Degradation Of Polymeric Materials Research Articles

Identification and recombinant expression of a cutinase from Papiliotrema laurentii that hydrolyzes natural and synthetic polyesters.

Given the multitude of extracellular enzymes at their disposal, many of which are designed to degrade nature's polymers (lignin, cutin, cellulose, etc.), fungi are adept at targeting synthetic polyesters with similar chemical composition. Microbial-influenced deterioration of xenobiotic polymeric surfaces is an area of interest for material scientists as these are important for the conservation of the underlying structural materials. Here, we describe the isolation and characterization of the Papiliotrema laurentii 5307AH (P. laurentii) cutinase, Plcut1. P. laurentii is basidiomycete yeast with the ability to disperse Impranil-DLN (Impranil), a colloidal polyester polyurethane, in agar plates. To test whether the fungal factor involved in this clearing was a secreted enzyme, we screened the ability of P. laurentii culture supernatants to disperse Impranil. Using size exclusion chromatography (SEC), we isolated fractions that contained Impranil-clearing activity. These fractions harbored a single ~22 kD band, which was excised and subjected to peptide sequencing. Homology searches using the peptide sequences identified, revealed that the protein Papla1 543643 (Plcut1) displays similarities to serine esterase and cutinase family of proteins. Biochemical assays using recombinant Plcut1 confirmed that this enzyme has the capability to hydrolyze Impranil, soluble esterase substrates, and apple cutin. Finally, we confirmed the presence of the Plcut1 in culture supernatants using a custom antibody that specifically recognizes this protein. The work shown here supports a major role for the Plcut1 in the fungal degradation of natural polyesters and xenobiotic polymer surfaces.IMPORTANCEFungi play a vital role in the execution of a broad range of biological processes that drive ecosystem function through production of a diverse arsenal of enzymes. However, the universal reactivity of these enzymes is a current problem for the built environment and the undesired degradation of polymeric materials in protective coatings. Here, we report the identification and characterization of a hydrolase from Papiliotrema laurentii 5307AH, an aircraft-derived fungal isolate found colonizing a biodeteriorated polymer-coated surface. We show that P. laurentii secretes a cutinase capable of hydrolyzing soluble esters as well as ester-based compounds forming solid surface coatings. These findings indicate that this fungus plays a significant role in biodeterioration through the production of a cutinase adept at degrading ester-based polymers, some of which form the backbone of protective surface coatings. The work shown here provides insights into the mechanisms employed by fungi to degrade xenobiotic polymers.

Development, Prospect and Challenge for Additive Manufacturing of Polymer Materials

As a manufacturing technology that fabricates three-dimensional objects by stacking materials layer by layer, additive manufacturing can be divided into laser fused deposition, electron beam fused deposition, inkjet printing and so on based on different additive manufacturing processes. In recent years, remarkable progress has been made in the additive manufacture of polymer materials. Firstly, the additive manufacturing equipment and process parameters suitable for polymer materials have been successfully developed, which realized the accurate manufacturing of complex structures. Secondly, by optimizing the formula and post-treatment of polymer materials, the performance and durability of additive products are improved. In addition, the researchers also explored the application potential of additive manufacturing of polymer materials in medical, aerospace and other fields. However, the additive manufacturing of polymer materials still faces some challenges. One of them is that the rheological properties of polymer materials have a great impact on the progress of additive manufacturing, which needs further research and improvement. Meanwhile, the heat and stress generated in additive manufacturing may lead to the deformation and degradation of polymer materials, which requires effective thermal management. Finally, compared with the traditional cutting process, the additive manufacturing cost of polymer materials is still high, so it is necessary to reduce the cost and promote production efficiency. In a word, additive manufacturing of polymer materials has broad prospects and application potential, but further research and improvement are still needed to overcome related challenges.

General Mechanism of Biological Degradation of Polymeric Materials (Review)

General Mechanism of Biological Degradation of Polymeric Materials (Review)

Research the Thermal Decomposition Processes of Copolymers Based on Polypropyleneglycolfumaratephthalate with Acrylic Acid.

Kinetics of thermal degradation of polymeric materials is usually studied by weight loss at a constant temperature or during heating. Hence, the activation energy and other kinetic parameters of the thermal destruction process are determined. One of the fastest and most accessible methods for studying the kinetics of these processes is TGA. Weight methods of TGA do not provide an opportunity to judge the proportion of gaseous degradation products. This is especially true for processes associated with the release of hydrogen and other substances with low molecular weights, the accuracy of determining the amount of which by the weight method is low. Meanwhile, the study of the gas evolution process can provide additional information about the kinetics and mechanism of thermal destruction processes. Of great interest is also the joint study of the total weight loss and gas evolution during the polymer heating. Using mass spectrometry, IR spectroscopy combined with thermal analysis (TGA/DSC-IR and TGA/DSC-MS) we have defined product composition and thermal destruction kinetics. As a result of the TGA/DSC-MS study of gaseous products of thermolysis in nitrogen atmosphere, there were found products with 44, 45, 59, 60, 68, and 88 phr. Quite a similar pattern for p-PGFPh:AA copolymers is also observed in TGA/DSC-IR studies: the same products and the same temperature range. However, in contrast to the TGA/DSC-MS study, CO release was also recorded by this method (weak signal). Kinetic characteristics of the processes were determined based on Friedman, Ozawa-Flynn-Wall and modified NPC methods. Obtained values of the activation energy and thermodynamic characteristics make it possible to predict the composition of polymers, which make a significant contribution to the development of theoretical ideas about the features of the physicochemical properties of polymers.

Modelling plasticiser loss inside closed environments

Plasticiser loss, a fundamental mechanism in the degradation of polymeric materials, leads to material instability and contamination of the environment. The process depends on environmental conditions, but the size of the container in which an object is housed and the thickness of the material also play key roles in the rate of plasticiser loss and the time at which equilibrium is reached. Understanding these dependencies provides valuable insight into the degradation of plastic museum artefacts inside enclosures as typified by museum storage and, more broadly, the deterioration of polymeric materials in closed environments. Migration of low molecular weight plasticisers, like diethyl phthalate or dimethyl phthalate, from plastics has been widely studied in accelerated ageing experiments at elevated temperatures and different airflows. Here, to investigate these effects, we modelled plasticiser loss in a stagnant environment inside an enclosure at room temperature. Our model is one-dimensional and describes loss through a two-phase transient diffusion process, between the solid plastic and the air. The comparison of numerical simulations to FTIR and 1H NMR spectroscopic data from cellulose acetate samples plasticised with diethyl phthalate aged at T = 70 °C and 50% relative humidity indicates that the model is appropriate for thin enclosed plastics. We applied the model over a range of diffusion coefficients [10−21–10−14 m2 s−1] and partition coefficients [103–107] to represent different polymeric materials. Under the investigated scenarios, thin plastics tolerate a maximum total plasticiser loss of 10% and the timescales vary between 1 and 109 years. The model provides insight into the relationship between plasticiser loss, enclosure dimensions and material thickness for different plastics and can suggest how to improve packaging dimensions of thin plastic products to minimise loss, as well as future conservation strategies and guidelines for plastic museum artefacts.

Trends for the Thermal Degradation of Polymeric Materials: Analysis of Available Techniques, Issues, and Opportunities

This paper examines the degradation trends of polymeric materials during heat conversion and solvolysis processes. The presence of different fractions of polymeric materials, such as PET, PP, SBR, ABS, resin, and tier waste, necessitates the use of different procedures for degradation, transformation, and further elimination from the natural environment. A significant part of the work was devoted to discussing the issue of thermal pyrolysis, taking into account the chemical composition and the possible impact of the process reaction mechanism, the type of raw material used, and the influence of the process temperature on the yields of low, medium, and high boiling products. The issue was extended to the possibility of decomposition of polymers based on the use of catalytic additives for the improvement and efficiency of the process and the structural modification of reactors. The major goal of this investigation of these various options was to generate a spectrum of accessible strategies for polymeric material degradation. The optimal technique depends on the polymer type and predicted final product qualities. Different catalysts, such as ZSM-5 (Zeolite Socony Mobil-5 one of the most efficient catalysts), ZSM-5 with ammonium groups, and ZSM-5 with 10% Ni, improved the efficiency of several heating processes. The final products after polymeric material degradation were determined by the type and conditions of the degradation processes, results of the materials characterisation, and the scale of the reactors utilised.

Effects of Hybrid Polymeric Material Based on Polycaprolactone on the Environment.

Polymers are of great interest in areas such as agriculture, medicine and pharmacy, the food and cosmetic industries, and the chemical and construction industries. However, many polymers are nonbiodegradable and are not environmentally friendly. They are highly resistant to degradation and therefore can lead to waste disposal problems. In recent years, the interest in the microbial degradation of polymeric materials has grown due to the desire for less waste pollution in the environment. In this study, the biodegradable polymer that was obtained by the ring-opening polymerization of ε-caprolactone (CL) using an aminopropyl-polydimethylsiloxane (APDMS) oligomer and the effects of the polymer towards the growth and development of tomato plants (Lypercosium esculentum) were investigated. The obtained product was characterized using FTIR spectroscopy, NMR spectroscopy, and energy dispersion spectroscopy (EDX) analysis, and the effects of this compound on the evolution of tomato plants (Lypercosium esculentum) were studied. We also studied the biological stability of the product by identifying some of the microorganisms that developed on the surface, given its susceptibility to biodegradation.

Product specific thermal degradation kinetics of bisphenol F epoxy in inert and oxidative atmospheres using evolved gas analysis–mass spectrometry

Knowledge of the degradation kinetics for polymer materials is important for understanding thermal stability. Here, evolved gas analysis–mass spectrometry and pyrolysis gas-chromatography-mass spectrometry were evaluated for the potential to deliver additional insight into thermal degradation kinetics of diglycidal ether of bisphenol F (DGEBF) epoxy thermoset under inert and oxidative atmospheres. Degradation products of selected precursor ions were evaluated for their uniqueness to the specific precursor using extracted ion thermographs. Unique mass peaks, solely attributed to a single reaction pathway of a specific product, were determined from extracted ion thermographs and used to determine both activation energy (Ea) and pre-exponential factors for the specific primary reaction pathways. These primary reaction pathways for DGEBF epoxy degradation were then evaluated in the context of transition state theory (TST) and related transition state enthalpies (ΔH‡) and entropies (ΔS‡) of activation to further elucidate the degradation process. It was determined under pyrolysis conditions, as suggested by the Ea, the formation of bisphenol F monomer was the rate-limiting step toward the formation of xanthene and phenol. In contrast, under thermo-oxidative conditions, reactions involving oxygen containing species were identified as the rate-limiting step for all observed products based on the large negative ΔS‡ calculated from TST. This work demonstrates a powerful combination of technique and theory that can provide new insight into the degradation of polymer materials.

Progress in Degradation Behavior of Most Common Types of Functionalized Polymers: A Review.

Nowadays, degradation of polymeric material is a hot topic, it is either related to environmental considerations to avoid pollution accumulation, or to biomedical applications to reduce the toxicity or to facilitate the excretion of foreign agents in the body. Functionalization is a promising and interesting method to tune polymers degradation kinetics and profiles in a robust and controllable way depending on the targeted application. The incorporation of a functionality to a macromolecule occurs through mainly two strategies: direct functionalization of the corresponding monomers before their polymerization, and postpolymerization modifications that can occur on the side, main or/and end chains of the polymers. Ideally, the lifespan of a material is restricted to the duration of the application, its mechanical and chemical properties do not deteriorate and does not produce toxic byproducts over the degradation process. This review presents the latest advances in polymer functionalization strategies in terms of their impact on the degradation process. Special considerations are given to the main classes of polymers including polyesters, polyurethanes, polyacetals, as well as vinyl-based and phosphorous-derived polymers.

Biodegradable Elastomers and Gels for Elastic Electronics.

Biodegradable electronics are considered as an important bio‐friendly solution for electronic waste (e‐waste) management, sustainable development, and emerging implantable devices. Elastic electronics with higher imitative mechanical characteristics of human tissues, have become crucial for human‐related applications. The convergence of biodegradability and elasticity has emerged a new paradigm of next‐generation electronics especially for wearable and implantable electronics. The corresponding biodegradable elastic materials are recognized as a key to drive this field toward the practical applications. The review first clarifies the relevant concepts including biodegradable and elastic electronics along with their general design principles. Subsequently, the crucial mechanisms of the degradation in polymeric materials are discussed in depth. The diverse types of biodegradable elastomers and gels for electronics are then summarized. Their molecular design, modification, processing, and device fabrication especially the structure–properties relationship as well as recent advanced are reviewed in detail. Finally, the current challenges and the future directions are proposed. The critical insights of biodegradability and elastic characteristics in the elastomers and gel allows them to be tailored and designed more effectively for electronic applications.

Oxidative biodegradation of a solid-solid polyether-urethane phase change material by Penicillium and Aspergillus

Polyurethane-based polymers are widely used in modern materials and as Phase Change Materials (PCMs) to improve the energy efficiency of buildings. The fungal development in buildings is favoured by the degradation of polymeric materials that act as nutritional substrates. In the present study, the fungal biodegradation of a polyether-urethane PCM (PUX1520) was investigated. Two methods of biodegradation by fungal growth on agar and in liquid media were used. Fungal growth on agar plates was monitored by measuring the surface area of each mycelium over a period of 11 days. The degradation products of PUX1520 were analysed by FT-IR and MALDI-TOF. The PUX1520 polymer had no impact on the growth of Aspergillus niger, while the growth of Penicillium sp. was increased in the presence of PUX1520. MALDI-TOF analysis revealed the existence of different soluble forms of the polymer whose concentration decreased after exposure to the fungal strains. From FT-IR analysis on the residual polymer material, an oxidation process is proposed to describe the dissociation of the urethane functions.

Property changes in materials due to atomic oxygen in the low Earth orbit

We expect satellites at altitude below 300 km, very low Earth orbit (VLEO), making observations of the Earth at optical wavelength with increasingly higher resolution. The density of atomic oxygen (AO) at VLEO is significantly higher than that at LEO; severe degradation of spacecraft materials (polymers) due to the high-flux AO is a serious concern. To clarify VLEO environmental effects on spacecraft materials, we designed the Material Degradation Monitor (MDM) and MDM2 missions. The MDM is a material exposure experiment onboard the Super Low-Altitude Test Satellite (SLATS). It aims to understand reactions and degradation of polymeric materials depending on AO fluence in VLEO. In the MDM, samples of spacecraft material were exposed at altitude of 160–560 km; their degradation behaviors were observed optically by a CCD camera for 1.8 years. The MDM2 is a material exposure experiment onboard the International Space Station (ISS) and aims to correctly understand surface reactions and degradation of the same samples used in the MDM at a given AO fluence. In the MDM2, the samples were exposed at altitude of 400 km for 1 year and then returned to Earth for analysis. Based on the results from both missions, we will help in the molecular design of more-durable materials, and establish design standards for future VLEO satellites. This study aims to quantitatively understand the surface reactions and degradation of the 11 types of thermal control materials exposed on the ISS in the MDM2. Five types of multilayer insulation (MLI) films (three types of Si-containing AO protective materials (a silsesquioxane-(SQ-) containing coated polyimide film, two types of polysiloxane-block polyimide (BSF-30) films), an ITO-coated polyimide film, and a Beta Cloth), and flexible optical solar reflectors (flexible OSRs) were found to have a high durability against erosion by AO. This was determined by measuring their loss of mass and thermo-optical properties. The Ag/Inconel layer’s discoloration and peeling were observed for three types of FEP/Ag films as determined by the Ag layer’s oxidation by AO. Also, X-ray photoelectron spectroscopy (XPS) showed that reactions of the Si-containing materials, the SQ-coated polyimide film and the BSF-30 film, form a layer of silica that protects against AO. Even though the concentration of Si in the SQ-coating is the same or greater than in the BSF-30 film, the amount of the SQ-coating that reacted was larger than that of the BSF-30 film under the same AO fluence. Moreover, the effective ability of the UV-shielding coating, composed of ITO and CeO2 coated onto one of the BSF-30 films, was demonstrated by UV–Vis spectrometry. Its sufficient AO protection was confirmed by mass measurements, XPS analyses, and FE-SEM observations.

A Study on the Life Estimation and Cavity Surface Degradation Due to Partial Discharges in Spherical Cavities within Solid Polymeric Dielectrics Using a Simulation Based Approach.

Partial Discharges (PD) in cavities are responsible for the greatest ageing rate in polymeric solid dielectrics due to chemical and physical deterioration mechanisms activated by the charge carriers, Ultra Violet (UV) radiation and local temperature rising during PDs activity. From the above, it is necessary to develop prognosis tools based on PDs measurements as diagnostic quantities in order to infer the time-to-breakdown, life, of solid dielectrics for improving the reliability of electrical assets, especially in current applications where they are subject to great electrical stresses in voltage frequency and magnitude. In this paper, the degradation in polymeric materials induced by PDs in cavities is briefly discussed from a phenomenological point of view, and then it is quantitatively evaluated using a simulation-based approach and a new proposed damage function. The time-to-breakdown calculated from simulations exhibits good agreement when compared with experimental measurements. Additionally, an analysis on the effect of the magnitude and frequency of the applied voltage on the degradation rate is also presented and the effectiveness of a degradation indicator, proposed by other authors, is evaluated under different stress conditions.

Synergism of the action of some stabilisers against the destruction of polymer materials

The process of thermal-oxidative degradation of polymer materials has been studied on the example of polyethylene in the presence of quinones and / or nitroxyl radicals. The synergistic effect of the positive action of a mixture of stabilisers from a number of quinones and nitroxyl radicals on the destructive process of polyethylene has been established. It has been shown that the rate of degradation has significantly slowed down when an equimolecular mixture of 4-acetylamino-2,2,6,6-tetramethylhexahydropyridine-1-oxyl and 2,6-di-tert-amyl-1,4-cyclohexadienone inhibitors has been introduced into the polymer. The kinetics of the initiated thermo-destructive process of polyethylene oxidation in the presence and absence of stabilisers has been studied. A mechanism of joint action of stabilisers based on their interaction with radicals and the breakage of radical chains, as well as a mechanism for the regeneration of stabilisers, has been proposed.

Surface damage characterization of photodegraded low-density polyethylene by means of friction measurements

Abstract Friction measurements have been carried out to characterize surface damages during photodegradation of low-density polyethylene. The average and mean deviation of the friction coefficients increase with the irradiation time in the early stage of photodegradation processes, indicating the increase in the surface roughness, whereas the mechanical properties remain essentially unchanged. In the following stage, where the ductile-brittle transition takes place, the mean deviation of the friction coefficients shows an appreciable decrease with maintaining almost constant average values, suggesting that the surface becomes more homogeneous. Beyond the ductile-brittle transition, both of the average and mean deviation of the friction coefficients gradually increase with the irradiation time, indicating further enhancement of surface roughness, followed by formation of surface cracks. The soundness of the friction measurements is confirmed by comparing with optical measurements of the surface roughness, and it is suggested that the present method gives a convenient and sensitive method of detection for degradation in polymeric materials.

Advances in studies of thermal degradation of polymeric materials. Part II. The influence of various factors on the thermal degradation of polymeric materials during their processing

Advances in studies of thermal degradation of polymeric materials. Part II. The influence of various factors on the thermal degradation of polymeric materials during their processing

Photostabilization mechanisms of the main wood photostabilizers from the heartwood extract in Acacia confusa: okanin and melanoxetin

Flavonoids are secondary metabolites with abilities to reduce the thermal- and photoinduced degradation of polymeric materials. Previous studies indicated that the flavonoids in Acacia confusa heartwood had photostabilities that can reduce the photoinduced degradation of lignin in wood. Hence, the photostabilities and the photostabilization mechanisms of major flavonoids in A. confusa heartwood merit further study. This study demonstrates that the flavone (7,3′,4′-trihydroxy-5-methoxyflavone), flavonols (melanoxetin and 7,8,3′-trihydroxy-3,4′-dimethoxyflavone) and chalcone (okanin) in A. confusa heartwood have good UV absorptivity, singlet oxygen quenching ability and phenoxyl radical scavenging ability, in particular, the two most abundant flavonoids, melanoxetin and okanin. Additionally, okanin can quench excited lignin. Accordingly, these flavonoids can remove hazards induced during lignin photodegradation.

Relation between degradation of polymeric components in crystalline silicon PV module and climatic conditions: A literature review

During their outdoor service, photovoltaic (PV) modules are exposed to different set of external stresses that can affect their efficiency and lifetime such as UV irradiation, temperature and humidity cycles, rain, snow and wind loads, hail, sand and/or salt. Moreover, internal stresses such as choice of materials and design (additives, morphology and compatibility of materials) can drive degradation of PV modules as well. The failure data collection started already in 1980s and is still ongoing. Most of these studies are focused mainly on power data or categorizing PV failure modes concerning solely climate, EVA or cell-technology. However, relationship between climate, degradation of polymeric materials and degradation of PV modules has not been reported so far. Hence, within this study a lot of effort was put into finding the appropriate data and publications with as many as possible data on PV, climate and materials degradation. As a result, a great overview of climate and polymeric materials induced PV failure modes is given. Based on the reported data, the topic of new, climate-based design of PV modules is discussed. This paper provides numerous number of selected references that can be beneficial in further studies on degradation of PV modules, design of PV modules and choice of materials.

Wpływ starzenia elektrochemicznego na właściwości wybranych pojemników medycznych

Presently, most of receptacles used in medicine are made of polymeric materials. This is due to, e.g., low price, low weight, and aesthetic values of these materials. The important issue is to ensure long life of polymer in order to protect the medicines closed in the boxes. However, all materials during exploitation are exposed to many factors, which can cause degradation of polymer materials. Degradation processes lead to deterioration of thermomechanical properties of polymers. The aim of this syudy was to examine the influence of electrochemical ageing on properties of polymeric materials used in production of receptacles for drugs and boxes for medical use. We conducted comparative analysis of samples before and after electrochemical ageing, cut out of receptacles for drugs made from polyethylene, as well as from boxes for medical use and Eppendorf tube made from polypropylene. Investigating methods included differential scanning calorimetry (DSC) and imaging of microstructure ×400 magnification. We noticed different value of the degree of crystallinity for the aged samples in comparison to not aged samples. The change in value of temperature of physical transformation was also detected. In the aged samples defragmentation of crystal structure was observed. Electrochemical ageing results in changes of properties of polymeric materials used in production of medical receptacles.

Coarse-grained molecular dynamics simulations of polymerization with forward and backward reactions.

We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non-bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e.g. water molecules or development of polymer morphology during the process of splitting off byproduct molecules. Another concept that could be studied is the degradation of polymeric materials, a very important topic in a recycling of polymer waste. We illustrate the method by simulating the polymerization of polyethylene terephthalate (PET) at the coarse-grained level as an example of a polycondensation reaction with water as a byproduct. The algorithms are implemented in a publicly available software package and are easily accessible using a domain-specific language that describes chemical reactions in an input configuration file. © 2018 Wiley Periodicals, Inc.