Search results for "Extrusion"
showing 10 items of 142 documents
Limits of the Open-Die Forward Extrusion: Numerical Analysis and Experimental Tests
1992
In the paper the open-die forward extrusion process is analysed in order to determine the influence of the most important geometrical and frictional parameters on the practical suitability of the operation. Experimental tests have been carried out and their results have been compared with the numerical ones derived by FEA.
Analysis of Joint Quality along Welding Plane
2009
Porthole die extrusion is an always more important process for industrial applications. It is, however, characterized by a considerable complexity; in fact, different parameters have to be carefully set for improving the final part. A critical zone that strongly influences the goodness of the extruded component is the so called “welding plane”. It is the junction area where material flows converge inside the welding chamber. The variables that have to be controlled for improving the material characteristics in this zone are the effective stress, the pressure and the time that the material takes to cross the welding chamber. Moreover, material temperature is another fundamental issue that in…
Chemical Modification of Nitrile to Oxazoline Functionality on a Styrene-Acrylonitrile Copolymer in the Melt
1998
Oxazoline is a very interesting functionality for reactive extrusion and other applications. In this paper, we report the possibility of chemically transforming nitrile group attached to a copolymer of styrene and acrylonitrile (SAN) to oxazoline group using 2-amino-ethanol (AE). The chemical modification of SAN with AE was done in the molten state. Among various catalysts tested, zinc acetate turned out to be the most efficient. The effects of the catalyst concentration, temperature and mixing on the overall kinetics were studied. The formation of the expected oxazoline functionality was confirmed by infrared spectroscopy and by reacting with 1-naphthylacetic acid. The reaction between the…
The Impact of Janus Nanoparticles on the Compatibilization of Immiscible Polymer Blends under Technologically Relevant Conditions
2014
Several hundred grams of Janus nanoparticles (d ≈ 40 nm) were synthesized from triblock terpolymers as compatibilizers for blending of technologically relevant polymers, PPE and SAN, on industry-scale extruders. The Janus nanoparticles (JPs) demonstrate superior compatibilization capabilities compared to the corresponding triblock terpolymer, attributed to the combined intrinsic properties, amphiphilicity and the Pickering effect. Straightforward mixing and extrusion protocols yield multiscale blend morphologies with "raspberry-like" structures of JPs-covered PPE phases in a SAN matrix. The JPs densely pack at the blend interface providing the necessary steric repulsion to suppress droplet …
X-ray micro-computed tomography investigation of fibre length degradation during the processing steps of short-fibre composites
2014
The mechanical properties of composites in the fibre direction are mainly attributed to the fibre slenderness, or aspect ratio. A trade-off between performance and processability is usually required, and dependent on the intended application. If the fibre length could be retained or not severely degraded during various processing steps towards the injection-moulded component, a stiffer and stronger composite product could be obtained. The processing steps for injection moulded wood-fibre composites here include: Pulping, commingling, extrusion, pelletizing, and injection moulding. To tune the processing parameters systematically for retained fibre length, it would be useful to investigate t…
Neural Network Techniques for Metal Forming Design
1993
Neural networks are computing structures able to predict the behaviour of a system on the basis of the knowledge of facts; main characteristic of a network is the capability to find a rule in a very complex environment. In the paper a neural network, based on the results of FEM simulations, is utilized to predict the occurrence of defects in a forward extrusion metal forming process. In particular a three layers neural network, relating the operative parameters with the failure or the success of the working process, has been used and the back-propagation algorithm has been employed to train the network. Few experimental data were enough to train the neural network allowing to achieve better…
Mechanical and barrier properties of extruded film made from sodium and calcium caseinates
2014
Abstract Over the past few years, much interest has been placed into the investigation of increased barrier and mechanical properties of protein films via a multitude of approaches. Generally, these techniques involve modifications of interactions among protein molecules, such as ionic crosslinking using divalent ions. To evaluate the crosslinking effect of Ca 2+ cations, films were made from calcium caseinate (CaCAS) and/or sodium caseinate (NaCAS). The production of caseinate thin films was carried out in two steps: first thermoplastic pellets were made using a co-rotating twin-screw extruder, then they were transformed into thin films (60 μm) using a classical film blowing machine. Tensi…
Textural characterization of native and n-alky-bonded silica monoliths by mercury intrusion/extrusion, inverse size exclusion chromatography and nitr…
2008
Native and n-alkyl-bonded (n-octadecyl) monolithic silica rods with mesopores in the range between 10 and 25 nm and macropores in the range between 1.8 and 6.0 microm were examined by mercury intrusion/extrusion, inverse size exclusion chromatography (ISEC) and nitrogen sorption. Our results reveal very good agreement for the mesopore size distribution obtained from nitrogen adsorption (in combination with an advanced NLDFT analysis) and ISEC. Our studies highlight the importance of mercury porosimetry for the assessment of the macropore size distribution and show that mercury porosimetry is the only method which allows obtaining a combined and comprehensive structural characterization of m…
Morphology and mechanical properties of extruded ribbons of LDPE/PA6 blends compatibilized with an ethylene-acrylic acid copolymer
2003
Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the 75/25 and 25/75 wt/wt ratios and shaped into ribbons with a Brabender single screw extruder. An ethylene-acrylic acid copolymer (EAA) was used in the 2 phr concentration as a compatibilizer precursor (CP). The morphology of the ribbons and its evolution during high temperature annealing were investigated by scanning electron microscopy (SEM). The results confirmed that EAA does actually behave as a reactive compatibilizer for the LDPE/PA blends. In fact, in the presence of EAA, the interfacial adhesion is improved, the dispersion of the minor phase particles is enhanced and their tendency toward fibrilla…
Multiscale microstructural characterization of particulate-reinforced composite with non-destructive X-ray micro- and nanotomography
2018
Abstract Methods based on X-ray tomography are developed to study the relevant statistical quantities describing the microstructural inhomogeneity of particulate reinforced composites. The developed methods are applied in estimating microstructural inhomogeneity parameters of composites containing metallic glass particles in metal matrix, extruded in varying pressure loads. This study indicates that the critical characteristics with regard to the effect of particle clustering are cluster size and shape, local volume fraction of particles in the cluster and the distance between clusters. The results demonstrate that the spatial distribution of reinforcement is very uneven and the amount of p…