Ultraviolet Light Stabilizers Research Articles

The Effect of Ultraviolet Light Stabilizers on Color Stability, Melt Properties and Tensile Properties of Mixed Waste Plastics Blends

Plastic waste disposal is among the most challenging problems of the current era. Therefore, new methods and applications for the utilization of waste plastics are increasingly needed. To find them, it is essential to research and develop the material properties of recycled plastics. The effect of different ultraviolet light (UV) stabilizers on the color stability, melt properties and tensile properties of mixed waste plastics blends was studied in this paper. The mixed waste plastics collected from two different waste sources were prepared as specimens by injection molding, and studied with two different types and loading amounts of UV stabilizers. UV absorbers (UVAs) and hindered amine light stabilizers (HALS) were used as UV stabilizers. A specimen produced without the addition of a UV stabilizer was used as a reference specimen of both the blends. After the accelerated weathering, the addition of a UVA provided an improved, smaller change in color than the addition of HALS. Among the tensile properties, the addition of UV stabilizers clearly improved the tensile strength and tensile modulus for almost all the studied specimens. Additionally, the melt properties of both the studied plastic blends were found to be increased by the addition of UV stabilizers.

Are We Underestimating Anthropogenic Microfiber Pollution? A Critical Review of Occurrence, Methods, and Reporting

Anthropogenic microfibers, a ubiquitous environmental contaminant, can be categorized as synthetic, semisynthetic, or natural according to material of origin and production process. Although natural fibers, such as cotton and wool, originated from natural sources, they often contain chemical additives, including colorants (e.g., dyes, pigments) and finishes (e.g., flame retardants, antimicrobial agents, ultraviolet light stabilizers). These additives are applied to textiles during production to give textiles desired properties like enhanced durability. Anthropogenically modified "natural" and semisynthetic fibers are sufficiently persistent to undergo long-range transport and accumulate in the environment, where they are ingested by biota. Although most research and communication on microfibers have focused on the sources, pathways, and effects of synthetic fibers in the environment, natural and semisynthetic fibers warrant further investigation because of their abundance. Because of the challenges in enumerating and identifying natural and semisynthetic fibers in environmental samples and the focus on microplastic or synthetic fibers, reports of anthropogenic microfibers in the environment may be underestimated. In this critical review, we 1) report that natural and semisynthetic microfibers are abundant, 2) highlight that some environmental compartments are relatively understudied in the microfiber literature, and 3) report which methods are suitable to enumerate and characterize the full suite of anthropogenic microfibers. We then use these findings to 4) recommend best practices to assess the abundance of anthropogenic microfibers in the environment, including natural and semisynthetic fibers. By focusing exclusively on synthetic fibers in the environment, we are neglecting a major component of anthropogenic microfiber pollution. Environ Toxicol Chem 2022;41:822-837. © 2021 SETAC.

Business Roundup

BUSINESS Business Roundup ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2017, 95 (37), p 13September 18, 2017Cite this:C&EN 95, 37, 13AbstractSolvay will start producing polyetherketoneketone (PEKK) at its site in Augusta, Ga., next year to meet growing demand from the aerospace industry. The firm already makes polyetheretherketone (PEEK) and other high-end polymers at the facility. Clariant has formed a joint venture with Tiangang Auxiliary to make ultraviolet light stabilizers in China’s Hebei province. A multi-million-dollar facility, to come on-line in 2019, will meet demand for the stabilizers from China’s textile and auto industries. Bayer has sold 19 million shares in Covestro, its former materials and plastics business, for $1.4 billion. The sell-off reduces Bayer’s stake in Covestro by 9.4% to 31.5%. MycoTechnology, a food technology start-up based in Aurora, Colo., has raised $35 million from undisclosed investors in a second round of funding. The company’s organic, powdered mushroom mycelium product is used to block bitter flavors of foods, beverages, and natural noncaloric sweeteners. Oxis Energy, a British lithium-sulfur battery materialsView: PDF | Full Text HTML

Photostabilizing efficiency of ultraviolet light stabilizers for rigid poly(vinyl chloride) against photo‐oxidation

AbstractThe photostabilizing efficiency of different light stabilizers in poly(vinyl chloride) (PVC) was investigated by discoloration, ultraviolet (UV) reflection experiment, Fourier transform infrared spectrum (FTIR), and scanning electron microscopy (SEM). The results show that the addition of light stabilizers can slow down discoloration of PVC. The UV reflection results verify that this change is due to the distribution of light stabilizers on irradiated surfaces, which can absorb (such as organic stabilizers) or reflect (such as titanium dioxide) UV light differently. The order of stabilizers that can slower the extent of discoloration is titanium dioxide (TiO2) > Tinuvin 234 (U4) > XT 833 (H2), U4 > Tinuvin 531 (U3) > Chimassorb 944 (H1), phenyl salicylate (U1). FTIR results show that the carbonyl group of pure PVC, TiO2, and H1‐doped PVC increases significantly, indicating that the photo‐oxidation reactions of these irradiated samples are relatively serious. The SEM results show that the surface damages of PVC doped with U2, U4, and H2 are somehow slighter, with only small holes or cavities on the surface, whereas the surfaces of pure PVC and H1‐doped PVC are full of big and deep holes and some holes or cavities of 10 μm are detected. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Determination of polyolefin additives by reversed-phase liquid chromatography

Abstract This article examines the contribution of liquid chromatography to the study of polyolefin additives commonly used to obtain improved environmental resistance (antioxidants, ultraviolet light stabilizers, antistatics, and so on) and appearance enhancements (e.g. colorants). Several reversed-phase liquid chromatographic methods are summarized, and a detailed description of different detectors is provided. In addition, ways of applying these methods to analyse food contact materials and plastic toys are emphasized. Finally, the potential use of these methods is addressed which complies with European health safety regulations.

Assessing direct analysis in real-time-mass spectrometry (DART-MS) for the rapid identification of additives in food packaging

The ambient ionization technique direct analysis in real time (DART) was characterized and evaluated for the screening of food packaging for the presence of packaging additives using a benchtop mass spectrometer (MS). Approximate optimum conditions were determined for 13 common food-packaging additives, including plasticizers, anti-oxidants, colorants, grease-proofers, and ultraviolet light stabilizers. Method sensitivity and linearity were evaluated using solutions and characterized polymer samples. Additionally, the response of a model additive (di-ethyl-hexyl-phthalate) was examined across a range of sample positions, DART, and MS conditions (temperature, voltage and helium flow). Under optimal conditions, molecular ion (M+H+) was the major ion for most additives. Additive responses were highly sensitive to sample and DART source orientation, as well as to DART flow rates, temperatures, and MS inlet voltages, respectively. DART-MS response was neither consistently linear nor quantitative in this setting, and sensitivity varied by additive. All additives studied were rapidly identified in multiple food-packaging materials by DART-MS/MS, suggesting this technique can be used to screen food packaging rapidly. However, method sensitivity and quantitation requires further study and improvement.

A low-cost intervention for cleaner drinking water in Karachi, Pakistan

Objective: To pilot test an inexpensive, home-based water decontamination and storage system in a low-income neighborhood of Karachi. Methods: Fifty households received a 20-L plastic water storage vessel with a high-quality spout and a regular supply of diluted hypochlorite solution. Twenty-five control households were recruited. Water samples were collected at baseline and during unannounced follow-up visits 1, 3, 6, and 10 weeks later. Results: Baseline drinking water samples among intervention households were contaminated with a mean 9397 colony-forming units (cfu)/100 mL of thermotolerant coliforms compared with a mean 10,990 cfu/100 mL from controls. After intervention the mean concentration of thermotolerant coliforms decreased by 99.8% among the intervention households compared with an 8% reduction among controls. Two years after vessel distribution, 34 (68%) of the families were still using the vessel. Thirteen of the households had stopped using their vessel because it had broken after more than 6 months of use, a pattern most consistent with ultraviolet radiation-induced degradation of the plastic. Conclusions: In a highly contaminated environment, a specifically designed water storage container and in-home water chlorination was acceptable and markedly improved water quality. Where plastic water vessels will be exposed to substantial sunlight, ultraviolet light stabilizers should be incorporated into the plastic.

Supercritical fluid chromatography and extraction in surface coatings analysis — review of representative applicationst

Supercritical fluid chromatography and extraction are investigated as techniques for analyzing surface coatings and many of the raw materials that go into their manufacture. Reactive oligomeric mixtures such as radiation curing coatings, polyisocyanate curing agents, and surface active agents are separated using capillary SFC with CO 2. Polar oligomeric mixtures such as epoxy, vinyl, and phenol-formaldehyde resins can be separated with modified mobile phases on packed columns. Optimization of chromatographic separation through pressure composition and flow programming is highlighted. On-line supercritical fluid extraction-capillary supercritical fluid chromatography is used to extract and separate ultraviolet light stabilizers incorporated into a cured automotive clear coating. Optimization of conditions for the extraction of polymers is discussed.

Identification of antioxidant and ultraviolet light stabilizing additives in plastics by liquid chromatography/mass spectrometry

The information obtained by absorbance detection when coupled with liquid chromatography is usually not specific enough to allow the qualitative ldentHication of compounds present in complex samples with any degree of certainty. With the use of mass spectrometric detection (LCIMS), characteristic mass spectral data can be obtained whkh greatly aid in eiucklating the Mentlty of unknown compounds. In this paper, ma88 spectrometric detection Is used in series with absorbance detectian to Identify or characterize antioxidants and UV light stabilizing addltives in plastic materlaIs which were separated by liquid chromatography. The two detectors were operated in series without any significant loss of chromatographic resolution. Nanogram quantities of additives could be detected by LCIMS. Lower detection limits were achieved by reconstructing mass chromatograms for selected ions. These studies demonstrate the feasibility of using LC/MS to Characterize additives In plastic materials. Chemical additives are frequently used to enhance the useful lifetime of polymeric materials. Antioxidants and ultraviolet (UV) light stabilizers are added to minimize potential polymer degradation by oxidative (1-3) or photochemical processes (3,4). Identification and quantitation of these compounds are necessary for polymer degradation studies and for quality-assurance tests. Due to the low concentration of additives in the polymer matrix (typically less than l%), a sensitive method of analysis must be employed. The high molecular weight and polarity of many antioxidants and UV light stabilizers often precludes the use of gas chromatography. High-performance liquid chromatography has been used to effectively separate these compounds (2,5-9). Identification of compounds present in real samples is based on comparison of the peaks' retention times or capacity factors (k') with those of known standards. Identification by this method not only is tedious and timeconsuming but also requires one to have all of the suspected compounds on hand so that tentative identifications can be made. Even so, erroneous identifications can often be made due to the relatively poor separating ability of HPLC (compared to capillary gas chromatography) and the chemical similarity of many compounds. The combination of liquid chromatography with mass spectrometric detection (LC/MS) can circumvent many of these problems. Many compounds, such as distearyl thiodipropionate (DSTDP), which do not absorb ultraviolet light at standard UV detection wavelengths (254 nm and 280 nm) will not be detected with a conventional UV absorbance detector. The mass spectrometer is a more universal detector. The information yielded by LC/MS greatly aids in elucidating the structure of unknown compounds. In our laboratory, ultraviolet absorbance and mass spectrometric detection were used in series to provide unique qualitative and quantitative information on plastic additives separated by liquid chromatography. Additional peak 0003-2700/85/0357-0672$01.50/0 broadening introduced by this detection arrangement was minimal. The system was used to characterize the additives present in several polymeric samples.

Glass transitions of poly(bisphenol‐A carbonate)/ultraviolet light stabilizer blends by DSC and TOA

AbstractGlass transition temperatures are reported for poly(bisphenol‐A‐carbonate) plasticized by 0–12 wt % of the ultraviolet light stabilizers 2‐hydroxy‐4‐methoxy‐benzophenone, 2‐hydroxy‐4‐n‐octooxy‐benzophenone, and 2‐hydroxy‐4‐dodecyloxy‐benzophenone. Differential scanning calorimetry (DSC) and thermooptical analysis (TOA) were employed. The glass transition temperatures increased somewhat with shelf time for the room temperature air‐dried 1‐mil films drawn from methylene chloride solutions. A Bierbaum scratch hardness of 8.8 kg·mm−2 was observed for a 10‐mil poly(bisphenol‐A carbonate) film. The effect of load applied to the diamond point (Bierbaum scratch technique) on the shape of TOA transmitted light intensity vs. temperature curves for the resultant scratches was examined. Although the curve shapes are greatly affected, the characteristic TOA temperatures derived therefrom remain essentially unchanged. The glass transition regions are not quite as broad for these polymer/plasticizer blends as they are for compatible polymer/polymer blends. TTOA, the temperature at which birefringence disappears in the scratched films, is found identical to Tf (DSC), the temperature at which the specific heat transition is completed.

Accelerated Outdoor Exposure Testing in Evaluation of Ultraviolet Light Stabilizers for Plastics

Accelerated Outdoor Exposure Testing in Evaluation of Ultraviolet Light Stabilizers for Plastics