PVC Products Research Articles

Machine Learning-Aided 3D Dynamic SERS Strategy for Physiological Mapping: Biotoxicity of Environmentally Dimensional Aged Nanoplastics and Corresponding Protein Corona Complexes.

Nanoplastics (NPs) are emerging pollutants that undergo inevitable aging in the environment, raising concerns about human exposure and health hazards. Research on the cytotoxicity of various polymer types of NPs, aged nanoplastics (aNPs), and their interactions with proteins (aNPs-protein corona) is still nascent. Traditional cytotoxicity detection methods often rely on end point assays with restricted temporal resolution and analysis of single or multiple biomarkers. Here, we propose a novel approach integrating the 3D dynamic SERS strategy (DSS) with machine learning to rapidly analyze the cell fate and death modes induced by NPs, aNPs, and aNPs-protein corona complexes at the molecular level. PS, PVC, PMMA, and PC products from the water environment were used to prepare the corresponding NPs, and the impact of UV irradiation on their physicochemical properties was examined. DSS systematically maps the molecular changes in the cellular secretome caused by these NPs. Machine learning effectively extracts information from complex spectra, differentiating between biological samples. Results show prolonged UV exposure increases cell sensitivity to ferroptosis and cytotoxicity in various aNPs, while the protein corona on aNPs significantly mitigates toxicity associated with surface oxygen-containing functional groups, resulting in a reduced similarity to ferroptosis signatures. 3D DSS with machine learning technique analyzes the overall metabolite profile at the molecular level rather than individual biomarkers. This study is the first attempt to compare the biotoxicity of diverse polymer NPs, aNPs, and aNPs-protein coronas at cellular and molecular levels in human hepatocytes, enhancing our understanding of the complex biological impacts of NPs.

Unveiling the comprehensive performance and safety advancements in PVC films through environmentally friendly PMgLaCe-LDH incorporation

Dioctyl terephthalate (DOTP) is the most widely used PVC plasticizer today. However, the poor migration and volatility resistance of toxic DOTP in PVC films lead to hazards for both the environment and human health. Therefore, there is an urgent need to develop a new, environmentally friendly, and multifunctional filler of PVC to improve the overall performance of PVC and reduce the release of toxic DOTP. Here the alkaline and neutral-modified Mg-based layered double hydroxides (PMgLaCe-LDHNe/Ae) with various La/Ce doping ratios was successfully synthesized through a co-precipitation method and used as multifunctional filler for PVC. Subsequently, composite membranes of PMgLaCe-LDH/PVC were prepared using the blending method, and their comprehensive properties were further investigated. The results demonstrated that the composite membrane, specifically 20Mg10Ce-LDHAe/PVC, exhibited exceptional qualities. These included improved plasticized flame retardancy, photo-thermal stability, hydrophobicity, low-temperature resistance, volatility resistance, and migration resistance. Furthermore, the short-term and long-term safety evaluation, cytotoxicity assay and intradermal irritation response test on SD rats revealed that the addition of the new environmentally friendly and non-toxic compound, 20Mg10Ce-LDHAe, effectively inhibited PVC degradation and the release of toxic substances. This research offers a potential solution to mitigate the environmental and health risks associated with PVC products, making them safer and more sustainable.

Synthesis and properties of bio‐based environmental plasticizer derived from oleic acid for poly (vinyl chloride)

AbstractUsing the abundant and cost‐effective oleic acid and isosorbide with excellent properties as raw materials, the plasticizers of isosorbide di‐oleate (IDO) and isosorbide di‐epoxidized oleate (IDEO) with good plasticizing effect, low cost and green safety were synthesized by esterification and epoxidation reaction. The molecular structure of the synthesized plasticizers was characterized by FT‐IR and 1H NMR. The PVC shows better flexibility when IDEO or IDO plasticizer is used than commercial DOP. In particular, IDEO‐40 has 34% higher tensile strength and 17% higher elongation at break than DOP‐40. The introduction of epoxy groups on the carbon–carbon double bond of fatty acids meets the high thermal stability of plasticized film. The residual amount of IDEO‐40 is 7.01%, and at a high temperature of 180 °C, it can maintain high heat resistance for more than 220 min and transmittance of over 86%. Moreover, IDEO demonstrates excellent resistance to migration and volatilization. However, PVC films plasticized with IDO display reduced mechanical properties, cold resistance, and resistance to volatilization and migration due to the presence of non‐rotating carbon–carbon double bonds. The results indicate that these bio‐based plasticizers hold promise for practical applications in PVC products, offering improved environmental sustainability and performance characteristics.

ENVIRONMENTAL ASSESSMENT OF POLLUTION IN AN INDUSTRIAL ENVIRONMENT USING HEAVY METAL POLLUTION INDICES AND STABLE ISOTOPES, CASE STUDY OF THE INDUSTRIAL ZONE OF SKIKDA, NORTH-EAST ALGERIA

An environmental assessment study was conducted in the industrial area of Skikda in the Northeast of Algeria which involved physicochemical parameters, heavy metal concentrations, and stable isotopes of surface water, groundwater, and soil. The results revealed high concentrations of Cd, Ni, Fe, Cu, As, Cr, Pb, Co, and Mn in groundwater. The southern part exhibited the lowest heavy metal concentrations, while the industrial zone in the North contained the highest levels. Therefore, the industrial area showed significant pollution in groundwater by Cr, Pb, and As with respectively 0.5, 0.69, and 0.44 mg/l, surpassing the respective WHO(World Health Organization) standards of 0.05, 0.01, and 0.01 mg/l. Spatial analysis showed that the industrial area presents higher concentrations of As, Cr, Cd, Pb, Cu, Zn, Ni, and Fe which demonstrated similar trends in spatial distribution, their concentrations increasing within the industrial zone. However, the western part had no significant pollution sources except for a public landfill and SONATRACH industrial complex, high concentrations of Co and Mn in the south and the west parts were observed. Mean concentration in soils indicated that Cd is ranged between35.32 to 95.12 ppm, for Fe between 145.1 and 702 ppm, As varies between 1.03 and 81.85 ppm, and Zn between 50 and 520.32 ppm and considered as dominant metals. However, Mn, Co and Cr were lower respectively with 1.97, 12.11 and 7.25 ppm. Cd and As were most influenced by the polluting companies, while Cr was mainly influenced by natural factors, such as pH and soil type. Based on the contamination degree index, the soil pollution levels of Cd, Pb, and As were classified as extremely contaminated. The statistical analysis indicated substantial anthropogenic contributions to groundwater contamination concentrated in the industrial area. The groundwater exhibits a range of δ18O and δ2H values, varying from 2.45 to -5.33‰ and 19.82 to -1.67‰ vs. the V-SMOW (Vienna-Standard Mean Ocean Water) standard, respectively. The mean isotopic composition is -2.50‰ for δ18O, -19.32‰ for δ2H, with a mean deuterium excess of 6.45. These values align with the Meteoric Water Line observed in the western Mediterranean region. It indicates a hydrological connection between recharge and groundwater which suggests a significant interaction between groundwater and surface water. Due to their proximity to the river and the shallow aquifer, the downstream area is more vulnerable to surface pollution. Furthermore, the young groundwater in the downstream can be attributed to the rapid recharge and replenishment of the aquifer caused by rainfall and quick infiltration and sustained by the shallow aquifer depth and sandy soil. Consequently, the rainwater and industrial wastes lead to faster pollutant infiltration. Anthropogenic sources, including industrial effluents from smelting, refining, manufacturing, steel and textile industries, electroplating, nickel-cadmium battery production, welding, PVC product and paint pigment manufacturing, were identified as major contributors to heavy metal pollution.

Conversion of waste poly(vinyl chloride) to branched polyethylene mediated by silylium ions.

Full dechlorination of poly(vinyl chloride) (PVC) in a controlled manner to yield useful polymeric and chlorinated products is of great interest for the processing of PVC waste. Forming polyethylene (PE) without corrosive by-products would allow for a pre-treatment of PE wastes that are often contaminated with PVC. Herein, full dechlorination of PVC has been achieved via generation of silylium ions in situ, to furnish PE products. Complete dechlorination of PVC can be achieved in 2 hours, yielding organic polymer that has similar spectroscopic and thermal signatures of branched PE, with no observable chlorine. The degree of branching can be tuned between 31 and 57 branches per 1000 carbons, with melting temperatures ranging from 51 to 93 °C. This method is applicable to not only pure PVC, but also commercial PVC products. Depending on if the PVC products are separated from plasticizers, different melting points of the resulting PE are observed. PVC dechlorination in the presence of PE waste is also shown. This is the first report of being able to cleanly convert PVC waste to PE in high yields and tune the thermal properties of the PE product, highlighting the remarkable control that silylium ion mediated transformations enables compared to past chemical methods.

Rapid Assessment of Di(2-ethylhexyl) Phthalate Migration from Consumer PVC Products.

Poly(vinyl chloride) (PVC) is widely used to produce various consumer goods, including food packaging, toys for children, building materials, and cosmetic products. However, despite their widespread use, phthalate plasticizers have been identified as endocrine disruptors, which cause adverse health effects, thus leading to increasing concerns regarding their migration from PVC products to the environment. This study proposed a method for rapidly measuring the migration of phthalates, particularly di(2-ethylhexyl) phthalate (DEHP), from PVC products to commonly encountered liquids. The release of DEHP under various conditions, including exposure to aqueous and organic solvents, different temperatures, and household microwaves, was investigated. The amount of DEHP released from both laboratory-produced PVC films and commercially available PVC products was measured to elucidate the potential risks associated with its real-world applications. Furthermore, tests were performed to evaluate cytotoxicity using estrogen-dependent and -independent cancer cell lines. The results revealed a dose-dependent impact on estrogen-dependent cells, thus emphasizing the potential health implications of phthalate release. This comprehensive study provides valuable insights into the migration patterns of DEHP from PVC products and forms a basis for further research on the safety of PVC and plasticizers.

Study on the lubrication behavior of low molecular weight poly(vinyl chloride‐co‐n‐butyl acrylate‐co‐vinyl acetate) ternary copolymer in rigid PVC

AbstractHerein, low molecular weight poly(vinyl chloride‐co‐n‐butyl acrylate‐co‐vinyl acetate) (PCBV) ternary copolymers with varied copolymer composition was employed as a novel polymeric lubricant in rigid PVC. The lubrication effect of PCBVs on the melting process and mechanical properties of the final PVC products were fully investigated. The results indicated that PCBV can serve either as an internal or as an external lubricant depending on its composition. PCBV‐45.5 terpolymer (PBA% ~ 45.5%) exhibits outstanding balance both internal and external lubricating roles. SEM‐EDS results show that addition PCBV‐45.5 form a film on the surface of PVC grains as similar as that adding both internal and external lubricants. Fusion characteristics and DMTA demonstrate that PCBV‐45.5 prolongs the fusion time (26% extension, 1.5 phr) and reduces the glass transition temperature (4.0 °C, 1.5 phr). Finally, the mechanical properties of rigid PVC have been greatly improved by using 1.5 phr PCBV‐45.5. In detail, the tensile strength increased from 54 to 59 MPa and the elongation at break increased from 10% to 30%, respectively. Meanwhile, the impact strength of PVC/PCBV‐45.5 is 3.6 times that of the blend without addition. The excellent performance of PCBV exhibited great potential as a polymeric lubricant candidate in rigid PVC composites.

Synthesis internal-plasticized PVC copolymer resin from industrial application view: Copolymerization of vinyl chloride with poly(ethylene glycol) monomethyl ether methacrylate via suspension polymerization

Developing internal-plasticized poly(vinyl chloride) (PVC) resin has been recognized as an effective way to deal with the issues of conventional PVC products such as toxicity and deterioration in properties caused by the migration of plasticizer. Herein, the copolymerization of vinyl chloride with commercial available poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) is firstly conducted via suspension polymerization and internally plasticized random copolymers (PVEGA) are synthesized successfully. These PVEGA copolymers were intensively characterized by FTIR, 1H NMR, GPC, DSC, DMTA, and SEM to determine the composition, number-average molecular weight (Mn), dispersity, glass transition temperature (Tg), and the micromorphology. As a result, the high transparency and the fracture images demonstrated the good compatability between PVC chains with long-chain polyether. The Tg of PVEGA decreased gradually from 80 to 0 °C with the fraction of PEGMA in the copolymer increased from 7 to 37 %. Furthermore, the PVEGA copolymer exhibits outstanding processibility and mechanical performance. Under optimal composition, the tensile strength and the elongation at break can reach to 8 MPa and 525 %, respectively. Meanwhile, the PVEGA copolymers exhibit much lower migration either in water or in orgnic solvent and excellent performance in hemolysis and cytotoxicity, showing great application potential in medical devices.

Utilizing a blend of expandable graphite and calcium/zinc stearate as a heat stabilizer environmentally friendly for polyvinyl chloride

AbstractPolyvinyl chloride (PVC) is one of the most important commercial plastics but it is thermally unstable at processing temperatures. Therefore, heat stabilizers are widely used to safeguard by improving resistance of PVC products at high temperature. But most of them are a highly toxic that can cause severe health issues in humans and harmful to the environment. In the present study mixed of calcium/zinc stearate heat stabilizer and green Expandable graphite (EG) is prepared via hydrothermal treatment using additives of nontoxic, environmental protection. The characteristics of the thermal stability of poly vinyl chloride can be investigated by Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) will be used to examine structure of the heat stabilizers, A universal testing equipment will be used to determine the mechanical properties and thermal gravimetric analysis (TGA). From TGA results the weight loss was 43.49% at 342°C for sample with Ca/Zn‐ stearate, while wt loss is 55.87% at 260°C for sample with EG which increase thermal stability. Differential scanning calorimetry affirmed the enhancement of PVC's thermal stability, showing a shift in the glass transition temperature an increase of 67°C. Mechanical tests indicated that samples with EG exhibited higher tensile strength and elongation at break, emphasizing the positive impact on PVC's mechanical properties. The burning test highlighted thermal stability of EG‐containing samples, retaining color and structure even after exposure to 180°C heat. This innovative approach not only enhances thermal stability but also aligns with eco‐friendly principles, making it a promising solution for improving PVC properties.Highlights Ca/Zn‐ stearate, expandable graphite developed by a safe hydrothermal process. Comprehensive analysis indicates improved thermal stability. Safe stabilization of eco‐friendly calcium/zinc, expandable graphite. Effective solution: Eco‐friendly, improved PVC properties. Expandable graphite improved mechanical properties of PVC.

Nature's Needles: Adapting Bacterial “Syringes” into Programmable Protein Delivery Devices

Nature's Needles: Adapting Bacterial “Syringes” into Programmable Protein Delivery Devices

Quantification of Poly(vinyl chloride) Microplastics via Pressurized Liquid Extraction and Combustion Ion Chromatography

A reliable analytical method has been developed to quantify poly(vinyl chloride) (PVC) in environmental samples. Quantification was conducted via combustion ion chromatography (C-IC). Hydrogen chloride (HCl) was quantitatively released from PVC during thermal decomposition and trapped in an absorption solution. Selectivity of the marker HCl in complex environmental samples was ensured using cleanup via pressurized liquid extraction (PLE) with methanol at 100 °C (discarded) and tetrahydrofuran at 185 °C (collected). Using this method, recoveries of 85.5 ± 11.5% and a limit of quantification down to 8.3 μg/g were achieved. A variety of hard and soft PVC products could be successfully analyzed via C-IC with recoveries exceeding >95%. Furthermore, no measurable overdetermination was found for various organic and inorganic matrix ingredients, such as sodium chloride, sucralose, hydroxychloroquine, diclofenac, chloramphenicol, triclosan, or polychlorinated biphenyls. In addition, sediments and suspended particular matter showed PVC concentrations ranging up to 16.0 and 220 μg/g, respectively. However, the gap between determined polymer mass and particle masses could be significant since soft PVC products contain plasticizers up to 50 wt %. Hence, the results of the described method represent a sum of all chlorine-containing polymers, which are extractable under the chosen conditions.

Enhanced migration of plasticizers from polyvinyl chloride consumer products through artificial sebum

In the present study, the migration of plasticizers from modeled and commercial polyvinyl chloride (mPVC and cPVC, respectively) to poly(dimethylsiloxane) via artificial sebum was assessed to mimic the dermal migration of plasticizers. In addition, the various factors affecting migration of phthalic acid esters (PAEs) from diverse PVC products were investigated. The migrated mass and migration ratio of PAEs increased but the migration rate decreased over time. The migration rate increased with sebum mass, contact time, and temperature but decreased under higher pressure. Low-molecular-weight PAEs (dimethyl phthalate and diethyl phthalate) migrated in higher amounts than high-molecular-weight PAEs (dicyclohexyl phthalate [DCHP] and diisononyl phthalate [DINP]). Diffusion of all PAEs in mPVC increased with temperature, with diffusion coefficients ranging from 10−13 to 10−15, 10−12 to 10−14, and 10−10 to 10−12 cm2·s−1 at 25 °C, 40 °C, and 60 °C, respectively; the enthalpy of activation ranged between 127 and 194 kJ·mol−1. Moreover, migration depended on total PAE content of the product, as the diffusion coefficient for DINP in cPVC (softer PVC) was approximately three orders of magnitude higher than that for DINP in mPVC (harder PVC); this may be due to the increase in free volume with increasing plasticizer content. Finally, the daily exposure doses of the plasticizers were estimated. These findings will be helpful for estimating dermal exposure risk.

The Effect of Dibutyl Phthalate (DBP) on Soybean Seed Germination

Industrial plasticizer phthalate esters (PAEs) is commonly utilized in PVC products. One of the most widespread plastic additives, dibutyl phthalate (DBP), is a known endocrine disruptor in the environment. The high volatility and low durability of DBP mean that it is present in soil, water, and air and can be taken up by the roots of plants, where it may stunt their development. Soybean seeds were used in a series of experiments in which the effects of DBP on germination were measured at doses of 0, 0.1, 0.5, 1.0, 5.0, and 10.0 mg/L. Soluble sugar content, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), isocitrate lyase (ICL), and malate dehydrogenase (MDH) levels were evaluated on days 1, 3, 5, and 7. The results demonstrated that the concentration and duration of DBP treatment both contribute to the observable effect on soybean seeds. Soybean germination, antioxidant enzyme activity, and glyoxylate cycling enzyme activity were all stimulated by DBP at concentrations below 1 mg/L, and the stimulatory impact was negatively linked with increasing DBP concentration. Soybean seed germination, antioxidant enzyme activity, and glyoxylate cycling enzyme were all suppressed at concentrations of DBP >1mg/L. Inhibitory action was improved with an elevation of DBP concentration.

Circular economy without chemicals controls? Evidence of recirculated toxic plasticizers in flexible PVC products

The global push towards a circular economy (CE) has led to increasing efforts to improve resource utilization efficiency, including plastics recycling. However, the presence of additives, especially those that are toxic, complicates plastics recycling in several ways. Without sufficient controls, the spread of hazardous additives via recycling activities represents a significant public health challenge, particularly among developing nations. This study demonstrates evidence of such uncontrolled recycling, based on an investigation of four household flexible PVC product groups available in Thailand. A versatile pyrolysis/thermal desorption gas chromatography-mass spectrometry (Py/TD-GC-MS) method was employed to simultaneously screen 18 target plasticizers in these products. Di-(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP) are the most frequently detected primary plasticizers. DEHP is dominant in vinyl boots, flooring sheets, and hoses, while DINP is dominant in cable sheaths, likely due to a spill-over effect from the EU Restriction of Hazardous Substances (RoHS) directive. Chlorinated paraffins (CPs) are secondary plasticizers that are also detected in most samples, except for boots. The other plasticizers detected include other ortho-phthalates and non-phthalates. These results provide insight into combinatory patterns of plasticizer ‘cocktails’, that comprise restricted, as-yet-unrestricted, and non-restricted plasticizers, embedded in the same individual samples, with a maximum of seven plasticizers found in a single cable sheath. These findings indicate the existence of potentially risky recycling practices that target embedded plasticizers to save cost, without due consideration of their inherent toxicity. Proper interventions are necessary to ensure that CE and chemical safety can be synergized.

Using waste poly(vinyl chloride) to synthesize chloroarenes by plasticizer-mediated electro(de)chlorination.

New approaches are needed to both reduce and reuse plastic waste. In this context, poly(vinyl chloride) (PVC) is an appealing target as it is the least recycled high-production-volume polymer due to its facile release of plasticizers and corrosive HCl gas. Herein, these limitations become advantageous in a paired-electrolysis reaction in which HCl is intentionally generated from PVC to chlorinate arenes in an air- and moisture-tolerant process that is mediated by the plasticizer. The reaction proceeds efficiently with other plastic waste present and a commercial plasticized PVC product (laboratory tubing) can be used directly. A simplified life-cycle assessment reveals that using PVC waste as the chlorine source in the paired-electrolysis reaction has a lower global warming potential than HCl. Overall, this method should inspire other strategies for repurposing waste PVC and related polymers using electrosynthetic reactions, including those that take advantage of existing polymer additives.

Highly stable and highly stretchable poly(vinyl chloride)‐based plastics prepared by adding novel green oligomeric lactate plasticizers

AbstractPoly(vinyl chloride) (PVC) is one of the most widely applied plastics in the world, with inherent mechanical brittleness and inflexibility in room temperature. With the growing concern for health and safety, especially in some fields (children's toys, food packaging, medical supplies) that require high‐safety plastics, there is an urgent need to develop phthalate‐free high‐performance green PVC products. Herein, by blending novel green oligomeric lactate plasticizers 1, 4‐cyclohexane dimethanol oligomeric lactate‐levulinate (CDOL‐L) and 1,4‐cyclohexane dimethanol oligomeric lactate‐levulinic acid ketal ester (CDOL‐LKE), highly stretchable and highly stable PVC‐based plastics were prepared successfully. CDOL‐L and CDOL‐LKE were synthesized by a green route of esterification and ketalization using biomass as the main raw material, and their structures were jointly confirmed by Fourier transform infrared spectroscopy,1H NMR and TOF‐MS. Through performance testing, CDOL‐L or CDOL‐LKE plasticized PVC material were determined to have triple high stability (thermal, mechanical and migration stability) superior to DOP, DOTP and ATBC plasticized PVC. The PVC plasticized by CDOL‐L exhibited break at elongation as high as 833.0% at 50 phr addition and 877.1% at 60 phr addition. Moreover, PVC plasticized by 50 phr CDOL‐LKE exhibited relatively better thermal stability (Ti,CDOL‐LKE = 271.4°C) for the special ketal structure on the plasticizer. In conclusion, CDOL‐L and CDOL‐LKE showed potential to substitute traditional plasticizers and pointed a new direction for the preparation of high‐performance PVC‐based plastics.

Plasticizing and thermal stabilizing effect of bio‐based epoxidized cardanol esters on PVC

AbstractPoly(vinyl chloride) (PVC) is a widely used plastics in different industries. It is an intrinsically hard and brittle polymer and requires the use of plasticizers to improve the processability. Commonly used phthalate‐based plasticizers have serious toxicity issues and we present alternatives based on epoxidized soybean oil (ESO) and epoxidized cardanol esters (ECEs). ECEs are synthesized from cardanol and three fatty acids (oleic, ricinoleic, and myristic) using 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC) as a coupling agent. Their structure and purity are confirmed by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance. Moreover, plasticized PVC films are prepared using a solvent‐free method. The replacement of 10 phr of ESO with 5 phr of ECE improves the plasticizing power due to the co‐solvency effect. Mechanical properties and thermal stability of plasticized PVC films are correlated with the chain length and the number of epoxy groups in ECE. The best plasticizing effect is observed for epoxidized cardanol‐myristate (ECD‐MA). ECD‐MA as a shorter‐chain secondary plasticizer is more compatible with ESO and allows higher conformational mobility of PVC chains. PVC/30ESO/5ECD‐MA polymer exhibits an exceptionally high initial thermal decomposition temperature (314.4°C) while preserving moderate ductility and tensile strength (263.4% and 23.3 MPa). Overall, this study highlights the potential applicability of ECD‐MA in combination with ESO as a sustainable, bio‐based plasticizer and heat stabilizer for flexible PVC products.

Preparation and thermal stability of bio-based Na/Zn composite liquid stabilizers for poly(vinyl chloride)

In this work, the adduct of maleic anhydride and methyl eleostearate (MAME) and dimer fatty acid (DFA) were converted to the sodium and zinc salts (L-Zn-MAME, L-Na-MAME, L-Zn-DFA, and L-Na-DFA), respectively, which were subsequently turned into Na/Zn composite liquid stabilizers(LTS-Na/Zn-MAME and LTS-Na/Zn-DFA) by formula combination. Na salts, Zn salts and mixed Na/Zn salts from these fatty acid salts were used as thermal stabilizers for poly(vinyl chloride) (PVC). The chemical structures of MAME, DFA, and their liquid zinc and sodium salts were verified using Fourier transform infrared (FTIR) spectra. Thermal stability and mechanical properties of the sodium and zinc salts, and their Na/Zn composite liquid stabilizers derived from MAME and DFA for PVC were investigated using discoloration and dynamic mechanical analyses, TGA-FTIR-MS, thermal decomposition kinetics, and Congo red and tensile tests. Thermal stability of pure PVC is poor, but membrane thermal stability can be improved by integrating thermal stabilizers. Results show that L-Na-MAME has an outstanding synergistic effect with the commercial general calcium/zinc stearate composite heat stabilizer(CaSt2/ZnSt2). CaSt2/ZnSt2/LTS-Na-MAME, LTS-Na/Zn-MAME and CaSt2/LTS-Zn-DFA/LTS-Na-DFA also have a better heat-stabilizing impact on PVC than CaSt2/ZnSt2, especially LTS-Na/Zn-MAME can more effectively enhance the primary coloring of PVC. In comparison to blank PVC and PVC/CaSt2/ZnSt2, both PVC/LTS-Na/Zn-MAME and PVC/LTS-Na/Zn-DFA display a larger elongation at break and acceptable tensile strength. The new stabilizers can largely enhance the heat stability of PVC resins, endowing PVC products with good plasticization performance, and can fully or partially replace the general calcium zinc stearate composite heat stabilizer and other heat stabilization products.

Initial assessment of imports of chlorinated paraffins into Nigeria and the need of improvement of the Stockholm and Rotterdam Conventions

Short-chain and medium-chain chlorinated paraffins (SCCPs/MCCPs) are of concern due to their persistence, bioaccumulation, and toxicity. SCCPs were listed in 2017 as persistent organic pollutants (POPs) in the Stockholm Convention and Rotterdam Convention for Prior Informed Consent (PIC) procedure. MCCPs are evaluated in the POPs Reviewing Committee for listing. Studies in Africa demonstrate high SCCP/MCCP levels in house dust and human milk. Therefore, this study undertook an initial assessment of the production and import situation in Nigeria. The Nigerian government has not assessed SCCPs yet and has no registered exemptions for SCCPs and therefore should not produce or use SCCPs. Also, Nigeria has not notified Rotterdam Convention of PIC procedure and, therefore, no SCCP should be imported into Nigeria. Since no local production of SCCPs/MCCPs was observed in Nigeria, this study therefore compiled data on importation of SCCPs/MCCPs and products which may likely contain these chemicals from the UN Comtrade Database for the period 1996 to 2018. Despite the listing of SCCPs in the Rotterdam Convention, there is still no specific Harmonized System (HS) codes for SCCPs/MCCPs. This study therefore used HS codes of product categories known to contain SCCPs/MCCPs. HS substance categories under which SCCP/MCCPs are usually imported include plasticisers and other product categories that amounted to 229,779 and 518,342 tonnes respectively but without specific information on the type of plasticiser. About 39% of PVC and rubber imports of 2,683,015 tonnes and 3,516,052 tonnes respectively contain plasticisers. Based on the SCCP and MCCP impact factors from literature for China, the highest amount of SCCP (33,712 tonnes) was imported in the different PVC products while rubber products accounted to 1386 tonnes and PUR foam to 2331 tonnes. The amount of imported MCCPs in PVC products (25,599 tonnes) and rubber products (32,317 tonnes) was in the same order of magnitude while MCCP imported in PUR foam was estimated to 2020 tonnes. At the end of life (EoL), these product categories most likely contain appreciable amount of SCCPs possibly above Basel Convention low POP limit. This will hamper recycling and circular economy for these waste categories and generate POPs stockpiles/wastes that are difficult to manage/destroy in Africa. Hence there is an urgent need for specific HS Codes for SCCPs and industrial POPs currently produced/used for better control. Presently, products containing SCCPs are not labelled and are imported in huge quantities into Nigeria, without monitoring. In its current form this rather conveys a pseudo-safety for industrial POPs that do not exist. The Rotterdam Convention needs to establish specific HS codes for POPs for an appropriate PIC procedure and effective control of industrial POPs still produced. Furthermore, products containing SCCPs (and other POPs) require labelling and should also be covered under the Rotterdam Convention. The study highlights that Nigeria should urgently update the NIP for chemicals listed from 2015 to 2019 with a detailed SCCP inventory and develop monitoring capacity for market surveys. The Rotterdam Convention does not function fully and need to significantly improve to assure PIC procedure.

Distribution and Emission Estimation of Short- and Medium-Chain Chlorinated Paraffins in Chinese Products through Detection-Based Mass Balancing.

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) have raised environmental concern due to their potential for persistence, long-range transport, bioaccumulation, and toxicity. However, little is known about the production, use, and environmental emissions of SCCPs and MCCPs in China, the world's largest producer and consumer. In this study, we estimated the amounts of SCCPs and MCCPs produced and used in China in 2018-2019 based on a nationwide survey and measurements of concentrations in products, from which we estimated the environmental emissions of SCCPs and MCCPs in China. Our results show that 225.2 and 236.4 metric kilotons (kt) of SCCPs and 428.5 and 450.2 kt of MCCPs were used in China in 2018 and 2019, respectively, with poly(vinyl chloride) (PVC) products dominating SCCP and MCCP usage. Moreover, a total of 3.9 and 4.2 kt SCCPs and 3.8 and 4.1 kt MCCPs were emitted into China's environment in 2018 and 2019, respectively. Although less MCCPs are released into the air relative to SCCPs, their level exceeds the emission of SCCPs into soil. Finally, detailed mass balance calculation indicates that, although emissions from the use of PVC products dominate SCCP and MCCP inputs into the air, emissions from the use of polyurethane foam adhesives are more closely related to input into surface waters for SCCPs and MCCPs. For input into soil, the main emission sources are the use of polyurethane foam adhesives (for SCCPs) and rubber products (for MCCPs). This study provides a preliminary overview of the distributions of SCCPs and MCCPs in products and insight into the mass balance of SCCPs and MCCPs from their production and use to emission in China. This assessment also provides an important foundation for better understanding the environmental risks and fates associated with SCCPs and MCCPs in China and around the world.