Strong synergistic toughening and compatibilization enhancement of carbon nanotubes and multi-functional epoxy compatibilizer in high toughened polylactic acid (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends

Different carbon nanotubes (CNTs) contents on high-toughness polylactic acid (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends were prepared by one-step melt blending using multifunctional epoxy oligomers (ADR) as reactive compatibilizer. During reactive blending, the PLA or PBAT chains were grafted onto the CNTs by allowing the carboxyl or hydroxyl groups to react with epoxy groups and form a branched CNTs-based copolymer. The branched copolymer at the interface between PLA and PBAT was dispersed through emulsion to improve the polymer-polymer or polymer-nanoparticle entanglement between the molecular chains. Interfacial adhesion, interface layer stability, and system viscoelasticity and compatibility were improved as indicated by rheological curves and dynamic mechanical analysis. The strength and toughness of the sample were simultaneously improved by the addition of CNTs and ADR. The impact strength reached 35.3 kJ/m2, which was approximately 7 times that of the PLA/PBAT blend, and the tensile strength was also increased from 33.6 MPa to 42.8 MPa. The properties of PLA/PBAT blend synergistically modified by ADR and CNTs were obviously better than those of PLA/PBAT blend modified by ADR or CNTs. The toughening synergistic effect of ADR and CNTs on PLA/PBAT was observed with efficiency reaching 3.05. With the further understanding of the toughening mechanism, the branched CNTs-based copolymers and CNTs clusters induce a synergistic effect, which increased the interfacial adhesion and ability of energy dissipation and stress transmission.

Enhanced Thermal Stability, Mechanical Properties and Structural Integrity of MWCNT Filled Bamboo/Kenaf Hybrid Polymer Nanocomposites

Recently, there has been an inclination towards natural fibre reinforced polymer composites owing to their merits such as environmental friendliness, light weight and excellent strength. In the present study, six laminates were fabricated consisting of natural fibres such as Kenaf fibre (Hibiscus cannabinus L.) and Bamboo fibre, together with multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers in the epoxy matrix. Mechanical testing revealed that hybridization of natural fibres was capable of yielding composites with enhanced tensile properties. Additionally, impact testing showed a maximum improvement of ≈80.6% with the inclusion of MWCNTs as nanofiller in the composites with very high energy absorption characteristics, which were attributed to the high specific energy absorption of carbon nanotubes. The viscoelastic behaviour of hybridised composites reinforced with MWCNTs also showed promising results with a significant improvement in the glass transition temperature (Tg) and 41% improvement in storage modulus. It is worth noting that treatment of the fibres in NaOH solution prior to composite fabrication was effective in improving the interfacial bonding with the epoxy matrix, which, in turn, resulted in improved mechanical properties.