One of the main applications in which elastomeric polymers are used is as a structural component in the formulation of tire compounds. However, to match the required performance standards for the final product, it is necessary to introduce inorganic components (fillers) (Silica and Carbon Black) into the polymer matrix. From this point of view, the compatibility between the polymeric and inorganic phases is, therefore, an aspect of crucial importance. In this context the present PhD project is set up, which aims to develop an innovative strategy to improve the final composite through the introduction of functional groups on the polymer matrix able to interact with the inorganic components present in a compound. First, the opportunities offered by the literature to find a reactivity able to affect the unsaturated bonds present in the polymer matrix were explored. In particular, three possible alternatives have been identified: 1) 1,3-dipolar cycloaddition 2) Tiol-Ene type reactions 3) Alder-Ene type reactions After having verified the strengths and weaknesses of each reactivity, the most promising one has been to be based on an Alder-Ene reaction, which involves the interaction between an olefin (bearing hydrogen in an allyl position) and an electron-poor enophile. The enophilic compound we studied as a model system was 4-phenyl-1,2,4-triazoline-3,5-dione (PhTAD). This system, once anchored on the polymer, has a secondary amide group, able to modify locally the polarity of the matrix and, at the same time, able to interact through hydrogen bonds with inorganic fillers such as silica. The research activity has been focused on the chemical modification, with PhTAD, of commercial unsaturated polymers. These modified polymers, with different amounts of functionalizer, were then characterized by a multitechnical approach (DSC, TGA, FT-IR and swelling tests) and subsequently introduced into the mixture. The rheological properties of the compounds obtained were evaluated both with an oscillating disk rheometer (ODR), and by dynamic mechanical analysis at variable temperatures (DMTA) and by analyzing stress-strain curves. Preliminary attempts have been performed to resolve the critical issues that emerged when using PhTAD as a functionalization agent. First, it was necessary to optimize the amount introduced into the mixture, arriving, at best, to obtain composites in which the values of the G' module were comparable with the industrial reference standards, which are based on the use of compatibilizing agents such as TESPT, with a slight contextual deterioration of the values such as tanδ or the Payne effect, indicating an effective interaction between the polymer matrix functionalized with silica fillers, even if not yet optimally. Moreover, one of the major intrinsic problems to be solved in the use of a molecule such as PhTAD lies in its high reactivity which makes it impossible to operate in bulk, directly on the pristine polymer. The last part of the project was then dedicated to the synthesis of functionalizers of a similar nature, based on diazenics, but less reactive, in order to make the reaction occur on the polymer directly in the formulation phase, at the temperatures normally used to process compounds (≈140 °C), thus avoiding the difficulty due to operating in solution. The successful functionalization of a model oligomeric system with ethyl (anilinocarbonyl) diazenecarboxylate has allowed to demonstrate the validity of the idea of a thermally stimulated mass functionalization, opening to the possibility of using other molecular systems, that can be tuned specifically to perform a specific function within the compound.

Una delle principali applicazioni in cui i polimeri elastomerici trovano impiego è come componente strutturale nella formulazione di mescole per pneumatici. Tuttavia, affinché il prodotto finale possa soddisfare gli standard di prestazione richiesti, è necessario introdurre nella matrice polimerica dei componenti (filler) inorganici (Silice e Carbon Black). Sotto questo profilo, la compatibilità tra la fase polimerica e inorganica è dunque un aspetto di cruciale importanza. In questo contesto si colloca il presente progetto di dottorato, che ha come obiettivo quello di sviluppare un’innovativa strategia per migliorare il composito finale attraverso l’introduzione di gruppi funzionali sulla matrice polimerica in grado di interagire con le componenti inorganiche presenti in una mescola. Come prima cosa sono state scandagliate le opportunità che la letteratura offriva per trovare una reattività in grado di interessare i legami insaturi presenti nella matrice polimerica. In particolare, sono state identificate tre possibili alternative:cicloaddizione 1,3-dipolare, reazioni di tipo Tiol-Ene e reazioni di tipo Alder-Ene. Dopo aver verificato pregi e difetti di ciascuna reattività, la più promettente si è rivelata essere quella basata su una reazione di tipo Alder-Ene, che prevede l’interazione tra un’olefina, recante idrogeni in posizione allilica, ed un enofilo elettron-povero. Il composto enofilo da noi utilizzato e studiato come sistema modello è stato il 4-phenyl-1,2,4-triazoline-3,5-dione (PhTAD). Questo sistema, una volta ancorato sul polimero, presenta un gruppo ammidico secondario libero, in grado di modificare localmente la polarità della matrice e, contemporaneamente, di interagire tramite legami ad idrogeno con i filler inorganici come la silice. L’attività di ricerca è stata dunque concentrata sulla modifica chimica, con PhTAD, di olefine commerciali. Tali polimeri modificati, con diverse quantità di funzionalizzante, sono stati quindi caratterizzati tramite un approccio multitecnica (DSC, TGA, FTIR e prove di swelling) ed in seguito introdotti in mescola. Le proprietà reologiche delle mescole ottenute sono state valutate sia con un reometro a disco oscillante (ODR) sia tramite analisi dinamico meccaniche a temperatura variabile (DMTA) ed analizzandone le curve di stress-strain. Si è quindi tentato di risolvere le criticità emerse nell’utilizzo di PhTAD come agente di funzionalizzazione. Innanzitutto, è stato necessario ottimizzarne la quantità introdotta in mescola arrivando, nel migliore dei casi, ad ottenere compositi in cui i valori di G’ fossero comparabili con gli standard di rifermento industriali, che si basano sull’utilizzo di agenti compatibilizzanti come il TESPT, con un contestuale leggero peggioramento dei valori come il tanδ o l’effetto Payne, indice di un’effettiva interazione tra la matrice polimerica funzionalizzata con le cariche di silice, seppur non ottimale. Inoltre, uno dei maggiori problemi intrinseci da risolvere nell’utilizzo di una molecola come il PhTAD, risiede nella sua alta reattività che rende impossibile operare in massa, direttamente sul polimero pristino. L’ultima parte del progetto è stata quindi dedicata alla sintesi di funzionalizzanti di natura simile, a base diazenica, ma meno reattivi, allo scopo di far avvenire la reazione sul polimero direttamente in fase di formulazione, alle temperature a cui vengono processate le mescole (≈140°C), svincolandosi così dalla difficoltà derivanti dell’operare in soluzione. In particolare,l’avvenuta funzionalizzazione di un sistema oligomerico modello con ethyl(anilinocarbonyl)diazenecarboxylate ha permesso di dimostrare la validità dell’idea di una funzionalizzazione in massa termicamente stimolata, aprendo alla possibilità di impiego di altri sistemi molecolari, modificabili appositamente per assolvere una funzione specifica all’interno della mescola.

(2019). FUNCTIONALIZATION OF UNSATURATED POLYMERS BACKBONE FOR TYRE COMPOUNDING APPLICATION. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2019).

FUNCTIONALIZATION OF UNSATURATED POLYMERS BACKBONE FOR TYRE COMPOUNDING APPLICATION

ANDREOSSO, IVAN
2019

Abstract

One of the main applications in which elastomeric polymers are used is as a structural component in the formulation of tire compounds. However, to match the required performance standards for the final product, it is necessary to introduce inorganic components (fillers) (Silica and Carbon Black) into the polymer matrix. From this point of view, the compatibility between the polymeric and inorganic phases is, therefore, an aspect of crucial importance. In this context the present PhD project is set up, which aims to develop an innovative strategy to improve the final composite through the introduction of functional groups on the polymer matrix able to interact with the inorganic components present in a compound. First, the opportunities offered by the literature to find a reactivity able to affect the unsaturated bonds present in the polymer matrix were explored. In particular, three possible alternatives have been identified: 1) 1,3-dipolar cycloaddition 2) Tiol-Ene type reactions 3) Alder-Ene type reactions After having verified the strengths and weaknesses of each reactivity, the most promising one has been to be based on an Alder-Ene reaction, which involves the interaction between an olefin (bearing hydrogen in an allyl position) and an electron-poor enophile. The enophilic compound we studied as a model system was 4-phenyl-1,2,4-triazoline-3,5-dione (PhTAD). This system, once anchored on the polymer, has a secondary amide group, able to modify locally the polarity of the matrix and, at the same time, able to interact through hydrogen bonds with inorganic fillers such as silica. The research activity has been focused on the chemical modification, with PhTAD, of commercial unsaturated polymers. These modified polymers, with different amounts of functionalizer, were then characterized by a multitechnical approach (DSC, TGA, FT-IR and swelling tests) and subsequently introduced into the mixture. The rheological properties of the compounds obtained were evaluated both with an oscillating disk rheometer (ODR), and by dynamic mechanical analysis at variable temperatures (DMTA) and by analyzing stress-strain curves. Preliminary attempts have been performed to resolve the critical issues that emerged when using PhTAD as a functionalization agent. First, it was necessary to optimize the amount introduced into the mixture, arriving, at best, to obtain composites in which the values of the G' module were comparable with the industrial reference standards, which are based on the use of compatibilizing agents such as TESPT, with a slight contextual deterioration of the values such as tanδ or the Payne effect, indicating an effective interaction between the polymer matrix functionalized with silica fillers, even if not yet optimally. Moreover, one of the major intrinsic problems to be solved in the use of a molecule such as PhTAD lies in its high reactivity which makes it impossible to operate in bulk, directly on the pristine polymer. The last part of the project was then dedicated to the synthesis of functionalizers of a similar nature, based on diazenics, but less reactive, in order to make the reaction occur on the polymer directly in the formulation phase, at the temperatures normally used to process compounds (≈140 °C), thus avoiding the difficulty due to operating in solution. The successful functionalization of a model oligomeric system with ethyl (anilinocarbonyl) diazenecarboxylate has allowed to demonstrate the validity of the idea of a thermally stimulated mass functionalization, opening to the possibility of using other molecular systems, that can be tuned specifically to perform a specific function within the compound.
PAPAGNI, ANTONIO
GIANNINI, LUCA
Funzionalizzazione; catena polimerica; formulazione mescole; Olefine; PhTAD
Polymer backbone; Functionalization; Tyre compounding; Olefins; PhTAD
CHIM/06 - CHIMICA ORGANICA
English
27-feb-2019
SCIENZA E NANOTECNOLOGIA DEI MATERIALI - 79R
31
2017/2018
open
(2019). FUNCTIONALIZATION OF UNSATURATED POLYMERS BACKBONE FOR TYRE COMPOUNDING APPLICATION. (Tesi di dottorato, Università degli Studi di Milano-Bicocca, 2019).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/241275
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