Effect of molecular weight, branching and temperature on dynamics of polypropylene melts at very high shear rates

Drábek, Jiří; Zatloukal, Martin; Martyn, M. T.

doi:10.1016/j.polymer.2018.04.046

Cited by 19 publications

(19 citation statements)

References 26 publications

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“…GPC is one of the most important methods to determine the MMD of polymers [63]. GPC measurement, a well-established concept in the literature, provides a further possibility to determine the molecular structure and any modifications made to polymers [51,[64][65][66][67][68].…”

Section: Molar Mass Determinationmentioning

confidence: 99%

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

et al. 2020

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Long-chain branching (LCB) is known as a suitable method to increase the melt strength behavior of linear polypropylene (PP), which is a fundamental weakness of this material. This enables the modification of various properties of PP, which can then be used—in the case of PP recyclates—as a practical “upcycling” method. In this study, the effect of five different peroxides and their effectiveness in building LCB as well as the obtained mechanical properties were studied. A single screw extruder at different temperatures (180 and 240 °C) was used, and long-chain branched polypropylene (PP-LCB) was prepared via reactive extrusion by directly mixing the peroxides. The peroxides used were dimyristyl peroxydicarbonate (PODIC C126), tert-butylperoxy isopropylcarbonate (BIC), tert-Butylperoxy 2-ethylhexyl carbonate (BEC), tert-amylperoxy 2-ethylhexylcarbonate (AEC), and dilauroyl peroxide (LP), all with a concentration of 20 mmol/kg. The influence of the temperature on the competitive prevalent reactions of degradation and branching was documented via melt mass-flow rate (MFR), rheology measurements, and gel permeation chromatography (GPC). However, via extensional rheology, strain hardening could be observed in all cases and the mechanical properties could be maintained or even improved. Particularly, PODIC C126 and LP signaled a promising possibility for LCB in this study.

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Section: Molar Mass Determinationmentioning

confidence: 99%

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

et al. 2020

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“…Rheology measurements have been shown in literature to be a good tool of identifying molecular structures and to be very sensitive to changes in them [ 36 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. Several studies have investigated the rheological behavior of blends with linear PP and branched PP or PE and have shown that these blends have a higher shear thinning effect or strain hardening compared to linear PP [ 47 , 48 , 49 , 65 ].…”

Section: Resultsmentioning

confidence: 99%

Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene

Stanic

Koch

Schmid³

et al. 2021

Polymers

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Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.

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“…Polyolefin, mostly low‐density polyethylene (PE‐LD), high‐density polyethylene (PE‐HD) and polypropylene (PP), are among the most widely used and produced polymeric materials in the world. They are used in different industry sectors for example packaging, food industry, biomedical applications, films, bags 1–4 . The operating life from most of these polyolefin products are lower than 1 month 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Upcycling of polypropylene with various concentrations of peroxydicarbonate and dilauroyl peroxide and two processing steps

Stanic

Koch

Schmid³

et al. 2021

J of Applied Polymer Sci

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The influence of two peroxides (peroxydicarbonate/dilauroyl peroxide) with various concentrations (10–200 mmol/kg PP) and their effective opportunity to introduce long chain branched (LCB) were investigated. The dependence of a single and double extrusion step and the changes of the properties were studied. Experiments were carried out in a single screw extruder at 180°C for the first extrusion step (modification) and at 240°C for the second extrusion step (processing simulation). Melt flow rate and dynamic rheological properties were studied at a measuring temperature of 230°C. For the definitive determination of long chain branched polypropylene (LCB‐PP) served the extensional rheology measurements. The mechanical properties were examined via tensile test and impact tensile test. Summarized, LCB (melt strength) could be observed via extensional rheology for all modified specimens and the mechanical properties were maintained or even improved for the modified samples. Particularly, samples containing dilauroyl peroxide display excellent mechanical properties in this study.

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Effect of molecular weight, branching and temperature on dynamics of polypropylene melts at very high shear rates

Cited by 19 publications

References 26 publications

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

Improving Rheological and Mechanical Properties of Various Virgin and Recycled Polypropylenes by Blending with Long-Chain Branched Polypropylene

Upcycling of polypropylene with various concentrations of peroxydicarbonate and dilauroyl peroxide and two processing steps

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