Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film

2012 ◽  
Vol 97 (7) ◽  
pp. 1164-1177 ◽  
Author(s):  
M. Atiqullah ◽  
M.S. Winston ◽  
J.E. Bercaw ◽  
I. Hussain ◽  
A. Fazal ◽  
...  
Keyword(s):  
Oxidative Degradation ◽  
Metallocene Catalyst ◽  
Polyethylene Film ◽  
Polymer Backbone

Stability of Partially Hydrolyzed Polyacrylamides at Elevated Temperatures in the Absence of Divalent Cations

SPE Journal ◽  
2009 ◽  
Vol 15 (02) ◽  
pp. 341-348 ◽  
Author(s):  
R.S.. S. Seright ◽  
A.R.. R. Campbell ◽  
P.S.. S. Mozley ◽  
Peihui Han
Keyword(s):  
Dissolved Oxygen ◽  
Oil Recovery ◽  
Elevated Temperatures ◽  
Divalent Cations ◽  
Oxidative Degradation ◽  
Reservoir Rock ◽  
Oxygen Scavengers ◽  
Polymer Backbone ◽  
Polymer Injection ◽  
The Stability

Summary At elevated temperatures in aqueous solution, partially hydrolyzed polyacrylamides (HPAMs) experience hydrolysis of amide side groups. However, in the absence of dissolved oxygen and divalent cations, the polymer backbone can remain stable so that HPAM solutions were projected to maintain at least half their original viscosity for more than 8 years at 100°C and for approximately 2 years at 120°C. Within our experimental error, HPAM stability was the same with and without oil (decane). An acrylamide-AMPS copolymer [with 25% 2-acrylamido-2-methylpropane sulphonic acid (AMPS)] showed similar stability to that for HPAM. Stability results were similar in brines with 0.3% NaCl, 3% NaCl, or 0.2% NaCl plus 0.1% NaHCO3. At temperatures of 160°C and greater, the polymers were more stable in brine with 2% NaCl plus 1% NaHCO3 than in the other brines. Even though no chemical oxygen scavengers or antioxidants were used in our study, we observed the highest level of thermal stability reported to date for these polymers. Our results provide considerable hope for the use of HPAM polymers in enhanced oil recovery (EOR) at temperatures up to 120°C if contact with dissolved oxygen and divalent cations can be minimized. Calculations performed considering oxygen reaction with oil and pyrite revealed that dissolved oxygen will be removed quickly from injected waters and will not propagate very far into porous reservoir rock. These findings have two positive implications with respect to polymer floods in high-temperature reservoirs. First, dissolved oxygen that entered the reservoir before polymer injection will have been consumed and will not aggravate polymer degradation. Second, if an oxygen leak (in the surface facilities or piping) develops during the course of polymer injection, that oxygen will not compromise the stability of the polymer that was injected before the leak developed or the polymer that is injected after the leak is fixed. Of course, the polymer that is injected while the leak is active will be susceptible to oxidative degradation. Maintaining dissolved oxygen at undetectable levels is necessary to maximize polymer stability. This can be accomplished readily without the use of chemical oxygen scavengers or antioxidants.

scholarly journals SYNTHESIS AND STUDY OF COPOLYMERS OF ETHYLENE WITH HEXENE-1, MODIFIED WITH FINISHED NANOFIBERS-Al2O3 (NAFEN) WITH INCREASED RESISTANCE TO THERMAL OXIDATIVE DEGRADATION

2021 ◽  
pp. 45-57
Author(s):  
S.V. Kondrashov ◽  
◽  
A.A. Pykhtin ◽  
A.A. Melnikov ◽  
N.V. Antyufeyeva ◽  
...  
Keyword(s):  
Mechanical Characteristics ◽  
Oxidative Degradation ◽  
Metallocene Catalyst ◽  
Melt Flow Index ◽  
Synthesis And Characterization ◽  
Flow Index ◽  
Thermal Oxidative Degradation ◽  
Catalytic Polymerization

Here we report the study on synthesis and characterization of nanocomposites obtained by in situ catalytic polymerization of ethylene and hexene-1 on metallocene catalyst in the presence of dispersed surface-functionalized -Al2O3 nanofibers (Nafen). It has been determined that surface treatment of Nafen nanofibers with organosilanes allows to obtain stable nanoscale dispersions under ultrasonication. It has been shown that nanocomposites based on copolymers of ethylene with hexene-1 demonstrate improved resistance to thermal oxidative degradation in comparison with nanocomposites based on copolymers of ethylene with propylene, while the influence of the silane chemistry on the mechanical characteristics in these nanocomposites is less pronounced. The best mechanical characteristics were achieved for nanocomposite with Nafen treated with trimethoxyvinylsilane. The melt flow index drop is observed after moderate heat treatment or combined temperature/humidity.

Photo-Oxidative Degradation of Metallocene Linear Low-Density Polyethylene

2009 ◽  
Vol 610-613 ◽  
pp. 243-247 ◽  
Author(s):  
Fu Chen Bai ◽  
Chun Xiao Zhang ◽  
Xi Yao Zhang ◽  
Jian Liu ◽  
Wei Tian
Keyword(s):  
Oxidative Degradation ◽  
Metallocene Catalyst ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Elongation At Break ◽  
Photo Oxidation ◽  
Chemical Structures ◽  
Natta Catalyst ◽  
Physical And Chemical ◽  
Ziegler Natta Catalyst

Films of linear-low density polyethylenes, made from metallocene catalyst and Ziegler-Natta catalyst , were exposed to accelerate photo-oxidation conditions. The investigations were focused on the changes of the physical and chemical structures and elongation at break occurring in the photo-oxidation process. The results showed that ethylene-hexene m-LLDPE was more favorer to photo-oxidize than ethylene-octene LLDPE. The other two ethylene-ocetene m-LLDPEs were comparable to LLDPE with the same comonomer. The oxidation rate of LDPE is slower than those of all the LLDPEs.

Mutual effect of plasma oxygen and oxidative degradation of a polyethylene film

2015 ◽  
Vol 53 (4) ◽  
pp. 459-462
Author(s):  
D. V. Kadnikov ◽  
S. A. Smirnov ◽  
V. V. Rybkin
Keyword(s):  
Oxidative Degradation ◽  
Mutual Effect ◽  
Polyethylene Film ◽  
Plasma Oxygen

Controlled Injection of Holes into ALQ3 Based Oleds by Means of An Oxidized Transport Layer

2001 ◽  
Vol 708 ◽  
Author(s):  
Mathew K. Mathai ◽  
Keith A. Higginson ◽  
Bing R. Hsieh ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Indium Tin Oxide ◽  
Oxidative Degradation ◽  
Transport Layer ◽  
Hole Injection ◽  
Carrier Injection ◽  
Salt Loading ◽  
Light Emitting ◽  
Hole Transporting ◽  
Intrinsic Degradation ◽  
Variable Conductivity

ABSTRACTIn this paper we report a method for tuning the extent of hole injection into the active light emitting tris- (8-hydroxyquinoline) aluminum (Alq3) layer in organic light emitting diodes (OLEDs). This is made possible by modifying the indium tin oxide (ITO) anode with an oxidized transport layer (OTL) comprising a hole transporting polycarbonate of N,N'-bis(3-hydroxymethyl)-N,N'-bis(phenyl) benzidine and diethylene glycol (PC-TPB-DEG) doped with varying concentrations of antimonium hexafluoride salt of N,N,N',N'-tetra-p-tolyl-4,4'-biphenyldiamine (TMTPD+ SbF6-). The conductivity of the OTL can be changed over three orders of magnitude depending on salt loading. The analysis of hole and electron current variations in these devices indicates that optimizing the conductivity of the OTL enables the modulation of hole injection into the Alq3 layer. The bipolar charge transport properties for OLEDs in which the interfacial carrier injection barriers have been minimized, are governed by the conductivities of the respective layers and in this case it is shown that the variable conductivity of the OTL does allow for better control of the same. Accordingly, varying the concentration of holes in the device indicates that beyond an optimum concentration of holes, further hole injection results in the formation of light quenching cationic species and the initiation of oxidative degradation processes in the Alq3 layer, thus accelerating the intrinsic degradation of these devices. The variable conductivity of the OTL can hence be used to minimize the occurrence of these processes.

Simple Modification Measurement of Photodegradability of Polymers by using Photo-induced Chemiluminescence Technique

2013 ◽  
Vol 10 (2) ◽  
pp. 51
Author(s):  
Siti Farhana Zakaria ◽  
Keith R Millington
Keyword(s):  
Free Radicals ◽  
Organic Materials ◽  
Oxidative Degradation ◽  
Working Life ◽  
Bimolecular Reaction ◽  
Synthetic Polymers ◽  
Accelerated Weathering ◽  
Simple Modification ◽  
Uv Absorbers ◽  
Irradiation Period

Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.

SuFExable Polymers with Helical Structures Derived from Thionyl Tetrafluoride (SOF4)

2019 ◽  
Author(s):  
Suhua Li ◽  
Gencheng Li ◽  
Bing Gao ◽  
Sidharam P. Pujari ◽  
Xiaoyan Chen ◽  
...  
Keyword(s):  
Functional Polymers ◽  
Polymer Chains ◽  
New Materials ◽  
Helical Structures ◽  
Polymer Backbone ◽  
Silyl Ethers ◽  
Helical Polymer ◽  
Key Characteristics ◽  
Post Modification ◽  
Individual Polymer

The first SuFEx click chemistry synthesis of SOF<sub>4</sub>-derived copolymers based upon the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers) is described. This novel class of SuFEx polymer presents two key characteristics: First, the newly created [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and primed to undergo further high-yielding and precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate the presence of helical polymer structures, which itself suggests a preferential approach of new monomers onto the growing polymer chain upon the formation of the stereogenic linking moiety.

Functional Poly(p-Xylylene)s via Chemical Reduction of Poly(p-Phenylene Vinylene)s

2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett
Keyword(s):  
Film Formation ◽  
Chemical Reduction ◽  
Water Soluble ◽  
Phenylene Vinylene ◽  
Polymer Modification ◽  
Polymer Backbone ◽  
Crosslinking Process ◽  
Conducting Membranes ◽  
In Situ Crosslinking

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.

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