Plasticizing Effect Research Articles

Extensive phase transformation in an equiatomic CrCoNi medium entropy alloy under extreme uniaxial tension

The dynamic tension behavior of an equiatomic CrCoNi medium entropy alloy (MEA) has been studied at both room temperature (RT, 298 K) and liquid nitrogen temperature (LNT, 77 K). Microstructural observations show that extensive phase transformations were activated in this alloy under dynamic tension at LNT instead of the activation of the deformation twins under high strain rate only or quasi-static loading at LNT. The appearance of massive nanoscale phase transformation bands along multiple slip directions even created a network structure of HCP lamellae in the FCC grains. This leads to defect accumulation at the intersection regions and results in the formation of new HCP variants, inverse phase transformations to FCC structure and even amorphous domains. Such transformation induced plasticity (TRIP) effects including the mutual interactions of crossover phase transformation bands on the plasticity and tension fracture of the MEA under extreme loading conditions were further discussed. These findings provide a deeper understanding of the deformation mechanisms in the equiatomic MEA under extreme loads.

The influence of palm oil-derived plasticizers and lubricants on the rheological and mechanical properties of styrene butadiene rubber

Researchers have recently focused on green processing aids made from plants and vegetables to avoid the high concentration of polycyclic aromatic hydrocarbons (PAHs) from petroleum-based processing oils, which is hazardous to human health. This paper focuses on the effect of lubricants and plasticisers produced from palm oil on the rheological, mechanical and thermal aging properties of styrene-butadiene rubber (SBR). These lubricants and plasticisers are known as glycerol trioleate (GTO), n-butyl stearate (NBS), ethylene bis-steramide (EBS), ethylene bis-oleamide (EBO), pentaerythritol tetrastearate (PETS) and stearyl stearate. The abrasion performance, visual inspection appearance, and cure characteristics of the lubricants and plasticisers on SBR were examined and compared to processing oil-treated distillate aromatic extract (TDAE), paraffin wax, microcrystalline wax, polyethylene (PE) wax, epoxidised soybean oil (ESBO), and stearic acid. It discovered that rubber compounds based on GTO, stearic acid, and EBS exhibited better abrasion resistance and cure properties than rubber compounds based on processing oil. These samples were selected and subjected to mechanical properties, thermal aging effects analysis and comparison with processing oil. Tensile strength shows that SBR with EBS (22.49 MPa) and EBS with GTO (EBS/GTO; 21.25 MPa) are closely similar to SBR compounds with processing oil (21.02 MPa). The findings imply that EBS and EBS/GTO, green plasticisers and lubricants, are viable alternatives to petroleum-based processing oils while being cost-effective for tire production.

Exploring the Influence of Plastic Powder Incorporation on Geotechnical Properties of Expansive Soil Stabilized with Granite Powder for Building Applications

An experimental study was undertaken to investigate the effect of plastic and granite waste powder on the geotechnical performance of expansive soil, using different mix ratios. The soil studied is Hachem, in the northwestof Algeria. In this context, first reinforcing the plastic powder with granite powder, then add the mixture to the expansive soil. The percentage of plastic powder is (0%, 1%, 2%, 3%, 4%) and reinforced at 2%, 4%, 6% and 8% with granite powder. The experimental results showed a gradual decrease in liquid limits, swell potentials, and swelling pressure as the proportions of plastic and granite powder increase. In terms of the results obtained by reducing swelling and swelling pressure values and increasing unconfined compressive strength (UCS) tests and ductility values, this mixture of waste plastics and granite can be of great importance in improving the mechanical properties of samples.

Influence of Complex Plasticizer on Plasticizing Effects and Rheological Properties of Plasticized Poly(Vinyl Alcohol)

AbstractPoly(vinyl alcohol) (PVA) was modified using D‐mannitol (DM) and 1‐butyl‐3‐methylimidazole bromide (BMIMBr) as the complex plasticizer (DB), and PVA/DB composite was prepared. The plasticizing effect of DB on PVA was studied by Fourier transform infrared spectroscopy (FT‐IR), differntial scanning calorimetry (DSC), thermos gravimetric analysis (TGA) and melt flow indexer (MI). FT‐IR analysis indicated that Br− of BMIMBr and OH of DM could form H‐bonds with OH of PVA. With the increase of DB, the melt temperature (Tm2) and crystallization temperature (Tc1) of PVA/DB composite decreased, the initial thermal decomposition temperatures (Td), thermal processing window (ΔT) and MI values increased respectively. Based on above studies, the influence of DB content on rheological properties of PVA/DB composite was investigated by the capillary rheometer. The result displayed that apparent viscosity of PVA/DB composite decreased with increasing DB content, shear rate and measured temperature. The non‐Newtonian index (n) increased and structural viscosity index (Δη) decreased with the increase of measured temperature and DB. The viscous flow activation energy (Eη) decreased as the shear rate and DB content increased. When the measured temperature, DB content and shear rate were in the range of Tm2+30 −Tm2+35 °C, 40–50 wt% and 764.8–1504.9 s−1, respectively, the spinnability of PVA/DB composite was optimal, which will lay a theoretical foundation for the exploration of melt spinning process in the future.

Towards the toughness-strength balance of poly(vinyl alcohol) films via synergic plasticization

Polyvinyl alcohol (PVA) films have significant rigidity due to the large number of hydrogen bonds within and between molecular chains. This feature hinders their industrial applications. Small molecule plasticizers can effectively improve the toughness of PVA films. However, this improvement decreases their modulus and strength. In this study, the effect of individual plasticizer, namely, diethanolamine (DEA), glycerol (GLY), and H2O, on the mechanical properties was first studied. It was found that adding an individual plasticizer increase the toughness but decrease the modulus for all the three plasticized PVA films, with DEA decreased least. Then, the property changes caused by of H2O and plasticizer content in two synergic plasticizing systems of DEA/H2O and GLY/H2O were systematically investigated and compared to demonstrate further the different effects of DEA and GLY on the toughness and modulus of the PVA film. Results indicated that the modulus and toughness of PVA casted film with a 10% DEA content improved after the addition of 3% H2O for the DEA/H2O plasticizing system. Despite a large improvement in toughness, the strength was always largely reduced with the increase in H2O or GLY content for the GLY/H2O system. The infrared spectrum results showed that H2O could be physically combined with both PVA and DEA to construct a cross-linked hydrogen bond network, because of the relatively strong electronegativity of the N atom in DEA. However, forming such a cross-linked hydrogen bond network in the GLY/H2O system is difficult. Thus, only a plasticizing effect was observed in the PVA/GLY/H2O films. Our work provides a better understanding of the effects of plasticizer and H2O on the hydrogen bonding and properties of PVA films to achieve toughness-strength balance via synergic plasticization.

Study of the dielectric and chemical properties of cellulose bio-based composites

Injection molded cellulose bio-based composites have been effectively manufactured using cellulose acetate (CA), environmentally friendly triethyl citrate (TEC) plasticizer, and cellulosic fibers. This study investigated the surface chemistry, the thermal stability, and the dielectric properties of CA biopolymer and its bio-based composites. DSC result of plasticized cellulose acetate (PCA) showed that the glass transition temperature decreased from 191°C to 101°C and the melting temperature from 224°C to about 140°C after plasticization, which improves the processing of the biopolymer Fourier Transform Infrared (FTIR) spectroscopy was used to determine the chemical properties of the raw materials and the bio-based composites. The results showed a good plasticization effect of TEC plasticizer by the presence of ester bonds at 1734 cm−1 in PCA spectra. Chemical interactions between hydroxyl groups of the different components were also observed in the 3200–3600 cm−1 region. Dielectric analysis at different frequencies of cellulose bio-based composites showed enhanced dielectric properties compared to pure PCA polymer. Composites with 50 wt% cellulose fibers had values of ε' and tan δ of about 4 and 0.13 at 1 MHz, respectively. These properties decreased as the frequency increased from 1 MHz to 3 GHz, reaching values of 2.8 and 0.04, respectively. The increase in temperature from the frozen state induced an increase in the dielectric properties and showed a relaxation process that shifted to higher temperatures at higher frequencies.

Polyester microfiber impacts on coastal sediment organic matter consumption

As plastic pollution continues to accumulate at the seafloor, concerns around benthic ecosystem functionality heightens. This research demonstrates the systematic effects of polyester microfibers on seafloor organic matter consumption rates, an important benthic ecosystem function connected to multiple reactions and processes. We used a field-based assay to measure the loss of organic matter, both with and without polyester microfiber contamination. We identified sediment organic matter content, mud content, and mean grain size as the main drivers of organic matter consumption, however, polyester microfiber contamination decoupled ecosystem relationships and altered observed organic matter cycling dynamics. Organic matter consumption rates varied across horizontal and vertical spaces, highlighting that consumption and associated plastic effects are dependent on environmental heterogeneity at both small (within sites) and larger (between sites) scales. Our results emphasize the important role habitat heterogeneity plays in seafloor organic matter consumption and the associated effects of plastic pollution on ecosystem function.

Abstract NG08: Dissecting and quantifying pancreatic cancer plasticity using single-cell multiomics, lineage tracing and functional genomics reveals novel mediators of therapy resistance

Abstract NG08: Dissecting and quantifying pancreatic cancer plasticity using single-cell multiomics, lineage tracing and functional genomics reveals novel mediators of therapy resistance

Repurpose of used frying sunflower oil as an ecofriendly plasticizer for polylactic acid

The development of competitive and sustainable additives for use in semicrystalline polymers is currently an area of growing interest in scientific and engineering areas. However, the feasibility of using waste oils as raw materials to produce effective plasticizers for these polymers has not yet been thoroughly investigated. In this work, the plasticization of polylactic acid (PLA), which is essential to improve its ductility, was studied using different contents of low molecular weight plasticizers: one synthesized from sunflower (Helianthus annuus) oil used in frying (USOP) and the bio-based commercial tributyrin (TB), selected as a control plasticizer. The experimental results revealed changes in the properties of pure PLA matrix that were explained considering the shape and chemical structure of the different plasticizers. Both compounds drastically decreased the glass transition temperature of PLA as well as the elastic modulus and tensile strength, although increase the elongation at break. The greatest plasticizing effect was obtained by adding 15 percent by weight of TB to the biodegradable matrix. However, the synthesized bio-based plasticizer exhibits a desirable low volatility, thus its thermal degradation occurs at higher temperatures in comparison with that of TB. Furthermore, the water vapor permeability of the PLA is not affected when USOP is used as plasticizer, which is a very interesting result for applications in which the material is in contact with food or humid environments.

STUDY OF THE EFFECT OF HALOGENATED FIRE RETARDANTS ON REDUCING THE FLAMMABILITY OF COMPOSITE REINFORCEMENT

The article is devoted to the issue of reducing the flammability of fiberglass composite reinforcement, which is obtained based on an epoxy anhydride binder by the needle extrusion method. The authors applied halogenated epoxy resins based on tetrabromobisphenol A and chlorine-containing resin EHD (N,N-tetraglycidyl-3,3′-dichloro-4,4′-diaminodiphenylmethane) as flame retardant components (modifiers). We controlled the degree of transformation (passage of the polyaddition reaction) of epoxy systems exposed to heat under the technology conditions by the method of sol-gel analysis. The conducted research established the ability of halogenated flame retardants not to exert a directed effect on reducing the flammability of composite reinforcement obtained in the short-term mode of formation. Under these conditions, the composition of the epoxy anhydride binder is of great importance, considering the ratio of epoxy and anhydride groups in the reaction system. We determined that to achieve an increased oxygen index and a relative decrease in the flammability of composite reinforcement in the conditions of a short-term hardening regime, a small addition of flame retardant, which contains only chlorine-containing oligomer EHD, is necessary. In this particular case, we observed a characteristic anti-plasticising effect, which leads to the preservation of the modulus of elasticity of the composite material and a decrease in the flammability of the composite. With a further increase in the amount of the antipyretic modifier, structural transformations occur at the supramolecular level, which possibly prolongs the distance between the mesh nodes of the hardened matrix of the composite and contributes to a decrease in its modulus of elasticity and loss of its ability to inhibit the spontaneous combustion reaction. As a result of the plasticising effect at the supramolecular level, molecules surround the internodal structural elements of the polymer. It leads not only to a decrease in the interaction between the macromolecules of the epoxy polymer but also to an increase in the diffusion characteristics of the entire system. Keywords: fibreglass composite reinforcement, flammability, oxygen index, halogenated fire retardant.

Axon morphology and intrinsic cellular properties determine repetitive transcranial magnetic stimulation threshold for plasticity.

Repetitive transcranial magnetic stimulation (rTMS) is a widely used therapeutic tool in neurology and psychiatry, but its cellular and molecular mechanisms are not fully understood. Standardizing stimulus parameters, specifically electric field strength, is crucial in experimental and clinical settings. It enables meaningful comparisons across studies and facilitates the translation of findings into clinical practice. However, the impact of biophysical properties inherent to the stimulated neurons and networks on the outcome of rTMS protocols remains not well understood. Consequently, achieving standardization of biological effects across different brain regions and subjects poses a significant challenge. This study compared the effects of 10 Hz repetitive magnetic stimulation (rMS) in entorhino-hippocampal tissue cultures from mice and rats, providing insights into the impact of the same stimulation protocol on similar neuronal networks under standardized conditions. We observed the previously described plastic changes in excitatory and inhibitory synaptic strength of CA1 pyramidal neurons in both mouse and rat tissue cultures, but a higher stimulation intensity was required for the induction of rMS-induced synaptic plasticity in rat tissue cultures. Through systematic comparison of neuronal structural and functional properties and computational modeling, we found that morphological parameters of CA1 pyramidal neurons alone are insufficient to explain the observed differences between the groups. Although morphologies of mouse and rat CA1 neurons showed no significant differences, simulations confirmed that axon morphologies significantly influence individual cell activation thresholds. Notably, differences in intrinsic cellular properties were sufficient to account for the 10% higher intensity required for the induction of synaptic plasticity in the rat tissue cultures. These findings demonstrate the critical importance of axon morphology and intrinsic cellular properties in predicting the plasticity effects of rTMS, carrying valuable implications for the development of computer models aimed at predicting and standardizing the biological effects of rTMS.

Effect of Si on the deformation behavior of retained austenite and annealed martensite in medium Mn steels

The present study systematically investigated the effect of Si additions from 0 to 4 wt % on the deformation mechanism of a Fe-0.2C-6.8Mn (wt. %) medium Mn steel. The duplex microstructure consisting of film-like retained austenite (RA) and lath-shaped annealed martensite (AM) was produced for different Si alloyed steels by annealing treatments. They have similar volume fraction of RA. The effect of Si content on the dynamic strain aging (DSA) of RA and the serration type of tensile curves, as well as the fine structure evolution within AM during deformation was studied in detail. For the different Si alloyed steels, their tensile curves all exhibit flow serrations, accompanied with the propagation of the Portevine-Le Châtelier (PLC) band caused by DSA in RA. The serration type was sensitive to Si content. For the high Si steel, only type B serrations appear. This is attributed to the high Si content in RA, promoting aged dislocations by C atoms due to the repulsive interaction between C and Si atoms. For the low Si and Si free steels, type A serrations occur after type B serrations disappear at a certain strain. The mechanical stability and Mn/Si contents of RA play an important role in the PLC band propagation. The Si content has also an important effect on the evolution of dislocation configuration within AM during deformation. In the low and Si free steels, the dislocation multiplication and tangles, as well as the formation of dislocation walls, dividing up the laths appear in the AM. While in the high Si steel, it is found that the dislocation cells appear within the AM due to Si addition promoting the formation of screw dislocations by neutron diffraction technique, and the cross slip of screw dislocations as a necessary mechanism for dislocation cell formation. The formation of dislocation configuration with low energy is believed to be another essential factor improving the mechanical properties, besides the transformation-induced plasticity effect. This work paves a new pathway towards tailoring dislocation configuration for designing a new generation advanced high-strength steel.

481 Spinal Cord Stimulator Promotes Neuroplasticity in Patients With Severe Spinal Cord Injury

INTRODUCTION: Traumatic spinal cord injury (SCI) is one of the leading causes of morbidity and mortality worldwide. Recently, epidural electrical stimulation (EES) has been shown to restore voluntary motor control in patients with severe SCI. METHODS: To this date, three patients with SCI have been implanted with 5-6-5-Specify-Medtronic electrodes and Medtronic-Intellis pulse generator. All procedures were approved by the local Ethics Committee. The age of the patients ranged from 38-69 y, and the levels of the SCI were C6-D5. Clinically, they were classified ASIA A (2) or B (1). The time frame after injury was 2-7 y. Intraoperative electrophysiological mapping was performed to ensure correct location of the lead at the levels involved in the control of L3-S2 nerve roots. Clinical assessments were performed every 3 m. Additionally, we measured superficial EMG each month, through sensors equipped with accelerometers and gyroscopes. RESULTS: One patient completed 12 m of intense rehabilitation program. The other two patients are currently on training and to this date they completed respectively 6 and 3 months of the program. All 3 patients were able to perform walking activities on a treadmill and stationary bicycle with stimulation turned on. There was an important improvement in the scales related to motor skills and balance, at expense of worsening in pain scores. After 8 months the first patient started to present voluntary movements even with stimulation turned off. CONCLUSIONS: EES allows restoration of voluntary motor control of the legs after severe traumatic SCI. Moreover, after 8 months, a plastic effect could be observed, and a patient was able to control movements even with off stimulation. The observed improvement in overall patient’s performance occurred at expense of more pain, which need to be addressed carefully.

Molecular Design of SERTlight: A Fluorescent Serotonin Probe for Neuronal Labeling in the Brain.

The serotonergic transmitter system plays fundamental roles in the nervous system in neurotransmission, synaptic plasticity, pathological processes, and therapeutic effects of antidepressants and psychedelics, as well as in the gastrointestinal and circulatory systems. We introduce a novel small molecule fluorescent agent, termed SERTlight, that specifically labels serotonergic neuronal cell bodies, dendrites, and axonal projections as a serotonin transporter (SERT) fluorescent substrate. SERTlight was developed by an iterative molecular design process, based on an aminoethyl-quinolone system, to integrate structural elements that impart SERT substrate activity, sufficient fluorescent brightness, and a broad absence of pharmacological activity, including at serotonin (5-hydroxytryptamine, 5HT) receptors, other G protein-coupled receptors (GPCRs), ion channels, and monoamine transporters. The high labeling selectivity is not achieved by high affinity binding to SERT itself but rather by a sufficient rate of SERT-mediated transport of SERTlight, resulting in accumulation of these molecules in 5HT neurons and yielding a robust and selective optical signal in the mammalian brain. SERTlight provides a stable signal, as it is not released via exocytosis nor by reverse SERT transport induced by 5HT releasers such as MDMA. SERTlight is optically, pharmacologically, and operationally orthogonal to a wide range of genetically encoded sensors, enabling multiplexed imaging. SERTlight enables labeling of distal 5HT axonal projections and simultaneous imaging of the release of endogenous 5HT using the GRAB5HT sensor, providing a new versatile molecular tool for the study of the serotonergic system.

Plastic Solid Waste Management Assessment Among Selected Schools in Gwadabawa Local Government, Sokoto, Nigeria

The objective of this work was to assess the plastic solid waste management among selected schools in Gwadabawa Local Government, Sokoto, Nigeria. A descriptive survey (cross-sectional) study was employed and collected data from portions of schools and respondents. The findings indicate that, demographic characteristics of teacher respondents involved in this study are: Males are 66.7%, females are 33.3%; and the levels of education include, NCE/diploma (58.0%), BSc (26.7%), MSc (13.3%), and PhD (2.0%). Regards to students involved, 48.0% are males, 60.0% are females; 36.0% are 18-20 years old, and 64.0% are above 20 years old. The level of education of students include, 60.0% diploma students, and 40.0% certificates students. The effects are listed in the order of frequency as submitted by participants: Release of gases (20.5%), land pollution (17.0%), water pollution (15.0%), attraction of vermin (11.0%), breeding of diseases (10.5%), loss of biodiversity (7.5%), reduction of beauty of environment (7.5%), offensive odour (5.0%), flooding (5.0%), and particulates release (1.0%). Methods of waste elimination are: open disposal occurs among 37.5% schools; likewise, open disposal and burning, occur in 37.5%; while, use as fertilizer was recorded in 12.5% schools. Waste collection methods are either open dumping (80.0%), or use of containers (20.0%). The use of segregation of waste; therewith, only 20.0% practice segregation, the remaining 80.0% do not practice segregation, rather openly display mixtures of waste materials. The possible remedies to mitigate plastic solid waste mismanagement and effects include, education (awareness) and behavior change (53.3%) was mostly stated, funding (26.7%), improvisation (15.3%), scavenging (3.3%), and innovations (1.3%). Policy makers need to act urgently in diverse ways, and the people are supposed to be educated on ways of remediating plastic waste pollution.

Current Status of Plastic Waste and Proposing Solutions to Raise Community Awareness in Reducing Plastic Waste in Vietnam

Research results showed that plastic waste in Vietnam arises from many different sources; The total amount of plastic waste in Vietnam is 3.27 million tons/year, accounting for about 8-12% of household solid waste and about 5% of medical waste; The treatment and recycling of plastic waste is still limited, up to 90% of plastic waste is burned, buried or discharged into the environment, only about 10% of plastic waste is recycled. To reduce plastic waste, it is necessary to raise awareness and and community responsibility in the production, distribution, use of plastic products and in the collection and classification, recycling and treatment of plastic waste. Propaganda solutions need to be implemented in many different forms, suitable for each audience. Propaganda activities must have long-term, clear, focused, and scripted strategies and campaigns to orient the community and help the community understand the harmful effects of plastic and microplastic waste, thereby changing consumption habits (refuse and minimize the use of plastic bags and single-use plastic products at the workplace and in entertainment services, restaurants, hotels, markets, supermarkets, conferences, seminars, meetings and holidays, anniversaries and other events); Encourage the use of recycled, environmentally friendly products to replace toxic plastic products.

Plastic Solid Waste Management Assessment Among Selected Schools in Gwadabawa Local Government, Sokoto, Nigeria

The objective of this work was to assess the plastic solid waste management among selected schools in Gwadabawa Local Government, Sokoto, Nigeria. A descriptive survey (cross-sectional) study was employed and collected data from portions of schools and respondents. The findings indicate that, demographic characteristics of teacher respondents involved in this study are: Males are 66.7%, females are 33.3%; and the levels of education include, NCE/diploma (58.0%), BSc (26.7%), MSc (13.3%), and PhD (2.0%). Regards to students involved, 48.0% are males, 60.0% are females; 36.0% are 18-20 years old, and 64.0% are above 20 years old. The level of education of students include, 60.0% diploma students, and 40.0% certificates students. The effects are listed in the order of frequency as submitted by participants: Release of gases (20.5%), land pollution (17.0%), water pollution (15.0%), attraction of vermin (11.0%), breeding of diseases (10.5%), loss of biodiversity (7.5%), reduction of beauty of environment (7.5%), offensive odour (5.0%), flooding (5.0%), and particulates release (1.0%). Methods of waste elimination are: open disposal occurs among 37.5% schools; likewise, open disposal and burning, occur in 37.5%; while, use as fertilizer was recorded in 12.5% schools. Waste collection methods are either open dumping (80.0%), or use of containers (20.0%). The use of segregation of waste; therewith, only 20.0% practice segregation, the remaining 80.0% do not practice segregation, rather openly display mixtures of waste materials. The possible remedies to mitigate plastic solid waste mismanagement and effects include, education (awareness) and behavior change (53.3%) was mostly stated, funding (26.7%), improvisation (15.3%), scavenging (3.3%), and innovations (1.3%). Policy makers need to act urgently in diverse ways, and the people are supposed to be educated on ways of remediating plastic waste pollution.

High strength and high ductility of 60Si2CrVAT spring steel through a novel quenching and partitioning (Q-P) process

The balance between strength and ductility in spring steel is a perennial issue. However, production using traditional quenching and tempering (Q-T) process is challenging because tempered martensite provides high tensile strength but significantly reduces ductility. To solve this problem, we propose a novel quenching and partitioning (Q-P) process to enhance the comprehensive properties of 60Si2CrVAT spring steel. The novel Q-P process introduced 31.56% excellent mechanical stability retained austenite, which existed mostly as a film-like between the martensite and bainite laths, and ensured a continuous and long-lasting transformation-induced plasticity (TRIP) effect. Moreover, Q-P process reduced the effective grain size due to the diffusion of carbon, and changed the fracture behavior due to the coordinated deformation of multiphase microstructure. Consequently, the total elongation of the spring steel increased by approximately 180%, from 7.8% to 21.7%, while the tensile strength of the spring steel was not affected and remained at a high of 1809 MPa. In conclusion, the novel Q-P process adjusted the volume fraction of the martensite, bainite, and retained austenite multiphase microstructure, and fully leveraged the synergistic effect of the multiphase microstructure to optimize the properties of spring steel.

Effect of Phosphorus-Nitrogen based Flame-Retardant Combined with Zinc Borate on Thermal Stability and Flame Retardancy of Epoxy Clay Nanocomposites

A phosphorus-nitrogen containing 6,6'-(piperazine-1,4-diyl)bis(6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (DOPO-PZ) flame-retardant was synthesized and its effect combined with zinc borate (ZnB) and nanoclay (NC) on thermal stability and flame retardancy of epoxy resin was studied. Various epoxy composites containing DOPO, DOPO-PZ, ZnB and NC using curing agent diaminodiphenylsulfone (DDS) were prepared. The X-ray diffraction (XRD) and transmission electron microscope (TEM) micrographs of the composites showed intercalated nanostructure of epoxy-clay nanocomposites. In thermogravimetric analysis (TGA), pure epoxy gave 3.4% char yield at 700 ºC in nitrogen atmosphere, while in case of EP/DOPO-PZ/ZnB/NC sample having 1% phosphorus content, 5 wt.% zinc borate (ZnB) and 3 wt.% nanoclay (NC), the char yield is increased to 24.0%. Differential scanning calorimetry (DSC) study showed decrease in the glass transition temperature (Tg) on the addition of flame-retardant due to plasticization effect and increase in Tg on addition of nanoclay due to formation of nanostructure of epoxy composites. The EP/DOPO-PZ/ZnB/NC nanocomposite sample exhibited a limiting oxygen index (LOI) value of 29.2% and passed the UL-94 test with a V-0 rating and thus achieved a sufficient flame retardancy.

Ongoing exposure to endocrine disrupting phthalates and alternative plasticizers in neonatal intensive care unit patients

Due to endocrine disrupting effects, di-(2-ethylhexyl) phthalate (DEHP), a plasticizer used to soften plastic medical devices, was restricted in the EU Medical Devices Regulation (EU MDR 2017/745) and gradually replaced by alternative plasticizers. Neonates hospitalized in the neonatal intensive care unit (NICU) are vulnerable to toxic effects of plasticizers. From June 2020 to August 2022, urine samples (n = 1070) were repeatedly collected from premature neonates (n = 132, 4–10 samples per patient) born at <31 weeks gestational age and/or <1500 g birth weight in the Antwerp University Hospital, Belgium. Term control neonates (n = 21, 1 sample per patient) were included from the maternity ward. Phthalate and alternative plasticizers’ metabolites were analyzed using liquid-chromatography coupled to tandem mass spectrometry. Phthalate metabolites were detected in almost all urine samples. Metabolites of alternative plasticizers, di-(2-ethylhexyl)-adipate (DEHA), di-(2-ethylhexyl)-terephthalate (DEHT) and cyclohexane-1,2-dicarboxylic-di-isononyl-ester (DINCH), had detection frequencies ranging 30–95 %. Urinary phthalate metabolite concentrations were significantly higher in premature compared to control neonates (p = 0.023). NICU exposure to respiratory support devices and blood products showed increased phthalate metabolite concentrations (p < 0.001). Phthalate exposure increased from birth until four weeks postnatally. The estimated phthalate intake exceeded animal-derived no-effect-levels (DNEL) in 10 % of samples, with maximum values reaching 24 times the DNEL. 29 % of premature neonates had at least once an estimated phthalate intake above the DNEL. Preterm neonates are still exposed to phthalates during NICU stay, despite the EU Medical Devices Regulation. NICU exposure to alternative plasticizers is increasing, though currently not regulated, with insufficient knowledge on their hazard profile.