Effects of Molecular Weight on Thermal Degradation of Poly(α-methyl styrene) in Nitrogen

Ye, Lina; Liu, Meifang; Huang, Yawen; Zhang, Zhanwen; Yang, Junxiao

doi:10.1080/00222348.2015.1094645

Cited by 10 publications

(5 citation statements)

References 28 publications

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“…Another interesting result is that, regardless the dipolar entity, those polymers prepared through RAFT polymerization show higher thermal stability. This result correlates well with previous works reporting a delay in the thermal decomposition with the decrease of molecular weight in polymers [41][42][43].…”

Section: Thermal Characterizationsupporting

confidence: 93%

Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities

et al. 2021

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In this work, polymethacrylates containing sulfonyl and nitrile functional groups were successfully prepared by conventional radical polymerization and reversible addition-fragmentation chain-transfer polymerization (RAFT). The thermal and dielectric properties were evaluated, for the first time, considering differences in their molecular weights and dispersity values. Variations of the aforementioned properties do not seem to substantially affect the polarized state of these materials, defined in terms of the parameters ε’r, ε”r and tan (δ). However, the earlier appearance of dissipative phenomena on the temperature scale for materials with lower molecular weights or broader molecular weight distributions, narrows the range of working temperatures in which they exhibit high dielectric constants along with low loss factors. Notwithstanding the above, as all polymers showed, at room temperature, ε’r values above 9 and loss factors below 0.02, presenting higher dielectric performance when compared to conventional polymer materials, they could be considered as good candidates for energy storage applications.

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Section: Thermal Characterizationsupporting

confidence: 93%

Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities

et al. 2021

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“…Elongation hovered around 4% for naturally weathered samples and around 10% for artificially aged samples; it is necessary to consider that those values were shallow and could therefore be assumed as a minimum for irradiated samples. A faster decrease in elongation for naturally weathered samples could be resulted from temperature fluctuations and rain washing of the sample surface and, thus, accelerated the degradation process [21]. The fact that chemi-crystallization and chain shortening generally led to decreased ductility was consistent with findings in this work [44].…”

Section: Mechanical Propertiessupporting

confidence: 85%

“…Material properties play a significant role, among them thickness of material [20], polymer crystallinity [21], molecular weight [22,23], or polymer composition [24,25]. The formation of peroxide substances in the main chain of a polymer is encountered as the primary step of oxidative degradation.…”

Section: Introductionmentioning

confidence: 99%

The degradation of poly(1-butene) extrudates subjected to artificial and natural aging

Zenzingerova,

Kudlacek,

Benicek

et al. 2024

Iran Polym J

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In this work, we examined the degradation behavior of isotactic poly(1-butene) (PB-1) under artificial aging and natural weathering conditions. PB-1 samples underwent accelerated aging through UV irradiation and natural weathering. Chemical and structural changes in the degraded samples were characterized using Fourier-transform infrared–attenuated total reflectance (FTIR–ATR) spectroscopy, surface analysis, and wide-angle X-ray scattering (WAXS). The mechanical properties were evaluated via tensile testing. FTIR–ATR analysis revealed the presence of carbonyl groups in the degraded samples, indicating oxidative degradation. Surface observations employing scanning electron microscopy (SEM) revealed the formation of surface cracks in both samples, with differing crack initiation mechanisms. The two aging methods affected the mechanical properties of the samples: artificial aging induced a gradual reduction in both tensile modulus and strength, whereas natural weathering engendered a marginal increment in modulus alongside diminished strength. Additionally, elongation-at-break value witnessed a marked decrease in both sample sets during the preliminary stages of degradation. This work employed accelerated time equivalent, obtained by juxtaposition of the values of carbonyl index during both artificial aging and natural weathering and their interpolation to determine the degradation rate and adequately to correlate the final properties of the aged PB-1. It was observed that surface morphology and mechanical attributes of degraded samples were subject to additional influences such as temperature, humidity, and precipitation during natural weathering. This research work provided significant insights into PB-1 degradation mechanisms and effect of different aging conditions on its performance. Graphical abstract

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“…It might be because that the treatments removed some weak parts of the materials, which were easy to degrade. Polymers with lower M w often have lower thermal degradation temperatures, but it has also been reported that some polymers could have an elevated degradation temperature with lower M w in some cases [ 26 ]. For Gown #1, the results were mixed.…”

Section: Resultsmentioning

confidence: 99%

Effects of chemical and autoclave sterilization treatments on medical personal protective equipment made of nonwoven polypropylene fibers for recycling

et al. 2022

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Medical personal protective equipment (PPE) made from nonwoven thermoplastic fibers has been intensively used, resulting in a large amount of biohazardous waste. Sterilization is indispensable before recycling medical waste. The aim of this work is to evaluate the effects of the decontamination treatments and help properly recycle the PPE materials. The study investigated the effects of three disinfection treatments (NaClO, H 2 O 2 , and autoclave) on chemical composition, molecular weight, thermal properties, crystallinity, crystallization kinetics, and mechanical tension of three types of PPE (Gown #1, Gown #2, and Wrap) made of isotactic polypropylene fibers. The chemical compositions of the materials were not evidently affected by any of the treatments. However, the M w of the polymers decreased about 2-7% after the treatments, although the changes were not statistically significant. The treatments barely affected the melting and crystallization temperatures and the maximum force at break, but they tended to elevate the thermal degradation temperatures. Although the treatments did not notably influence the crystallinities, crystallization rates and crystal growths were altered based on the Avrami model regression. Since the detected changes would not significantly affect polymer processing, the treated materials were suitable for recycling. Meanwhile, evident differences in the three types of raw materials were recorded. Their initial properties fluctuated notably, and they often behaved differently during the treatments, which could affect recycling operation. Recyclers should test and sort the raw materials to assure product quality. The results in this study provide fundamental data for recycling medical PPE to reduce its environmental footprint.

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Effects of Molecular Weight on Thermal Degradation of Poly(α-methyl styrene) in Nitrogen

Cited by 10 publications

References 28 publications

Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities

Molecular Weight Enables Fine-Tuning the Thermal and Dielectric Properties of Polymethacrylates Bearing Sulfonyl and Nitrile Groups as Dipolar Entities

The degradation of poly(1-butene) extrudates subjected to artificial and natural aging

Effects of chemical and autoclave sterilization treatments on medical personal protective equipment made of nonwoven polypropylene fibers for recycling

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