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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Al-Malaika, Sahar
Aston University
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (18/18 displayed)
- 2021Influence of anti-ageing compounds on rheological properties of bitumencitations
- 2021Effect of processing conditions and catalyst type on the thermal oxidative degradation mechanisms and melt stability of metallocene and Ziegler‐catalyzed ethylene‐1‐hexene copolymerscitations
- 2021New and novel stabilisation approach for radiation-crosslinked Ultrahigh Molecular Weight Polyethylene (XL-UHMWPE) targeted for use in orthopeadic implantscitations
- 2020Photo-stabilization of biopolymers-based nanocomposites with UV-modified layered silicatescitations
- 2017Novel strategic approach for the thermo- and photo-oxidative stabilization of polyolefin/clay nanocompositescitations
- 2017Novel strategic approach for the thermo- and photo- oxidative stabilization of polyolefin/clay nanocompositescitations
- 2017Thermo-oxidative stabilization of poly(lactic acid)-based nanocomposites through the incorporation of clay with in-built antioxidant activitycitations
- 2015Novel organo-modifier for thermally-stable polymer-layered silicate nanocompositescitations
- 2013Influence of processing and clay type on nanostructure and stability of polypropylene-clay nanocompositescitations
- 2011Effect of contact surfaces on the thermal and photoxidation of dehydrated castor oilcitations
- 2010Reactive processing of polymerscitations
- 2009Effect of extrusion and photo-oxidation on polyethylene/clay nanocompositescitations
- 2009Reactive processing of polymers: structural characterization of products by 1H and 13C NMR spectroscopy for glycidyl methacrylate grafting onto EPR in the absence and presence of a reactive comonomercitations
- 2008Special issue of PDS - Based on PDDG meeting, Aston University, September 2007, in honour of Professor Norman Billingham
- 2006Metallocene ethylene-1-octene copolymerscitations
- 2005Polymer degradation and stabilitycitations
- 2004Perspectives in stabilisation of polyolefinscitations
- 2003Oxidative degradation and stabilisation of polymerscitations
Places of action
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article
Metallocene ethylene-1-octene copolymers
Abstract
<p>The influence of the comonomer content in a series of metallocene-based ethylene-1-octene copolymers (m-LLDPE) on thermo-mechanical, rheological, and thermo-oxidative behaviours during melt processing were examined using a range of characterisation techniques. The amount of branching was calculated from <sup>13</sup>C NMR and studies using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to determine the effect of short chain branching (SCB, comonomer content) on thermal and mechanical characteristics of the polymer. The effect of melt processing at different temperatures on the thermo-oxidative behaviour of the polymers was investigated by examining the changes in rheological properties, using both melt flow and capillary rheometry, and the evolution of oxidation products during processing using infrared spectroscopy. The results show that the comonomer content and catalyst type greatly affect thermal, mechanical and oxidative behaviour of the polymers. For the metallocene polymer series, it was shown from both DSC and DMA that (i) crystallinity and melting temperatures decreased linearly with comonomer content, (ii) the intensity of the ß-transition increased, and (iii) the position of the tan <em>δ</em><sub>max</sub> peak corresponding to the a-transition shifted to lower temperatures, with higher comonomer content. In contrast, a corresponding Ziegler polymer containing the same level of SCB as in one of the m-LLDPE polymers, showed different characteristics due to its more heterogeneous nature: higher elongational viscosity, and a double melting peak with broader intensity that occurred at higher temperature (from DSC endotherm) indicating a much broader short chain branch distribution. The thermo-oxidative behaviour of the polymers after melt processing was similarly influenced by the comonomer content. Rheological characteristics and changes in concentrations of carbonyl and the different unsaturated groups, particularly vinyl, vinylidene and trans-vinylene, during processing of m-LLDPE polymers, showed that polymers with lower levels of SCB gave rise to predominantly crosslinking reactions at all processing temperatures. By contrast, chain scission reactions at higher processing temperatures became more favoured in the higher comonomer-containing polymers. Compared to its metallocene analogue, the Ziegler polymer showed a much higher degree of crosslinking at all temperatures because of the high levels of vinyl unsaturation initially present.</p>