Mechanochemical Degradation of Denpols: Synthesis and Ultrasound-Induced Chain Scission of Polyphenylene-Based Dendronized Polymers

2018 ◽  
Vol 140 (27) ◽  
pp. 8599-8608 ◽  
Author(s):  
Gregory I. Peterson ◽  
Ki-Taek Bang ◽  
Tae-Lim Choi
Keyword(s):  
Chain Scission ◽  
Dendronized Polymers ◽  
Mechanochemical Degradation

scholarly journals Main-chain scission of individual macromolecules induced by solvent swelling

2019 ◽  
Vol 10 (24) ◽  
pp. 6125-6139 ◽  
Author(s):  
Daniel Messmer ◽  
Oscar Bertran ◽  
Reinhard Kissner ◽  
Carlos Alemán ◽  
A. Dieter Schlüter
Keyword(s):  
Main Chain ◽  
Chain Scission ◽  
Comprehensive Investigation ◽  
Dendronized Polymers ◽  
Solvent Swelling

We present a comprehensive investigation of main-chain scission processes affecting peripherally charged and neutral members of a class of dendronized polymers (DPs) studied in our laboratory.

Changes in molecular weight distribution caused by main-chain scission of electron beam resists

2020 ◽  
Vol 59 (12) ◽  
pp. 126506
Author(s):  
Takahiro Kozawa ◽  
Ayako Nakajima ◽  
Manabu Hoshino
Keyword(s):  
Molecular Weight ◽  
Electron Beam ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Main Chain ◽  
Chain Scission

Mechanochemical Reactivity of Bottlebrush and Dendronized Polymers: Solid vs Solution States

2021 ◽  
Author(s):  
Jinkyung Noh ◽  
Gregory I. Peterson ◽  
Tae-Lim Choi
Keyword(s):  
Dendronized Polymers

scholarly journals Best Practice for De-Vulcanization of Waste Passenger Car Tire Rubber Granulate Using 2-2′-dibenzamidodiphenyldisulfide as De-Vulcanization Agent in a Twin-Screw Extruder

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1139
Author(s):  
Hans van Hoek ◽  
Jacques Noordermeer ◽  
Geert Heideman ◽  
Anke Blume ◽  
Wilma Dierkes
Keyword(s):  
Best Practice ◽  
Chain Scission ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Passenger Car ◽  
Tire Rubber ◽  
Twin Screw ◽  
Styrene Butadiene

De-vulcanization of rubber has been shown to be a viable process to reuse this valuable material. The purpose of the de-vulcanization is to release the crosslinked nature of the highly elastic tire rubber granulate. For present day passenger car tires containing the synthetic rubbers Styrene-Butadiene Rubber (SBR) and Butadiene Rubber (BR) and a high amount of silica as reinforcing filler, producing high quality devulcanizate is a major challenge. In previous research a thermo-chemical mechanical approach was developed, using a twin-screw extruder and diphenyldisulfide (DPDS) as de-vulcanization agent.The screw configuration was designed for low shear in order to protect the polymers from chain scission, or uncontrolled spontaneuous recombination which is the largest problem involved in de-vulcanization of passenger car tire rubber. Because of disadvantages of DPDS for commercial use, 2-2′-dibenzamidodiphenyldisulfide (DBD) was used in the present study. Due to its high melting point of 140 °C the twin-screw extruder process needed to be redesigned. Subsequent milling of the devulcanizate at 60 °C with a narrow gap-width between the mill rolls greatly improved the quality of the devulcanizate in terms of coherence and tensile properties after renewed vulcanization. As the composition of passenger car tire granulate is very complex, the usefulness of the Horikx-Verbruggen analysis as optimization parameter for the de-vulcanization process was limited. Instead, stress-strain properties of re-vulcanized de-vulcanizates were used. The capacity of the twin-screw extruder was limited by the required residence time, implying a low screw speed. A best tensile strength of 8 MPa at a strain at break of 160% of the unblended renewed vulcanizate was found under optimal conditions.

Kinetic study of random chain scission by viscometry

1990 ◽  
Vol 41 (56) ◽  
pp. 985-994 ◽  
Author(s):  
K. K. Chee
Keyword(s):  
Kinetic Study ◽  
Chain Scission

Study in performance and morphology of polyamide 12 produced by selective laser sintering technology

2018 ◽  
Vol 24 (5) ◽  
pp. 813-820 ◽  
Author(s):  
Junjie Wu ◽  
Xiang Xu ◽  
Zhihao Zhao ◽  
Minjie Wang ◽  
Jie Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Polarized Light ◽  
Chain Scission ◽  
High Energy ◽  
Laser Sintering ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Polyamide 12

Purpose The purpose of this paper is to investigate the effect of selective laser sintering (SLS) method on morphology and performance of polyamide 12. Design/methodology/approach Crystallization behavior is critical to the properties of semi-crystalline polymers. The crystallization condition of SLS process is much different from others. The morphology of polyamide 12 produced by SLS technology was investigated using scanning electron microscopy, polarized light microscopy, differential scanning calorimetry, X-ray diffraction and wide-angle X-ray diffraction. Findings Too low fill laser power brought about bad fusion of powders, while too high energy input resulted in bad performance due to chain scission of macromolecules. There were three types of crystal in the raw powder material, denoted as overgrowth crystal, ring-banded spherulite and normal spherulite. Originality/value In this work, SLS samples with different sintering parameters, as well as compression molding sample for the purpose of comparison, were made to study the morphology and crystal structure of sintered PA12 in detail.

EXPERIMENTAL VALIDATION OF THE CHARLESBY AND HORIKX MODELS APPLIED TO DE-VULCANIZATION OF SULFUR AND PEROXIDE VULCANIZATES OF NR AND EPDM

2016 ◽  
Vol 89 (4) ◽  
pp. 671-688 ◽  
Author(s):  
M. A. L. Verbruggen ◽  
L. van der Does ◽  
W. K. Dierkes ◽  
J. W. M. Noordermeer
Keyword(s):  
Experimental Validation ◽  
Main Chain ◽  
Sol Gel ◽  
Chain Scission ◽  
Cross Linking ◽  
Cross Link ◽  
Practical Reality ◽  
Cross Links ◽  
The Cross ◽  
Theoretical Considerations

ABSTRACT The theoretical model developed by Charlesby to quantify the balance between cross-links creation of polymers and chain scission during radiation cross-linking and further modifications by Horikx to describe network breakdown from aging were merged to characterize the balance of both types of scission on the development of the sol content during de-vulcanization of rubber networks. There are, however, disturbing factors in these theoretical considerations vis-à-vis practical reality. Sulfur- and peroxide-cured NR and EPDM vulcanizates were de-vulcanized under conditions of selective cross-link and random main-chain scissions. Cross-link scission was obtained using thiol-amine reagents for selective cleavage of sulfur cross-links. Random main-chain scission was achieved by heating peroxide vulcanizates of NR with diphenyldisulfide, a method commonly employed for NR reclaiming. An important factor in the analyses of these experiments is the cross-linking index. Its value must be calculated using the sol fraction of the cross-linked network before de-vulcanization to obtain reliable results. The values for the cross-linking index calculated with sol-gel data before de-vulcanization appear to fit the experimentally determined modes of network scission during de-vulcanization very well. This study confirms that the treatment of de-vulcanization data with the merged Charlesby and Horikx models can be used satisfactorily to characterize the de-vulcanization of NR and EPDM vulcanizates.

Dendronized Polymers: Molecular Objects between Conventional Linear Polymers and Colloidal Particles

2014 ◽  
Vol 3 (10) ◽  
pp. 991-998 ◽  
Author(s):  
A. Dieter Schlüter ◽  
Avraham Halperin ◽  
Martin Kröger ◽  
Dimitris Vlassopoulos ◽  
Gerhard Wegner ◽  
...  
Keyword(s):  
Colloidal Particles ◽  
Linear Polymers ◽  
Dendronized Polymers

Internal photoreduction and chain scission in polyvinylbenzophenone

1982 ◽  
Vol 2 (3) ◽  
pp. 167-173 ◽  
Author(s):  
R. Knoesel ◽  
G. Weill
Keyword(s):  
Chain Scission
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