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Wednesday, November 18, 2020 | History

2 edition of Time controlled photo-oxidation of polyolefins by polymer bound additives. found in the catalog.

Time controlled photo-oxidation of polyolefins by polymer bound additives.

Shahida Islam

Time controlled photo-oxidation of polyolefins by polymer bound additives.

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Published by Aston University. Department of Chemical Engineering and Applied Chemistry in Birmingham .
Written in English

Edition Notes

Thesis (PhD) - Aston University, 1992.

ID Numbers
Open LibraryOL13907606M

Blowing agents that disperse more uniformly and provide more controlled foaming action with polyolefins, polystyrene, ABS, PPO and other polymers. The new +Foam series offers an exothermic azodicarbonamide blowing agent, an endothermic variety and a version with both — all used at letdown ratios of percent to %. PhD graduati. Degrees were awarded in Polymer Science, except where stated differently. Graduati since are listed below. Information about earlier graduati can be obtained from the Webmaster.. Last revision: 3 November,

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Time controlled photo-oxidation of polyolefins by polymer bound additives. by Shahida Islam Download PDF EPUB FB2

Time controlled photo-oxidation of polyolefins by polymer bound additives Author: Islam, Shahida ISNI: Awarding Body: University of Aston in Birmingham Current Institution: Aston University Date of Award: Availability of Full Text: Author: Shahida Islam.

Time controlled photo-oxidation of polyolefins by polymer bound additives. By Shahida Islam. Abstract. A variety of iron compounds containing vinyl or thiol functional groups (used as photoactivators) have been synthesised and some of these were successfully bound to both polyethylene and polypropylene backbones during processing in the Author: Shahida Islam.

It seemed appropriate then to investigate the possibility of applying the polymer-bound antioxidant technology to time-controlled photo-activators. Two methods previously used for attaching antioxidants to polymers are adapted in this study to the covalent binding of typical metal-containing compounds to polyolefins 8, by: 9.

Polymer Degradation and Stability 49 () for the photo-oxidation of polyolefins. In the. minimized by purging for a controlled time. Polymer Degradation and Stability 2 () PHOTO-DEGRADATION AND PHOTO-OXIDATION OF POLYOLEFINS: IMPORTANCE OF OXYGEN-POLYMER CHARGE TRANSFER COMPLEXES NORMAN S.

ALLEN Department of Chemistry, John Dalton Faculty of Technology, Manchester Polytechnic, Chester Street, Manchester M1 5GD, Great Britain (Received: Cited by: Moreover, the VE and FA at high concentrations can be considered as suitable eco-friendly pro-degradant additives for PE, also in order to control the polyolefin degradation times.

The photo-oxidation of PP is most effective at wavelengths between and nm. With increasing periods of radiation, the wavelength shifts to a range from to nm. Therefore, glass is able to prevent some effects of weathering.

The photo-oxidation of PP under mercury lamp irradiation is slowed down by a Pyrex glass filter. The. TGA, also called thermogravimetry, is a technique used to measure the mass of samples as a function of the temperature or time in which the sample is subjected to a controlled temperature program in a controlled atmosphere.

18 TGA has been used widely as a method for studying the thermal stability and decomposition of polyolefins and polyolefin. Polymer Degradation and Stability 18 () Mechanisms of Antioxidant Action: Time-Controlled Stabilisation of Polypropylene by Transition Metal Dithiocarbamates S.

AI-Malaiaka, A. Marogi & G. Scott Aston University, Department of Molecular Sciences, Aston Triangle, Birmingham B4 7ET, Great Britain (Received 27 November ; accepted 16 December ) ABSTRACT.

Additives are absolutely essential in the development of commercial polymeric materials. Accordingly, an exhaustive control of composition and evolution in these additives over time is necessary to validate their performance and safety during their shelf life and, consequently, their ultimate applications.

Gas chromatography coupled with mass spectrometry, GC–MS, is described in the present. Polyolefin Soluble Polyisobutylene Oligomer-Bound Metallophthalocyanine and Azo Dye Additives February Journal of Polymer Science Part A Polymer Chemistry 52(4).

The degradation processes of the various types of polymer have specific mechanisms and depend on both the main macromolecular chain nature and structure and on the chemical nature of the branched groups. It is well known for the oxidation of polyolefins or rubber (natural and some synthetic types) that.

This article discusses photo-oxidation degradation (the behavior of polymers as a result of outdoor factors) and mainly concentrates on the photo-oxidative degradation of polyolefins and poly (vinyl) chloride.

Polymer photostabilization with ultraviolet screeners, quenchers, hydroperoxide decomposers, and radical scavengers is also described. The oxodegradation of an injection molding grade polypropylene (PP), formulated with 0%, %, and 3% w/w of a pro-oxidant additive, was studied.

Polymers will change over time when exposed to UV radiation. These changes are the result of light-induced homolytic fission of chemical bonds (photolysis) and photo-oxidation. The UV resistance of unprotected polymers varies widely and depends on the structure and composition. Photo-oxidation is the degradation of a polymer surface in the presence of oxygen or ozone.

The effect is facilitated by radiant energy such as UV or artificial light. This process is the most significant factor in weathering of -oxidation is a chemical change that reduces the polymer's molecular a consequence of this change the material becomes more brittle, with a. Manuela Da Cruz, Laetitia Van Schoors, Karim Benzarti, Xavier Colin, Thermo‐oxidative degradation of additive free polyethylene.

Part I. Analysis of chemical modifications at molecular and macromolecular scales, Journal of Applied Polymer Science, /app,18, ().

In book: Long Term Properties of Polyolefins (pp) to measure faint light emissions and polymer chemiluminescence has become an important method to follow the initial stages in the. The curing process of a thermosetting polymer such as an epoxy is exothermic (heat releasing) and also registers in a DSC thermogram.

Oxidation is also exothermic and in polyolefins it tends to occur relatively quickly, releasing heat at a readily defined point in time.

Marine and inland pollution by non-degradable plastic bags and other plastic articles is a topic of great concern. Natural degradation processes based on oxidation of plastic pollutants could possibly contribute to limit the extent of pollution.

Thermal degradation of polyolefins in the absence of light by non-polluting pro-oxidants has not been presented before. In this study, we show that. Degradation of Plastics and Polymers D. Hourston Department of Materials, Loughborough University, UK This article is a revision of the Third Edition article by J.

Brysdon, volume 2, pp –, Elsevier B.V. Both companies claim a cost advantage for their approach as compared with inherently biodegradable polymers (see PT, March'02, p. 50; Sept. '02, p. 66). On a cost-per-cubic-inch basis, they say, biodegradable copolyester and polylactic acid polymers are at least 10 times more costly than polyolefin additive masterbatches.

the first time, accurately replicates several key forms of degradation (such as gloss loss, colour change, delamination and photo-oxidation) because the research thoroughly evaluated the importance of all three key weathering vari-ables, namely light, heat and moisture.

In the past, researchers thought the light spectrum was the main issue. The additive-free polymer powders were pelletized using a Rheomex S ¾” type single screw extruder attached to a Haake Rheocord EU 10 V driving unit at 50 rpm and barrel tem-peratures of, and °C, then compression-moulded to films at °C using an.

(2) Polymer-bound hindered piperidines have a similar level of photo- antioxidant activity to a commercial hindered piperidine (Tinuvin ) used as an additive at the same molar concentration.

(3) DCP treatment of BPM significantly increases photo-antioxidant activity up to a limiting molar ratio. Polyethylene Resins 5 C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H C H H LDPE LLDPE/VLDPE HDPE – g cm−3 – g cm −3/ – g cm – g cm−3 Figure Classification of polyethylene types according to branching structure and density.

number of acronyms in this book, we have often grouped MDPE, LLDPE, ULDPE. Photooxidation of Poly(phenylene oxide) Polymer JAMES E. PICKETT Chap DOI: /bkch Publication Date (Print): J Purchase Polymer Science: A Comprehensive Reference - 1st Edition. Print Book & E-Book.

ISBN  Polyethylene and polypropylene are converted into billions of pounds of products every year by essentially every process used in plastics. They are low-cost materials that are also among the lightest materials in existence, therefore the cost per unit weight (lb or kg) gets even better when the calculation is made as cost per unit volume (in.³ or cm³).

Its compact design, easy handling and proven reliability make it the ideal quality control and R&D screening device for a variety of industries, such as plastics, packaging, pharmaceuticals, cosmetics, and many more. 1x W air-cooled Xenon Lamps cm2 exposure area Direct Setting and Control of Irradiance in the wavelength range Only absorbed light has a degenerative effect.

Which type of polymer is more sensitive to photo oxidation. Light that is absorbed excites the chromophoric group, and when oxygen is present photo oxidation occurs free radicals form C. Effects are magnified by heat, oxygen, and humidity Additives. Plastics Light Stabilizers (continued) 5.

Polyolefins float in the oceans, because they are normally lighter than salty water. They do not normally contain toxic ingredients, although toxic metals may be introduced as pigments.

Usual additives are antiacids (e.g., Mg or Ca stearates at ~%) and antioxidants (e.g., hindered phenols and phosphites at ~ – %). Fluorophosphonites as Co-Stabilizers in Stabilization of Polyolefins G.

Klender Chap DOI: /bach Publication Date (Print): May 5, About 3% by weight of carbon black adequately protects polyethylene against photo‐oxidation and, under accelerated test conditions, slightly inhibits thermal oxidation. As a rule small amounts of organic antioxidants are also added to the polymer for optimum protection.

When polymer degradation poses the key threat to physical property maintenance, restabilization is the prime solution. "By restabilizing, you can protect properties and go back into high-value applications," says Joseph Puglisi, director of polymer products at Ciba Additives.

Over the last 15 years, additive masterbatches (i. concentrates containing a higher level of additives dispersed in the parent polymer) have become very popular alternatives to pure additives and have found a very wide range of applications, e.

FRs, impact modifiers, antimicrobials, colour masterbatches, etc. Polyolefin materials, particularly polyethylene (PE) and polypropylene (PP), are susceptible to oxidation in the presence of air during long-term service. Oxidation may also be deliberately carried out during the manufacturing process, as a means of chain length control, or surface modification such as corona treatment (1, 2).

and Stability 68 () • Polyolefins with controlled environmental degradability, Polymer Degradation and Stability 91 () Koutny M, Lemaire J, Delort A.-M. Biodegradation of polyethylene films with pro-oxidant additives. These results confirmed that the additive was necessary to obtain controlled degradation in the composites and the composites attained not only superior mechanical, thermal and Theological performance by the addition of additive, but also resulted in controlled photo-oxidation, which subsequently facilitates the biodegradation of the polymer.

Introduction. To reduce polymer waste and environmental pollution, the use of degradable polymers has been often stressed, and it is further beneficial, if the degradation can be tuned in accordance with needed service life [1, 2].High molecular weight and hydrophobicity of the commercial polyolefins hinder their direct biodegradation by microbes.

(vii) introducing into the post-reaction zone(s), one or more thermal and/or photo-oxidation stabilizers in an amount sufficient to substantially prevent the thermal and photo-oxidation of the polymer.

with the proviso that, in said process, the polymer is not in a molten state. 2.OXO-biodegradation is biodegradation as defined by the European Committee for Standardization (CEN) in CEN/TR –, as "degradation resulting from oxidative and cell-mediated phenomena, either simultaneously or successively".

This degradation is sometimes termed "OXO-degradable", but this latter term describes only the first or oxidative phase of degradation and should not be used for. 24, articles and books. Periodicals Literature. has a low basicity and is shown to be a highly effective UV stabilizer that does not react with other polyolefin additives.

Reaction of this polymer-bound hindered amine with a polymer peroxy radical produces a dialkyl peroxide and regenerates the active nitroxyl radical. A key.