Bonding refers to surface treatments applied to reinforcing fibres as they leave the nozzle (textile bonding) and to fabrics (plastic bonding). It also denotes the products used.
"Textile" bonding applied to filaments as they leave the nozzle consists in depositing binder to ensure cohesion of the filaments thereby reducing abrasion and making subsequent operations (weaving) easier, and preventing electrostatic charges from forming.
It is particularly used for glass and ceramic fibres in relatively large proportions (5 to 10% by weight). In general it is not compatible with resin impregnation systems.
When delivered with bonding a fabric is called "loomstate fabric"
"Plastic" or finish bonding applied to fabrics consist in depositing a binding agent to provide physical-chemical bonding between the fibres and the resin and to protect the fibre from its environment.
Bonding is chosen depending on the subsequent impregnation and is an important quality parameter for fibre/matrix bonding and for fatigue strength and ageing.
"Textile-plastic" bonding provides a compromise between textile and plastic properties (resin compatibility). It is increasingly used with carbon fibres.