Time-resolved rheology as a tool to monitor the progress of polymer degradation in the melt state – Part II: Thermal and thermo-oxidative degradation of polyamide 11/organo-clay nanocomposites

Filippone, Giovanni; Carroccio, Sabrina; Curcuruto, Giusy; Passaglia, Elisa; Gambarotti, Cristian; Dintcheva, Nadka Tzankova

doi:10.1016/j.polymer.2015.07.042

Cited by 41 publications

(36 citation statements)

References 25 publications

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“…Furthermore, the OIt measurements allow investigating the behaviour at relatively low temperature (230°C) during the time and then, in this condition, the capability of dispersed MMT layers to protect the PLA from heat and oxygen is proved ( Table 2). Such evidence is due to gas barrier activity exerted not only by dispersed clay layers [34] but even by confined polymer chains as previously stated for different polymer matrix [35] and here demonstrated even for PLA. By increasing the content of MMT-PLANH 3 the oxidation time (OIt, Table 2) was remarkably increased, confirming such behaviour and definitely assessing that the use of MMThybrids with surfactant able to specifically interact with PLA polymer is able to provide nanocomposites with good dispersion and improved oxidation stability.…”

Section: Resultssupporting

confidence: 85%

MMT and LDH organo-modification with surfactants tailored for PLA nanocomposites

Coiai¹,

Cicogna²,

Santi³

et al. 2017

Express Polym. Lett.

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Abstract. Low molecular weight polyesters were end-functionalized with ammonium and carboxylate salts and used in ionic exchange reactions with respectively cationic (MMT) and anionic (LDH) clays. The hybrid organic-inorganic substrates were structurally analysed to determine the ester oligomers' modification degree and their thermal behaviour owing to confinement effects. The dispersion of such hybrids in polylactic acid (PLA) matrix was performed and the ultimate structural, morphological and thermal properties of the collected nanocomposites were investigated and correlated to the tailored interfacial properties with the different inorganic substrates. While the composites with MMT proved to be stable under thermo-oxidative conditions, the samples obtained by dispersing the LDH hybrid suffered from poor final thermostability owing to molecular weights decrease. Deeper insights about the effect of the interactions at interface (polymer chain-surfactant and polymer chain-inorganic surface) evidenced that by promoting an intimate contact between PLA chains and LDH surface (through oligoester used as inorganic substrate modifier) a certain extent of PLA hydrolysis triggered by both surfactant and inorganic surface (LDH) occurred and cannot completely avoided.

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Section: Resultssupporting

confidence: 85%

MMT and LDH organo-modification with surfactants tailored for PLA nanocomposites

Coiai¹,

Cicogna²,

Santi³

et al. 2017

Express Polym. Lett.

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“…Overall, our analysis provides useful guidelines for a profitable use of rheological techniques in the field of degradation of polymeric materials in the melt state. The study continues in Part II, where the implications stemming from the presence of nanoparticles, which are able to remarkably alter the rheology of the host polymer, are critically discussed [25].…”

Section: Introductionmentioning

confidence: 99%

Time-resolved rheology as a tool to monitor the progress of polymer degradation in the melt state – Part I: Thermal and thermo-oxidative degradation of polyamide 11

Filippone

Carroccio

Mendichi

et al. 2015

Polymer

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“…Figure 9 shows recombination of broken chains (formed through initial chain scission processes) and/or post condensation reactions. Furthermore, it has also been shown recently [34] that the presence of organo-clay in PA11 matrix give rise to an accelerated rate of the crosslinking reactions. These literature findings fully support the melt processing torque results shown in Fig.…”

Section: Processing Morphological and Calorimetric Characterizationsmentioning

confidence: 92%

Novel organo-modifier for thermally-stable polymer-layered silicate nanocomposites

Dintcheva

Al‐Malaika

Morici

2015

Polymer Degradation and Stability

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A new novel approach for the stabilisation of polymer-clay nanocomposites has been investigated based on reacting chemically an antioxidant function, a hindered phenol moiety, with an organic modifier based on a quaternary ammonium salt. The chemically linked antioxidant-containing organic modifier (AO-OM) was then introduced into natural montmorillonite (MMt) through a cation-exchange reaction resulting in antioxidant-containing organo-modified clay (AO-OM-MMt). The new antioxidant-containing modified clay, along with other organo-modified clays having a similar organo-modifier but without the reacted antioxidant, were characterised by spectroscopic, thermogravimetric and x-ray diffraction techniques and tested for their thermo-oxidative stability. PA11-based clay nanocomposites samples containing the AO-OM-MMt and the other organo-modified clays, both without and with an added (i.e. not chemically reacted) hindered phenol antioxidant (similar to the one used in the AO-OM) were prepared by melt processing and examined for their processing and long-term thermal-oxidative stability at high temperatures. It was shown that although the new organo-modifier, AO-OM, was also susceptible to the Hoffman elimination reaction, the nanocomposites containing this newly modified clay (PA11/AO-OM-MMt) showed higher melt processing and long-term thermo-oxidative stability, along with excellent clay dispersion and exfoliation, compared to the other PA11-nanocomposites examined here (with and without the conventionally added antioxidant). It is suggested here that the excellent overall performance observed for the PA11/AO-OM-MMt nanocomposites is due to an in-situ partial release of low molecular weight antioxidant species having stabilising functionalities that are capable of acting locally at the interface between the inorganic clay platelets and the polymeric matrix which is a critical area for the onset of degradation processes

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Time-resolved rheology as a tool to monitor the progress of polymer degradation in the melt state – Part II: Thermal and thermo-oxidative degradation of polyamide 11/organo-clay nanocomposites

Cited by 41 publications

References 25 publications

MMT and LDH organo-modification with surfactants tailored for PLA nanocomposites

MMT and LDH organo-modification with surfactants tailored for PLA nanocomposites

Time-resolved rheology as a tool to monitor the progress of polymer degradation in the melt state – Part I: Thermal and thermo-oxidative degradation of polyamide 11

Novel organo-modifier for thermally-stable polymer-layered silicate nanocomposites

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