well propagated between the filler and the matrix polymer, resulting in enhanced flexural strength and
modulus in response to stress. In addition, the fracture surface showed a very limited amount of torn matrix,
suggesting that the composite is more brittle. In general, coupling agent is randomly distributed in
composites and randomly reacted with wood flours and the matrix to form graft polymerization. Hence,
grafting sites are randomly distributed on wood, and a network of coupling agent is formed at the interface.
However, there is a limit for chemical coupling reaction and only part of coupling agent was grafted onto
wood surface and even cross-linked at the interface. Further, the fracture surface of the composite containing
5 wt % MAPP showed a very limited amount of torn matrix, suggesting that the matrix is more brittle than
those in composites containing 3 wt % MAPP. This phenomenon is mainly due to the excessive modification
of the base polymer.