Summary: Multifunctional poly(tartar amides) have been synthesized and used as bio‐inspired antifreeze additives. It is shown that these polymers strongly interfere with the crystallization process of water in comparison to commercially available commodity polymers. While the addition of the poly(tartar amides) results in minor freezing point depression, as is shown by differential scanning calorimetry, a strong change in the ice crystal morphology is evident. Wide‐angle X‐ray scattering and optical microscopy indicate that the hexagonal structure of undisturbed ice‐crystals is oriented and partly deformed.Light microscopy image of ice crystals at 223 K after a freezing assay with poly(tartar amides) shown at a polymer concentration of 2 wt.‐%.imageLight microscopy image of ice crystals at 223 K after a freezing assay with poly(tartar amides) shown at a polymer concentration of 2 wt.‐%.

Homogeneous dispersion of graphene into thermoplastic polymer matrices during melt-mixing is still challenging due to its agglomeration and weak interfacial interactions with the selected polymer matrix. In this study, an ideal dispersion of graphene within the PA66 matrix was achieved under high shear rates by thermokinetic mixing. The flow direction of graphene was monitored by the developed numerical methodology with a combination of its rheological behaviors. Graphene nanoplatelets (GNP) produced from waste-tire by upcycling and recycling techniques having high oxygen surface functional groups were used to increase the compatibility with PA66 chains. This study revealed that GNP addition increased the crystallization temperature of nanocomposites since it acted as both a nucleating and reinforcing agent. Tensile strength and modulus of PA66 nanocomposites were improved at 30% and 42%, respectively, by the addition of 0.3 wt% GNP. Flexural strength and modulus were reached at 20% and 43%, respectively. In addition, the flow model, which simulates the injection molding process of PA66 resin with different GNP loadings considering the rheological behavior and alignment characteristics of GNP, served as a tool to describe the mechanical performance of these developed GNP based nanocomposites.

In the present work, single layer graphene nanoplatelets (GNPs) derived from waste tires by recycling and upcycling approaches were integrated in homopolymer (Homo-) and copolymer (Copo-) polypropylene (PP) matrices by fast and efficient mixing in the melt phase. The effect of GNP content on crystallization and mechanical behaviors was investigated in detail at different loading levels. Regarding isothermal and non-isothermal crystallization experiments, GNPs significantly accelerated the nucleation and growth of crystallites, and the crystallization degree in Homo-PP nanocomposites was slightly higher than that of Copo-PP based nanocomposites. Also, there was significant improvement in mechanical and thermal properties of GNP reinforced polymers compared to neat polymers. As the GNP concentration increased from 1 to 5 wt%, there was a gradual increase in flexural modulus and strength values. In tensile tests, an increase in GNP content in both polymer grades led to a slight increase in yield strength coming from the proper distribution of nano-reinforcement by creating stress concentration sites. After the yield point, Homo-PP based nanocomposites showed higher strain hardening than GNP reinforced Copo-PP owing to a high crystallization degree and linear chains of Homo-PP. This work showed that functionalized graphene can act as both nucleating and reinforcing agent in the compounding process and its exfoliation through polymer chains is much better in homopolymers at a faster and high shear rate.

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The design of lightweight composite structures is a principal keystone in improving part performance by reducing adverse environmental impacts and adopting energy-efficient manufacturing technologies. This study replaced long glass fiber reinforced homoPP compounds as an injection grade with short hemp fiber reinforced homopolymer polypropylene (homoPP) by incorporating graphene nanoplatelets (GNP) produced from the source of recycled carbon black coming from pyrolysis of waste tires by providing 15% lightweighting. With new compound formulation by adjusting the amounts of compatibilizer and GNP, injection moulding process was integrated with overmoulding process by using bio-based UD prepregs to enhance the adhesion of injected part and interfacial interaction by decreasing the stress concentrations in the structure. This novel hybrid composite design having 40% hemp fiber, 1.0wt% GNP and 2.7wt% compatibilizer provided to improve flexural modulus and strength by 169% and 67.9%, respectively, compared to neat homoPP. For overmoulding process, bio-based natural fibers reinforced UD tapes were used as an insert and combined with injected hemp fiber reinforced composites with the enhancement of 211% and 93.6% in tensile modulus and strength compared to neat homoPP. This work achieved to convert conventional composite structures into recyclable and sustainable thermoplastic composites having multi-scale reinforcements with tailorable functionality.