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.

In this study, the effect of ethylene‐methyl acrylate (EMA) compatibilizer on the thermo‐mechanical, rheological, and morphological properties of poly(lactic acid) (PLA)/biopolyethylene (BioPE)/OMMT clay biocomposites was investigated. The biocomposites containing 1 and 3 phr of OMMT clay were characterized by X‐ray diffraction (XRD), mechanical properties, scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA), and rheological properties under oscillatory shear flow. XRD results indicated that bionanocomposites with an intercalated structure were obtained for the PLA/BioPE/EMA/OMMT system containing 1 and 3 phr of OMMT clay. The addition of OMMT clay to PLA/BioPE blend led to a decrease in the modulus and tensile strength, while the impact strength was increased. The increase in the clay content from 1 to 3 phr did not affect the modulus and the tensile strength of the PLA/BioPE blend, while the impact strength was decreased. The impact strength of the PLA/BioPE/EMA/OMMT biocomposite containing 3 phr of clay was superior to that containing 1 phr of clay. The addition of EMA to PLA/BioPE/OMMT biocomposites substantially decreased the average size of the BioPE phase domains. DMTA results showed a decrease in the glass transition temperature (Tg) of PLA with the addition of OMMT clay to PLA/BioPE blend. Rheological measurements showed an increase in the viscosity at low frequencies with the addition OMMT to PLA/BioPE blend. Further increase in the viscosity was observed when EMA compatibilizer was added to PLA/BioPE/OMMT biocomposite. The results of DMTA and rheological measurements were ascribed to the morphology refinement and corroborated the results obtained by SEM. POLYM. COMPOS., 39:E164–E173, 2018. © 2016 Society of Plastics Engineers

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.

In this work, conductive polymer composites (CPCs) of bio‐based polyethylene (BioPe) containing different concentrations of carbon black (CB) were developed. By using oscillatory rheology analysis, a Newtonian plateau was observed in BioPe, and all BioPe/CB composites had a behavior of a pseudo‐solid and that composites with volume fractions ranging from 0.24 to 0.56 presented higher viscosity, storage, and loss modulus. This suggests the formation of a percolated network and by using the power‐law models, it was observed that the electrical percolation threshold was higher than the rheological percolation threshold. The electrical conductivity was measured using the four‐point probe method and a sigmoid model was used to predict the CPCs' electrical conductivity percolation threshold. The results indicated that the four‐point probe method presented satisfactory results according to the calculated standard deviations and voltage–current characteristics for each round of measurements considering the same ranging as used in rheology analysis. The analytical model used showed a coefficient of determination (R2) higher than 95%, allowing the prediction of the electrical conductivity of the CPC and the percolation threshold as a function of the volumetric fraction of the CB.