Polymer Polyethylene Research Articles

Effect of Rheological on the Physical and Electrical Properties of Extruded Micro Carbon -LLDPE Composites

This study focuses on formulating and optimizing a conductive polymer composite (CPC) material tailored for electromechanical applications. Linear Low-Density Polyethylene (LLDPE) polymer and micro carbon particles derived from rice husk were compounded using a hot compaction process and melt blended through a single-screw extrusion machine. A mix of 50% loading of microcarbon particles was used in this research. It was determined that the experiment was successfully conducted, resulting in a stabilized density of approximately 1 g/cm³. The research demonstrates how the prototype Extruder Head effectively stabilizes the density of composites. Electrical conductivity demonstrated a notable increase in conductivity toward higher density. These findings underscore the successful development of a CPC material with improved electrical conductivity, making it a highly suitable tool for high carbon-loading composite material.

From microplastics to pixels: testing the robustness of two machine learning approaches for automated, Nile red-based marine microplastic identification.

Despite the urgent need for accurate and robust observations of microplastics in the marine environment to assess current and future environmental risks, existing procedures remain labour-intensive, especially for smaller-sized microplastics. In addition to this, microplastic analysis faces challenges due to environmental weathering, impacting the reliability of research relying on pristine plastics. This study addresses these knowledge gaps by testing the robustness of two automated analysis techniques which combine machine learning algorithms with fluorescent colouration of Nile red (NR)-stained particles. Heterogeneously shaped uncoloured microplastics of various polymers-polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC)-ranging from 100 to 1000µm in size and weathered under semi-controlled surface and deep-sea conditions, were stained with NR and imaged using fluorescence stereomicroscopy. This study assessed and compared the accuracy of decision tree (DT) and random forest (RF) models in detecting and identifying these weathered plastics. Additionally, their analysis time and model complexity were evaluated, as well as the lower size limit (2-4µm) and the interoperability of the approach. Decision tree and RF models were comparably accurate in detecting and identifying pristine plastic polymers (both > 90%). For the detection of weathered microplastics, both yielded sufficiently high accuracies (> 77%), although only RF models were reliable for polymer identification (> 70%), except for PET particles. The RF models showed an accuracy > 90% for particle predictions based on 12-30 pixels, which translated to microplastics sized < 10µm. Although the RF classifier did not produce consistent results across different labs, the inherent flexibility of the method allows for its swift adaptation and optimisation, ensuring the possibility to fine-tune the method to specific research goals through customised datasets, thereby strengthening its robustness. The developed method is particularly relevant due to its ability to accurately analyse microplasticsweathered under various marine conditions, as well as ecotoxicologically relevant microplastic sizes, making it highly applicable to real-world environmental samples.

Multidimensional analysis of textiles coated with electroactive polymers for actuators

This paper presents a multidimensional analysis of textiles coated with conductive polymers for actuators. The purpose of using multidimensional scaling analysis is to compare similarities and dissimilarities between conductive textiles obtained through conductive polymeric film deposition to observe the optimal value for electrical resistance and to select an adequate method to achieve conductive fabric using different polymers (polyethylene glycol, polyvinyl alcohol or polyvinylidene fluoride) and metal microparticles (copper or nickel). The multidimensional analysis is based on mapping a series of material properties from a proximity matrix (similarities or dissimilarities) between these properties. Multidimensional scaling allows rebuilding the exact map of the values (within approximately a symmetry or rotation). To fit dissimilarity or similarity matrices for multiple variables into one common space estimating the weight parameters for each variable, the INDSCAL model (individual differences multidimensional scaling) was used.

Microplastics at Environmentally Relevant Concentrations Had Minimal Impacts on Pelagic Zooplankton Communities in a Large In-Lake Mesocosm Experiment.

To assess the potential risks of contemporary levels of plastic pollution in freshwater ecosystems, a large-scale experiment was conducted over 10 weeks in a boreal lake at the IISD-Experimental Lakes Area (Ontario, Canada). Fragments of common polymers (polyethylene, polystyrene, and polyethylene terephthalate), each with distinct colors and buoyancies, were added as a single pulse to seven in-lake mesocosms in equal contributions in a range of environmentally relevant nominal concentrations (6-29,240 particles/L). Two additional mesocosms with no added microplastics were used as controls. Zooplankton ingested low levels of microplastics (mean of 0.06 particles/individual ± SD 0.07) and generally their total abundance and community composition were not negatively impacted. Temporary changes were however observed; total zooplankton abundance and abundance of calanoid copepods were temporarily stimulated by increasing nominal microplastic concentrations, and modest, short-term reductions in egg production of the cyclopoid copepod Tropocyclops extensus and abundance of copepod nauplii occurred. Collectively, these results suggest that microplastics could have complex impacts on zooplankton communities, stimulating some species while negatively impacting others.

Development of a comprehensive theoretical and experimental methodology for evaluating the parameters of recycling by pyrolysis of plastic based on polycarbonate and polyethylene

The results of thermogravimetric and Fourier transform infrared (FTIR) analysis of polymer composite materials (PCM) based on polyethylene and polycarbonate are presented and compared to the polymers polyethylene and polycarbonate. Empirical data were obtained for mathematical modeling, including the amount of solid residue upon pyrolysis, volatile yield, and ash content of the studied PCMs and polymers. Results of the mathematical modeling of the pyrolysis process at a temperature of 600 °C are presented to quantitatively assess the composition of the pyrolysis gas.

Passive sampling of polycyclic aromatic hydrocarbons with low-density polyethylene: Equilibration limitations in aqueous suspensions

Polyethylene (PE) and other polymers are widely and successfully used as passive samplers for organic pollutants in the environment. This study provides high-resolution experimental data from batch shaking tests on the uptake, reversibility, and linear equilibrium partitioning of polycyclic aromatic hydrocarbons (PAHs) using two different PE sheets of 30 µm and 80 µm thickness. Kinetics for phenanthrene are well described by a mechanistic first-order model with mass transfer limited by an aqueous boundary layer (with a mean thickness of 170 µm). Equilibration in laboratory batch systems during uptake and desorption is very rapid with characteristic times of 1–2 h but this depends on the boundary condition, e.g., the ratio of PE mass to water volume. Therefore, equilibration of PE in other setups, e.g., in soil slurries or sediment suspensions, may take orders of magnitude longer because the boundary condition for PE changes from finite to infinite bath conditions (soil or sediment particles may keep the concentration in water almost constant). Solid precipitates for high molecular weight PAHs explain partition coefficients below expected values because of kinetic limitations in such a system. Nevertheless, passive sampling can be employed safely if such limitations are considered; furthermore, partition coefficients can be estimated accurately by empirical relationships (e.g., within 0.1 log unit) based on molecular weight, octanol/water partition coefficients, or subcooled liquid solubilities.

Assessing ecological risks and microplastic pollution in a tropical coastal ecosystem: Effects of rainfall variability in Southeast India

Microplastic pollution poses a significant threat to coastal ecosystems, prompting an in-depth investigation into its seasonal fluctuations and ecological impacts. This study examines microplastics in Cuddalore’s coastal waters and sediments across four seasons. Results show varying microplastic concentrations, peaking during the monsoon and pre-monsoon seasons, likely influenced by rainfall variability. Fibers dominate in both water (69–100 %) and sediment samples (66–92 %), with polyethylene and polyethylene terephthalate as the predominant polymer types in water. Sediments exhibit a more diverse polymer distribution, with polypropylene and polyethylene terephthalate being prevalent. Elevated polymer hazard index and potential ecological risk index raise concerns, reaching values of 108930 and 1125, respectively. This underscores the urgency of implementing effective management strategies to safeguard tropical coastal ecosystems from microplastic pollution. This study highlights the complex interplay between seasonal dynamics, rainfall variability, polymer types, and pollution levels, emphasizing the need for proactive environmental management measures.

Investigation of Microplastic Contamination in the Gastrointestinal Tract of Fish: A Comparative Study of Various Freshwater Species

The aqueous environment has been reported to be seriously threatened by the pollution of microplastics (MPs), which has been confirmed in numerous studies affecting various aquatic habitats. Despite this, few investigations exist on MP contamination in fish of specific regions. Thus, the current study aims to determine MP concentrations in the fish species of the Chhota Nagpur zone of eastern India. From August to September 2023, fish samples were collected from 10 km distance between two locations of Subarnarekha and Kharkai river banks through fishermen. Microplastics were found in the gastrointestinal tract of 45 fish of 8 species out of 48 samples. Of these species, six species were secondary consumers, while the remaining two were primary consumers. The average amount of microplastics consumed by each fish (n = 48) was 3.0 ± 1.8. A total of 144 microplastics were found in collected samples of fish species. Among the analyzed sample of MPs, 69.4% were fibers, films were (22.3%), and (8.3%) were fragments. The least contaminated species was T. ilisha (0.8 ± 0.7 particles/ind.), while L. rohita had the highest microplastic contamination (4.5 ± 1.7 particles/ind.). The present study found a negative correlation of - 0.83 between MP consumption and the mean body weight of fish. Similarly, a negative correlation of - 0.5 was found between the length of fish and MP intake. Polyamide (nylon), polypropylene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, and polyethylene polymers were found. The size of MPs ranged from 45-355 μm and mainly were fibers. They were also predominantly blue and black. Polyamide and polyvinyl chloride were the common MP types in every specimen. The possible sources of MPs were fishing nets, ropes, and packaging material. This investigation points to MP contamination in aquatic ecosystems and particular species. It provides advanced knowledge of MP pollution, sources, and effects on regional ecosystems and public health.

Slurry Casted Ultrathin Li3Zr2Si2PO12 Electrolyte Film for Solid-State Lithium Metal Batteries.

Thin and flexible solid-state electrolyte (SSE) films with high ionic conductivity and low interfacial resistance are urgently required for lithium metal batteries (LMBs). However, it's still challenging to reduce the film thickness to <20µm, especially for those with high ceramic contents. Herein, a facile slurry casting method is developed to prepare the ultra-thin (14µm) Li3Zr2Si2PO12 (LZSP) films with ceramic content up to 91% using a composite polymer binder, polyvinylidene fluoride (PVDF), and polyethylene oxide (PEO). It shows that PEO not only enhanced the film flexibility but also makes it be easily peeled off to form a freestanding membrane, PLN. To promote the interfacial ion transport, PEO/lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) is introduced to the film surface, and the resultant tri-layer film, PPLN, shows a satisfying room temperature ionic conductivity of 0.116mScm-1, high Li+ transference number of 0.79, and good compatibility with metal lithium. As a result, LMBs using LiFePO4 cathode and PPLN electrolyte exhibit excellent safety as well as electrochemical performances in the wide temperature range between room temperature (RT) and 100°C.

Microplastics in the Atmospheric Deposited Dust Collected from Different Traffic Intersections in Dhaka City

Plastic particles less than 5 mm in size, known as microplastics, can infiltrate the environment from a variety of sources. This study aimed to assess the presence of microplastics (MPs) in the atmosphere at fifteen major traffic intersections in the greater Dhaka city from July to August 2022.The deposition rate (DP) of MPs was calculated and the observed DPs value ranged from 1.11×106 MPs/m2/day to 5.78×106 MPs/m2/day with a portion of microplastics exhibiting fluorescence activity. Fourier Transform Infrared (FTIR) spectroscopy was used to analyze the functional groups present in microplastics. The identified polymer compositions of MPs were polyethylene (PE), Nylon-6 and natural polymers (cellulose and rubber). The current study highlights the data and knowledge gaps on the atmospheric transport of microplastics and their impact to the deterioration of overall urban air quality. Dhaka Univ. J. Sci. 72(2): 07-14, 2024 (July)

Dynamic Complexity of a Discrete-time Prey-Predator Model with Mixed Functional Responses

Plastic particles less than 5 mm in size, known as microplastics, can infiltrate the environment from a variety of sources. This study aimed to assess the presence of microplastics (MPs) in the atmosphere at fifteen major traffic intersections in the greater Dhaka city from July to August 2022.The deposition rate (DP) of MPs was calculated and the observed DPs value ranged from 1.11×106 MPs/m2/day to 5.78×106 MPs/m2/day with a portion of microplastics exhibiting fluorescence activity. Fourier Transform Infrared (FTIR) spectroscopy was used to analyze the functional groups present in microplastics. The identified polymer compositions of MPs were polyethylene (PE), Nylon-6 and natural polymers (cellulose and rubber). The current study highlights the data and knowledge gaps on the atmospheric transport of microplastics and their impact to the deterioration of overall urban air quality. Dhaka Univ. J. Sci. 72(2): 15-24, 2024 (July)

Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries.

Microplastic pollution has raised significant concerns among scientific communities and society in recent years due to its increase and lesser-known effects on the environment. To improve the knowledge of microplastic pollution in freshwater, we investigated microplastics in Anzali Wetland, a Ramsar site in northern Iran, as well as its nine main entering rivers. The extracted microplastics were characterized via visual identification, SEM-EDX, and μ-Raman methods. Microplastics (size range: 50-5000 μm) were found in all water and sediment samples with concentration of fibrous particles as well as polypropylene and polyethylene polymers. The mean concentration of microplastics in bottom sediment and surface water samples of the wetland was 301 ± 222 particles∙kg-1 d.w. and 235 ± 115 particles∙m-3 (0.23 particles∙L-1), respectively. The microplastic concentration in the central and eastern parts of the wetland was higher than in other areas; however, the mean concentrations revealed homogeneity across the wetland area. Water properties (dissolved oxygen, pH, temperature, electrical conductivity, and salinity in water) did not affect the concentration of microplastic particles, though correlational analysis revealed a strong positive association between microplastic quantity and turbidity. There was a significant positive relationship between microplastic concentration and the percentage of clay in sediment samples. The quantity of microplastics in river water was higher than in wetland water, but the difference between the results was not significant. However, the quantity of microplastics in the river's littoral sediment was higher than in the bottom sediment of the wetland where the difference between the results was significant. Microplastic ecological risk assessment showed high potential ecological risk. The findings underscore the importance of effective management strategies and the implementation of policies to mitigate the negative impact of MP pollution on ecosystems and human health.

Rapid removal of methyl orange from aqueous media by modified Mg–Al layered double hydroxides

The current work deals with the synthesis of polymer modified synthetic clay, composed of Mg–Al layered double hydroxides (LDHs) and using a non-toxic organic polymer polyethylene glycol-400 (PEG400). A series of polymer-composites of Mg–Al LDH (LDHP-400) are prepared by changing concentrations of PEG-400 from 4% to 20 %, to find out the maximum adsorption efficiency for the adsorption of an industrially important anionic azo dye, MO from aqueous. The results depicted that LDH-P400, with 16 % PEG-400 shown the removal efficiency of 99.49 % for 100 ppm solution of MO (20 min). Effect of different factors such as dose of adsorbate, temperature, contact time, and pH of the solution, etc. are systematically investigated using batch experiments and thermodynamics parameters as well as kinetic studies are also carried out for the quick and instantaneous removal of MO from aqueous media. Maximum adsorption capacity of 198 mg/g has been achieved at pH4.2 and at temperature 313K for 100 ppm (mg/l) of MO in aqueous media using 0.5 g/l of adsorbent dose. Desorption studies reveal that prepared LDHP-400 can be reused and recycle up to three successive cycles with achieving 88.23 % recovery of MO, which confirmed that prepared LDHP-400 can be reused effectively for laboratory or industrial wastewater which has MO concentrations up to 100 ppm.

Fucoidan based polymeric nanoparticles encapsulating epirubicin: A novel and effective chemotherapeutic formulation against colorectal cancer

Colorectal cancer (CRC) is one of the most common and challenging malignancy that needs some effective and safer chemotherapeutic agents for the treatment. In this study, anticancer agent epirubicin (Epi) was loaded in polymeric polyethylene glycol-polylactic acid-nanoparticles (mPEG-PLA-NPs) coated with a marine anti-cancer non-toxic polysaccharide fucoidan (FC), to achieve a synergistic activity against CRC. The characterization of the NPs revealed that they were spherical, monodispersed, stable, with a negative zeta potential, and exhibited good biocompatibility and controlled release. In vitro anti-cancer activity of the NPs on HCT116 cell line was found to be promising, and corroborated well with in vivo studies involving BALB/C mice injected with C26 murine cancer cells. The outcome of MTT assay demonstrated that IC50 value of free Epi was 3.72 µM, and that of non-coated and coated Epi nano-formulations was 33.67 and 10.19 µM, respectively. Higher tumor regression, better survival and reduced off-side cardiotoxicity were observed when this novel NPs formulation was used to treat tumor-bearing mice. Free FC and Epi treated mice showed 37.73 % and 61.49 % regression in tumor size, whereas there was 79.76 % and 90.34 % tumor regression in mice treated with non-coated Epi NPs and coated Epi NPs, respectively. Therefore, mPEG-PLA-FC-Epi-NPs hold a potential to be used as an effective chemotherapeutic formulation against CRC, since it exhibited better efficacy and lower toxicity.

Polyethylene and related hydrocarbon polymers (“plastics”) are not biodegradable

Research on the biodegradation of polyethylene (PE), polystyrene (PS) and related polymers has become popular and the number of publications on this topic is rapidly increasing. However, there is no convincing evidence that the frequently claimed biodegradability of these so-called “plastics” really exists. Rather, a diffuse definition of the term “biodegradability” has led to the publication of reports showing either marginal weight losses of hydrocarbon polymers by the action of isolated bacterial strains or mechanical disintegration and polymer surface modification in case of hydrocarbon polymer-consuming insect larvae. Most of the data can be alternatively explained by the utilization of polymer impurities/additives, by the utilization of low molecular weight oligomers, and/or by physical fragmentation and subsequent loss of small fragments. Evidence for a (partial) biotic and/or abiotic oxidation of the amorphous polymer fraction and of surface-exposed hydrocarbon side chains is not sufficient to claim that PE is biodegradable. To the best of my knowledge, no report has been so far published in which substantial biodegradation and mineralization of PE or related (long chain length) hydrocarbon polymers to carbon dioxide has been convincingly demonstrated by the determination of the fate of carbon atoms in isotope-labeled polymers. It is disappointing that publications with a critical view on biodegradation of hydrocarbon polymers are not cited in most of these reports. The possibility should be considered that the rapidly expanding research field of hydrocarbon polymer biodegradation is chasing rainbows.

Enhancing osmotic stress tolerance of cell mimetics by modulating lipid bilayer

Seeking effective ways to maintain cellular homeostasis is crucial to the survival of organisms when they encounter osmotic stress. Glycine betaine (GB) is a widely generated natural osmolyte, but its endogenous production and action are limited. Herein, a kind of nonionic surfactant dodecyl-β-d-glucopyranoside (DG) and a common polymer polyethylene glycol (PEG) are proven to have the ability to enhance the osmotic stress (induced by sugar concentration changes) tolerance of cell and organism models, those are giant unilamellar vesicles (GUVs) and gram-negative Escherichia coli. DG or PEG only induces small size decrease and certain shape change of GUVs. Importantly, DG or PEG at the concentration 100 times lower than that of GB effectively increases the survival rate of bacteria under both hypoosmotic and hyperosmotic conditions. This intriguing result is attributed to the insertion of DG or adsorption of PEG in the lipid bilayer membrane, leading to enhanced membrane permeability. These exogenous substances can replace GB to facilely and highly efficiently augment adaptation of organisms to osmotic stress.

Enhancing tribological performance of high‐density polyethylene polymer with diamond‐like carbon coating and mollusk shells filler

AbstractThis study explores the tribological properties of mollusk‐shell‐high‐density polyethylene (MS‐HDPE) biocomposites and diamond‐like carbon (DLC)‐coated metal beads as potential substitutes for hip joint prostheses. HDPE biocomposites with 0, 5, and 10 wt% of MS were developed using hot compression molding. Coatings included pure DLC, DLC‐Si, and DLC W:H. Wear tests on a ball‐on‐disk tribometer examined friction and wear rates against coated and uncoated balls, along with wear morphology. MS‐HDPE demonstrated superior tribological performance against DLC, achieving a 67% reduction in specific wear rate compared to pure HDPE. The study suggests that 5 wt% MS‐HDPE coupled with a DLC‐coated counterpart coating could be a promising combination for orthopedic applications, presenting a potential solution to metal corrosion and wear debris issues in orthopedic implants.Highlights Tested coatings: DLC, DLC‐Si, and DLC W:H. Biocomposite wear versus coated balls. DLC coating improves wear with shell fillers. Mollusk shell strengthens biocomposites. Reduced wear rate by 63% and friction by 77%.

The effects of some common inorganic soil components on the pyrolytic analysis of plastics

Plastics and microplastics are major hazards for the environment and human health. Plastic materials in the sedimentary record are a marker for modern anthropogenic activity. One environmental reservoir of plastics and microplastics is soil. One method to detect the presence of plastics in soil, and to thereby recognise the presence of its hazards, is pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Yet soils are multicomponent mixtures and any analytical artefacts generated will reduce our ability to monitor the presence of plastics. We have studied the Py-GC-MS responses for the polymers polyethylene (PE), polypropylene (PP), polystyrene (PS) and poly(vinyl chloride) (PVC), in the presence of individual phyllosilicate (kaolinite, illite and montmorillonite) and iron oxyhydroxide/oxide (goethite and magnetite) minerals that may be present in soil. Our data show the distinctive polymer fingerprint becomes obscured when analysed with minerals. We have isolated the effects of some potential inorganic soil components so that responses from complex matrices can be deconvolved. The mineral-assisted aromatisation of compounds affects the diagnostic signals of the original polymer, particularly for those polymers (PE and PP) which have a large aliphatic hydrocarbon signature when analysed alone. Iron oxyhydroxide/oxide are shown to have a greater effect on the data than phyllosilicates. Our results will help guide future interpretations of Py-GC-MS data obtained when monitoring soils for plastic contamination. Py-GC-MS is most commonly applied as a qualitative method, yet detailed quantitation of the organic-inorganic reactions we have described, albeit analytically complex, would represent a useful future study.

Open- and Closed-Loop Recycling: Highly Active Zinc Bisguanidine Polymerization Catalyst for the Depolymerization of Polyesters.

In this study, the aliphatic N,N-bisguanidine zinc complex [Zn(DMEG2ch)2](OTf)2 ⋅ THF is introduced as a promising candidate for the chemical recycling of (bio) polyesters. This catalyst is highly active in the ring-opening polymerization (ROP) of lactide (LA) and ϵ-caprolactone (CL). The combination of polymerization and depolymerization activity creates new pathways towards a sustainable circular economy. The catalytic activity of [Zn(DMEG2ch)2](OTf)2 ⋅ THF for the chemical recycling of polylactide (PLA) via alcoholysis was investigated by detailed kinetic and thermodynamic studies. It is shown that various high value-added alkyl lactates can be obtained efficiently under mild reaction conditions. Catalyst recycling was successfully tested using ethanol for the degradation of PLA. In addition, LA can be recovered directly from PLA, enabling either open- or closed-loop recycling. Selective PLA degradation from mixtures with polyethylene terephthalate (PET) and polymer blends are presented. For the first time, a cascade recycling reaction of a PLA/polycaprolactone (PCL) blend is tested with a zinc-based bisguanidine catalyst, whereby PLA is degraded selectively at first and subsequent modification of the reaction conditions leads to efficient degradation of the remaining PCL. The highly active, universally applicable benign zinc catalyst allows the implementation of a circular plastics economy and thus the reduction of plastic pollution in the environment.

Double glass transition in polyethylene naphthalate by MDSC, BDS, and TSDC.

In this work, we present an experimental study of the primary and secondary relaxations of the semi-crystalline polymer polyethylene naphthalate by modulated differential scanning calorimetry, Thermally Stimulated Depolarization Currents (TSDCs), and Broadband Dielectric Spectroscopy (BDS) and how they are affected by physical aging. Three dipolar relaxation modes can be observed: from slowest to fastest: the primary α relaxation, which vitrifies at the glass transition temperature, Tgα, and two secondary relaxations, named β* and β. Modulated differential scanning calorimetry results show how the secondary β* relaxation also vitrifies, giving rise to an additional glass transition at Tgβ* < Tgα. In fact, the α and β* relaxations can be considered as part of a very broad and distributed relaxation. Its main part is the primary α relaxation with a shoulder at the high-frequency region corresponding to a complex secondary β* relaxation. BDS results about β* can be modeled by a main contribution (β3*) and two additional ones (β1* and β2*) with a weaker dielectric strength. TSDC results show that each single mode of the relaxation has its own glass transition temperature and they are compatible with the structure inferred by BDS. This scenario gives rise to an extended glass transition dually centered in the Tgβ* ∼ 305K and Tgα ∼ 387K temperatures.