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Cellulose Nanocrystals (CNC) are abundant, renewable, and highly crystalline by-products from the forestry industry. CNCs are known to have excellent thermal and mechanical properties which have been exploited in a variety of applications across numerous fields, such as drug delivery, photonics, and in films. With the focus of integrating CNC into functional materials, there have been a multitude of methods for the surface modification of CNC and for incorporation in polymer composites. It is known that CNC can increase the mechanical strength of many polymers, however, Polyamides (including Nylon 6) have not yet been thoroughly investigated. This thesis describes the effects of CNC in Nylon 6 composites and the influence of CNC on the mechanical strength and characteristics of the polymer. Nanofibers were produced using solution electrospinning and freestanding thin films were produced using spin coating. Further, a comparison of the reinforcing impact of CNC in randomly distributed and aligned nanofibres, and the effect of each of the electrospinning processing parameters on fibre diameter and alignment is described. Furthermore, the influence of CNC on the crystallization of Nylon 6 in both thin films and electrospun fibres is also studied. Further modification of CNC with diazonium salts and with an alkylamine group via diazonium-mediated surface functionalization was performed. Both the unmodified and modified CNC was incorporated into Nylon 6 solutions and spin coated into freestanding thin films. The modification of CNC with hydrophobic aryl and alkyl groups using diazonium chemistry provides a quick and facile route towards increased interactions with hydrophobic polymers. Due to the wide range of applications that CNC has in functional materials, it is crucial to understand the factors attributed to changes in the mechanical strength of CNC-polymer composites, and to develop methods that effectively yield and control high quality nanocomposites. By detailing the effects of CNC in polymer composites, recommendations can be established for industry to use as guidelines when using CNC in Polyamides. The large reinforcing impact of a bio-renewable resource at low loadings is an exciting route for stronger materials and a stepping-stone towards more sustainable products.