Contents - Akademi Sains Malaysia

addition, examination of the frequency-dependence ofthe relaxation temperatures allows the determination ofactivation energies of the associated transitions (Whiteet al characterize the thermal and mechanical properties ofcured thermosets and cured thermoset-based compositesDMTA can be used to study the effect of cross-linking.When a polymer is cross-linked, covalent bonds are formedbetween the polymer chains, which bring them closertogether. This reduced the free volume and causes anincrease in the T g (Ward & Hardley 1993). Another effectof cross-linking is to cause a broadening of the loss factorpeak; to the extent that very highly cross-linked materialshave no glass transition at all since the motion of longsegments of the chain is not possible. This can also be seenas a decrease in the amount by which the storage modulusdecreases at T g (Ward & Hadley 1993).The cross-linking of epoxy adhesives is achievedthrough the addition of hardener. Depending on the type are different (Pascault et alis an aliphatic amine, the curing process occurs at roomtemperature, but it is slow and often incomplete. Followinginitial cure the polymer network has a low glass-transitiontemperature (T g ) and high ability to absorb water (Prolongoet altemperature and high humidity, the molecular structureis altered, causing dimensional changes and reduction orincrease in T g Bonding of rods into timber members has been be made with epoxy adhesives due to their capabilityto produce thicker gluelines. There are many types ofadhesives available in the market but among the studies low for service temperature. Hence the previous workby researchers (Ahmad et al and micro-particles and found that the additions of nano Therefore this study investigated the thermal propertiesof epoxy-based adhesive reinforced with nano- andmicro-particles before and after exposure to the different (to study the effect of humidities), soaked in water (todetermine the effect of moisture alone) and placed in the MaterialsMATERIALS AND METHODSThe adhesive system under investigation is a thixotropic, monofunctional and di-functional reactive epoxy diluents contains polyetheramines combined with a rheology modifying the standard adhesive with the addition ofeither liquid rubber (carboxyl-terminated butadiene and (ceramics particles, a mixture of bentonite, quartz andmica) and these adhesives were designated as Albipox andTimberset, respectively. The rheology and the mechanicalproperties of these adhesives have been reported by variousauthors (Ahmad et alPreparation of SpecimensThe adhesives were mixed manually and then the mixturewas transferred into a plastic rectangular mould of 3 mm mould was coated with release agent. Another glass platewas placed on top of the mould and weights were added toof curing, the samples were removed from the moulds andadhesive plates were cut using a diamond cutter into bars3 3 mmthickness 3 arranged on the plastic shelves inside the chamber. In orderto make sure that the environmental chamber provides the humidity were monitored using the built-in temperature andhumidity meter and from time to time, the temperature andhumidity was counter checked with thermometer, externalhumidity meter and humidity indicator. The specimensTest MethodsViscosity measurementsout by employing a cone and plate method using a Bohlin 38