Controlled peroxide-induced degradation of polypropylene in a twin-screw extruder: Change of molecular weight distribution under conditions controlled by micromixing

Iedema, Piet D.; Remerie, Klaas; Ham, M. van der; Biemond, E.; Tacx, J.C.J.F.

doi:10.1016/j.ces.2011.06.071

Cited by 19 publications

(21 citation statements)

References 19 publications

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“…Other efforts include the modeling of the thermal degradation of polymeric materials specifically. [67][68][69][70][71][72][73][74][75] Most of them however, are not elementary reaction step driven as they generally adopt a very basic reaction scheme (e.g. only random chain fission) with mostly first order reactions and involve TGA analyses with overall degradation rates.…”

Section: Introductionmentioning

confidence: 99%

Connecting polymer synthesis and chemical recycling on a chain-by-chain basis: a unified matrix-based kinetic Monte Carlo strategy

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Connecting polymer synthesis and chemical recycling on a chain-by-chain basis: a unified matrix-based kinetic Monte Carlo strategy

et al. 2020

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“…To protect the mechanical properties of the product, the number of extrusions must be limited to preserve the desired properties of the polymer. The degradation of the polymer under multiple extrusions has been evaluated by traditional measurements, such as the mechanical properties test [5,6], gel permeation chromatography (GPC) [7,8], and rheological measurement [9,10,11]. In order to characterize the degradation mechanism of the polymer, a combination of several off-line measurement methods is often required.…”

Section: Introductionmentioning

confidence: 99%

In-Line Monitoring the Degradation of Polypropylene under Multiple Extrusions Based on Raman Spectroscopy

et al. 2019

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Polymer degradation is a common problem in the extrusion process. In this work, Raman spectroscopy, a robust, rapid, and non-destructive tool for in-line monitoring, was utilized to in-line monitor the degradation of polypropylene (PP) under multiple extrusions. Raw spectra were pretreated by chemometrics methods to extract variations of spectra and eliminate noise. The variation of Raman intensity with the increasing number of extrusions was caused by the scission of PP chains and oxidative degradation, and the variation trend of Raman intensity indicated that long chains were more likely to be damaged by the extrusion. For the quantitative analysis of degradation, the partial least square was used to build a model to predict the degree of PP degradation measured by gel permeation chromatography (GPC). For the calibration set, the coefficient of determination (R2) and the root mean square error of cross-validation (RMSECV) were 0.9859 and 1.2676%, and for the prediction set, R2 and the root mean square error of prediction (RMSEP) were 0.9752 and 1.7228%, which demonstrated the accuracy of the proposed model. The in-line Raman spectroscopy combined with the chemometrics methods was proved to be an accurate and highly effective tool, which can monitor the degradation of polymer in real time.

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“…In contrast, the process and mechanism of vis‐breaking for conventional polypropylene is well documented. [ 8,11–14 ]…”

Section: Introductionmentioning

confidence: 99%

NMR Characterization of Vis‐Broken Heterophasic Ethylene−Propylene Copolymers

Matthews

Magagula

Reenen

2020

Macro Reaction Engineering

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a narrower molecular weight distribution by effectively removing the high molecular weight tail of the distribution. This results in a more Newtonian shear viscosity behavior permitting the use of lower processing temperatures and higher spinning speeds when processing into fibers or thin films. [8] In the case of HEPCs a similar vis-breaking treatment can be applied for the same reasons. The necessity of this step is due to the incapability of the catalyst system to provide low molecular weight material. While this step is necessary, its effect on the mechanical properties of the resultant impact copolymer is undesirable. [9,10] The effect of the visbreaking process on impact copolymers is not well understood as the chemical structure of these copolymers is highly complex. HEPCs contain varying distributions of ethylene-and propylene-rich regions. This presents challenges in predicting the manner in which the copolymers will be affected by vis-breaking. In contrast, the process and mechanism of vis-breaking for conventional polypropylene is well documented. [8,11-14] Controlled rheology (also referred to as vis-breaking) is based on chain scission induced by free radicals, exploiting the mechanism of oxidative degradation of polypropylene. As polyolefins in general are susceptible to oxidative and photochemical degradation, polymer modifications which make use of these radical reactions need precise decomposition rates depending on the processing conditions. Therefore radical sources with specific thermal decomposition temperatures and thus controlled radical initiation are ideal. The radical source is most often an organic peroxide such as dicumylperoxide, [14-16] 2,5dimethyl-2,5-di-tert-butylperoxyhexane (DHBP), [7,17,18] or cyclic peroxides such as 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane (Trigonox 301) [9] which forms primary radicals following thermal decomposition. The cyclic peroxides have the advantage of not releasing volatile gases as in the case of the acyclic organic peroxides. [7,19] Since the radicals attack in a random fashion the statistical probability that a monomer in a longer chain reacts with a radical is greater since the distribution of chain sizes generally implies that monomers are more likely to occur in longer chains than shorter chains. This leads to break down of the longer chains and decrease of the overall molecular weight distribution. The use of inorganic peroxides has been reported in the literature [8] but has not been implemented industrially due to the high reactivity of these peroxides which require low reaction temperatures. This limits the applicability Solution 13 C nuclear magnetic resonance (NMR) is used in conjunction with in situ solid-state NMR to determine the effect of peroxide treatment on the chemical structure and morphology of ethylene−propylene copolymers. The copolymers contain increasing quantities of ethylene with the lowest ethylene content corresponding to pure isotactic polypropylene. The vis-breaking of heterophasic ethylene-propylene copolyme...

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Controlled peroxide-induced degradation of polypropylene in a twin-screw extruder: Change of molecular weight distribution under conditions controlled by micromixing

Cited by 19 publications

References 19 publications

Connecting polymer synthesis and chemical recycling on a chain-by-chain basis: a unified matrix-based kinetic Monte Carlo strategy

Connecting polymer synthesis and chemical recycling on a chain-by-chain basis: a unified matrix-based kinetic Monte Carlo strategy

In-Line Monitoring the Degradation of Polypropylene under Multiple Extrusions Based on Raman Spectroscopy

NMR Characterization of Vis‐Broken Heterophasic Ethylene−Propylene Copolymers

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