Degradation Of Films Research Articles

Hydrogen Embrittlement Susceptibility of Ti-6Al-4V Alloys Fabricated by Electron Beam Melting in Simulated Deep-Sea Environment

The hydrogen embrittlement susceptibility of electron beam melted Ti-6Al-4V alloy (ET) was compared with that of conventional wrought alloy (WT). Hydrogen permeation, electrochemical, and slow strain rate tensile tests as well as surface observation were conducted under a simulated sea environment. The results show that the hydrogen embrittlement susceptibility of ET is lower than that of WT, which can be attributed to the intense texture of ET with a smaller specific surface area of grain boundary, preventing hydrogen permeation. Moreover, with increasing depth of the ocean, the hydrogen embrittlement susceptibility of both ET and WT TC4 alloys increases considerably. This reduced hydrogen embrittlement resistance can be attributed to the degradation of the passivation film, accelerating the permeation flux of hydrogen.

Effects of crop residue incorporation on soil‐biodegradable mulch film degradation in a broccoli‐sorghum rotation system

AbstractSoil‐biodegradable mulch films are designed to be incorporated into the soil at the end of the crop cycle, to be degraded by soil microorganisms. Despite growing scientific interest, open‐field studies about the fate of these mulch films in soils are rare, with most research conducted in laboratories. We performed an open‐field trial to evaluate the effects of soil incorporation of both a combining a commercial soil‐biodegradable mulch film and broccoli and sorghum crop residues over two cropping seasons. The mulch film was sampled after broccoli harvesting and placed inside mesh bags that were buried horizontally or vertically at different depths. Film biodegradation was assessed by direct (CO2 emissions) and indirect indicators (film mass and area loss). Three experiments were conducted to evaluate (a) how incorporating crop residues affect mulch film degradation; (b) temporal changes of soil microbial activity after the incorporation of crop residues and mulch films; and (c) possible bias in the measurement of soil CO2 emissions due to horizontal vs. vertical mesh bag orientation. Incorporation of crop residues enhanced mulch film degradation and increased the soil esterase activity. However, abundance of soil fungi and bacteria in bulk soil was not increased by mulch film presence. Mesh bag orientation did not alter the soil CO2 efflux or affect the degradation degree of mulch films. Film in mesh bags buried at 10–15 cm depth showed greater degradation than those buried at 0–5 cm. Further in‐field studies are necessary to evaluate the effects of soil incorporation of residue from different crops and impacts of other associated management practices such as various soil tillage regimes.

Environmental impact of biodegradable and non-biodegradable agricultural mulch film: A case study for Nordic conditions

PurposeBiodegradable mulch film is considered an environmentally friendly alternative to non-biodegradable-based mulch film for agricultural use. The purpose of this study is to compare the environmental impact of non-biodegradable mulch film to biodegradable mulch films for use in Nordic conditions, including assessing their plastic pollution potential.MethodsA life cycle assessment was conducted to calculate the potential environmental impacts of the films, while the plastic pollution potential was assessed with a dynamic material flow analysis, considering degradation over time and fate to various environmental compartments. The plastic pollution potential was based on empirical degradation data in Nordic conditions.Results and discussionThe results of the LCA and MFA analyses show that the use of non-biodegradable material in Nordic conditions leads to the lowest environmental impacts and pollution if it is fully collected after use. In fact, biodegradable mulch film leads to higher environmental impacts over its life cycle in most environmental impact categories. However, comparing environmental burdens from non-biodegradable and biodegradable mulch film is difficult due to the lack of data on biodegradable films. The results further highlight that biodegradable films will reach a dynamic equilibrium (a plateau phase) in soils in Nordic conditions between the degradation of old film and the application of new film, if not enough time is given for the films to entirely degrade. Farmers would need to apply biodegradable films with several years of interval, if the films should be entirely degraded.ConclusionsThis study supports the recommendations that biodegradable plastic has potential when used as mulch film, but these recommendations should be situation-specific, depending on farmers’ ability to handle the mulch film properly. The authors highlight that the LCA results are uncertain due to limited data availability and encourage the biodegradable plastic industry to be more transparent by making their LCIA data available.

Degradation Characteristics of Cellulose Acetate in Different Aqueous Conditions.

Cellulose acetate (CA) is widely used in cigarette filters and packaging films, but due to its acetylation, it is difficult to degrade in the natural environment, and the problem of pollution has become a serious challenge. Understanding the degradation behavior and performance of CA in different environments is the basis and prerequisite for achieving its comprehensive utilization and developing efficient degradation methods. In this study, we investigated the degradation performance of CA in different aqueous environments to evaluate the effects of pH, salinity and microorganisms on CA degradation. The CA tows and films were immersed in HCl, NaOH solution, river water, seawater or homemade seawater for 16 weeks and the degradation mechanism was investigated by the changes in weight loss rate, degree of substitution, hydrophilicity, molecular structure and surface morphology. The results showed that the degradation of CA tow and film were the fastest in NaOH solution; the weight loss rates after 16 weeks were 40.29% and 39.63%, respectively, followed by HCl solution, and the degradation performance of CA tow was better than that of film. After 16 weeks of degradation in river water, seawater and homemade seawater, all the weight loss rates were less than 3%. In summary, this study illustrated that the environmental acidity, basicity and high concentration of inorganic salts had a critical promotion effect on the non-enzymatic hydrolysis of CA, whereas the number and type of microorganisms were the key factors affecting the biodegradation of CA.

Modification of passive film on Ti–6Al–4V alloy induced by Bacillus vietnamensis

The utilization of Ti–6Al–4V alloy in marine infrastructures is somehow limited by susceptibility to biofouling and bacteria attachment, making studies on microbes-induced passive film degradation timely matter. The impact of Bacillus vietnamensis on passive film integrity of Ti–6Al–4V alloy was investigated. Electrochemical measurements and surface analysis revealed that, B. vietnamensis, which adhered preferentially on the α phase, accelerated dissolution of Ti2O3 in the passive film of Ti–6Al–4V alloy. Power-law model (PLM) revealed the changes in resistivity after exposure to B. vietnamensis. After 21 days of incubation, the icorr value in biotic medium (6.50 ± 3.4 nA cm−2) was slightly higher than that in sterile medium (1.89 ± 1.1 nA cm−2), suggesting corrosivity of B. vietnamensis against Ti–6Al–4V alloy. This study established comprehensive understanding of interaction between passive film and marine-corrosive microbial fouling.

Impact of swift heavy ion irradiation on as-grown gallium nitride epilayers by MOCVD technique

The as-grown GaN by Metalorganic Chemical Vapor Deposition was utilized to study the irradiation effects on GaN epilayers. The stopping range of ions in the matter is studied to choose the energy range for irradiation. The grown epilayers were irradiated with light and heavy ions of O7+ and Ag12+ by varying ion fluence. The X-ray Diffraction confirmed the wurtzite crystal structure for pristine and all the irradiated GaN epilayers. Atomic force microscopy showed high surface roughness for heavy ion irradiation when compared with light ion. Micro-Raman analysis was carried out through the Lorentz line fitting and calculated the carrier concentration and phonon lifetime. In light and heavy ion irradiation, the carrier concentration enhances with defect formations. X-ray Photoelectron Spectroscopy analysis showed that light ion irradiation caused oxygen bonding, while heavy ion irradiation led to the Ga–Ga bond shift, revealing film degradation.

Thermochemical degradation of agricultural mulch films for potential organic fertilizer precursors: Low-temperature pyrolysis in nitric acid

Polyethylene mulch films (PEMFs) are widely used in agriculture to boost crop yields but pose significant environmental challenges due to their non-degradable nature. This study investigated the pyrolysis of PEMFs in nitric acid (HNO3) using micro-glass reactors under mild conditions for the production of thermochemical degradation products (TDP) as potential organic fertilizer precursors. The effects of HNO3 concentration (10–60 %), HNO3:PEMF ratio (0.5–2), pyrolysis temperature (150–250 °C), and reaction time (1 – 45 min) on the yield of TDP, tetrahydrofuran-soluble fraction (THF-S), tetrahydrofuran-insoluble fraction (THF-IS), and HNO3 consumption were studied. SEM, elemental analysis, GPC, and FTIR were employed to assess product characteristics and degradability potential. Optimal conditions were HNO3 concentration of 36 %, HNO3:PEMF ratio of 0.5, pyrolysis temperature of 200 °C, and reaction time of 10 min. Higher temperatures or longer time would lead to TDP condensation to carbonaceous residues. The introduction of N and O-containing functional groups in TDP suggested its potential as an organic soil fertilizer. This study presents a novel, eco-friendly, and cost-effective solution to address the waste PEMF disposal problem.

Degradation behavior of multilayer pouches containing liquid and powder hot sauce for Meal, Ready-to-Eat (MRE) rations

Hot sauce is a highly desired condiment by Warfighters. This research investigates possible multilayer Meal, Ready-to-Eat (MRE) ration packaging films for hot sauce, focusing on performance and characterization of film degradation. Four films were made into pouches for an accelerated storage study at 80°F and 100°F with hot sauce (liquid and powder) and water as a control. For a comprehensive examination of the unique characteristics presented by the innermost layers, particularly linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and polypropylene (PP), evaluations were conducted on the mass, thickness, morphology, chemical composition of the innermost layer, barrier performance, and seal strength of each type of pouch at one, six, and 12 months. Sensory tests evaluated the food quality of hot sauce. Liquid hot sauce caused delamination of two pouch structures after one month of storage at both storage temperatures. At 12 months, liquid and powder hot sauce delaminated another pouch structure at 80°F, reducing its seal strength by 62 % and 24 %, respectively. Only one pouch structure exhibited no notable degradation at 12 months, and hot sauce quality was effectively preserved. This research provides a comparative analysis of the effects of liquid and powder hot sauce on multilayer pouches, offering new insights into how hot sauce induces degradation in these pouches, which could guide future design of MRE ration packaging.

Testing the Uniformity of Surface Resistance on Large-Format Transparent Heating Glass.

The design of a glazing package containing heating glass can make a window a radiator simultaneously. For such bulky glass to act as an effective radiator simultaneously, it should be possible to provide a constant temperature over the entire surface. The continuous surface temperature of the glass depends on the uniformity of the surface resistance of the resistive layer. This paper will demonstrate the testing of heating glass parameters using a specialised apparatus. The research will mainly focus on measuring the value and distribution of the surface resistance of the transparent heating layer. A thermographic study will verify the results. As the heating glass will be subjected to a toughening process, the effect of the toughening process parameters on the degradation of the transparent heating film will be investigated.

Engineered Geobacillus lipolytic enzymes – Attractive polyesterases that degrade polycaprolactones and simultaneously produce esters

Plastic pollution is one of the biggest environmental problems plaguing the modern world. Polyester-based plastics contribute significantly to this ecological safety concern. In this study, lipolytic biocatalysts GD-95RM and GDEst-lip developed based on lipase/esterase produced by Geobacillus sp. 95 strain were applied for the degradation of polycaprolactone films (Mn 45.000 (PCL45000) and Mn 80.000 (PCL80000)). The degradation efficiency was significantly enhanced by the addition of short chain alcohols. Lipase GD-95RM (1 mg) can depolymerize 264.0 mg and 280.7 mg of PCL45000 and PCL80000, films respectively, in a 24 h period at 30 °C, while the fused enzyme GDEst-lip (1 mg) is capable of degrading 145.5 mg PCL45000 and 134.0 mg of PCL80000 films in 24 h. The addition of ethanol (25 %) improves the degradation efficiency ~2.5 fold in the case of GD-95RM. In the case of GDEst-lip, 50 % methanol was found to be the optimal alcohol solution and the degradation efficiency was increased by ~3.25 times. The addition of alcohols not only increased degradation speeds but also allowed for simultaneous synthesis of industrially valuable 6-hydroxyhexonic acid esters. The suggested system is an attractive approach for removing of plastic waste and supports the principles of bioeconomics.

Degradation of low-density polyethylene by the bacterium Rhodococcus sp. C-2 isolated from seawater

Low-density polyethylene (LDPE), which accounts for 20% of the global plastic production, is discharged in great quantities into the ocean, threatening marine life and ecosystems. Marine microorganisms have previously been reported to degrade LDPE plastics; however, the exploration of strains and enzymes that degrade LDPE is still limited. Here, an LDPE-degrading bacterium was isolated from seawater of the Changjiang Estuary, China and identified as Rhodococcus sp. C-2, the relative abundance of which was dramatically enhanced during PE-degrading microbial enrichment. The strain C-2 exhibited the degradation of LDPE films, leading to their morphological deterioration, reduced hydrophobicity and tensile strength, weight loss, as well as the formation of oxygen-containing functional groups in short-chain products. Sixteen bacterial enzymes potentially involved in LDPE degradation were screened using genomic, transcriptomic, and degradation product analyses. Thereinto, the glutathione peroxidase GPx with exposed active sites catalyzed the LDPE depolymerization with the cooperation of its dissociated superoxide anion radicals. Furthermore, an LDPE degradation model involving multiple enzymes was proposed. The present study identifies a novel PE-degrading enzyme (PEase) for polyethylene bioremediation and promotes the understanding of LDPE degradation.

Terahertz Probing of Anisotropic Conductivity and Morphology of CuMnAs Epitaxial Thin Films

AbstractAntiferromagnetic CuMnAs thin films have attracted attention since the discovery of the manipulation of their magnetic structure via electrical, optical, and terahertz pulses, enabling convenient approaches for switching between magnetoresistive states of the film for information storage. However, the magnetic structure and, thus, the efficiency of the manipulation can be affected by the film morphology and growth defects. In this study, the properties of CuMnAs thin films are investigated by probing the asymmetrical growth‐related uniaxial anisotropy of electric conductivity by contact‐free terahertz transmission spectroscopy. It is shown that the terahertz measurements conveniently detect the conductivity anisotropy that is consistent with conventional DC Hall‐bar measurements. Moreover, the terahertz technique allows for considerably finer determination of anisotropy axes, and it is less sensitive to the local film degradation. Thanks to the averaging over a large detection area, the THz probing also allows an analysis of strongly non‐uniform thin films. Using scanning electron and near‐field terahertz microscopies, the observed anisotropic conductivity of CuMnAs is related to the elongation and orientation of growth defects, which both originate in the anisotropic growth of the films. In addition, control over the morphology of defects is demonstrated by using vicinal substrates.

Promotion effect of foam formation on the degradation of polyvinyl alcohol by ozone microbubble

Polyvinyl alcohol (PVA), extensively utilized in diverse industries, presents a challenge in terms of degradation. The combination of ozone (O3) with microbubbles enhances ozone's residence time and oxidation efficiency, offering a promising avenue for effective PVA degradation. This study investigated PVA degradation using ozone microbubble (MB/O3) and oxygen microbubble (MB/O2). Bubbles evolving into remarkably resistant foam was observed for the first time. PVA removal via MB/O3 and MB/O2 followed a first-order kinetic model, exhibiting removal rates of 98.58 % and 48.68 %, respectively, within the initial 20 min. The physicochemical reaction of PVA degradation by MB/O3 and the physical removal reaction by MB/O2 were demonstrated. The microscale changes of bubbles and foam were captured, uncovering the phenomenon of self-pressurized dissolution of MB/O3 and the creation of larger foam structures through intact microbubbles, ultimately leading to their rupture. A comprehensive four-stage theory was proposed to explain PVA degradation by MB/O3, where physical separation, foam film degradation, and bubble coalescence within the foam play crucial roles. This theory was validated under varying pH and salt concentration conditions. Moreover, when the pH was decreased from 8.69 to 3.3, there was a 33.2 % increase in the COD removal rate. Mechanism analysis further confirmed the theory and revealed that, during PVA degradation, MB/O3 underwent stochastic cleavage, yielding small molecule remnants comprising aldehyde, carboxyl, and ester moieties. Finally, by comparison with other PVA degradation processes, the trial of MB/O3 was proven to be a straightforward and effective treatment approach for PVA degradation.

Influence of an Organic Salt-Based Stabilizing Additive on Charge Carrier Dynamics in Triple Cation Perovskite Solar Cells.

Besides further improvement in the power conversion efficiency (PCE) of perovskite solar cells (PSC), their long-term stability must also be ensured. Additives such as organic cations with halide counter anions are considered promising candidates to address this challenge, conferring both higher performance and increased stability to perovskite-based devices. Here, a stabilizing additive (N,N-dimethylmethyleneiminium chloride, [Dmmim]Cl) is identified, and its effect on charge carrier mobility and lifetime under thermal stress in triple cation perovskite (Cs0.05 MA0.05 FA0.90 PbI3 ) thin films is investigated. To explore the fundamental mechanisms limiting charge carrier mobility, temperature-dependent microwave conductivity measurements are performed. Different mobility behaviors across two temperature regions are revealed, following the power law Tm , indicating two different dominant scattering mechanisms. The low-temperature region is assigned to charge carrier scattering with polar optical phonons, while a strong decrease in mobility at high temperatures is due to dynamic disorder. The results obtained rationalize the improved stability of the [Dmmim]Cl-doped films and devices compared to the undoped reference samples, by limiting temperature-activated mobile ions and retarding degradation of the perovskite film.

Photocatalytic Degradation of Methylene Blue by Magnetic Opal/Fe3O4 Colloidal Crystals under Visible Light Irradiation

In this study, opal–magnetite photocatalysts based on SiO2 artificial opal crystals infiltrated with different concentrations of Fe3O4 nanoparticles (NPs) were synthesized using a combination of lateral infiltration and co-assembly methods. By adjusting the concentration of Fe3O4 NPs in the SiO2 opal crystal, the energy band gap (Eg) was tuned to enable efficient degradation of methylene blue (MB) under visible light (410 nm and 575 nm). The photocatalytic process involved two stages: MB adsorption on the surface due to charge differences in the composite film and subsequent degradation through oxidative radicals on the catalyst’s surface. The developed material exhibited potential for applications in water remediation.

Performance degradation mechanism of γ-ray irradiated sol-gel silica film

γ-ray radiation effect on sol-gel silica films was investigated at different absorbed doses ranging from 10 kGy to 1000 kGy. The defect and microstructure evolutions of silica films were analyzed to understand the performance degradation behavior and mechanism of the γ-ray irradiated silica films. The cracks appear on the silica film surface and further expand at larger γ-ray absorbed dose, while surface roughness slightly decreases. During γ-ray irradiation, the thermal effect and the increased rate of diffusion-controlled process lead to the condensation of Si-OH groups and the recombination of ODCs. However, the ionization of atoms leads to generation and accumulation of E′ centers and NBOHCs. γ-ray irradiation leads to the reductions of bond lengths and bond angles of Si-O-Si groups, thus causing the densification of films. The refractive index and mechanical property firstly enhance and then reduce with the increase of absorbed dose associated with the change of silica film density. After γ-ray irradiation, the decreased contact angle and increased surface free energy indicate the reduction of anti-pollution ability of silica films. The dose-dependent surface quality, defects and mechanical properties determine the variation in laser-induced damage threshold (LIDT) of silica film. The results provide a reference to control the structural damage and performance degradation of silica films, which is very important for the research of safe operation of high-power laser facilities for inertial confinement fusion (ICF).

Soil burial degradation studies of photo‐crosslinked PCL‐PDMS‐PCL triblock copolymer films

AbstractThis article focuses on the soil burial degradation behavior of photo‐crosslinked Polycaprolactone (PCL) homopolymer and Polycaprolactone‐Polydimethylsiloxane‐Polycaprolactone (PCL‐PDMS‐PCL) triblock copolymer films. PCL homopolymer and PCL‐PDMS‐PCL triblock copolymer films with varying the chain length of PCL were synthesized. The microlevel, macrolevel, and structural changes in the samples of homopolymer and triblock copolymer were analyzed before and after soil burial test. Microlevel changes were determined by the evaluation of morphological properties with the digital camera, optical microscope (OM), and scanning electron microscope (SEM) images. These changes revealed that the degradation of copolymer films enhanced with increasing PCL chain length. The Macrolevel structural changes were examined by Fourier transform infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) crystallinity. The soil burial degradation mechanism was proposed for PCL‐PDMS‐PCL triblock copolymer films based on the obtained results.

Degradation of polypropylene by fungi Coniochaeta hoffmannii and Pleurostoma richardsiae

The urgent need for better disposal and recycling of plastics has motivated a search for microbes with the ability to degrade synthetic polymers. While microbes capable of metabolizing polyurethane and polyethylene terephthalate have been discovered and even leveraged in enzymatic recycling approaches, microbial degradation of additive-free polypropylene (PP) remains elusive. Here we report the isolation and characterization of two fungal strains with the potential to degrade pure PP. Twenty-seven fungal strains, many isolated from hydrocarbon contaminated sites, were screened for degradation of commercially used textile plastic. Of the candidate strains, two identified as Coniochaeta hoffmannii and Pleurostoma richardsiae were found to colonize the plastic fibers using scanning electron microscopy (SEM). Further experiments probing degradation of pure PP films were performed using C. hoffmannii and P. richardsiae and analyzed using SEM, Raman spectroscopy and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). The results showed that the selected fungi were active against pure PP, with distinct differences in the bonds targeted and the degree to which each was altered. Whole genome and transcriptome sequencing was conducted for both strains and the abundance of carbohydrate active enzymes, GC content, and codon usage bias were analyzed in predicted proteomes for each. Enzymatic assays were conducted to assess each strain’s ability to degrade naturally occurring compounds as well as synthetic polymers. These investigations revealed potential adaptations to hydrocarbon-rich environments and provide a foundation for further investigation of PP degrading activity in C. hoffmannii and P. richardsiae.

Contribution of free hydroxyl radical to the formation of micro(nano)plastics and release of additives during polyethylene degradation in water

The omnipresence of secondary microplastics (MPs) in aquatic ecosystems has become an increasingly alarming public health concern. Hydrogen peroxide (H2O2) is an important oxidant in nature and the most stable reactive oxygen species occurred in natural water. In order to explore the contribution of free ˙OH generated from H2O2-driven Fenton-like reactions on the degradation of polyethylene (PE) and generation of micro- and nano-scale plastics in water, a batch experiment was conducted over a period of 620 days in water treated with micromolar H2O2. The incorporation of H2O2 in water induced the formation of flake-like micro(nano)-sized particles due to intensified oxidative degradation of PE films. The presence of ˙OH significantly enhanced the generation of both micro- and nano-scale plastics exhibiting a higher proportion of particles in the range of 200–500 nm compared to the Control. Total organic carbon in the H2O2 treated solution was nearly 174-fold higher than that of the Control indicating a substantial liberation of organic compounds due to the oxidative degradation of native carbon chain of PE and subsequent decomposition of its additives. The highly toxic butylated hydroxytoluene detected from the gas chromatography-mass spectrometry (GC-MS) analysis implied the toxicological behavior of secondary micro(nano)plastics influenced by the oxidation and decomposition processes The findings from this study further expand our understanding of the role of ˙OH in degrading PE micro-scale plastics into nanoparticles as an implication of naturally occurring H2O2 in aquatic environments. In the future, further attention should be drawn to the underlying mechanisms of H2O2-driven in-situ Fenton reaction mediated by natural environmental conditions targeting the alternation of light and darkness on the oxidative degradation of plastics.

Biodegradation of polysaccharides, polyesters and proteins in soil based on the determination of produced carbon dioxide

The biodegradation of polymers can be determined by measuring the CO2 evolution from the biodegradation medium, for example soil. In this work, the biological degradation of cellulose (powder and fibers), polylactic acid (PLA, powder and films), a combination of both and lupin protein isolate (LPI, films) was investigated. Therefore, a reliable method using a respirometric system needed to be developed. The soil to sample ratio, the system boundaries concerning the maximum CO2 uptake and O2 consumption in addition to the change in electrical conductivity of the KOH absorbant solution caused by CO2 uptake were investigated. LPI-based films showed the highest biodegradation in %, followed by regenerated cellulose fibers (RC fibers). In case of PLA only the samples with powder morphology were biological degraded. The degradation of PLA films was highly increased to 68 % by addition of microfibrillated cellulose (MFC). The samples were analyzed before and after biodegradation using scanning electron microscopy (SEM) and gel permeation chromatography (SEC). The developed method was successful to validate the degree of biodegradation for a large variety of biogenic polymers and can be generally applied.