Antonio B. Martínez

Influence of annealing on the microstructural, tensile and fracture properties of polypropylene films

Abstract The influence of annealing temperature on the fracture properties of iPP films (one homopolymer and two propylene–ethylene block copolymers) is presented. The fracture behaviour is studied by means of the Essential Work of Fracture (EWF) procedure, and is complemented by the study of the effect of thermal treatment on tensile properties and microstructure, using differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS). It is shown that the initial metastable phase of quenched iPP films, widely known as smectic, transforms gradually into the monoclinic form as the annealing temperature is increased, resulting in an important improvement of the tensile properties, whereas the fracture parameters have different evolutions depending on the ethylene content. The reasons for a decrease in the essential work term and an increase in the plastic term as the crystal perfection grows are discussed on the basis of the microstructural changes of the crystalline phase and the smectic–monoclinic strain-induced phase transformation.

CRYSTALLIZATION BEHAVIOR OF POLYPROPYLENE FILLED WITH SURFACE-MODIFIED TALC

Talc-filled polypropylene (PP) composites were prepared by extrusion in a wide composition range (0–40 wt %). To improve the affinity relation between talc and the PP matrix, we modified the talc surface with silane coupling agents. Differential scanning calorimetry investigations on test samples, prepared by injection moulding, revealed that the talc content and its surface modification had a pronounced effect on the crystallization behavior of the filled PP composites. The experimental results indicate that a talc concentration of 2 wt % strongly affects the nonisothermal crystallization process of the PP, especially when talc is silane treated Isothermal crystallization experiments on samples with minimum amounts of talc (2 wt %) revealed an improved nucleation activity with silane-treated talc.

The effect of filler type, morphology and coating on the anisotropy and microstructure heterogeneity of injection-moulded discs of polypropylene filled with aluminium and magnesium hydroxides. Part 2. Thermal and dynamic mechanical properties

Abstract Thermal and dynamic mechanical characteristics of injection-moulded discs of polypropylene (PP) filled with 40% by weight of magnesium and aluminium hydroxides have been studied by means of differential scanning calorimetry and dynamic mechanical thermal analysis, and have been related to the anisotropy and microstructure heterogeneity of the discs. The effect of filler type, particle morphology and surface coating has been analysed. The nucleation activity of filler particles on PP has been quantified and found to be reduced in coated grades of magnesium hydroxide. The employed coatings worked isolating and preserving particles surface from direct interaction with polymer chains. The different orientations of both filler particles and PP α crystals were found to be the main cause of the differences observed in mechanical properties.

The effect of filler type, morphology and coating on the anisotropy and microstructure heterogeneity of injection-moulded discs of polypropylene filled with aluminium and magnesium hydroxides. Part 1. A wide-angle X-ray diffraction study

The influence of aluminium hydroxide particle morphology and magnesium hydroxide surface coating on the anisotropy and microstructure heterogeneity of injection-moulded discs of polypropylene (PP) filled with 40% by weight of these fillers has been studied through wide-angle X-ray diffraction measures. In general, the discs displayed an anisotropic structure due to different orientations of both filler particles and PP crystals through the part thickness. The samples also exhibited some degree of heterogeneity due to different levels of particle orientations in specimens far away and close to the disc mould entrance.

Assistive technologies for the new generation of senior citizens: the SHARE-it approach

In this paper, we present the SHARE-it approach to the integration of agent technology with other existing technologies to build specific intelligent and semi-autonomous assistive devices for older persons and people with disabilities (both cognitive and/or motor). In particular, we explored the benefits of the concept of situated intelligence to build mobility platforms and other artefacts that enhance the autonomy of the target user group in their daily life so that they can be self-dependent enough to autonomously live in their preferred environment.

Using Laser and Vision to Locate a Robot in an Industrial Environment: A Practical Experience

The fully flexible navigation of autonomous vehicles in industrial environments is still unsolved. It is hard to conciliate strict precision requirements with quick adaptivity to new settings without undergoing costly rearrangements. We are pursuing a research project trying to combine the precision of laser-based local positioning with the flexibility of vision-based robot motion estimation. An enhanced circle approach to dynamic triangulation combining laser and odometric signals has been used to improve positioning accuracy. As regards to vision, a novel technique relating the deformation of contours in an image sequence to the 3D motion underwent by the camera has been developed. Interestingly, contours are fitted to objects already present in the environment, without requiring any presetting. In this paper, we describe a practical experience conducted in the warehouse of a beer production factory in Barcelona. A database containing the laser readings, image sequences and robot odometry along several trajectories was compiled, and subsequently processed off-line in order to assess the accuracies of both techniques under a variety of circumstances. In all, vision-based estimation turned out to be about one order of magnitude less precise than laser-based positioning, which qualifies the vision-based technique as a promising alternative to accomplish robot transfers across long distances, such as those needed in a warehouse, while backing up on laser-based positioning when accurate docking for loading and unloading operations is needed.

Influence of the injection moulding parameters on the microstructure and thermal properties of microcellular polyethylene terephthalate glycol foams

Microcellular injection moulding is capable of producing lightweight polymeric products. The present study analyses the influence of several representative injection moulding parameters on the foam’s morphology, apparent density and thermo-mechanical properties of PETG, poly(ethylene terephthalate-co-1,4-cyclohexylene-dimethylene terephthalate) specimens. A strong variation of the cell morphology along the melt flow direction has been found, as well as a dependence on the shot volume. The most homogeneous microcellular structure is achieved when low shot volume, intermediate injection speed and low mould temperature are employed. The skin–core structure of the injected parts, determined the thermo-mechanical features of the specimen, which are ruled by the skin layer.

Anisotropy and Microstructure Heterogeneity of Injection‐Moulded Discs of Poly(propylene) Filled with Platy Magnesium Hydroxide

The anisotropy and microstructure heterogeneity induced by filler presence and processing has been studied on injection-moulded discs of poly(propylene) homopolymer (PP) filled with a wide range of concentration (0-60 wt.-%) of uncoated platy magnesium hydroxide. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM) techniques were used to help state the microscopic structure and justify properties measured by dynamic mechanical thermal analysis (DMTA). On the one hand, the anistropy has been analysed by measuring samples in the parallel and perpendicular directions to the dises surface. On the other hadn, the heterogeneity has been characterised by testing salokes cut from different zones of the discs. It has been found that the nucleation activity of magnesium hydroxide on the α-phase od poly-(propylene) increases with the filler concentration up to the maximum level studied (60 wt.-%). The polymer crystalline β-phase was only detected in unfilled PP and in samples containing less than 20 wt.-% of magnesium hydroxide. Remarkable differences in the polymer (α-phase) and particle orientation degrees have been observed in the composites depending on whether the analysis was carried out over the disc skin or core. The anisotropy degree of poly(propylene) crystalsd in the composites was independent on that of the filler particles up to 10 wt.-% of Mg(OH) 2 concentration; however, from 20 wt.-% of filler the orientation of magnesium hydroxide particles clearly influenced the orientation and anisotropy of the polymer. Moreover, the differences of orientation in the specimen skin were mainly responsible for the heterogeneity of the discs. Composites with lower magnesium hydroxide concentration exhibited the higher heterogeneity. These factors were found to be the main causes of the different dynamic mechanical properties obtained for these materials when the experiments were performed in different zones and/or through different directions in the injection-moulded discs.

Heat Transfer of Mineral-Filled Polypropylene Foams

The thermal conductivity of unfilled polypropylene foams produced using different foaming processes has previously been demonstrated to be mainly affected by the foam’s bulk density [1]. The influence of adding inorganic particles is now studied, with the thermal conductivity of the mineral-filled PP foams being determined using the Transient Plane Source Method (TPS). To this end, two different fillers were used. The incorporation of high amounts (50 and 70 wt.%) of magnesium hydroxide resulted in considerably higher thermally conductive foamed materials, with interesting thermal anisotropies being observed for the higher expansion ratio foams. On the contrary, adding montmorillonite (MMT) nanoparticles did not considerably alter the thermal conductivity of the foams, their value being mainly affected by the relative density.

Supported Human Autonomy for Recovery and Enhancement of Cognitive and Motor Abilities Using Agent Technologies

The goal of SHARE-it, an EU FP6 funded project, is to develop a scalable, adaptive system of add-ons to sensor and assistive technology so that they can be modularly integrated into an intelligent home environment to enhance the individuals autonomy. The system will be designed to inform and assist the user and his/her caregivers through monitoring and mobility help. Thus, we plan to contribute to the development of the next generation of assistive devices for older persons or people with disabilities so that they can be self-dependent as long as possible. We focus on add-ons to be compatible with existing technologies and to achieve an easier integration into existing systems. We also aim at adaptive systems as transparent and, consequently, as easy to use to the person as possible. Scalability is meant to include or remove devices from the system in a simple, intuitive way. SHARE-it will provide an Agent-based Intelligent Decision Support System to aid the elders.