Yield and fracture behaviour of cross-linked epoxies

Vakil, U. M.; Martin, G. C.

doi:10.1007/bf01154954

Cited by 22 publications

(15 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The literature has generally shown that decreasing the crosslink density causes toughness to increase because of the formation of a looser, more mobile network that is able to absorb energy more efficiently than a highly crosslinked network 9–11. As early as 1965, Broutman and McGarry12 observed an increase in toughness with a decrease in crosslink density while using both epoxy and polyester resin systems.…”

Section: Introductionmentioning

confidence: 99%

Toughening of trifunctional epoxy system. V. Structure-property relationships of neat resin

Varley

Hodgkin

Simon

2000

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

ABSTRACT:This work presents an investigation into the structure-property relationships of a cured highly crosslinked epoxy/amine resin system. The mechanical, physical, and thermal properties of the cured and postcured networks were measured and compared to the chemical structures. Crosslink density was shown to be dependent upon secondary amine conversion and it determined the glass transition temperatures, water uptake, density, toughness, and compressive strength. Other properties such as compressive modulus and yield stress were determined by more short-range molecular motions. Curing at a temperature of 150°C was shown to be the minimum temperature required to "completely" cure the network and achieve optimum mechanical, physical, and thermal properties.

show abstract

Section: Introductionmentioning

confidence: 99%

Toughening of trifunctional epoxy system. V. Structure-property relationships of neat resin

Varley

Hodgkin

Simon

2000

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

show abstract

“…Misra et al identified the components of their blends, which included Epon 1004F with a major component of n = 12, but did not quantify the PDI. Vakil and Martin did not consider molecular weight distributions of their epoxies …”

Section: Resultsmentioning

confidence: 99%

“…Vakil and Martin investigated yield and fracture behavior of various epoxies, including two bimodal blends, cured with m ‐phenylenediamine . Their blends were mixtures of Epon 825 (EEW = 175 g/mol) with Epon 1004F (833 g/mol) matching the EEW of 1001F (545 g/mol) and Epon 825 with Epon 1001F to match Epon 836 (EEW = 315 g/mol).…”

Section: Introductionmentioning

confidence: 99%

“…A distribution in the epoxy with a constant amine molecular weight could yield similar results. The previous studies with blends of various molecular weight epoxies only used aromatic or anhydride curing agents, so there was little flexibility in the resulting networks; any influence the epoxy distribution had could have easily been masked. In addition, few of the prior studies had a comparable single distribution epoxy for reference.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Epoxy‐amine networks with varying epoxy polydispersity

Aninch

Palmese

Lenhart

et al. 2014

J of Applied Polymer Sci

View full text Add to dashboard Cite

Solid, high molecular weight DGEBA-based epoxies were blended with high purity liquid DGEBA to create several resins with equivalent epoxy equivalent weights, but with polydispersity indices (PDIs) ranging from 3 to over 10. The resins were cured with a stoichiometric amount of polyetheramine and compared to a nonblended epoxy with PDI of 1.8. Modulus, glass transition temperatures, and molecular weight between cross-links were measured using dynamic mechanical analysis. Coefficients of thermal expansion (CTE) were measured and used to extend room temperature density measurements as a function of temperature. Fracture properties were also measured. Overall, the increased polydispersity has almost negligible effect, with the main difference occurring in the slope of the glassy CTE, with more polydisperse epoxies having a slower increase in CTE. In comparison to previous work where bimodal amines were blended with DGEBA, we conclude that epoxy resins are far more sensitive to distributions in the flexible portion, rather than the more rigid one.

show abstract

“…Experimental investigations provide insight into reaction kinetics and associated effects of temperature [2][3][4][5] for diglycidyl ether of bisphenol A (DGEBA) epoxy-based resin formulations. Additional experimental investigations provide insight into the relations among thermal processing and the resulting mechanical and physical properties [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

On the Nature of Epoxy Resin Post-Curing

2020

View full text Add to dashboard Cite

Post-curing is intended to improve strength, elevate glass transition, and reduce residual stress and outgassing in thermosets. Also, experiments indicate post-curing temperatures lead to ether crosslinks and backbone dehydration. These results informed molecular dynamics methods to represent them and compare the resulting thermomechanical effects. Diglycidyl ether of bisphenol A (DGEBA)-diamino diphenyl sulfone (DDS) systems were examined. Independent variables were resin length, stoichiometry, and reaction type (i.e., amine addition, etherification, and dehydration). Etherification affected excess epoxide systems most. These were strengthened and became strain hardening. Systems which were both etherified and dehydrated were most consistent with results of post-curing experiments. Dehydration stiffened and strengthened systems with the longer resin molecules due to their intermediate hydroxyl groups for crosslinking. Changes in the concavity of functions fit to the specific volume versus temperature were used to detect thermal transitions. Etherification generally increased transition temperatures. Dehydration resulted in more transitions.

show abstract

Yield and fracture behaviour of cross-linked epoxies

Cited by 22 publications

References 15 publications

Toughening of trifunctional epoxy system. V. Structure-property relationships of neat resin

Toughening of trifunctional epoxy system. V. Structure-property relationships of neat resin

Epoxy‐amine networks with varying epoxy polydispersity

On the Nature of Epoxy Resin Post-Curing

Contact Info

Product

Resources

About