Radiation Induced Long Chain Branching in High-Density Polyethylene through a Reactive Extrusion Process

2013 ◽  
Vol 8 (2) ◽  
pp. 100-111 ◽  
Author(s):  
Pouyan Sardashti ◽  
Costas Tzoganakis ◽  
Maria A. Polak ◽  
Alexander Penlidis
Keyword(s):  
High Density Polyethylene ◽  
Reactive Extrusion ◽  
Extrusion Process ◽  
High Density ◽  
Chain Branching ◽  
Long Chain Branching ◽  
Radiation Induced ◽  
Reactive Extrusion Process ◽  
Long Chain

Development of high melt strength polypropylene and its application in thermoplastic elastomeric composition

2021 ◽  
pp. 009524432110510
Author(s):  
Mousumi De Sarkar ◽  
Nishant Chandel ◽  
Shib Shankar Banerjee ◽  
Subhabrata Saha ◽  
Anil K Bhowmick ◽  
...  
Keyword(s):  
Fixed Ratio ◽  
Reactive Extrusion ◽  
Extrusion Process ◽  
Structure Property ◽  
Chain Branching ◽  
Melt Strength ◽  
Long Chain Branching ◽  
Zinc Diethyldithiocarbamate ◽  
Long Chain ◽  
High Melt Strength Polypropylene

High melt strength polypropylene (HMS-PP) with a long-chain branched structure is a modified form of polypropylene (PP) which has basic properties of regular PP but with superior melt drawability. This paper reports on the development of gel-free HMS-PP from a linear isotactic PP through the introduction of long-chain branching on its backbone via a reactive extrusion process, using dicetyl-peroxydicarbonate (PODIC) alone or in combination with a coagent. The melt strength and the mechanical properties such as impact and flexural strength of PP showed improvements with the modification with PODIC. 5000 ppm by weight of PODIC was found to provide the best balance of properties. The efficacies of zinc diethyldithiocarbamate (ZDC) and tetramethyl thiuram disulphide (TMTD) as coagents in combination with PODIC to augment properties of HMS-PP further were explored. TMTD offered slightly enhanced performance benefits as compared to ZDC at an optimized concentration of 100 ppm by weight. The application potential of HMS-PP in thermoplastic elastomeric blends of HMS-PP with ethylene-propylene-diene monomer (EPDM) rubber at a fixed ratio of 35/65 by weight was also investigated. Structure-property correlations were established between the extent of long-chain branching in the modified PP and the properties of the resultant thermoplastic elastomeric composition.

scholarly journals Modelling of Elongational Flow of HDPE Melts by Hierarchical Multi-Mode Molecular Stress Function Model

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3217
Author(s):  
Leslie Poh ◽  
Esmaeil Narimissa ◽  
Manfred H. Wagner
Keyword(s):  
Stress Function ◽  
High Density Polyethylene ◽  
High Density ◽  
Molecular Characteristics ◽  
Chain Branching ◽  
Data Set ◽  
Long Chain Branching ◽  
Molecular Stress Function ◽  
Multi Mode ◽  
Long Chain

The transient elongational data set obtained by filament-stretching rheometry of four commercial high-density polyethylene (HDPE) melts with different molecular characteristics was reported by Morelly and Alvarez [Rheologica Acta 59, 797–807 (2020)]. We use the Hierarchical Multi-mode Molecular Stress Function (HMMSF) model of Narimissa and Wagner [Rheol. Acta 54, 779–791 (2015), and J. Rheology 60, 625–636 (2016)] for linear and long-chain branched (LCB) polymer melts to analyze the extensional rheological behavior of the four HDPEs with different polydispersity and long-chain branching content. Model predictions based solely on the linear-viscoelastic spectrum and a single nonlinear parameter, the dilution modulus GD for extensional flows reveals good agreement with elongational stress growth data. The relationship of dilution modulus GD to molecular characteristics (e.g., polydispersity index (PDI), long-chain branching index (LCBI), disengagement time τd) of the high-density polyethylene melts are presented in this paper. A new measure of the maximum strain hardening factor (MSHF) is proposed, which allows separation of the effects of orientation and chain stretching.

Mechanism for long-chain branching in the thermal degradation of linear high-density polyethylene

1982 ◽  
Vol 15 (6) ◽  
pp. 1460-1464 ◽  
Author(s):  
Takeshi Kuroki ◽  
Takashi Sawaguchi ◽  
Sadayuki Niikuni ◽  
Tadashi Ikemura
Keyword(s):  
Thermal Degradation ◽  
High Density Polyethylene ◽  
High Density ◽  
Chain Branching ◽  
Long Chain Branching ◽  
Long Chain

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

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 886 ◽  
Author(s):  
Sascha Stanic ◽  
Gergö Gottlieb ◽  
Thomas Koch ◽  
Lukas Göpperl ◽  
Klaus Schmid ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gel Permeation Chromatography ◽  
Reactive Extrusion ◽  
Chain Branching ◽  
Long Chain Branching ◽  
Single Screw Extruder ◽  
Strength Behavior ◽  
Different Temperatures ◽  
Branched Polypropylene ◽  
Long Chain

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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