This thesis focuses on the development of a new manufacturing process for a starch and cellulose biocomposites. The composite material was processed from starch powder and nonwoven hemp fibre mat, with water used to gelatinise the starch and also act as a plasticiser, enabling more effective penetration of the thermoplastic starch into the fibre mat.
Although water is required to process the biocomposite, moisture adsorption when stored at different relative humidities can have an appreciable effect on the mechanical properties, due to the hydrophilic nature of both materials. Once an effective processing method was developed, the mechanical properties of the biocomposite material were investigated with respect to moisture content.
The samples were stored at different effective relative humidities (ERH), with moisture contents reaching equilibrium after approximately 7 days. Generally an increase in effective relative humidity increased the equilibrium moisture content of the composite samples.
No statistical trend could be determined with respect Young's modulus and tensile strength as a function of moisture content due to large variances in the data. A reduction in the materials properties was apparent at the highest ERH storage condition, with properties approximately half that of all other storage conditions. Inconsistency in properties between samples stored at the same ERH seemed to be caused by poor granular fusion of the starch. Factors such as drying times and moisture content during compression moulding were thought to be the primary reason for this occurrence.
The production of a non-reinforced starch sample is recommended to confirm that the processing conditions are capable of making a suitable starch matrix material. In order to
make this a viable processing method, further optimisation of the processing parameters is require to increase the mechanical properties and reduce variance.