In this work, the effect of the vermiculite (VMT) clay loading on the rheological properties and flammability of bio-based high-density polyethylene/organically modified VMT (BioHDPE/OVMT) clay biocomposites containing 0.5–10 phr of OVMT clay was investigated. X-ray diffraction patterns showed that the BioHDPE was intercalated between the OVMT clay galleries. BioHDPE/OVMT biocomposites containing 5 and 10 phr of OVMT clay exhibited a shear-thinning behavior and a better dispersion/distribution in the BioHDPE matrix. The biocomposite containing 10 phr of organoclay presented a percolated network structure. The elastic modulus increased with the increase in the OVMT loading whereas the tensile and impact strength remained almost unaffected. For the biocomposites containing the unmodified VMT clay, the burning rate decreased with the increase in the VMT loading. The opposite was observed for the biocomposites containing OVMT clay.
This work aims to evaluate the electrical conductivity and the rheological and mechanical properties of copolymer/carbon black (CB) conductive polymer composites (CPCs). The copolymers, containing ethylene groups in their structure, used as matrix were polyethylene grafted with maleic anhydride (PEgMA), ethylene‐methyl acrylate–glycidyl methacrylate (EMA‐GMA), and ethylene‐vinyl acetate (EVA). For comparison purposes, bio‐based polyethylene (BioPE)/CB composites were also studied. The electrical conductivity results showed that the electrical percolation threshold of BioPE/CB composite was 0.36 volume fraction of CB, whereas the rheological percolation threshold was 0.25 volume fraction of CB. The most conductive CPC was BioPE/CB. Among the copolymer/CB CPCs, PEgMA/CB showed the highest conductivity, which can be attributed to the fact that the PEgMA copolymer had higher crystallinity. It also has a higher amount of ethylene groups in its structure. Torque rheometry analysis indicated that EMA‐GMA copolymer may have reacted with CB. Rheological measurements under oscillatory shear flow indicated the formation of a percolated network in BioPE/CB and copolymer/CB composites. Morphology analysis by scanning electron microscopy (SEM) indicated the formation of a percolated network structure in BioPE/CB composite and finely dispersed CB particles within the PEgMA copolymer. Wetting of CB particles/agglomerates by the copolymer matrix was observed in EVA/CB and EMA‐GMA/CB composites. Conductive CB acted as reinforcing filler as it increased the elastic modulus and tensile strength of BioPE and the copolymers.
Summary
The aim of this work is the development of a bionanocomposite from Poly (lactic acid)‐PLA/Biopolyethylene (PE) blend and clay. The montmorillonite (MMT) clay was organically modified with an ionic surfactant to become organophilic (OMMT). The MMT and OMMT clays were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X‐Ray Diffraction (XRD) techniques. The blends and the biocomposites were prepared by extrusion followed by injection molding and characterized by XRD, mechanical properties and Scanning Electron Microscopy (SEM). XRD and FTIR results indicated that the MMT clay was sucessfully modified becoming OMMT. XRD results also indicated that for the PLA/PE/EMA‐GMA biocomposite a bionanocomposite with an intercalated structure was obtained. SEM results showed that the addition of the OMMT clay to both PLA/PE and PLA/PE/EMA‐GMA blends led to a substantial decrease in the PE dispersed phase domains size. This decrease was more pronounced in the PLA/EMA‐GMA/OMMT bionanocomposite.
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