Influence of constituents and process parameters on mechanical properties of flax fibre-reinforced polyamide 11 composite

Abstract

Flax unidirectional (UD) fabrics and polyamide 11 (PA11) are used to create a 100% biosourced composite. The fabrication process is hot press moulding. Different configurations are studied by varying process parameters and composite constituents. Three temperature values (190 C, 200 C and 210 C) are combined with three pressure levels (35, 65 and 100 bars). In addition, two types of flax fabric (A and B) are tested and two types of PA11 (in the form of powder or film) are used. The two forms of PA11 are characterized using differential scanning calorimetry and rheological methods. Ten different composites are then manufactured. They are compared by means of tensile tests and dynamic mechanical analysis (DMA). Results are correlated with microstructural study: measurements of porosity degree and scanning electron microscopic observations are also performed. Finally, an optimum configuration is determined: the composite flax B/PA11 film manufactured with a temperature value of 210 C and using gradual levels of pressure (25 bars during 2 min, 40 bars during 2 min and 65 bars until the end of cycle). This configuration leads to a Young's modulus value of 36 GPa and a tensile strength of 174 MPa, with the highest storage modulus and the lowest damping factor values measured by DMA.

Investigation about the Effect of Manufacturing Parameters on the Mechanical Behaviour of Natural Fibre Nonwovens Reinforced Thermoplastic Composites

“…All the tested composites were manufactured by a hot-press moulding process (see Table 2). The influence on the mechanical properties of natural fibre reinforced thermoplastic composites during the hot-press moulding process has been investigated in the literature [36,37]. Several important process parameters such as the pressure, the temperature, and the time of the cycle were pointed out.…”

Influence of the stacking sequence on the low-energy impact resistance of flax/PA11 composite

“…Flax fiber fabrics layers and PA11 film were piled up alternatively and compressed in a mould with dimensions of 450x500x4mm 3 . The applied process has been optimized in a previous paper [34]. Composites were compressed at 210°C, with a pressure of 25 bars during two minutes, 40 bars during two minutes and 65 bars until the end of the process as described in These lay-ups have the same number of plies (8), the same thickness (4mm), the same average fiber volume fraction (44%) and porosity ratio (9%).…”

Effect of Carbon Nanostructures and Fatty Acid Treatment on the Mechanical and Thermal Performances of Flax/Polypropylene Composites

“…Goudenhooft et al [7] recently showed that tensile properties of flax fibers are not significantly affected over time, regardless of the fiber yield and variety, and that the resulting dispersion in the specific mechanical properties is in the same range as that of glass fibers. Another significant issue is related to the processing conditions of the composites (temperature, dwell time, pressure), which have a major impact on the final mechanical properties, especially for thermoplastic-based composites [8][9][10].…”