Polymer Degradation Research Articles

Durable-polymer versus biodegradable-polymer drug-eluting stents in acute coronary syndromes: three-year outcomes of the HOST REDUCE POLYTECH RCT Trial.

Long-term follow-up is essential to evaluate the impact of polymer degradation in drug-eluting stents (DES). We aimed to compare durable-polymer DES (DP-DES) and biodegradable-polymer DES (BP-DES) during a 3-year follow-up to evaluate the entire period of polymer resolution (before, during, and after degradation). The HOST REDUCE POLYTECH RCT Trial was a randomised clinical trial enrolling patients with acute coronary syndrome (ACS) and comparing the efficacy and safety of DP-DES and BP-DES. The primary outcome was a patient-oriented composite outcome (POCO), and the key secondary outcome was a device-oriented composite outcome (DOCO). A total of 3,413 ACS patients were randomised to either the DP-DES (1,713 patients) or BP-DES (1,700 patients) group. During the 3-year follow-up, the risk of the POCO was similar between the DP-DES and BP-DES groups (14.8% vs 15.4%, hazard ratio [HR] 0.96, 95% confidence interval [CI]: 0.80-1.14; p=0.613). However, the risk of the DOCO was lower in the DP-DES group (6.0% vs 8.0%, HR 0.73, 95% CI: 0.57-0.95; p=0.020). In a landmark analysis, the lower risk of the DOCO for the DP-DES group was evident during the transition from the early to the late period after percutaneous coronary intervention (PCI) (from 8 to 16 months post-PCI; 1.8% vs 3.3%, HR 0.54, 95% CI: 0.34-0.84; p=0.007), which was mainly driven by a risk reduction of target lesion revascularisation. In ACS patients, DP-DES showed similar results to BP-DES regarding the POCO up to 3 years. For the DOCO, DP-DES were superior to BP-DES; this was due to the higher event rate during the period of polymer degradation.

The Effect of Polycaprolactone Polymer Degradation in Compost on Seed Germination

Abstract Polycaprolactone (PCL) is a biodegradable synthetic polymer derived from petroleum that can be broken down by microorganisms. Due to its low melting point, it is suitable for composting. PCL has various applications, including in medicine and agriculture. This study investigates whether PCL degradation in compost affects seed germination. The study tested the effect of PCL extracts from compost with different temperatures and concentrations on the germination of seeds from four edible plant species: cress, lettuce, mustard, and rocket. The results showed that at low temperatures and low PCL concentrations, there was no effect on seed germination. However, at higher temperatures (55°C) and higher PCL concentrations (10% and 5%), there was a signiIicant negative effect on seed germination, with no germination in 10% PCL treatments and only 53.3% germination in 5% PCL treatments. This inhibition was observed across all plant species. The study concludes that high temperatures and high PCL concentrations in compost can negatively impact seed germination.

Radiolysis of composite polypropylene/hemp fibers

Abstract This paper presents the results of the research on the effects of ionizing radiation on the properties of a composite material consisting of polypropylene (PP) and hemp fibers (HFs). The radiolysis effects were investigated for the composites having HF contents in the amounts of 10, 20, 30, and 40% by weight, as well as for pure PP. Particular attention was paid to the protective effects the aromatic compounds contained in the HF had on the radiolysis of PP/HF composites. This phenomenon may explain the deviations that the irradiated composites displayed upon the addition of HFs and their dependency on the HF content. Both the granules and the standardized composite specimens were subjected to radiation treatment. The gas chromatography (GC) technique was employed to determine the yield of radiolytically generated hydrogen (GH2) and absorbed oxygen (GO2). The oxidation phenomenon was studied during irradiation, 24 h after irradiation, and after a 40-day aging period at room temperature. Changes in the melt flow rate (MFR) and the mechanical properties were also determined. It was described how the radiation treatment of the investigated composites accelerates their degradation. It was found that this effect applies to both HF and PP. It was also demonstrated that PP not only does not enhance the resistance of HF to oxidation but, on the contrary, accelerates the processes of their post-radiation degradation. It was further observed that the phenomenon of postradiation degradation can be controlled by changing the PP content in the composite, as well as the amount of aromatic compounds present in the HF. The amount of the absorbed dose allows us to control the degradation time of the PP/HF composites. This applies in particular to the chain oxidation of the PP matrix triggered by the ionizing radiation. It was also found that composites based on PP and natural fibers susceptible to radiation degradation may have significant implications for the use of easily degradable polymer materials in the environment.

Cellulose from dinoflagellates as a versatile and environmentally friendly platform for the production of functionalised cellulose nanofibres

Cellulose nanofibres (CNFs), also known as nano-fibrillated cellulose, have emerged as highly promising sustainable biomaterials owing to their numerous advantages, including high accessibility, long-term sustainability, low toxicity, and mechanical properties. Recently, marine organisms have been explored as novel and environmentally friendly sources of cellulose fibers (CFs) due to their easy cultivation, extraction and biocompatibility. Dinoflagellates, a group of marine phytoplankton, have gained particular attention due to their unique cellulosic morphology and lignin-free biomass. Previously, we showed that the unique amorphous nature of dinoflagellate-derived cellulose offers various benefits. This study further explores the potential of dinoflagellate-derived CFs as a sustainable and versatile CNF source. Extracted dinoflagellate cellulose is effectively converted into CNFs via one-step TEMPO oxidation without significant polymer degradation. In addition, the biological compatibility of the CNFs is improved by amine-grafting using putrescine and folic acid. The products are characterised by conductometric titration, zeta potential measurements, TGA, GPC, FTIR, SEM/TEM, XRD, and XPS. Finally, in a proof-of-principle study, the application of the functionalised CNFs in drug delivery is tested using methylene blue as a drug model. Our findings suggest that dinoflagellate-derived CNFs provide an eco-friendly platform that can be easily functionalised for various applications, including drug delivery.

Simulation and on-line monitoring using optical fiber Bragg grating sensors of temperature history during laser-assisted automated fiber placement

Automated fiber placement (AFP) in situ consolidation (ISC) of thermoplastic composite possess the potential to reduce manufacturing costs and improve manufacturing efficiency. The properties of composite manufactured by the ISC are affected by several mechanisms including polymer degradation, crystallization, intimate contact, polymer healing and void dynamics. All these mechanisms are directly affected by the temperature history. Consequently, the control and accurate measurement of temperature history during ISC are particularly important for improving the properties of composite. In this study, a simplified three-dimensional transient heat transfer model was established. The effect of tool temperature and placement speed on the temperature history and peak temperature were predicted. Simultaneously, an online temperature monitoring system was built and the optical Fiber Bragg Grating sensors (FBGS) was used to measure the temperature history. The results indicated that the predicted results of the model were consistent with the measured results, the error was below 8%. In addition, the temperature history of layers was significantly affected by the tool temperature and placement speed. The temperature of the layers decreased to near the tool temperature after cooling, and a higher tool temperature increasing its peak temperature because of the reduce of the cooling rate. On the contrary, an increase in placement speed will reduce the peak temperature of the layers.

Polyurethanes Thermal, Hydrolytic and Soil Degradation: Systematic Literature Review

A search in the Scopus and Web of Science databases covering the period from 2016 to 2021 was carried out and used to update the methodology of polyurethanes hydrolytic, thermal and soil degradation assessment. To that effect, three groups of search words were used: (1) polymer degradation AND “hydrolytic degradation” AND polyurethane; (2) polymer degradation AND “thermal degradation” AND polyurethane; and (3) polymer degradation AND “soil degradation” AND polyurethane. It was observed that the studies on the degradation of polymers are disseminated in different research groups and on a continuous basis during the survey period. The main methodologies found to perform the degradation of polymers were: method of immersion of samples in aqueous solution to evaluate hydrolytic degradation, thermogravimetric analysis, differential exploratory calorimetry and accelerated weathering to evaluate thermal degradation and inoculation of the polymer in soils with different characteristics, such as pH, moisture and organic load to assess soil degradation. Polymers can become a biodegradable solution to the environmental issues generated by plastic waste.

A non-spherical nanoparticles system for the delivery of peptides using polymer grafted nanocellulose

AbstractPeptide drugs are increasingly used to treat a variety of diseases ranging from cancer, and infections to cardiovascular diseases. However, peptides can suffer from low stability in the bloodstream. Entrapment of peptides into nano-sized carriers of various types has widely been explored, but all of them have spherical shapes. Nanocellulose can in contrast serve as a non-spherical nanoparticle with a high aspect ratio. After the isolation of nanocellulose by TEMPO-mediated oxidation, the material needs to be modified with polymers to generate nanoparticles with high water-solubility that can also favourably interact with peptide drugs. We have here chosen insulin as the model drug, which can strongly interact with cationic polymers. As it is known that cationic polymer may retain charged drugs too tightly, we have selected poly(2-(dimethylamino)ethyl acrylate) PDMAEA as a degradable polymer that undergoes self-hydrolysis to poly(acrylic acid) in water. This polymer was compared to poly(N-(3-(dimethylamino)propyl) acrylamide) PDMAPAA, which is a stable cationic polymer. The cationic polymer was co-grafted with poly(2-hydroxyethyl acrylate) PHEA as a water-soluble neutral polymer using the three-component Passerini reaction. A combination of fluorescence and UV-Vis techniques were used to quantify the amount of polymer that was conjugated to the surface. The polymer-coated nanocellulose was labelled with the fluorescent cyanine dye Cy5 while insulin was labelled with Cy3 creating a FRET system that allows monitoring of the interaction between insulin and polymer in cell growth media. We observed that despite the self-hydrolysis of PDMAEA into a negatively charged polymer, the negatively charged insulin was not released in buffer solution according to the FRET studies. Only the addition of serum-supplemented cell growth media led to insulin release. The limited release was explained with the fact that insulin, as well as other peptides, have a mixture of negative and positive charges, with the pH value and the isoelectric point determining the balance between both. Negative-charged polymers can therefore still interact favourably with negatively charged peptides by interacting with cationic amino acids. Graphical Abstract

Simulation and Experimental Study of the Isothermal Thermogravimetric Analysis and the Apparent Alterations of the Thermal Stability of Composite Polymers.

Composite polymers are an interesting class of materials with a wide range of applications. Among the properties of polymers which are currently being enhanced via the development of composite materials is their thermal stability, which is typically evaluated via thermogravimetric analysis (TGA). In this work, a paradox is recognized regarding the considered relationship between the polymer-filler interactions leading to a good dispersion of the filler and the improvement of thermal stability. Simulation of the TGA signal during isothermal measurements of composite polymers is performed along with experimental measurements. It is shown that there are at least three factors that can cause apparent alterations of the thermal stability of composite polymers, namely, the different buoyancy due to the different densities of the composites and the neat polymer, the different thermal diffusivity of the composites and the fact that the mass loss (or remaining mass) of the composites, conventionally, is expressed per overall mass of the composite and not per mass of polymer. The relative contributions of these factors are evaluated and it is found that the conventional expression of mass loss has the most profound effect. Furthermore, it is shown that it is proper to express and evaluate the TGA results of composite polymers per degradable (polymer) mass of the composite and not per overall mass of the composite.

Study of Different Method of Plastic Waste Management in the Light of Ecosystem Balance

The present study is related to different method of plastic waste management in the light of ecosystem balance. Plastic waste has become a major environmental concern, causing pollution in both land and marine ecosystems. As a result, plastic debris is accumulating in landfills and natural environments instead of decomposing. This accumulation is causing various environmental hazards and negatively impacting habitats and species distribution. To address this issue, researchers have been focusing on finding effective methods of plastic waste management that promote ecosystem balance. These methods include microbial agents and their metabolic enzymes for polymer degradation and destructive thermal treatments like combustion or pyrolysis. In addition, different countries have implemented varying waste management strategies to tackle plastic pollution. Indiscriminate use of plastics such as polyethylene causes environmental pollution and impacts human health due to irreversible changes in the ecological cycle. The future of plastic waste management research lies in the continuous innovation of recycling technologies, the development of environmentally friendly alternatives, and the integration of social and behavioural considerations in waste management strategies. By addressing these areas, research can contribute to the advancement of sustainable and effective solutions for plastic waste handling, furthering the goal of achieving ecosystem balance and minimizing environmental harm. A comprehensive assessment of plastic management strategies should consider their environmental, economic, and social implications to gauge their overall effectiveness in addressing the challenges of plastic waste. This multifaceted approach will provide a holistic understanding of the impact of plastic waste management efforts and guide future decision-making to further enhance the sustainability and effectiveness of plastic waste handling..

Genetic Modifications in Bacteria for the Degradation of Synthetic Polymers: A Review.

Synthetic polymers, commonly known as plastics, are currently present in all aspects of our lives. Although they are useful, they present the problem of what to do with them after their lifespan. There are currently mechanical and chemical methods to treat plastics, but these are methods that, among other disadvantages, can be expensive in terms of energy or produce polluting gases. A more environmentally friendly alternative is recycling, although this practice is not widespread. Based on the practice of the so-called circular economy, many studies are focused on the biodegradation of these polymers by enzymes. Using enzymes is a harmless method that can also generate substances with high added value. Novel and enhanced plastic-degrading enzymes have been obtained by modifying the amino acid sequence of existing ones, especially on their active site, using a wide variety of genetic approaches. Currently, many studies focus on the common aim of achieving strains with greater hydrolytic activity toward a different range of plastic polymers. Although in most cases the depolymerization rate is improved, more research is required to develop effective biodegradation strategies for plastic recycling or upcycling. This review focuses on a compilation and discussion of the most important research outcomes carried out on microbial biotechnology to degrade and recycle plastics.

Sustainable waterborne polyurethane/lignin nanoparticles composites: Durability meets degradability

Optimizing the durability and degradability of polymers is essential for prolonging their useful life and minimizing their environmental footprint post-use, contributing to a sustainable world; however, durability in many cases conflicts with degradability. In this context, we developed lignin-based waterborne polyurethane (WPU) composites that bypass this dichotomy. Lignin nanoparticles (LNP), derived from enzymatic hydrolysis lignin (EHL), were synthesized using the anti-solvent method and incorporated into WPU emulsions through solution blending. The introduction of 5 wt% LNP notably improved the tensile strength of WPU composites, increasing it from 21.5 MPa to 29.7 MPa, a surge of up to 38 %. Moreover, 5 wt% of LNP significantly enhanced the durability of WPU by reducing creep strain (under a stress of 1 MPa for 3000 s) from 606 % to 70 % with an 88 % decrease, and by increasing molecular weight retention rate from 11 % to 87 % after 15 days of UV exposure. Concurrently, LNP notably accelerated the alkaline degradability of WPU/LNP composites, with weight loss rate increasing from 38 % to 92 % (a 142 % increase) and molecular weight loss from 17 % to 44 % (a 159 % increase), compared to pure WPU. The strategy employed in this study leverages the inherent properties of LNP to offer a promising approach to enhancing polymer sustainability, presenting an effective solution to the significant end-of-life challenge.

Experimental characterization and numerical prediction for mechanical aging of epoxy and its carbon fiber‐reinforced composite under hydrothermal conditions

AbstractThe Aqueous environment impairs the mechanical performance of carbon fiber‐reinforced polymers (CFRPs) and decreases the durability of engineering structures made of CFRPs primarily by degrading the resin matrix. Hence, the objective of this study is to investigate and accurately predict the influence of hydrothermal aging on the epoxy and its carbon fiber reinforced polymer (CFRP). Particularly, this work developed a modeling method that combined Fick's model, empirical aging model and elastoplastic constitutive model to predict the mechanical behavior of hydrothermally aged epoxy matrix. After the experimental characterization, this epoxy modeling method demonstrated its predictive capability on the mechanical response of the deteriorated epoxy under different hydro‐thermal‐salt conditions, with the mean absolute percent error (MAPE) of approximately 4.61%. Furthermore, the transverse compressive behavior of unidirectional (UD) CFRPs could be predicted by using the representative volume element (RVE) model with the degraded matrix behavior predicted via this epoxy modeling method. Integrated with this CFRP modeling, results from mechanical tests and fracture analysis further demonstrated that the hydrothermal aging effect on the transverse compressive performance of the UD CFRPs was dominated by the deterioration of their resin matrix. Therefore, this study demonstrates the feasibility of the finite element analysis (FEA) for mechanical aging of the epoxy matrix and its CFRP under hydrothermal conditions via employing the proposed integrated modeling method.Highlights Degradation of epoxy polymer under hydro‐thermal‐salt aging conditions. Integrated model to predict mechanical response of hydrothermally aged epoxy. RVE model to predict the mechanical behavior of hydrothermally aged CFRP. Hydrothermal aging on the transverse compressive behavior of UD CFRP.

The Use of Raman Spectroscopy to Assess the Degradation of Poly(p-dioxanone) Fibre Intended for Medical Purposes

Raman spectroscopy can be used in chemistry not just to determine chemical composition, but also to obtain further information on the material structure. In the spectra of semi-crystalline polymers, distinct bands characteristic of the crystalline or the amorphous phase can be found, the degree of crystallinity determined from them, and the degree of polymer degradation estimated from the crystallinity. In the present study, changes in the 1733 cm−1 band shoulder in Raman spectra of poly(p-di­oxanone) fibres subjected to hydrolytic degradation were evaluated. For different degradation periods, the areas under the shoulder of this band were calculated and a model deconvolution of this band into assumed crystalline and amorphous peaks was also performed. The areas under the shoulder, as well as the model peaks' parameters, were compared with the crystallinity values obtained by differential scanning calorimetry, achieving a good agreement. This work shows an example of using Raman spectroscopy when studying the hydrolytic degradation of polymers.

One-pot two-step biocatalytic upgrading of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid (FDCA) through a sequential oxidation process

2, 5-furandicarboxylic acid (FDCA) is a versatile bio-based building block that can be used for the synthesis of degradable polymers. Recently, developing green and sustainable catalytic processes for producing FDCA from renewable platform chemical molecules has attracted continuing attention. In this study, we proposed a green and sustainable one-pot, two-step biocatalytic process for the sequential oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to form FDCA with good yield and excellent selectivity. The initial step involves the oxidation of HMF to 2, 5-diformylfuran (DFF) and 5-formyl-2-furancarboxylic acid (FFCA) catalyzed by recombinant E. coli cells expressing a 5-hydroxymethylfurfural oxidase. The second step is to convert DFF and FFCA into FDCA final product via aldehyde oxidation reaction catalyzed by Deinococcus wulumuqiensis R12 whole cells. Combining the two different whole-cell biocatalysts, 180 mM of HMF could be easily converted into FDCA with a yield of 99% under optimized reaction conditions. This study offers an efficient and sustainable approach for the valorization of biomass-based HMF to form value-added FDCA.

Development of Degradable Polymers with Controlled Degradation and Applications to Transient Organic Solar Cells

Development of Degradable Polymers with Controlled Degradation and Applications to Transient Organic Solar Cells

The potential of White Rot fungi from Indonesia for biodegradation of expanded polystyrene

Expanded polystyrene (EPS) is a polymer known for its remarkable resistance to degradation. Despite several studies conducted on polymer degradation, there is still limited information about the use of White Rot fungi (WRF) to degrade EPS. Our study aims to explore the potential of WRF, which are known to have several isozymes of laccase, a powerful oxidoreductases that potentially could aid in EPS biodegradation. We evaluated the results based on two parameters: (1) morphological damage observed through gravimetry and Scanning Electron Microscope (SEM), and (2) physical, chemical, and mechanical properties of degraded EPS characterized using Universal Attenuated Total Reflection-Fourier Transform Infrared (UATR-FTIR), Thermogravimetric (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), and Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS). Our findings revealed that Phelinus noxius BRB 11 and Leiotrametes menziesii BRB 73 were able to resist 10.000 ppm EPS and demonstrated growth rates of 1.86 and 1.22 cm/day, respectively, causing 16 and 1% EPS weight loss after 30 days of incubation. UATR-FTIR analysis showed significant changes in the transmittance value of treated EPS. Phelinus noxius BRB 11 exhibited the highest crystallinity and the lowest styrene percentage area compared to Leiotrametes menziesii BRB 73. Based on all parameters in this study, our results suggest that Phelinus noxius BRB 11 has the best potential as a polymer degradation agent, particularly for EPS.

Synthetic Degradable Polyvinyl Alcohol Polymer and Its Blends with Starch and Cellulose-A Comprehensive Overview.

Approximately 50% of global plastic wastes are produced from plastic packaging, a substantial amount of which is disposed of within a few minutes of its use. Although many plastic types are designed for single use, they are not always disposable. It is now widely acknowledged that the production and disposal of plastics have led to a plethora of negative consequences, including the contamination of both groundwater and soil resources and the deterioration of human health. The undeniable impact of excessive plastic manufacturing and waste generation on the global plastic pollution crisis has been well documented. Therefore, degradable polymers are a crucial solution to the problem of the non-degradation of plastic wastes. The disadvantage of degradable polymers is their high cost, so blending them with natural polymers will reduce the cost of final products and maximize their degradation rate, making degradable polymers competitive with industrial polymers that are currently in use daily. In this work, we will delineate various degradable polymers, including polycaprolactone, starch, and cellulose. Furthermore, we will elucidate several aspects of polyvinyl alcohol (PVA) and its blends with natural polymers to show the effects of adding natural polymers on PVA properties. This paper will study cost-effective and ecologically acceptable polymers by combining inexpensive natural polymers with readily accessible biodegradable polymers such as polyvinyl alcohol (PVA).

Bulk Free Radical Terpolymerization of Butyl Acrylate, 2-Methylene-1,3-Dioxepane and Vinyl Acetate: Terpolymer Reactivity Ratio Estimation.

This investigation introduces the first estimation of ternary reactivity ratios for a butyl acrylate (BA), 2-methylene-1,3-dioxepane (MDO), and vinyl acetate (VAc) system at 50 °C, with an aim to develop biodegradable pressure-sensitive adhesives (PSAs). In this study, we applied the error-in-variables model (EVM) to estimate reactivity ratios. The ternary reactivity ratios were found to be r12 = 0.417, r21 = 0.071, r13 = 4.459, r31 = 0.198, r23 = 0.260, and r32 = 55.339 (BA/MDO/VAc 1/2/3), contrasting with their binary counterparts, which are significantly different, indicating the critical need for ternary system analysis to accurately model multicomponent polymerization systems. Through the application of a recast Alfrey-Goldfinger model, this investigation predicts the terpolymer's instantaneous and cumulative compositions at various conversion levels, based on the ternary reactivity ratios. These predictions not only provide crucial insights into the incorporation of MDO across different initial feed compositions but also offer estimates of the final terpolymer compositions and distributions, underscoring their potential in designing compostable or degradable polymers.

One-Pot Four-Component Synthesis of Acid-Responsive and Degradable Heterochain Polymers with Nonconventional Luminescence

One-Pot Four-Component Synthesis of Acid-Responsive and Degradable Heterochain Polymers with Nonconventional Luminescence

Towards scalable and degradable bioplastic films from Moringa oleifera gum/poly(vinyl alcohol) as packaging material

The use of plant gum-based biodegradable bioplastic films as a packaging material is limited due to their poor physicochemical properties. However, combining plant gum with synthetic degradable polymer and some additives can improve these properties. Keeping in view, the present study aimed to synthesize a series of bioplastic films using Moringa oleifera gum, polyvinyl alcohol, glycerol, and citric acid via thermal treatment followed by a solution casting method. The films were characterized using analytical techniques such as FTIR, XRD, SEM, AFM, TGA, and DSC. The study examined properties such as water sensitivity, gas barrier attributes, tensile strength, the shelf life of food, and biodegradability. The films containing higher citric acid amounts showed appreciable %elongation without compromising tensile strength, good oxygen barrier properties, and biodegradation rates (>95%). Varying the amounts of glycerol and citric acid in the films broadened their physicochemical properties ranging from hydrophilicity to hydrophobicity and rigidity to flexibility. As all the films were synthesized using economical and environmentally safe materials, and showed better physicochemical and barrier properties, this study suggests that these bioplastic films can prove to be a potential alternative for various packaging applications.