Giuseppe Recca

Composites Based on Natural Fibre Fabrics

In the latest years industry is attempting to decrease the dependence on petroleum based fuels and products due to the increased environmental consciousness. This is leading to the need to investigate environmentally friendly, sustainable materials to replace existing ones. The tremendous increase of production and use of plastics in every sector of our life lead to huge plastic wastes. Disposal problems, as well as strong regulations and criteria for cleaner and safer environment, have directed great part of the scientific research toward ecocomposite materials. Among the different types of eco-composites those which contain natural fibers (NF) and natural polymers have a key role. Since few years polymeric biodegradable matrices have appeared as commercial products, however their high price represents the main restriction to wide usage. Currently the most viable way toward ecofriendly composites is the use of natural fibres as reinforcement. Natural fibres represent a traditional class of renewable materials which, nowadays, are experiencing a great revival. In the latest years there have been many researches developed in the field of natural fibre reinforced plastics (Bledzki & Gassan, 1999). Most of them are based on the study of the mechanical properties of composites reinforced with short fibers. The components obtained therefore are mostly used to produce non-structural parts for the automotive industry such as covers, car doors panels and car roofs ( Magurno, 1999, John at al., 2008) (Fig.1,2).

Engineering thermoplastics for additive manufacturing: a critical perspective with experimental evidence to support functional applications

Background Among additive manufacturing techniques, the filament-based technique involves what is referred to as fused deposition modeling (FDM). FDM materials are currently limited to a selected number of polymers. The present study focused on investigating the potential of using high-end engineering polymers in FDM. In addition, a critical review of the materials available on the market compared with those studied here was completed. Methods Different engineering thermoplastics, ranging from industrial grade polycarbonates to novel polyetheretherketones (PEEKs), were processed by FDM. Prior to this, for innovative filaments based on PEEK, extrusion processing was carried out. Mechanical properties (i.e., tensile and flexural) were investigated for each extruded material. An industrial-type FDM machine (Stratasys Fortus® 400 mc) was used to fully characterize the effect of printing parameters on the mechanical properties of polycarbonate. The obtained properties were compared with samples obtained by injection molding. Finally, FDM samples made of PEEK were also characterized and compared with those obtained by injection molding. Results The effect of raster to raster air gap and raster angle on tensile and flexural properties of printed PC was evidenced; the potential of PEEK filaments, as novel FDM material, was highlighted in comparison to state of the art materials. Conclusions Comparison with injection molded parts allowed to better understand FDM potential for functional applications. The study discussed pros and cons of the different materials. Finally, the development of novel PEEK filaments achieved important results offering a novel solution to the market when high mechanical and thermal properties are required.

Comparison of Ultem 9085 Used in Fused Deposition Modelling (FDM) with Polytherimide Blends

Polyetherimide (PEI) blends modified by either polycarbonate (PC) or polyethylene terephthalate glycol-modified (PETG) were prepared. The latter modifier (PETG) was an industrial grade widely used for fused deposition modelling (FDM) printing. PEI blends were compared to Ultem 9085, which is the standard PEI grade for FDM printing in advanced applications. All the blends were thoroughly characterized in terms of their rheological, morphological, thermomechanical and tensile properties. Ultem 9085 showed improved rheology for processing over standard PEI. PEI/PC blends with 10 wt % of modifier developed here closely matched the viscosity behavior of Ultem 9085. On the other hand, the blends with low PC content (i.e., less than 20 wt %) outperformed Ultem 9085 in terms of thermal and tensile properties. When PETG was added, similar tensile properties to Ultem 9085 were found. The immiscibility for PC contents higher than 20 wt % deteriorated the tensile properties, making it less attractive for applications, although melt viscosity decreased further for increasing PC contents.

Environmental benefits of using ground tyre rubber in new pneumatic formulations: A life cycle assessment approach

Life cycle assessment methodology was applied as a tool to evaluate the real environmental benefit of using recycled waste tyres in mixture with virgin rubber. Styrene–isoprene–styrene rubber was mixed with different amounts of ground tyre rubber and vulcanised. Thermomechanical analysis (i.e. differential scanning calorimetry and thermogravimetric analysis) and dynamic mechanical thermal analysis were carried out in order to evaluate the compatibility of the rubber mixture and the chemical–physical properties of the vulcanised products. Experimental analysis results show that the addition of ground tyre rubber up to 50 phr does not sensibly affect the vulcanisation reaction, the wet skid resistance and the rolling resistance. Life cycle assessment results show that the main environmental impacts of the ground tyre rubber are associated to the use of virgin rubber (47.1%) and carbon black (34.3%) while the tyre grinding process contributes only for 4%. Because ground tyre rubber contains carbon black in its formulation, the substitution of virgin rubber with ground tyre rubber has double environmental benefits: to reduce the need of both amounts of virgin rubber and fresh carbon black in the new formulation.

Controlled release of cortisone drugs from block copolymers synthetized by ATRP

Diseases affecting posterior eye segment, like macular edema, infection and neovascularization, may cause visual impairment. Traditional treatments, such as steroidal-drugs intravitreal injections, involve chronic course of therapy usually over a period of years. Moreover, they can require frequent administrations of drug in order to have an adequately disease control. This dramatically reduce patient’s compliance. Efforts have been made to develop implantable devices that offer an alternative therapeutic approach to bypass many challenges of conventional type of therapy. Implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their slow release in the specific site. Polymeric materials can play an essential role in modulating drug delivery and their use in such field has become indispensable. During last decades, acrylic polymers have obtained growing interest. Biocompatibility and chemical properties make them extremely versatile, allowing their...

Poly-paper: a sustainable material for packaging, based on recycled paper and recyclable with paper

Background Until now, environmental sustainability issues are almost entirely unsolved for packaging materials. With the final aim of finding materials with a single recycling channel, cellulose fiber/poly(vinyl)alcohol composites were investigated. Methods After extrusion and injection molding, samples of composite with different cellulose fiber content (30%, 50% and 70% w/w) were tested. Results Tensile mechanical tests exhibited an improvement in composite stiffness when the reinforcement content was increased together with a decrease in composite elongation. Solubility tests performed at room temperature and 45°C showed different behavior depending on the water-resistant film applied on the composite (50% cellulose fiber content). In particular, the uncoated composite showed complete solubility after 2 hours, whereas at the same time point, no solubility occurred when a non-water-soluble varnish was used. Conclusions The proposed composites, named Poly-paper, appear to warrant further investigation as highly sustainable packaging.

Embedding Intelligence for RTM Process Monitoring and Control

A technique to control the resin flow front in closed and open mould is described. The technique consists in embedding linear capacitive sensors to provide the position of the moving flow front. The embedded capacitor is made with two parallel wires while the resin, between the wires, acts as a moving dielectric which changes the capacitance values. Therefore the position of the resin is obtained from the measured capacitance variation. In order to validate the proposed methodology the sensor has been characterized and the obtained characteristic curve showed a quasi-linear trend. The shape of the resin front could be modified, if necessary, acting locally with controlled injectors.