The influence of heating temperature, pressure, type of fibre
and matrix, and number of plies is studied in this work. The results
of 21 tests configurations are analysed, leading to the next
conclusions:
– Biocomposite strength is directly related to fibre strength. This
conclusion is not obvious because implies similar adhesion
between the matrix and the different fibres. Thus, biocomposites
manufactured with basket weave flax fibres presented the
higher tensile strength.
– The influence of matrix is related to the number of plies. For
two-plies biocomposites the higher strength was obtained with
3260HP PLA matrix. However, this matrix presented spreading
problems for higher number of plies due to the non-uniform
temperature distribution. Thus, 10361D PLA matrix was
selected as the best option.
– A heating temperature of 185 C was found as the optimum
value. Higher heating temperatures produce less-strength biocomposites
because fibres are damaged due to overheating.
While, matrix melting is not complete for lower heating temperatures
and short processing times.
– A wide range of pressure during compression moulding, from
8 MPa to 32 MPa, leaded to similar values of tensile strength.
Lower pressure implies lack of cohesion in the biocomposite,
and higher pressure produce fibre breakage.
The present method can produce a biocomposite with a tensile
strength higher than 100 MPa in a production time of 5 min, 2 min
of preheating and 3 min of heating under pressure. This result
implies a significant reduction of production time leading to a
reduction of the manufacture cost of biocomposites.
However, more studies must be carried out to improve
this method. The conclusions are stated only from the tensile
strength point of view. There are other mechanical and physical
properties, as biodegradability, that should be studied to verify
the quality of biocomposite manufactured with the present
method.