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The objective of this work was to examine the effect of thermal history during cooling from the melt on the degree of crystallinity, morphology and as well as the relationship between morphology/thermal history and mechanical properties of a 60:40 weight % mixture of woven glass fibres/PP composites. Mechanical properties studied include low velocity falling weight impact strength, flexural properties (modulus and strength) and interlaminar shear strength (ILSS). However the main focus was low velocity impact strength. The composite laminates were manufactured within a flat mould using a compression moulding press. Three thermal treatments were employed: isothermal crystallization from the melt in the range 106 to 156°C for 10, 30, 60 and 240 minutes in an oven; non-isothermal crystallization from the melt at rates varying from 0.67°C/Min. to 62.4°C/Min; and quenching from 190°C to rzooc and then annealing at 155, 160 and 165°C for one hour. The degree of crystallinity developed in the matrix polymer was determine using differential scanning calorimetry (DSC) and the matrix morphology was examined by reflected light microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). TEM was used for quenched and annealed specimens.

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A new family of aliphatic, polyurethane dendritic macromolecules has been designed, synthesised and characterised. The convergent route to dendrimers and the reactions of the selective coupling agent, carbonyl diimidazole (GDI) were employed. The method was successful in the preparation of first, second and third generation dendrimers and dendrons of the first to fourth generations. The structure of the termini of these branched macromolecules was varied to consist of r-butyl, benzhydryl, cyclohexyl or 4-heptyl groups. The dendrons were also coupled to a trifunctional aromatic core unit to create another series of dendrimers with an innermost layer of ester functions. The compounds prepared were soluble in most common organic solvents and insoluble in water. The physical state of the materials ranged from sticky oils to hard, amorphous solids depending on the nature of the end groups and the molecular weight of the macromolecules. The synthesis of the second generation dendrimer with (-butyl end groups was adapted to make a series of six codendrimers with differing arrangements of concentric layers of urethane and carbonate functions as well as the polycarbonate analogue. These second-generation dendrimers varied in their physical state from oils of low viscosity to hard amorphous solids depending on the proportion of carbonate and urethane functions in the molecule. The hydrogen bonding interactions in solution of some of the dendritic compounds were investigated by (^1)H NMR and infrared spectroscopy. From the analysis it was concluded that the hydrogen bonding was intramolecular rather than intermolecular in nature and that the degree of hydrogen bonding was dependent on the generation and the terminal groups of the structures. In addition, the degree of hydrogen bonding of the urethane functions was observed to be dependent on the location of the urethane layers in the second generation poly(urethane-carbonate) codendrimers. The thermal properties of the dendrimers were investigated and the materials observed to have a single glass transition. The glass transition temperatures of the dendritic families with different termini were found to be dependent on the composition of the end group and the molecular weight of the molecule. The glass transition temperatures of the codendrimers were dependent on the proportion of urethane and carbonate links in the structure and also the relative location of the layers. In a preliminary study, it was shown that blends of two different dendrimers were characterised by only one glass transition.