Vecchione, Paolo
(2017)
LAMINATI COMPOSITI AUTORINFORZATI A BASE DI POLIAMMIDI.
[Tesi di dottorato]
| Tipologia del documento: |
Tesi di dottorato
|
| Lingua: |
Italiano |
| Titolo: |
LAMINATI COMPOSITI AUTORINFORZATI A BASE DI POLIAMMIDI |
| Autori: |
| Autore | Email |
|---|
| Vecchione, Paolo | paolo.vecchione@unina.it |
|
| Data: |
8 Aprile 2017 |
| Numero di pagine: |
144 |
| Istituzione: |
Università degli Studi di Napoli Federico II |
| Dipartimento: |
Ingegneria Chimica, dei Materiali e della Produzione Industriale |
| Dottorato: |
Ingegneria dei prodotti e dei processi industriali |
| Ciclo di dottorato: |
29 |
| Coordinatore del Corso di dottorato: |
| nome | email |
|---|
| Mensitieri, Giuseppe | mensitie@unina.it |
|
| Tutor: |
| nome | email |
|---|
| Di Maio, Ernesto | [non definito] | | Acierno, Domenico | [non definito] | | Russo, Pietro | [non definito] |
|
| Data: |
8 Aprile 2017 |
| Numero di pagine: |
144 |
| Parole chiave: |
Compositi autorinforzati; Hot compaction; PA self reinforced |
| Settori scientifico-disciplinari del MIUR: |
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 - Scienza e tecnologia dei materiali |
[error in script]
[error in script]
| Depositato il: |
25 Apr 2017 17:12 |
| Ultima modifica: |
08 Mar 2018 14:23 |
| URI: |
http://www.fedoa.unina.it/id/eprint/11649 |
| DOI: |
10.6093/UNINA/FEDOA/11649 |
Abstract
Isotropic polymers lack adequate strength and stiffness for many engineering applications. In order to improve these properties polymers can be filled with structural reinforcements such as glass, carbon and natural fibres or fabrics. However, current major trends focus on simple monocomponent systems in an effort to reduce costs and increase recyclability. Composite systems, by definition, involve at least two phases with different material properties. With the introduction of careful processing routes, it has been proven possible to create a fibrous, two phase composite, in which both components are similar or belonging to the same family of polymers. In light of this observation, the research is found on composite hybridized structures based on commercial cloths and prepared by a technology best known as hot compaction. In particular the interest is concentrated on two commercial fabrics constituted by nylon 6 fibers and an high tenacity cloth constituted by woven polyamide 6,6 fibers.
The processing temperature is chosen from previous calorimetric tests to have a selective surface melting of the fibers and to obtain new composite structures in which the matrix is formed by the recrystallization of the melted fraction while the portion of not melted fibers constitutes the reinforcement. About the pressure conditions, instead, the choices are mostly based on previous experiences.
Operating in this way, single polymer composites (SRPMs) based on each PA6 fabric involving 24, 30 and 36 layers of each fabric, and on the PA6,6 involving 8 layers of cloth are prepared and investigated taking compression molded plates based on a commercial neat PA6 grade, even containing 30% by weight of glass fibers, and analogous systems based on PA6,6 resins, as reference materials for the former and the latter samples, respectively. All reference materials are prepared under similar processing conditions in terms of pressure profile and duration of the various stages of compaction but using a higher consolidation temperature with respect to composite laminated systems.
The improvement of both static and dynamic flexural moduli and the simultaneous reduction of the Charpy impact parameters, by increasing of the reinforcement effect for PA6 based systems, confirms the typical need to balance stiffness and toughness performances, well established for conventional composite systems, unless optimized production process and/or hybridization approaches are considered. In fact, a good compromise of mechanical performances is detected for the thickest red SRPM laminates and ascribed to the occurrence of more efficient failure mechanisms rather than the simple fiber breakage as witnessed by morphological analyses, confirmed by low velocity impact tests and probably due to a lower compaction as can be seen from C-san measurements.
PA6,6 single polymer composites, with slow cooling rate in the temperature range of matrix crystallization, shows the best properties among the materials analysed, in terms of flexural performances, in static and dynamic configurations and toughness ability.
Overall, experimental findings collected so far can be considered as a good starting point to support the potential use of investigated single polymer composites for production of automotive components in replacing traditional glass fibers composites.
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