Bartolomeo Coppola

Morphology Development and Mechanical Properties Variation during Cold-Drawing of Polyethylene-Clay Nanocomposite Fibers

In this work, the influence of composition and cold-drawing on nano- and micro-scale morphology and tensile mechanical properties of PE/organoclay nanocomposite fibers was investigated. Nanocomposites were prepared by melt compounding in a twin-screw extruder, using a maleic anhydride grafted linear low density polyethylene (LLDPE–g–MA) and an organomodified montmorillonite (Dellite 67G) at three different loadings (3, 5 and 10 wt %). Fibers were produced by a single-screw extruder and drawn at five draw ratios (DRs): 7.25, 10, 13.5, 16 and 19. All nanocomposites, characterized by XRD, SEM, TEM, and FT-IR techniques, showed an intercalated/exfoliated morphology. The study evidenced that the nanoclay presence significantly increases both elastic modulus (up to +115% for fibers containing 10 wt % of D67G) and drawability of as-spun nanocomposite fibers. Moreover, at fixed nanocomposite composition, the cold-drawing process increases fibers elastic modulus and tensile strength at increasing DRs. However, at high DRs, “face-to-edge” rearrangement phenomena of clay layers (i.e., clay layers tend to rotate and touch each other) arise in fibers at high nanoclay loadings. Finally, nanocomposite fibers show a lower diameter reduction during drawing, with respect to the plain system, and surface feature of adjustable roughness by controlling the composition and the drawing conditions.

Binders alternative to Portland cement and waste management for sustainable construction—part 1:

This review presents “a state of the art” report on sustainability in construction materials. The authors propose different solutions to make the concrete industry more environmentally friendly in order to reduce greenhouse gases emissions and consumption of non-renewable resources. Part 1—the present paper—focuses on the use of binders alternative to Portland cement, including sulfoaluminate cements, alkali-activated materials, and geopolymers. Part 2 will be dedicated to traditional Portland-free binders and waste management and recycling in mortar and concrete production.

Investigation on the use of PLA/hemp composites for the fused deposition modelling (FDM) 3D printing

This work is a preliminary study about the use of hemp powder as filler in a biopolymer, i.e. polylactic acid (PLA), and the following use of such composites in the 3D printing via FDM technique. In particular, hemp powder (diameter between 75 and 180 µm) was added via melt-compounding into PLA 4043D at three different volume percentages (1, 3 and 5%). Rheological properties of the blends were determined using a rotational rheometer resulting in a decrease of complex viscosity at increasing hemp loading. PLA/hemp filaments (diameter of 2.85 mm) were produced using a single screw extruder. Dynamic mechanical analysis (DMA) on PLA/hemp filaments reported an increase of storage modulus at increasing hemp volume fraction, but compared to the neat PLA filament only the PLA+5%H blend has a higher storage modulus. Finally, filaments were used to print, using a commercial printer (Ultimaker 3, Netherlands), dog-bone specimens for tensile tests. PLA/hemp printed samples exhibited always higher elastic modulus than PLA specimens and it increases at increasing hemp content.This work is a preliminary study about the use of hemp powder as filler in a biopolymer, i.e. polylactic acid (PLA), and the following use of such composites in the 3D printing via FDM technique. In particular, hemp powder (diameter between 75 and 180 µm) was added via melt-compounding into PLA 4043D at three different volume percentages (1, 3 and 5%). Rheological properties of the blends were determined using a rotational rheometer resulting in a decrease of complex viscosity at increasing hemp loading. PLA/hemp filaments (diameter of 2.85 mm) were produced using a single screw extruder. Dynamic mechanical analysis (DMA) on PLA/hemp filaments reported an increase of storage modulus at increasing hemp volume fraction, but compared to the neat PLA filament only the PLA+5%H blend has a higher storage modulus. Finally, filaments were used to print, using a commercial printer (Ultimaker 3, Netherlands), dog-bone specimens for tensile tests. PLA/hemp printed samples exhibited always higher elastic modulus than...

Influence of 3D printing parameters on the properties of PLA/clay nanocomposites

The aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, PLA 4032D was melt compounded in a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt%. Then, using a single screw extruder, PLA and PLA/clay filaments were produced so as to obtain the required diameter (1.75 mm). Finally, dog-bone specimens were 3D printed via FDM technique using three different temperatures (185, 200 and 215°C) and such specimens were mechanically tested in tensile mode. Dynamic mechanical analysis (DMA) on PLA/clay filaments reported an increase of storage modulus both at 35°C and 70 °C (8 and 40 %, respectively) in comparison to the PLA filament. Differential scanning calorimetry (DSC) demonstrated the ability of nanoclay to act as nucleating agent because cold crystallization temperature decreased of about 10°C. Finally, nanocomposite 3D printed samples exhibited always higher elastic modulus than PLA specimens and it increases at increasing printing temperature.The aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, PLA 4032D was melt compounded in a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt%. Then, using a single screw extruder, PLA and PLA/clay filaments were produced so as to obtain the required diameter (1.75 mm). Finally, dog-bone specimens were 3D printed via FDM technique using three different temperatures (185, 200 and 215°C) and such specimens were mechanically tested in tensile mode. Dynamic mechanical analysis (DMA) on PLA/clay filaments reported an increase of storage modulus both at 35°C and 70 °C (8 and 40 %, respectively) in comparison to the PLA filament. Differential scanning calorimetry (DSC) demonstrated the ability of nanoclay to act as nucleating agent because cold crystallization temperature decreased of about 10°C. Finally, nanocomposite 3D printed samples exhibited always higher elastic modulus than PLA specimens and it increas...

3D Printing of PLA/clay Nanocomposites: Influence of Printing Temperature on Printed Samples Properties

In this study, the possibility of using a layered silicate-reinforced polylactic acid (PLA) in additive manufacturing applications was investigated. In particular, the aim of this work was to study the influence of printing temperature in the 3D printing process of PLA/clay nanocomposites. For this reason, two PLA grades (4032D and 2003D, D-isomer content 1.5 and 4, respectively) were melt-compounded by a twin screw extruder with a layered silicate (Cloisite 30B) at 4 wt %. Then, PLA and PLA/clay feedstock filaments (diameter 1.75 mm) were produced using a single screw extruder. Dog-bone and prismatic specimens were 3D printed using the FDM technique at three different temperatures, which were progressively increased from melting temperature (185–200–215 °C for PLA 4032D and 165–180–195 °C for PLA 2003D). PLA and PLA/clay specimens were characterized using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and tensile tests. Moreover, the morphology of the 3D printed specimens was investigated using optical microscopy and contact angle measurements. The different polymer matrix and the resulting nanocomposite morphology strongly influenced 3D printed specimen properties. DMA on PLA/clay filaments reported an increase in storage modulus both at ambient temperature and above the glass transition temperature in comparison to neat PLA filaments. Furthermore, the presence of nanoclay increased thermal stability, as demonstrated by TGA, and acted as a nucleating agent, as observed from the DSC measurements. Finally, for 3D printed samples, when increasing printing temperature, a different behavior was observed for the two PLA grades and their nanocomposites. In particular, 3D printed nanocomposite samples exhibited higher elastic modulus than neat PLA specimens, but for PLA 4032D+C30B, elastic modulus increased at increasing printing temperature while for PLA 2003D+C30B slightly decreased. Such different behavior can be explained considering the different polymer macromolecular structure and the different nanocomposite morphology (exfoliated in PLA 4032D matrix and intercalated in PLA 2003D matrix).

Data on thermal conductivity, water vapour permeability and water absorption of a cementitious mortar containing end-of-waste plastic aggregates

The data presented in this article are related to the research article entitled “Hygro-thermal and durability properties of a lightweight mortar made with foamed plastic waste aggregates” (Coppola et al., 2018) [1]. This article focuses the attention on thermal conductivity, water vapour permeability and water absorption of a lightweight cementitious mortar containing foamed end-of-waste plastic aggregates, produced via foam extrusion process [2]. Thermal conductivity, water vapour permeability and water absorption data are made available to allow comparison and/or extend the analysis. Experimental investigations showed that the presence of plastic aggregates decreased thermal conductivity, water vapour resistance and capillary water absorption.

Production and characterization of polyethylene/organoclay oriented fiber

The aim of this work was to study the influence of drawing process on the mechanical properties of polyethylene/clay fibers. To this extent, three different PE/clay blends (3, 5 and 10 wt.%) were prepared by melt compounding in a twin-screw extruder. The investigated clay was a commercial organically modified montmorillonite (Dellite 67G). After compounding fibers were produced by a single-screw extruder and drawn at different draw ratios. At increasing draw ratio an increase of elastic modulus and tensile strength was attained. The presence of clay layers increases fibers ductility hindering fibrils formation during the drawing process. Moreover, at increasing clay contents a decrease of tensile strength for high draw ratios was observed. These results demonstrated that the dispersed clay layers can be re-aggregated by the uniaxial flow induced by the drawing process resulting in a decay of mechanical properties at high draw ratios.