On the mechanism of structural stabilization of isotactic polypropylene

Rapoport, Natalya; Miller, V.B.

doi:10.1016/0032-3950(77)90189-7

Cited by 12 publications

(13 citation statements)

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“…It has been shown that the physical structure of PP fibers originated in high‐speed spinning is different from those produced at low spinning speed . Researchers have determined that the effect of physical structure on photodegradation as well as the effects of orientation and drawing on photodegradation are indefinite . In the present work, we have examined the consequences of drawing on the photodegradation of PP filaments produced by relatively high‐speed spinning.…”

Section: Introductionmentioning

confidence: 96%

“…The mechanism of photodegradation of polypropylene (PP) is very well documented . To prevent thermal and photodegradation, different stabilizers are commonly added to commercial products .…”

Section: Introductionmentioning

confidence: 99%

“…To prevent thermal and photodegradation, different stabilizers are commonly added to commercial products . The photodegradation is due to free radical content in PP . These radicals form during the manufacturing process as the result of bond rupture and polymerization impurities .…”

Section: Introductionmentioning

confidence: 99%

“…The effects of physical structure on photodegradation of PP have been controversial in the literature . It has been reported that the rate of the degradation increases with the increase of orientation and the crystalline fraction.…”

Section: Introductionmentioning

confidence: 99%

“…In investigations, it was believed that elongated macromolecular conformation in an ordered sample has a longer oxidation induction period than an isotropic sample . Elongation at the break of a highly‐oriented PP monofilament was much less affected by photo‐oxidation than undrawn or partially oriented filaments .…”

Section: Introductionmentioning

confidence: 99%

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Photodegradation of partially oriented and drawn polypropylene filaments

Mahmoodabadi

Kish

Aslanzadeh

2017

J of Applied Polymer Sci

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The effects of fiber structure on the process of photodegradation are controversial in the field. We tested polypropylene fibers of various form for their effects on photodegradation. Fiber grade polypropylene granules were spun into partially oriented multifilament yarns at a spinning speed of 2000 m min−1. The yarns were drawn using a draw‐twist unit. Yarns were exposed to ultra‐violet radiations in a covered open air chamber for different periods of time under two different sources of emissions (UVA; λ > 300 nm and UVC; λ = 254 nm). The samples were examined by Fourier transform infrared spectroscopy, mechanical testing, differential scanning calorimetry, microscopy, and density measurements. In photodegradation process, the drawn filaments had a longer induction time than undrawn ones. The mechanical properties of the undrawn yarns deteriorate faster than the drawn yarns. During the early periods of degradation helical content increases considerably, while the density fluctuates and increases. The degradation rate under UVC radiation was faster than under UVA radiation because of the higher energy of the UVC radiation. The upper photostability of the drawn yarns compared to the undrawn ones was due to the higher crystalline fraction and greater molecular orientation in the drawn yarn. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45716.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%