Injection-Molded Parts of Partially Biobased Polyamide 610 and Biobased Halloysite Nanotubes

This works focuses on the development of environmentally friendly composites with a partially biobased polyamide 610 (PA610), containing 63% biobased content, and a natural inorganic filler at the nanoscale, namely, halloysite nanotubes (HNTs). PA610 composites containing 10, 20, and 30 wt% HNTs were obtained by melt extrusion in a twin screw co-rotating extruder. The resulting composites were injection-molded for further characterization. The obtained materials were characterized to obtain reliable data about their mechanical, thermal, and morphological properties. The effect of the HNTs wt% on these properties was evaluated. From a mechanical standpoint, the addition of 30 wt% HNTs gave an increase in tensile modulus of twice the initial value, thus verifying how this type of natural load provides increased stiffness on injection molded parts. The materials prepared with HNTs slightly improved the thermal stability, while a noticeable improvement on thermomechanical resistance over a wide temperature range was observed with increasing HNTs content. The obtained results indicate that high biobased content composites can be obtained with an engineering thermoplastic, i.e., PA610, and a natural inorganic nanotube-shaped filler, i.e., HNTs, with balanced mechanical properties and attractive behavior against high temperature.

Manufacturing of composite materials with high environmental efficiency using epoxy resin of renewable origin and permeable light cores for vacuum-assisted infusion molding

This work focuses on the manufacturing and characterization of novel and lightweight hybrid sandwich-type structures, using different stacking sequences of flax and basalt fabrics as reinforcement fibers, both of them previously silanized. To reduce the overall weight and facilitate the manufacturing process, a polyester non-woven core, was used which, besides reducing the weight of the composite it also acts as a media to spread the resin. These composites were manufactured with a partially bio-based epoxy resin with a reactive diluent derived from epoxidized vegetable oils that contributes to a 31 % of biobased content. The hybrid composites were obtained by vacuum-assisted resin infusion moulding (VARIM), where the core was used as a media to spread the resin. The mechanical properties were evaluated in flexural and impact conditions. The interactions in the fiber-matrix interface were studied through field emission scanning electron microscopy (FESEM). The obtained data revealed that the silane (coupling agent) treatment works better on basalt fibers than on flax fibers, resulting in superior flexural properties on structures where these fibers are present. It is noteworthy to mention that the stacking sequence of plies directly influences the flexural properties, but it does not significantly affect the energy absorbed when these composites work on impact conditions.