Glass transition temperature effect deterioration

It is generally believed that plasma treating processes provide surfaces with greater stability than chemical etch, corona, flame or other common polymeric treatment processes. Plasma-treated parts can be stored for weeks or longer in a clean, dry storage area, whereas it is normally recommended that corona- or flame-treated polymers be bonded immediately after surface preparation. Exposure to temperatures near the polymer s glass transition temperature will deteriorate any surface treatment. Once bonded, the surfaces of treated polymers are relatively stable, excluding the effects of outside environmental influences. 

Diluents. These are generally incorporated to reduce the viseosity of the freshly mixed adhesive to offset the effect of the filler. This may be required to improve handling and spreading characteristics or to allow filler additions which tend to reduce cost. Other properties of the fresh and hardened adhesive can be affected by the use of diluents, for example pot life, flexibility and glass transition temperature. If the diluent is non-reactive, such as solvents which remain in the cured system, the net result is a deterioration of chemical and mechanical properties such as increased shrinkage and reduced adhesion. Reactive diluents containing epoxy compounds are capable of combining chemically with the resin/hardener system. 

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