Adhesion Measurement
Mechanical evaluation of the adhesive bond between a single reinforcing fiber and the surrounding polymer matrix defines the load transfer capacity of a composite material. A high interfacial shear strength is required to ensure that stress is efficiently transferred from the polymer to the flax fiber during mechanical loading. Mills testing natural fiber composites record this parameter in Megapascals using specialized single-fiber pull-out equipment.
Fibre Treatment
Chemical modification of the raw flax surface through alkalization or silane treatment increases the micro-mechanical interlocking between the fiber and the resin. These treatments remove the weak outer layer of hemicellulose and pectin, exposing the crystalline cellulose core which offers a higher surface energy. When spinners prepare yarn for composite applications, the laboratory documentation certifies the treatment parameters to guarantee consistent bonding behavior.
Process control records from the treatment line are kept to ensure that the chemical concentration and exposure time remain within the specified limits.
Composite Performance
Failure of the composite structure occurs by fiber pull-out or matrix cracking when the bond strength is inadequate. High values of this metric ensure that the material can absorb energy without delaminating under stress. The buyer’s specification sheets require minimum values to ensure long-term durability in structural applications.
