Environmental stability of Dgeba-based epoxy adhesives reinforced with nano- and microfiller additives for bonded-in timber connections

Zakiah A. Teknologi Mara Univ., . and Ansell M. P., . and Smedley D., . (2009) Environmental stability of Dgeba-based epoxy adhesives reinforced with nano- and microfiller additives for bonded-in timber connections. [Proceedings Paper]

Commercial epoxy-based adhesives manufactured by Rotafix Ltd. are used for timber repair and bonded-in timber connections. To improve strength and prolong service life nanofillers and microfillers have been added to a standard adhesive formulation Rotafix CB10TSS. A room-temperature-cured epoxy adhesive diglycidylether of bisphenol A DGEBA crosslinked with polyetheramines was modified with either liquid rubber nanofiller carboxyl-terminated butadiene and acrylonitrile CTBN or a mixture of quartz mica and bentonite microfillers. The DGEBAbased adhesive and the two modified adhesives were exposed to a high-temperature and high-humidity environment at 50C and 95 RH. Changes in properties of the adhesives and bonded timber specimens were assessed as a function of time. Stress-strain characteristics for adhesives were generated in tension. The adhesive bonding strengths were measured as a function of exposure time using controlled pull-out of bonded-in pultruded rods from laminated veneer lumber LVL cubes and block shear tests across bonded gluelines in LVL. The high-humidity/hightemperature environment was seen to have a strong influence on mechanical properties such as tensile and shear strength and the choice of filler has a significant influence on adhesive properties and bond integrity. The liquid rubber nanofilled adhesive formulation was able to resist the negative effect of high humidity on tensile strength and had a lower reduction in shear strength in block shear tests and pull-out tests compared with the other adhesives. However the microfilled epoxy formulation retained high modulus of elasticity with very low elongation at break.

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Abstract

Commercial epoxy-based adhesives manufactured by Rotafix Ltd. are used for timber repair and bonded-in timber connections. To improve strength and prolong service life nanofillers and microfillers have been added to a standard adhesive formulation Rotafix CB10TSS. A room-temperature-cured epoxy adhesive diglycidylether of bisphenol A DGEBA crosslinked with polyetheramines was modified with either liquid rubber nanofiller carboxyl-terminated butadiene and acrylonitrile CTBN or a mixture of quartz mica and bentonite microfillers. The DGEBAbased adhesive and the two modified adhesives were exposed to a high-temperature and high-humidity environment at 50C and 95 RH. Changes in properties of the adhesives and bonded timber specimens were assessed as a function of time. Stress-strain characteristics for adhesives were generated in tension. The adhesive bonding strengths were measured as a function of exposure time using controlled pull-out of bonded-in pultruded rods from laminated veneer lumber LVL cubes and block shear tests across bonded gluelines in LVL. The high-humidity/hightemperature environment was seen to have a strong influence on mechanical properties such as tensile and shear strength and the choice of filler has a significant influence on adhesive properties and bond integrity. The liquid rubber nanofilled adhesive formulation was able to resist the negative effect of high humidity on tensile strength and had a lower reduction in shear strength in block shear tests and pull-out tests compared with the other adhesives. However the microfilled epoxy formulation retained high modulus of elasticity with very low elongation at break.

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Item Type:	Proceedings Paper
Additional Information:	2 tables
AGROVOC Term:	Joints timber
AGROVOC Term:	Timber joints
AGROVOC Term:	Dowels
AGROVOC Term:	Fasteners
AGROVOC Term:	Veneers
AGROVOC Term:	Tensile strength
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:14
URI:	http://webagris.upm.edu.my/id/eprint/11450

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