The effect of moisture on the physical and mechanical integrity of epoxies

Morgan, Roger J.; O’Neal, James E.; Fanter, Dale L.

doi:10.1007/bf00551743

Cited by 108 publications

(51 citation statements)

References 27 publications

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“…Using periodical thermal spikes, moisture absorption rate can be increased. 33,34 Xiang and Jones 35 found an equilibrium stage in their experiments at high spike temperatures.…”

Section: 30mentioning

confidence: 97%

FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

Jana

Zhong

2007

J of Applied Polymer Sci

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We previously developed a novel modified epoxy matrix for macrocomposites using reactive graphitic nanofibers (r-GNFs), which showed improved mechanical properties. This article is devoted to study the efficacy of the r-GNFs against the damage due to exposition of the matrix to hygrothermal environment and UV radiation. Moisture sorption characteristics of the pure epoxy and nanoepoxy were investigated and all kinds of matrices showed similar absorption behavior. Both diffusion and relaxation processes in sorption were observed. DSC curves of nonaged specimens of all concentrations confirmed that samples were not fully cured and r-GNFs lowered the curing degree. The effects of ageing were studied through the changes of molecular conformation by Fourier Transform infrared spectroscopy (FTIR). The results show that UV radiation assists in post-curing of the matrices. Hydroxyl unit, carbonyl unit, and epoxide unit were chosen to study the degradation. It is observed that the degradation due to UV radiation is more severe compared with that due to hygrothermal expose. It also reveals that r-GNFs resist the degradation of the epoxy resin; particularly, the nanoepoxy with 0.3 wt % of r-GNFs has the highest ageing resistance, which is in agreement with our previously tested results of mechanical properties.

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“…Using periodical thermal spikes, moisture absorption rate can be increased. 33,34 Xiang and Jones 35 found an equilibrium stage in their experiments at high spike temperatures.…”

Section: 30mentioning

confidence: 97%

FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

Jana

Zhong

2007

J of Applied Polymer Sci

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“…7 strength lowered by the pick-up of aggressive enApart from diffusion following a Fickian patvironments such as water. [1][2][3][4][5] This is unfortunate, tern 8,9 in which absorption can be expressed as a function of two intrinsic parameters, the (conbecause epoxy-based materials are employed in stant) coefficient of diffusion, D, and the fracstructural applications, be this in the form of adtional mass gain at saturation, M ϱ , the Langmuir hesives or matrices for composite materials, and two-phase model 10,11 was also found to describe thus, water exposure is a common hazard. As a water uptake.…”

Section: Introductionmentioning

confidence: 99%

Water absorption and desorption in an epoxy resin with degradation

Xiao¹,

Shanahan²

1997

J. Polym. Sci. B Polym. Phys.

160

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“…(16) However, these reactions are often incom plete due to steric and diffusional restrictions, and additional reactions such as epoxide homopolymerization can occur. (8,12,13,16,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28) The physical structures of epoxies are also complex on a macroscopic and microscopic scale and have not been charac terized in detail.…”

Section: Jj18)mentioning

confidence: 99%

“…(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) Generally, there is no direct correlation between the chemistry of the epoxide and amine monomers and the mechanical properties of epoxies with the exception that as the distance between crosslinks becomes shorter, these glasses become more brittle. (1,10,15) Also, for a specific amine-cured epoxide system, the Tg is always highest for the fully reacted, highest crosslink density glass.…”

mentioning

confidence: 98%

Structure—Property Relations of Polyethertriamine-Cured Bisphenol-A-diglycidyl Ether Epoxies

Kong

Walkup

Morgan

1983

ACS Symposium Series

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The relations between the chemical and physical network structure, the deformation and failure pro cesses and the tensile mechanical properties of polyethertriamine cured bisphenol-A-diglycidyl ether epoxies are reported for a series of epoxy glasses prepared from a range of polyethertriamine concen trations. Near infrared spectroscopy indicates that these glasses form exclusively from epoxide-amine addition reactions. Their Tg exhibits a maximum and their swell ratio a minimum at the highest crosslink density. Stress-birefringence studies reveal that these highly crosslinked glasses are ductile and undergo necking and plastic deformation. The plastic deformation initially occurs homogen eously, but ultimately becomes inhomogeneous and shear bands develop. Tensile failure occurs in the high strain shear band region. The ultimate tensile strain of these epoxies attains a maximum of 15% for the highest crosslinked glass. Off-stoichiometric networks fail at lower strains because such networks inherently contain more defects in the form of unreacted ends. The density, yield stress, tensile strength, and modulus of these glasses all decrease with increasing polyethertriamine concentration as a result of increasing free volume because of the poor packing ability of the amine molecule. A minimum is superimposed on this downtrend in density and mechan ical properties with increasing amine content at the highest crosslink density because of geometric con straints imposed on segmental packing by the net work crosslinks. The ability of these crosslinked glasses to undergo deformation is discussed in terms of the free volume and the crosslinked network topo graphy. Network failure is considered in terms of stress-induced chain scission which is determined by the concentration and extensibility of the least extensible network segments.

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The effect of moisture on the physical and mechanical integrity of epoxies

Cited by 108 publications

References 27 publications

FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

FTIR study of ageing epoxy resin reinforced by reactive graphitic nanofibers

Water absorption and desorption in an epoxy resin with degradation

Structure—Property Relations of Polyethertriamine-Cured Bisphenol-A-diglycidyl Ether Epoxies

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