Ana Lúcia Nazareth da Silva

Polymer blends based on polyolefin elastomer and polypropylene

A new family of homogeneous polyolefin polymers that exhibit unique molecular and rheological properties designated polyolefin elastomers (POEs) are characterized by a narrow molecular weight and high degrees of comonomer distribution. Because these copolymers are often elastomeric in nature, one of the uses for these materials is as impact properties improver for brittle polymers such as polypropylene at low temperatures. In this work a study was carried out about the effectiveness of the polyethylene elastomer (POE) as an impact modifier for polypropylene in relation to the traditional modifier EPDM. In this study the flow properties of of the POE/PP and EPDM/PP blends were also evaluated. The blends were analyzed by solid-state 13C nuclear magnetic resonance (13C-NMR) spectroscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The results showed that PEE/PP and EPDM/PP blends present a similar crystalline behavior, which resulted in a similar mechanical performance of the blends, on the composition analyzed. It was also verified that the POE/PP blend presents lower torque values than the EPDM/PP blend, which indicates a better processability when POE is used as an impact modifier.

Rheological, mechanical, thermal, and morphological properties of polypropylene/ethylene‐octene copolymer blends

Rheological and morphological studies were performed on polymer blends of ethylene-octene copolymer [polyethylene elastomer (PEE)] and polypropylene (PP). The viscosities of PEE, PP, and PEE/PP blends were analyzed using an Instron capillary rheometer and a Rheometrics Dynamic Stress Rheometer, SR 200. A non-Newtonian flow behavior was observed in all samples in the shear rate range from 27 to 2700 s−1, whereas at shear rates in the range from 0.01 to 0.04 s−1, a Newtonian flow behavior was verified. The scanning electron micrographs showed that dual-phase continuity may occur between 50 and 60 (wt %) of PEE. This result is consistent with the Sperlings model. The mechanical analysis showed that PEE/PP, with 5 wt % of PEE, presented an increase on the mechanical properties and as the PEE content increased, a negative deviation in relation to an empirical equation was observed. Thermal analysis showed that there were no change in the crystallization behavior of the matrix when different elastomer contents were added. Dynamic mechanical thermal analysis showed that samples with low PEE contents presented only one peak, indicating a certain degree of miscibility between the components of these blends.

Some properties of polymer blends based on EPDM/PP

This work describes the effect of the addition of EPDM to polypropylene on the mechanical performance of EPDM/PP blends prepared in different composition ranges and mixing conditions, and evaluates the effect on the mechanical properties when controlled degraded polypropylene is added to these blends as a third component. It was found that as the EPDM content increased, the impact strength of EPDM/PP blends increased; the tensile strength and Youngs modulus decreased and the elongation increased but showed a slight decrease at 5050 composition.

Rheological and morphological properties of blends based on ethylene-octene copolymer and polypropylene

Rheological studies have been performed on polymer blends based on ethylene-octene copolymer and polypropylene. The flow behaviour of polyethylene elastomer (PEE), polypropylene (PP) and PEE/PP blends were analysed using an Instron capillary rheometer and a Rheometrics dynamic stress rheometer, SR 200. A non-Newtonian flow behaviour was observed in all the samples at high shear rates, and a Newtonian flow behaviour at shear rates in the range of low values. The scanning electron micrographs showed that the size of the elastomer domains increases as the PEE content increases. The SEM analysis also showed that dual-phase continuity may occur between 50 and 60 (wt.%) of PEE. The morphology of the extrudates examined by optical microscopy revealed that a more severe distortion of the extrudate was only observed at high PEE content and high shear rate.

Rheological, mechanical and morphological behavior of polylactide/nano-sized calcium carbonate composites

Semicrystalline polylactide (PLA) is a promising material to replace petroleum-based plastics since it can be synthesized from renewable resources. PLA exhibits high tensile strength and modulus, but very low strain-at-break and toughness. In this study, the effects of the nano-sized calcium carbonate (nCaCO3) on the rheological, mechanical and morphological properties of polylactide are evaluated. The PLA/nCaCO3 composites with different filler compositions, as well as neat PLA (used as reference) were prepared by melt mixing in a twin-screw extruder. The results show that the presence of 7.0 wt% of nCaCO3 in the composite not only produced an ultimate strain improvement, but also better overall toughness balance in comparison to the other compositions. MEV micrographs showed the presence of microvoids with composition containing 7.0 wt% nCaCO3, which explains the mentioned mechanical behavior. This composition also showed more viscous behavior in relation to neat PLA and 5.0 wt% nCaCO3 composite. Composite with 3 wt% of nanofiller presented the highest viscous behavior in relation to neat PLA and other composites. Both mechanical data and Cole–Cole plots indicated the overall absence of higher filler aggregates in the composites analyzed, corroborating the MEV micrographs.

Effect of structure and viscosity of the components on some properties of starch-rich hybrid blends.

Glycerol-plasticized cornstarch and poly(lactic acid) (PLA) were melt-blended alone and at a constant 70:30 (m/m) composition, in the present of an organoclay. The effect of increasing contents of the organoclay on extruded and compression-molded samples was evaluated by X-ray diffraction (XRD), capillary rheometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests. XRD and shear viscosity results obtained for the hybrid components (TPS/organoclay and PLA/organoclay) were correlated with the hybrid blends properties. XRD and TGA results suggested that the organoclay was similarly dispersed within both phases. SEM images revealed improved adhesion between the phases. Shear viscosities results indicated improved compatibilization as the organoclay content was increased. Some of the extruded materials were also submitted to injection molding, and characterized by SEM and by tensile tests. For the extruded and compression-molded samples, improved mechanical properties were obtained for the samples with higher contents of the organoclay. For the injection-molded samples, the mechanical properties seemed to be dependent on the organoclay dispersion.

Rheological Behavior of Renewable Polyethylene (HDPE) Composites and Sponge Gourd (Luffa cylindrica) Residue

The present study reports the results of rheological behavior of renewable composites, based on a matrix of high density polyethylene (HDPE), made from ethanol distilled from sugarcane, and lignocellulose filler from waste generated in the processing of sponge gourds for bathing use. The composites were prepared with 10, 20, 30, and 40%wt of filler in a twin-screw extruder. The materials were analyzed in a parallel plate rheometer and a melt-flow indexer. The composite morphology was determined by scanning electron microscopy. The composite viscosity increased with filler content, suggesting possible formation of filler agglomerates. This result was confirmed by Cole-Cole diagrams.

Performance fibers for deep water offshore mooring ropes: Evaluation and analysis

Offshore mooring ropes using synthetic fibers have been used extensively since 1990s to moor permanent oil production platforms (FPSO) in water depths above 500 meters and in the last decade in water depths up to 3000 meters. High tenacity polyester yarn is still the main yarn been used but the challenges of large production platforms in ultra-deep water (>1500 meters) are now considering high performance fibers with higher tenacity with a much higher tenacity and modulus. This work compares the performance of different fibers in terms of mechanical performance (tenacity. modulus, stiffness etc.), lifetime performance and endurance (abrasion, creep, failure etc.) as well as overall rope and deployment costs.

Influence of lubricant oil residual fraction on recycled high density polyethylene properties and plastic packaging reverse logistics proposal

To recycle post-consumer HDPE contaminated with waste lubricating oils, companies include prior washing and drying in the process. This consumes large amounts of water and energy, generates significant effluent requiring treatment. This study assesses lubricating oil influence on HDPE properties to evaluate the feasibility of its direct mechanical recycling without washing. The current lubricating oil packaging reverse logistics in Rio de Janeiro municipality is also analyzed. HDPE bottle samples were processed with seven oil contents ranging from 1.6-29.4 (wt%). The results indicated the possibility to reprocess the polymer with oily residue not exceeding 3.2%. At higher levels, the external oil lubricating action affects the plastic matrix processing in the extruder and injection, and the recycled material has a burnt oil odor and free oil on the surface. Small residual oil amounts retain the plastic properties comparable to the washed recycled polymer and exhibited benefits associated with the oil plasticizer action. However, oil presence above 7.7% significantly changes the properties and reduces the elasticity and flexural modulus and the plastic matrix crystallinity.

Sustainable recycling of mooring ropes from decommissioned offshore platforms

Decommissioning offshore Floating Production, Storage and Offloading (FPSO) platforms requires extensive technical knowledge, since it generates different post-consumer materials, including mooring lines. These ropes are made from polyester high tenacity yarn, based on polyethylene terephthalate (PET), and their high added value means they should not be discarded as scrap. This paper aims to present a review and technical opportunities, from an economic standpoint, of recycling the mooring lines recovered from decommissioned FPSOs. Studies conducted over the last two years have researched and developed different potential applications for the fibers. These studies include collaborative project initiatives involving technical and management professionals, universities and private enterprises, with a view to achieving a more sustainable destination for these fibers.