-
Molecules (Basel, Switzerland) Jan 2022While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home... (Review)
Review
While bio-based but chemically synthesized polymers such as polylactic acid require industrial conditions for biodegradation, protein-based materials are home compostable and show high potential for disposable products that are not collected. However, so far, such materials lack in their mechanical properties to reach the requirements for, e.g., packaging applications. Relevant measures for such a modification of protein-based materials are plasticization and cross-linking; the former increasing the elasticity and the latter the tensile strength of the polymer matrix. The assessment shows that compared to other polymers, the major bottleneck of proteins is their complex structure, which can, if developed accordingly, be used to design materials with desired functional properties. Chemicals can act as cross-linkers but require controlled reaction conditions. Physical methods such as heat curing and radiation show higher effectiveness but are not easy to control and can even damage the polymer backbone. Concerning plasticization, effectiveness and compatibility follow opposite trends due to weak interactions between the plasticizer and the protein. Internal plasticization by covalent bonding surpasses these limitations but requires further research specific for each protein. In addition, synergistic approaches, where different plasticization/cross-linking methods are combined, have shown high potential and emphasize the complexity in the design of the polymer matrix.
Topics: Biocompatible Materials; Cross-Linking Reagents; Enzymes; Hot Temperature; Mechanical Phenomena; Plasticizers; Proteins
PubMed: 35056758
DOI: 10.3390/molecules27020446 -
The Science of the Total Environment Jan 2023Plastic pollution in our oceans is of growing concern particularly due to the presence of toxic additives, such as plasticisers. Therefore, this work aims to develop a...
Plastic pollution in our oceans is of growing concern particularly due to the presence of toxic additives, such as plasticisers. Therefore, this work aims to develop a comprehensive understanding of the leaching properties of plasticisers from microplastics. This work investigates the leaching of phthalate acid ester (dioctyl terephthalate (DEHT) and diethylhexyl phthalate (DEHP)) and diphenol (bisphenol A (BPA) and bisphenol S (BPS)) plasticisers from polystyrene (PS) microplastics (mean diameter = 136 μm to 1.4 mm) under controlled aqueous conditions (temperature, agitation, pH and salinity). The leaching behaviours of plasticised polymers were quantified using gel permeation chromatography, high performance liquid chromatography and thermal gravimetric analysis, and the particle's plasticisation characterised using differential scanning calorimetry. Leaching rates of phthalate acid ester and diphenol plasticisers were modelled using a diffusion and boundary layer model, whereby these behaviours varied depending on their plasticisation efficiency of PS, the size of the microplastic particle and the surrounding abiotic conditions. Leaching behaviours of DEHT and DEHP were strongly influenced by the microplastic-surface water boundary layer properties, thus wave action (i.e., water agitation) increased the leaching rate of these plasticiser up to 66 % over 21-days, whereas BPA and BPS plasticisers displayed temperature- and size-dependent leaching and were limited by molecular diffusion throughout the bulk polymer (i.e., the microplastic). This information will improve predictions of plasticiser concentration (both that remain in the plastic and released into the surrounding water) at specific time points during the lifetime of a plastic, ultimately ensuring greater accuracy in the assessment of toxicity responses and environmental water quality.
Topics: Microplastics; Plasticizers; Plastics; Polystyrenes; Diethylhexyl Phthalate; Polymers; Esters
PubMed: 36181812
DOI: 10.1016/j.scitotenv.2022.159099 -
Advances in Clinical and Experimental... Jul 2017Tissue conditioners (TCs) are short-term soft liners, formed in situ from a mixture of a polymer powder and a liquid plasticizer. This article reviews the recent... (Review)
Review
Tissue conditioners (TCs) are short-term soft liners, formed in situ from a mixture of a polymer powder and a liquid plasticizer. This article reviews the recent advances in the composition, functions, clinical use, gelation process, and physical properties of TCs and their effects on denture bases and oral mucosa. TCs are used to improve the fit and function of an ill-fitting denture. They can also be used to treat abused mucosal tissues underlying ill-fitting acrylic dentures as temporary expedients. TCs are recommended as provisional liners to maintain the fit of removable dentures and to prevent mechanical irritation from the denture. TCs may also be used to rehabilitate cancer patients. The polymer powder, used in the formulation of TCs generally consists of polyethyl methacrylate (PEMA) and the liquid plasticizer is ester-based in ethyl alcohol solution without an acrylic monomer. The plasticizers are low molecular weight aromatic esters. Mixing of the powder and liquid results in polymer chain entanglement and the formation of a coherent gel characterized by viscoelastic behavior appropriate to its intended clinical use. The loss of surface integrity and surface roughness of TCs are regarded as the main problems in the denture bearing oral mucosa conditions resulting in inflammation of oral mucosa of the denture-bearing area - denture stomatitis. TCs provide an even distribution of masticatory force, accurately modeling itself to the changes which occur during the healing of lesion of substrate and can act therapeutically by incorporating antifungal or antibacterial agents.
Topics: Denture Bases; Denture Liners; Humans; Methylmethacrylates; Plasticizers
PubMed: 28691420
DOI: 10.17219/acem/62634 -
Environment International Jan 2021We present a list of Chemicals of Concern (CoCs) in plastic toys. We started from available studies reporting chemical composition of toys to group plastic materials, as...
We present a list of Chemicals of Concern (CoCs) in plastic toys. We started from available studies reporting chemical composition of toys to group plastic materials, as well as to gather mass fractions and function of chemicals in these materials. Chemical emissions from plastic toys and subsequent human exposures were then estimated using a series of models and a coupled near-field and far-field exposure assessment framework. Comparing human doses with reference doses shows high Hazard Quotients of up to 387 and cancer risk calculated using cancer slope factors of up to 0.0005. Plasticizers in soft plastic materials show the highest risk, with 31 out of the 126 chemicals identified as CoCs, with sum of Hazard Quotients >1 or child cancer risk >10. Our results indicate that a relevant amount of chemicals used in plastic toy materials may pose a non-negligible health risk to children, calling for more refined investigations and more human- and eco-friendly alternatives. The 126 chemicals identified as CoCs were compared with other existing regulatory prioritization lists. While some of our chemicals appear in other lists, we also identified additional priority chemicals that are not yet covered elsewhere and thus require further attention. We finally derive for all considered chemicals the maximum Acceptable Chemical Content (ACC) in the grouped toy plastic materials as powerful green chemistry tool to check whether chemical alternatives could create substantial risks.
Topics: Child; Environmental Exposure; Humans; Plasticizers; Plastics; Play and Playthings; Risk Assessment
PubMed: 33115697
DOI: 10.1016/j.envint.2020.106194 -
The Science of the Total Environment Dec 2022The study highlights the potential of Environmental Specimen Banks (ESBs) for implementing the Zero Pollution Ambition and the Biodiversity Strategy of the European... (Review)
Review
The study highlights the potential of Environmental Specimen Banks (ESBs) for implementing the Zero Pollution Ambition and the Biodiversity Strategy of the European Green Deal. By drawing on recent monitoring studies of European ESBs, we illustrate the role ESBs already play in assessing the state of ecosystems in Europe and how they help to make developments over time visible. The studies reveal the ubiquitous presence of per- and polyfluoroalkyl substances, halogenated flame retardants, chlorinated paraffins, plasticizers, cyclic volatile methyl siloxanes, UV-filters, pharmaceuticals, and microplastics in the European environment. Temporal trends demonstrate the effectiveness of European regulations on perfluorooctane sulfonic acid, pentabrominated diphenylethers and diethylhexyl phthalate, but also point to the rise of substitutes such as non-phthalate plasticizers and short-chain perfluoroalkyl substances. Other studies are wake-up calls indicating the emergence of currently unregulated compounds such as long-chain chlorinated paraffins. Ecological studies show temporal trends in biometric parameters and stable isotope signatures that suggest long-term changes in environmental conditions. Studies on biodiversity of ecosystems using environmental DNA are still in their beginnings, but here too there is evidence of shifts in community composition that can be linked to changing environmental conditions. This review demonstrates the value of ESBs (a) for describing the status of the environment, (b) for monitoring temporal changes in environmental pollution and the ecologic condition of ecosystems and thereby (c) for supporting regulators in prioritizing their actions towards the objectives of the Green Deal.
Topics: Environmental Monitoring; Ecosystem; Plasticizers; Fluorocarbons; Flame Retardants; Diethylhexyl Phthalate; Microplastics; DNA, Environmental; Plastics; Siloxanes; Paraffin; Pharmaceutical Preparations
PubMed: 36055484
DOI: 10.1016/j.scitotenv.2022.158430 -
International Journal of Biological... Jan 2022The structures of starch and starch-based materials determine additives migration from material matrix. Propionylated starch derived from waxy, normal, G50 and G80...
The structures of starch and starch-based materials determine additives migration from material matrix. Propionylated starch derived from waxy, normal, G50 and G80 starch were selected as the matrix, the amylose effect on plasticizer (triacetin) migration as well as structural changes in hydrophobic starch-based films were discussed. The constant (k) of first-order rate and initial release rate (V) of triacetin migration were consistent with the increment of amylose content. Meanwhile, diffusion model disclosed that Fick's second law was apposite to characterize the short-term migration of triacetin, and larger diffusion coefficient (D) values of short- and long-term migration were also found in films with higher amylose content, indicating that amylose-formed structures were in favor of triacetin migration. In comparison of propionylated amylopectin, Van der Waals's interactions between propionylated amylose and triacetin were easier to be weakened with the migration of triacetin, which promoted the decrease of wavenumber of C-O-C, and enlarged the inter-planner spacing of crystalline structures, promoting the formation of amorphous structures and wrinkles and embossments in films with higher amylose content. This work confirmed that regulating the structures of starch were effective to control the migration behavior of additives from starch-based films.
Topics: Amylopectin; Amylose; Hydrophobic and Hydrophilic Interactions; Microscopy, Electron, Scanning; Plasticizers; Scattering, Small Angle; Starch; X-Ray Diffraction
PubMed: 34838859
DOI: 10.1016/j.ijbiomac.2021.11.138 -
International Journal of Biological... Nov 2022Polyvinylidene fluoride (PVDF) is commonly used in the chemical, electronic, and petrochemical industries because of its chemical and physical attributes. This study...
Polyvinylidene fluoride (PVDF) is commonly used in the chemical, electronic, and petrochemical industries because of its chemical and physical attributes. This study aimed to make novel PVDF-based composite with a high loading of silanized wood powder and micro/nanocellulose fibers, where glycerol acts as both a dispersant and a plasticizer all-in-one composite application for the first time. The purpose was also extended to systematically investigate their mechanical properties and melt flow. Results have demonstrated the efficiency of utilizing the cellulose fibers in bio-composites. With the addition of 30 wt% of filling materials, When the content of silanized cellulose fibers in glycerol dispersion is 25 wt%, the flexural strength and tensile strength reach the maximum value 72.30 MPa and 52.28 MPa. The experimental results indicate that silanized micro/nanocellulose fiber-reinforced PVDF/wood composites are a promising composite formula to help improve performance and reduce costs. It is an excellent example of utilizing biomass resources as a renewable/recyclable, sustainable and low-cost material to reduce the use of petroleum-based polymer, and improve the mechanical properties of composites.
Topics: Cellulose; Fluorocarbon Polymers; Glycerol; Materials Testing; Petroleum; Plasticizers; Polymers; Polyvinyls; Powders; Wood
PubMed: 35987360
DOI: 10.1016/j.ijbiomac.2022.08.105 -
Indoor Air Nov 2019Degrading 2-ethylhexyl-containing PVC floorings (eg DEHP-PVC floorings) and adhesives emit 2-ethylhexanol (2-EH) in the indoor air. The danger of flooring degradation...
Degrading 2-ethylhexyl-containing PVC floorings (eg DEHP-PVC floorings) and adhesives emit 2-ethylhexanol (2-EH) in the indoor air. The danger of flooring degradation comes from exposing occupants to harmful phthalates plasticisers (eg DEHP), but not from 2-EH as such. Since the EU banned the use of phthalates in sensitive applications, the market is shifting to use DEHP-free and alternative types of plasticisers in PVC products. However, data on emissions from DEHP-free PVC floorings are scarce. This study aimed at assessing the surface and bulk emissions of two DEHP-free PVC floorings over three years. The floorings were glued on the screed layer of concrete casts at 75%, 85%, and 95% RH. The volatile organic compounds (VOCs) were actively sampled using FLEC (surface emissions) and micro-chamber/thermal extractor (µ-CTE, bulk emissions) onto Tenax TA adsorbents and analyzed with TD-GC-MS. 2-EH, C9-alcohols, and total volatile organic compound (TVOC) emissions are reported. Emissions at 75% and 85% RH were similar. As expected, the highest emissions occurred at 95% RH. 2-EH emissions originated from the adhesive. Because the two DEHP-free floorings tested emitted C9-alcohols at all tested RH, it makes the detection of flooring degradation harder, particularly if the adhesive used does not emit 2-EH.
Topics: Adhesives; Air Pollution, Indoor; Alcohols; Environmental Exposure; Environmental Monitoring; Floors and Floorcoverings; Hexanols; Humans; Plasticizers; Volatile Organic Compounds
PubMed: 31348556
DOI: 10.1111/ina.12591 -
Journal of Hazardous Materials Feb 2021Human and wildlife are continually exposed to a wide range of compounds and substances, which reach the body through the air, water, food, or personal care products.... (Review)
Review
Human and wildlife are continually exposed to a wide range of compounds and substances, which reach the body through the air, water, food, or personal care products. Plasticizers are compounds added to plastics and can be released to the environment under certain conditions. Toxicological studies have concluded that plasticizers, phthalates, and bisphenols are endocrine disruptors, alter the endocrine system and functioning of the immune system and metabolic process. A functional immune response indicates favourable living conditions for an organism; conversely, a weak immune response could reveal a degraded environment that requires organisms to adapt. There is growing concern about the presence of plastic debris in the environment. In this review, the current knowledge of the action of plasticizers on leukocyte cells will be itemized. We also point out critically the role of some nuclear and membrane receptors as key players in the action of plasticizers on cells possess immune function. We discuss the role of erythrocytes within the immune responses and the alteration caused by plasticizers. Finally, we highlight data evidencing mitochondrial dysfunctions triggered by plasticizing toxic action, which can lead to immunosuppression.
Topics: Endocrine Disruptors; Humans; Immunity; Phthalic Acids; Plasticizers; Plastics
PubMed: 33035909
DOI: 10.1016/j.jhazmat.2020.124114 -
Critical Reviews in Food Science and... Feb 2018Interest increased recently in manufacturing food packaging, such as films and coatings, from protein-based biopolymers. Among various protein sources, canola protein is... (Review)
Review
Interest increased recently in manufacturing food packaging, such as films and coatings, from protein-based biopolymers. Among various protein sources, canola protein is a novel source for manufacturing polymer films. It can be concentrated or isolated by aqueous extraction technology followed by protein precipitation. Using this procedure, it was claimed that more than 99% of protein was extracted from the defatted canola meal, and protein recovery was 87.5%. Canola protein exhibits thermoplastic properties when plasticizers are present, including water, glycerol, polyethylene glycol, and sorbitol. Addition of these plasticizers allows the canola protein to undergo glass transition and facilitates deformation and processability. Normally, canola protein-based bioplastics showed low mechanical properties, which had tensile strength (TS) of 1.19 to 4.31 MPa. So, various factors were explored to improve it, including blending with synthetic polymers, modifying protein functionality through controlled denaturation, and adding cross-linking agents. Canola protein-based bioplastics were reported to have glass transition temperature, T, below -50°C but it highly depends on the plasticizer content. Canola protein-based bioplastics have demonstrated comparable mechanical and moisture barrier properties compared with other plant protein-based bioplastics. They have great potential in food packaging applications, including their use as wraps, sacks, sachets, or pouches.
Topics: Biodegradable Plastics; Biopolymers; Brassica rapa; Food Packaging; Plant Proteins; Plasticizers
PubMed: 27379431
DOI: 10.1080/10408398.2016.1193463