Advanced Test Setup for Accelerated Aging of Plastics by Visible LED Radiation

Hemmerich, M.; Meyer, Jörg; Walther, Frank

doi:10.3390/ma13194261

Cited by 8 publications

(4 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…blue light), PLA is proven to be highly resistant against photodegradation 38 . Due to the prevalence of light emitting diodes (LED) in lighting technology, this is of great interest, as these light sources emit comparably high amounts of blue light and possess extremely long lifetimes (compared to conventional light sources like incandescent or discharge lamps) [87][88][89][90][91][92] .…”

Section: Optical Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of Polylactide as Optical Material

Kesting

Meyer

Seide

2023

Preprint

View full text Add to dashboard Cite

Due to environmental concerns, interest in bioplastics is rising. For optical applications, materials have to meet high requirements. Polylactide (PLA), a known bioplastic, is already applied in high tech applications such as medicine. The material shows favorable optical properties and excellent resistance against photodegradation. However, the material turns hazy due to crystallization when exposed to temperatures above 55-60 °C. This renders it useless for optical applications. Clouding might be avoided by influencing PLA’s crystallization behavior. In this critical review the broad use of PLA is discussed. It is also shown, that currently no material is commercially available that meets all requirements set while being biodegradable and exclusively based on renewable feedstocks. Finally, an overview of the current state in research is provided, considering PLA-based materials with adapted crystallization behavior under the aspect of transparency. At last, recommendations for the goal of achieving highly sustainable PLA-based optical components are given.

show abstract

Section: Optical Propertiesmentioning

confidence: 99%

“…As PLA shows excellent optical properties in its glassy state, as well as high resistance to radiation induced aging, its use for optical applications seems consequential 38,91 . However, close to its Tg PLA crystallizes and turns hazy 78,79 .…”

Section: Pla For Optical Applicationsmentioning

confidence: 99%

Assessment of Polylactide as Optical Material

Kesting

Meyer

Seide

2023

Preprint

View full text Add to dashboard Cite

show abstract

“…temperature and radiation separated. On this topic, Baltscheit et al [16] and Hemmerich et al [17,18] report on the simulation of the aging behavior of transparent materials under accelerated artificial conditions with prioritizing effects under blue light radiation with shortwavelength and high energy.…”

Section: Thermal and Light-induced Degradation Mechanisms In Polymerimentioning

confidence: 99%

Impact of Solar Radiation on Chemical Structure and Micromechanical Properties of Cellulose-Based Humidity-Sensing Material Cottonid

Scholz

Langhansl

Hemmerich

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Renewable and environmentally responsive materials are an energy- and resource-efficient approach in terms of civil engineering applications, e.g. as so-called smart building skins. To evaluate the influence of different environmental stimuli, like humidity or solar radiation, on the long-term actuation behavior and mechanical robustness of these materials, it is necessary to precisely characterize the magnitude and range of stimuli that trigger reactions and the resulting kinetics of a material, respectively, with suitable testing equipment and techniques. The overall aim is to correlate actuation potential and mechanical properties with process- or application-oriented parameters in terms of demand-oriented stimuli-responsive element production. In this study, the impact of solar radiation as environmental trigger on the cellulose-based humidity-sensing material Cottonid, which is a promising candidate for adaptive and autonomously moving elements, was investigated. For simulating solar radiation in the lab, specimens were exposed to short-wavelength blue light as well as a standardized artificial solar irradiation (CIE Solar ID65) in long-term aging experiments. Photodegradation behavior was analyzed by Fourier-transform infrared as well as electron paramagnetic resonance spectroscopy measurements to assess changes in Cottonid’s chemical composition. Subsequently, changes in micromechanical properties on the respective specimens’ surface were investigated with roughness measurements and ultra-micro-hardness tests to characterize variations in stiffness distribution in comparison to the initial condition. Also, thermal effects during long-term aging were considered and contrasted to pure radiative effects. In addition, to investigate the influence of process-related parameters on Cottonid’s humidity-driven deformation behavior, actuation tests were performed in an alternating climate chamber using a customized specimen holder, instrumented with digital image correlation (DIC). DIC was used for precise actuation strain measurements to comparatively evaluate different influences on the material’s sorption behavior. The infrared absorbance spectra of different aging states of irradiated Cottonid show decreased absorption at 2,900 cm-1, i.e. the spectral region of C - H stretching vibrations, and increased absorption at 1,800-1,700 cm-1, i.e. the spectral region of C = O stretching vibrations, with respect to unaged samples and therefore indicate oxidative stress on the surface. These findings differ under pure thermal loads. EPR spectra could corroborate these findings as radicals were detected, which were attributed to oxidation processes. Instrumented actuation experiments revealed the influence of processing-related parameters on the sorption behavior of the tested and structurally optimized Cottonid variant. Experimental data supports the definition of an optimal process window for stimuli-responsive element production. Based on these results, tailor-made functional materials shall be generated in the future where stimuli-responsiveness can be adjusted through the manufacturing process.

show abstract

“…Commercial testing equipment has recently become available to expose polymer samples to high-intensity blue light LEDs in the 400-500 nm domain and used to study the yellowing of polycarbonate 6 . A newly developed test setup to age optical plastics by visible radiation (450 nm) has been recently described and applied to the photodegradation of polycarbonate 7 . Ageing experiments were performed over a period of 5000 h to evaluate the stability of PLA under the influence of extreme levels of optical LED radiation (λ max = 450 nm) 8 .…”

Section: Introductionmentioning

confidence: 99%