Handbook of Polymer Degradation

Hamid, Syed

doi:10.1201/9781482270181

Cited by 172 publications

(46 citation statements)

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“…The thermo-oxidative degradation of isotactic polypropylene and recycled polypropylene stabilized with lignin was studied measuring the melt volume rate of the extruded samples after multiple extrusions at 2008C by method described in literature. 8,24 MVR values obtained after multiple extrusions of both polypropylene samples containing lignin in concentration from 0.5 to 10 wt % are shown in Table III and 4. From these results it is obvious that MVR of both nonstabilized polypropylene increased rapidly with the number of extrusions, which indicate the degradation of polypropylene matrices due to the chain scission similarly as described in literature.…”

Section: Melt Propertiesmentioning

confidence: 99%

“…[1][2][3][4][5][6][7] From the view point of the various principles of degradation processes antioxidants are divided into a few series such as scavengers of free radicals, hydroperoxide decompositors, metal deactivators, antiozonants, photoantioxidants, photostabilizers and heat stabilizers. 8,9 Generally, free radical character of degradation is considered for very frequent mode. Therefore major interest is devoted just to free radical scavenging additives, especially phenolic and amine antioxidants.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore major interest is devoted just to free radical scavenging additives, especially phenolic and amine antioxidants. 8 Nowadays, new criteria for chemicals are required such as environmental friendliness, nontoxicity, economical accessibility, and desirable waste disposal. According to CMAI (Chemical Market Associates) analysis polyolefins represent the largest segment of the global thermoplastic business, which was 92 million metric tons for the year 2004.…”

Section: Introductionmentioning

confidence: 99%

“…It is known that even though manufacturing of plastic materials was stabilized at first, their reprocessing for use achieving required properties required stabilization. 8,11 On the other hand, the most of synthetic stabilizers decelerates the decomposition of the plastic waste. Using a polymeric natural antioxidant, which is nontoxic and compatible with the base polymer and could affect the degradation of the polyolefin matrix, can solve this problem.…”

Section: Introductionmentioning

confidence: 99%

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Radical scavenging capacity of lignin and its effect on processing stabilization of virgin and recycled polypropylene

Gregorová

Košíková

Staško

2007

J of Applied Polymer Sci

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ABSTRACT:The radical scavenging capacity of lignin was determined using spectrophotometric method by means of scavenging of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH ) and compared with that of synthetic antioxidant Irganox 1010. Lignin reacted progressively with the DPPH reaching a steady state in 6 h, showing high antiradical activity with a stochiometry of 5.5 reduced DPPH molecules. Irganox 1010 showed lower antiradical activity reaching a steady state with DPPH after 13 h. Moreover, stabilization efficiency of lignin has been investigated in virgin and recycled polypropylene. The stabilization effect of lignin was evaluated by melt volume rate (MVR). The efficiency of lignin as processing stabilizer in both series polypropylene samples was compared with that of synthetic antioxidant Irganox 1010. The presence and behavior of free radicals in the lignin/polypropylene composites formed during processing was determined by electron paramagnetic resonance (EPR). It was observed that used lignin sample could stabilise both virgin and recycled polypropylene.

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Section: Melt Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radical scavenging capacity of lignin and its effect on processing stabilization of virgin and recycled polypropylene

Gregorová

Košíková

Staško

2007

J of Applied Polymer Sci

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“…Moreover, when more than two components are mixed or copolymerized, different components tend to separate, and this phenomenon is called “phase separation.”14 From the aspect of surface energy, the tendency to lower surface energy is stronger for the block copolymers because the contribution of the hydrophobic component to surface energy is larger in block copolymers than in random copolymers 15. It is therefore thought that the possibility of phase separation would enhance as the number of amide group increases and thus the surface energy decreases accordingly.…”

Section: Resultsmentioning

confidence: 99%

Effect of hydrophilicity on the biodegradability of polyesteramides

Park

Kim

Yoo

et al. 2003

J of Applied Polymer Sci

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ABSTRACT:The effect of surface hydrophilicity was induced from the amide units in the polyesteramide. The surface energies and compositions of the polyesteramides were studied by employing contact angle and interfacial tension measurements and ESCA analysis. Biodegradability was evaluated form various methods including activated sludge test, enzyme hydrolysis, and soil burial test, which determine the amount of evolved CO 2 , weight loss, and TOC values, respectively. It was found that the introduction of amide groups to the aliphatic polyester improved the biodegradability, although the increase of biodegradation rate was not directly proportional to the amide content. The biodegradability of aliphatic polyesters increased with the addition of amide functionality. Therefore, it can be concluded that the addition of appropriate contents of hydrophile enhanced the biodegradability of aliphatic polyesters as well as their physical properties. Also, the experimental results revealed the relation between hydrophilicity and biodegradability of polyesteramides.

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Ultraviolet-induced degradation of Ziegler-Natta and metallocene catalyzed polyethylenes

Hamid

2000

J. Appl. Polym. Sci.

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The metallocene revolution has aroused a storm of interest and associated questions regarding the performance and durability of polyolefins. This new technology has impacted the additives used to stabilize and process polymers. In this work, Ziegler‐Natta and metallocene polyethylene (PE) samples were exposed to natural weather conditions under high doses of ultraviolet radiation, high temperature, and increased humidity. Weather‐induced degradation of the two sets of PEs was studied using gel permeation chromatography, mechanical properties testing, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The gel permeation chromatography analysis indicated the change in molecular weight distribution and molecular weights of metallocene PE to be more stable than conventional Ziegler‐Natta PE. The tensile properties of metallocene PE are known to have higher values than Ziegler‐Natta PE. The former exhibited a lower drop rate in mechanical properties when exposed to natural weather. Formations of nonvolatile carbonyl oxidation products, which absorb in the infrared region with a maximum absorbance level at 1742 cm−1 were determined. This indicated a higher rate of photo‐oxidative and thermal degradation of Ziegler‐Natta PE as compared with metallocene PE. The ultraviolet stabilization of metallocene PE may require different doses and a new kind of stabilizer system that can impart a longer useful lifetime and are cost effective for PE used for outdoor purposes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1591–1596, 2000

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Handbook of Polymer Degradation

Cited by 172 publications

References 0 publications

Radical scavenging capacity of lignin and its effect on processing stabilization of virgin and recycled polypropylene

Radical scavenging capacity of lignin and its effect on processing stabilization of virgin and recycled polypropylene

Effect of hydrophilicity on the biodegradability of polyesteramides

Ultraviolet-induced degradation of Ziegler-Natta and metallocene catalyzed polyethylenes

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