Uncharted Territory in the Use of PVC Products: Photo Effects

Schiller, Michael

doi:10.3139/9781569905449.004

Cited by 1 publication

(18 citation statements)

References 23 publications

(28 reference statements)

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“…As PVC is only transparent at wavelengths of more than 250 nm, the initiation is likely due to chromophores found in the PVC resin. However, polyenes rapidly become the main absorbing species among chromophores due to their high extinction coefficient [ 18 ]. Only polyene sequences with more than four double bonds can interact with sunlight at the ground, as the atmosphere screens wavelengths shorter than about 290 nm ( Table 1 , [ 19 ]).…”

Section: Introductionmentioning

confidence: 99%

“…When photons hit the PVC item, two kinds of reactions take place. The first generates conjugated polyene sequences and HCl [ 18 ]. The chromophores absorb the photons, and one of the non-radiative pathways releases Cl radicals, starting the zip-elimination quickly before oxygen can become involved [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…The first generates conjugated polyene sequences and HCl [ 18 ]. The chromophores absorb the photons, and one of the non-radiative pathways releases Cl radicals, starting the zip-elimination quickly before oxygen can become involved [ 18 ]. This yields conjugate-polyene sequences and their crosslinking.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 outlines the overall first stage of the PVC photodegradation and photo-oxidation mechanism leading to chain scission, polyene sequence formation, and crosslinking, depending on the exposure conditions [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…As is evident from the calculated quantum yields ( Table 2 ), the presence of oxygen also enhances chain scission and triggers the generation of peroxides and ketones [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

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Surface Chalking upon Weathering of Dark-Colored PVC Articles and Relevant Stabilizers

Gardi,

Giannone,

Sarti

et al. 2024

Polymers

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PVC items (38% carbon atoms w/w) are environmentally friendly as, unlike polyolefins (86% carbon atoms w/w), they are mainly based on chlorine, one of the most abundant elements on Earth and, so, less based on fossil resources. However, in the eco-design context, articles’ durability plays a crucial role, contributing to the enhancement of their sustainability. In this framework, the research on additives capable of increasing the weatherability of outdoor articles is essential. The theory section of the paper reviews the mechanisms of weathering that lead to PVC degradation and undermine the durability of items such as window frames or roller shutters. The weathering of PVC items is a complex phenomenon, involving photo-chemical and secondary chemical reactions, that yields the formation of conjugated polyene sequences underskin in the absence of oxygen and carbonyls in the surface. Here, the chain scission of the polymer backbone occurs, bringing about the disintegration of the surface of the item and causing the typical discoloration called chalking, especially evident in dark-colored articles. In the experimental section of the paper, the effect of different acid scavengers on item weathering has been studied using a natural outdoor and two accelerated exposures with xenon-arc and Q-UV testing devices. Results confirm that some acid scavengers are efficient in preventing chalking, but some are ineffective or even detrimental. Thus, the PVC formulations of durable articles upon weathering still depend on a complex choice of the appropriate ingredients, and several outdoor and indoor accelerated-weathering tests are needed to predict the articles’ lifetime.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…As is evident from the calculated quantum yields ( Table 2 ), the presence of oxygen also enhances chain scission and triggers the generation of peroxides and ketones [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

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