scholarly journals Introduction of a long-chain branching structure by ultraviolet-induced reactive extrusion to improve cell morphology and processing properties of polylactide foam

RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6266-6277 ◽  
Author(s):  
Shaojie Li ◽  
Guangjian He ◽  
Xia Liao ◽  
Chul B. Park ◽  
Qi Yang ◽  
...  
Keyword(s):  
Cell Morphology ◽  
Reactive Extrusion ◽  
Chain Branching ◽  
Long Chain Branching ◽  
Processing Window ◽  
Processing Properties ◽  
Long Chain

Long-chain branching structure introduced by UV-induced reactive extrusion could widen its foaming processing window.

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 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.

An Ultraviolet-Induced Reactive Extrusion To Control Chain Scission and Long-Chain Branching Reactions of Polylactide

2016 ◽  
Vol 55 (3) ◽  
pp. 597-605 ◽  
Author(s):  
Chang-Qian Chen ◽  
Ding-Meng Ke ◽  
Ting-Ting Zheng ◽  
Guang-Jian He ◽  
Xian-Wu Cao ◽  
...  
Keyword(s):  
Reactive Extrusion ◽  
Chain Scission ◽  
Chain Branching ◽  
Long Chain Branching ◽  
Long Chain

Characterization of long chain branching: Dilution rheology of industrial polyethylenes

2002 ◽  
Vol 46 (2) ◽  
pp. 401-426 ◽  
Author(s):  
B. J. Crosby ◽  
M. Mangnus ◽  
W. de Groot ◽  
R. Daniels ◽  
T. C. B. McLeish
Keyword(s):  
Chain Branching ◽  
Long Chain Branching ◽  
Long Chain
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