorus and nitrogen atoms . Meanwhile, the synergistically flame retarding effect through the simultaneous addition of phosphorus‐ and nitrogen‐containing flame retardants has been well‐documented and is absolutely undoubted .…”