Francesco Paolo La Mantia

Recycling poly(ethyleneterephthalate)

Abstract Recycling of PET from bottles has been carried out by using multiple extrusions, considering in particular, the effect of drying of the material before processing. Hydrolytic chain scission and thermomechanical degradation induce a remarkable reduction of the properties of PET. It is worth noting, however, that the rate of decrease of the properties drops after three extrusions; with further recycling steps no remarkable changes of the properties are observed.

Mechanical properties-structure relationships for immiscible blends of low density polyethylene with nylon-6

Abstract Data on mechanical properties of blends of low density polyethylene with nylon-6 as a function of the composition are presented. They suggest that these blends are immiscible in the solid state. However both a theoretical model and scanning electron microscopy seem to indicate some degree of interaction at high content of nylon.

Effect of graphene nanoplatelets on the physical and antimicrobial properties of biopolymer-based nanocomposites

In this work, biopolymer-based nanocomposites with antimicrobial properties were prepared via melt-compounding. In particular, graphene nanoplatelets (GnPs) as fillers and an antibiotic, i.e., ciprofloxacin (CFX), as biocide were incorporated in a commercial biodegradable polymer blend of poly(lactic acid) (PLA) and a copolyester (BioFlex®). The prepared materials were characterized by scanning electron microscopy (SEM), and rheological and mechanical measurements. Moreover, the effect of GnPs on the antimicrobial properties and release kinetics of CFX was evaluated. The results indicated that the incorporation of GnPs increased the stiffness of the biopolymeric matrix and allowed for the tuning of the release of CFX without hindering the antimicrobial activity of the obtained materials.

Rheological properties of immiscible blends of low density polyethylene with nylon-6

Abstract Rheological properties of low density polyethylene/nylon-6 blends have been studied both in shear and in non-isothermal extensional flow. The results show that the rheological properties do not vary linearly with the composition. They indicate complete immiscibility in molten state and show that the morphology of these blends depends on the composition and changes with the flow.

Recycling of heterogeneous plastics wastes: I—Blends with low-density polyethylene

Abstract Heterogeneous plastics wastes are usually recycled by means of ad hoc designed equipment which, in a single step, produces objects with large dimensions and poor mechanical properties. In this preliminary work, the possibility of preparing blends of plastics waste and low-density polyethylene is investigated. These ‘secondary’ materials (with plastics waste content up to 50%) show mechanical properties similar, except for the elongation at break, to those of the virgin polyethylene. The addition of moderate amounts of calcium carbonate does not significantly reduce the properties of these materials.

Oxazoline functionalization of polyethylenes and their blends with polyamides and polyesters

The compatibilization of blends of polyamide-6 (PA6) with linear low density polyethylene (LLDPE) and of poly(ethylene terephthalate) (PET) with high density polyethylene (HDPE), by functionalization of the polyethylenes with oxazoline groups was investigated. Chemical modification of LLDPE and HDPE was carried out by melt free radical grafting with ricinoloxazoline maleinate. Blends preparation was made either with a two-steps procedure comprising functionalization and blending, and in a single step in which the chemical modification of polyethylene with the oxazoline monomer was realized in situ, during blending. The characterization of the products was carried out by FTIR spectroscopy and scanning electron microscopy (SEM). The rheological and mechanical properties of the blends were also investigated. The results show that functionalization of the polyethylenes can be achieved by melt blending with ricinoloxazoline maleinate even in the absence of free radical initiators. The compatibilization of the blends enhances the dispersion of the minor phase significantly, increases the melt viscosity, and improves the mechanical properties. The one-step preparation of the compatibilized blends was also found to be effective, and is thought to be even more promising in view of commercial application.

Transient Shear and Elongational Data for Polyisobutylene Melts

For a commercial polyisobutylene, at room temperature, stress relaxation after a sudden imposition of a shear or elongational strain has been performed in the limit of linear viscoelasticity. Transient shear and elongational stresses have been determined in the non‐linear region by using a Universal Instron Testing Machine. While for shear flow steady‐state conditions were reached in some cases, the elongational results are only transient because the experimental procedure gives a rate of stretching which decreases in time. Some steady shear results have been obtained at higher temperatures with a capillary viscometer. The results have been interpreted by means of a one‐parameter model which attributes the non‐linearities arising from the change in the spectrum of relaxation times to modification of the entangled network. The Bogue‐White model has been also considered for comparison.

A Facile and Eco-friendly Route to Fabricate Poly(Lactic Acid) Scaffolds with Graded Pore Size

Over the recent years, functionally graded scaffolds (FGS) gaineda crucial role for manufacturing of devices for tissue engineering. The importance of this new field of biomaterials research is due to the necessity to develop implants capable of mimicking the complex functionality of the various tissues, including a continuous change from one structure or composition to another. In this latter context, one topic of main interest concerns the design of appropriate scaffolds for bone-cartilage interface tissue. In this study, three-layered scaffolds with graded pore size were achieved by melt mixing poly(lactic acid) (PLA), sodium chloride (NaCl) and polyethylene glycol (PEG). Pore size distributions were controlled by NaCl granulometry and PEG solvation. Scaffolds were characterized from a morphological and mechanical point of view. A correlation between the preparation method, the pore architecture and compressive mechanical behavior was found. The interface adhesion strength was quantitatively evaluated by using a custom-designed interfacial strength test. Furthermore, in order to imitate the human physiology, mechanical tests were also performed in phosphate buffered saline (PBS) solution at 37 °C. The method herein presented provides a high control of porosity, pore size distribution and mechanical performance, thus offering the possibility to fabricate three-layered scaffolds with tailored properties by following a simple and eco-friendly route.

On the Improvement of the Processability of UHMW-HDPE by Adding a Liquid Crystalline Polymer and a Fluoroelastomer

Ultra-high molecular weight polyethylene possesses many interesting properties but a very bad processability. This material is not usually processed in conventional devices but only by compression moulding and RAM extrusion. Low molecular weight polyethylene can be used to improve the processability. In this work small amounts of a fluoroelastomer and of a liquid crystalline polymer have been used as processing aids to improve the extrudability of this polymer. In fact, the die pressure decreases whereas the output flow rate slightly increases with increasing concentration of the processing aids. Solution viscosity data shows that reduction of the mechanical stress during extrusion decreases the degradation of the polyethylene.

Use of PP-g-OXA in the Compatibilization of PP/LCP Blends

Abstract Adding small amounts of liquid crystalline polymers (LCP) to flexible thermoplastic matrices (FTP) allows to enhance the mechanical and thermomechanical properties. Therefore it is possible to obtain materials with new properties only by simple mixing. A strong shortcoming is the incompatibility between LCP and FTP that leads to materials with very poor properties unusable for commercial pourposes. The presence of a compatibilizer is therefore required. Oxazoline functionality is known to be highly reactive toward many other functional groups and then oxazoline functionalized polymers can be efficiently used as compatibilizer precursors. In this work the compatibilizazion of polypropylene (PP) with a semirigid LCP by using an ad hoc tailored oxazoline functionalized PP has been studied.