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Long chain branching on linear polypropylene in the melt by free radical reaction

Goumans, I.C. (2013) Long chain branching on linear polypropylene in the melt by free radical reaction. Master's Thesis / Essay, Chemistry.

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Abstract

This thesis describes the research that is performed towards the free radical melt modification of long chain branched (LCB) isotactic-Polypropylene (iPP). The synthesis and characterization of LCB-iPP was performed. For reference, chapter 2 captures an overview of the available and useful literature regarding the branching process and the science of rheology. The synthesis and characterization of LCB-iPP is described in chapter 3. The synthesis was carried out with dicumyl peroxide as free radical initiator and five selected co-agents. The characterization was performed by differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and rheological measurements. An attempt was made to quantitatively correlate the co-agent properties with the zero shear viscosity, but it was not possible to fit the data in statistically significant way. Nevertheless, at a more qualitative level, few important co-agent properties were defined and a ranking of the use co-agents regarding their ability in inducing long chain branches is presented. It was found that hydroquinone (HQ) resulted in modified iPP with the highest degree of branching while allyl-2-furoate (A2F) was not capable of inducing a branched structure. Regarding the choice of co-agent, a wide range of different molecules can be used. Many different co-agents which are capable of inducing a branched structure can be found in literature. Various strategies have been proposed to restrain the degradation of iPP and suppress crosslinking during the melt modification. However, to our knowledge, a systematic study towards the choice of co-agent has not been performed yet. This gives rise to the question; what are key features for inducing a branched structure? In this work a systematic study towards the choice of co-agent was performed and few important co-agent properties were defined which can be used for selecting a co-agent.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Chemistry
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:53
Last Modified: 15 Feb 2018 07:53
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/11130

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