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Polyamide 6 nanocomposites (PA6/NC) are novel type of composite materials comprising extremely thin, "nanometer scale" dispersions of smectitic silicate platelets. We prepared such PA6/NC materials via a melt compounding technique using suitably organomodified montmorillonite or hectorite type clays. The high surface to volume ratio of such thin silicate dispersions in PA6/NC leads to a high reinforcement efficiency even at 2 to 5 wt% of clay, achieving high specific modulus, strength and heat distortion temperature under load (DTUL). In addition, the platelet orientation and their surface nucleation effects seem to promote a faster crystallization and higher crystallinity in PA-6/NC (particularly at the surface and in thin-wall injection moldings), as compared to the standard PA-6. Such morphological features in PA-6/NC also result in improved moisture resistance. Recognizing these benefits, we investigated the use of PA-G/NC as a matrix for making both short and long glass fiber (GF) reinforced composites. Signifkant improvements in modulus were achievable in both the dry and the moisture conditioned state for PA-G/NC compared to standard PA-6, at any given level of glass fiber reinforcement. In general a small amount (3-4 wtYo) of the nanometer scale dispersed clay is capable of replacing up to 40 wtYo of a standard mineral filler or 10-15 wtVo of glass fiber in PA-6 composites to give equivalent stiffness at a lower density or a lower part weight advantage. In addition, improved moisture resistance, permeation banier and fast crystallization/mold cycle time contribute to the usefulness of such composites.

Preferential diffusion of deuterated solvents into the amorphous regions of a semicrystalline polymer enhances the contrast between the crystalline and amorphous regions measurable by smallangle neutron scattering. This scattering in nylons from the diffusion of D2O and deuterated ethylene glycol (d-EG) is analyzed by identifying the distinct contribution to scattering from the two amorphous regions, one in the interlamellar spaces and the other outside the lamellar stacks. The central diffuse scattering (Id) is the non-Bragg, liquidlike, or independent scattering, and is attributed to the solvents (D2O/d-EG) in the amorphous domains outside the lamellar stacks. The lamellar scattering (Il) is the interference peak from the lamellae in the stacks and is used to evaluate the distance between the lamellae, the thickness of the interlamellar spaces, and the coherence length of the lamellar stacks. The invariant calculations show that 70%-80% of the lamellar stack is crystalline. About one-third of the amorphous material in a highly crystalline nylon is in the interlamellar space, and two-thirds is outside the lamellar stacks. The thickness of the interlamellar amorphous regions into which solvent molecules diffuse varies from 10 to 60 Å depending on the thermal history and is a major contributor to the observed increase in lamellae spacing. Structural changes in nylon 6 immersed in water are accelerated at 125°C, and this temperature could be the hydrated-equivalent of the Brill transition observed at 160°C in dry nylon 6. Water or EG diffuses into the fold surfaces of nylon lamellae at elevated temperatures, and subsequent structural changes are accompanied by hydrolysis of the nylon chains. EG being a stronger solvent reduces the lamellar thickness at elevated temperatures.

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The recent growth in the post‐consumer recycling of plastics presents an opportunity for developing new, value‐added blend products from the recycled polymers. However, in order to develop blends with useful performance characteristics, suitable techniques of compatibilization and impact modification must be employed. In this study, reactive toughening and compatibilization techniques have been found to be particularly useful in achieving high thermal embrittlement resistance in the blends of recycled poly(ethylene terephthalate) containing functionalized ethylene copolymers and polycarbonate. Reactive compatibilization of recycled polyolefin blends with poly(ethylene terephthalate) and polyamide has also been investigated.