Plasticization mechanism of biobased plasticizers comprising polyethylene glycol diglycidyl ether-butyl citrate with both long and short chains on poly(lactic acid)

Polylactic acid (PLA), a biodegradable polymer with low flexibility, is commonly plasticized with small molecules like tributyl citrate (TBC) for film production. However, these plasticizers, which lack chemical bonds or strong intermolecular interactions with the matrix, tend to migrate to the film surface over time. Their inclusion often compromises material strength for flexibility, increasing elongation at break but reducing tensile strength. In this research, by combining citric acid with n-butanol (B) and poly(ethylene glycol) diglycidyl ether (E), we synthesized three plasticizers, namely TE3, TE2B1, and TE1B2, to enhance the flexibility of PLA. TE2B1 and TE1B2 are equipped with butyl ester groups that offer effective plasticizing effects. Additionally, the incorporation of long-chain alkyl featuring epoxy groups can boost the interaction with PLA. The results showed that the epoxy groups of the long-chain alkyl plasticizers can improve the elongation at break without compromising tensile strength significantly. The migration of plasticizer from PLA matrix can be reduced by strong interactions like chemical bonds, entanglements, and hydrogen bonding with PLA. TE1B2 demonstrated the best plasticizing effect. Adding 15 portions of TE1B2 and TBC separately increased PLA's elongation at break to 304 % and 242 %, with tensile strengths of 36.1 MPa and 22.3 MPa, respectively.

Assessment of biodegradation and toxicity of alternative plasticizer di(2-ethylhexyl) terephthalate: Impacts on microbial biofilms, metabolism, and reactive oxygen species-mediated stress response

Although di(2-ethylhexyl) terephthalate (DOTP) is being widely adopted as a non-phthalate plasticizer, existing research primarily focuses on human and rat toxicity. This leaves a significant gap in our understanding of their impact on microbial communities. This study assessed the biodegradation and toxicity of DOTP on microbes, focusing on its impact on biofilms and microbial metabolism using Rhodococcus ruber as a representative bacterial strain. DOTP is commonly found in mass fractions between 0.6 and 20% v/v in various soft plastic products. This study used polyvinyl chloride films (PVC) with varying DOTP concentrations (range 1-10% v/v) as a surface for analysis of biofilm growth. Cell viability and bacterial stress responses were tested using LIVE/DEAD™ BacLight™ Bacterial Viability Kit and by the detection of reactive oxygen species using CellROX™ Green Reagent, respectively. An increase in the volume of dead cells (in the plastisphere biofilm) was observed with increasing DOTP concentrations in experiments using PVC films, indicating the potential negative impact of DOTP on microbial communities. Even at a relatively low concentration of DOTP (1%), signs of stress in the microbes were noticed, while concentrations above 5% compromised their ability to survive. This research provides a new understanding of the environmental impacts of alternative plasticizers, prompting the need for additional research into their wider effects on both the environment and human health.

Impacts of pristine, aged and leachate of conventional and biodegradable plastics on plant growth and soil organic carbon

Plastic is an essential component of agriculture globally, becoming a concerning form of pollution. Biodegradable alternatives are gaining attention as a potential replacement for commonly used, non-degradable plastics, but there is little known about the impacts of biodegradable plastics as they age and potential leachates are released. In this study, different types (conventional: polyethylene and polypropylene and biodegradable: polyhydroxybutyrate and polylactic acid) of micro- and meso-films were added to soil at 0.1% (w/w) prior to being planted with Lolium perenne (perennial ryegrass) to evaluate the plant and soil biophysical responses in a pot experiment. Root and shoot biomass and chlorophyll content were reduced when soil was exposed to plastics, whether conventional or biodegradable, pristine, aged or when just their leachate was present. The pH and organic matter content of soil exposed to these plastics and their leachates was significantly reduced compared to control samples; furthermore, there was an increase in CO2 respiration rate from soil. In general, meso (> 5 mm) and micro (< 5 mm) plastic films did not differ in the impact on plants or soil. This study provides evidence that conventional and biodegradable plastics have both physical and chemical impacts on essential soil characteristics and the growth of L. perenne, potentially leading to wider effects on soil carbon cycling.

Effects of UV-based oxidation processes on the degradation of microplastic: Fragmentation, organic matter release, toxicity and disinfection byproduct formation

The occurrence and transformation of microplastics (MPs) remaining in the water treatment plants has recently attracted considerable attention. However, few efforts have been made to investigate the behavior of dissolved organic matter (DOM) derived from MPs during oxidation processes. In this study, the characteristics of DOM leached from MPs during typical ultraviolet (UV)-based oxidation was focused on. The toxicity and disinfection byproduct (DBP) formation potentials of MP-derived DOM were further investigated. Overall, UV-based oxidation significantly enhanced the aging and fragmentation of highly hydroscopic MPs. The mass scales of leachates to MPs increased from 0.03% - 0.18% at initial stage to 0.09% - 0.71% after oxidation, which were significantly higher than those leached by natural light exposure. Combined fluorescence analysis with high resolution mass spectrometer scan confirmed that the dominant MP-derived DOM are chemical additives. PET-derived DOM and PA6-derived DOM showed inhibition of Vibrio fischeri activity with corresponding EC₅₀ of 2.84 mg/L and 4.58 mg/L of DOC. Bioassay testing with Chlorella vulgaris and Microcystis aeruginosa showed that high concentrations of MP-derived DOM inhibited algal growth by disrupting the cell membrane permeability and integrity. MP-derived DOM had a similar chlorine consumption (1.63 ± 0.41 mg/DOC) as surface water (1.0 - 2.0 mg/DOC), and MP-derived DOM mainly served as precursors for the investigated DBPs. Contrary to the results of previous studies, the DBP yields from MP-derived DOM were relatively lower than those of aquatic DOM under simulated distribution system conditions. This suggests that MP-derived DOM itself rather than serving as DBP precursor might be potential toxic concern.

Synthesizing Polyurethane Using Isosorbide in Primary Alcohol Form, and Its Biocompatibility Properties

Isosorbide is a bio-based renewable resource that has been utilized as a stiffness component in the synthesis of novel polymers. Modified isosorbide-based bis(2-hydroxyethyl)isosorbide (BHIS) has favorable structural features, such as fused bicyclic rings and a primary hydroxyl function with improved reactivity to polymerization when compared to isosorbide itself. Polyurethane series (PBH PU series) using polycarbonate diol (PCD) and bis(2-hydroxyethyl)isosorbide (BHIS) were polymerized through a simple, one-shot polymerization without a catalyst using various ratios of BHIS, PCD, and hexamethylene diisocyanate (HDI). The synthesized BHIS and PUs were characterized using proton nuclear magnetic resonance (¹H-NMR), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), and mechanical testing. To determine the feasibility of using these PUs as biomedical materials, we investigated the effects of their BHIS content on PBH PU series physical and mechanical properties. The PBH PU series has excellent elasticity, with a breaking strain ranging from 686.55 to 984.69% at a 33.26 to 63.87 MPa tensile stress. The material showed superb biocompatibility with its high adhesion and proliferation in the bone marrow cells. Given their outstanding mechanical properties and biocompatibility, the polymerized bio-based PUs can contribute toward various applications in the medical field.

Effects of aging on environmental behavior of plastic additives: Migration, leaching, and ecotoxicity

Microplastics (MPs), an emerging pollutant, are of global concern due to their wide distribution and large quantities. In addition to MPs themselves, various additives within MPs (such as plasticizers, flame retardants, antioxidants and heavy metals) may also have harmful effects on the environment. Most of these additives are physically bound to plastics and can therefore be leached from the plastic and released into the environment. Aging of MPs in the actual environment can affect the migration and release of additives, further increasing the ecotoxicological risk of additives to organisms. This work reviews the functions of several commonly used additives in MPs, and summarizes the representative characterization methods. Furthermore, the migration and leaching of additives in the human environment and marine environment are outlined. As aging promotes the internal chain breaking of MPs and the increase of specific surface area, it in turn stimulates the release of additives. The hazards of additive exposure have been elucidated, and various studies from the laboratory have shown that more toxic additives such as phthalates and brominated flame retardants can disrupt a variety of biological processes in organisms, including metabolism, skeletal development and so on. Increase of MPs ecological risk caused by the leaching of toxic additives is discussed, especially under the effect of aging. This study presents a systematic summary of various functional and environmental behaviors of additives in plastics, using weathering forces as the main factor, which helps to better assess the environmental impact and potential risks of MPs.

An environmentally sustainable isosorbide-based plasticizer for biodegradable poly(butylene succinate)

In this article, isosorbide divalerate (SDV), an alternative renewable resource plasticizer for degradable poly(butylene succinate) (PBS) was successfully synthesized with isosorbide and valeric acid, and was characterized by Fourier transform infrared (FTIR). The mechanical properties, glass transition temperature (T g ), crystallization properties, rheological behavior of PBS/SDV blends was studied in detail. The results showed that incorporation of SDV had successfully reduced T g of the PBS composites, particularly at 20 wt% SDV, where the value of T g exhibited a reduction of 12 °C or 39% compared to pure PBS, demonstrating SDV possessed plasticizing efficacy. The crystallinity of PBS was declined by presence of SDV in the blends, and the incorporation of 20 wt% SDV into PBS matrix promoted an impressive decrease of exceeding 22%. Significant enhancement of the toughness and flexibility of PBS was achieved by the addition of SDV. The rheological test revealed that the decrease of modulus and viscosity improved the processing properties of the materials, which broadened the PBS applications. Altogether the SEM showed the fracture surface of the composites undergoes a brittle-tough transition with increasing SDV content below 12% content, meanwhile, significant phase separation was observed in the composites with high content of SDV.

Developments of biobased plasticizers for compostable polymers in the green packaging applications: A review

The demand for biobased materials for various end-uses in the bioplastic industry is substantially growing due to increasing awareness of health and environmental concerns, along with the toxicity of synthetic plasticizers such as phthalates. This fact has stimulated new regulations requiring the replacement of synthetic conventional plasticizers, particularly for packaging applications. Biobased plasticizers have recently been considered as essential additives, which may be used during the processing of compostable polymers to enormously boost biobased packaging applications. The development and utilization of biobased plasticizers derived from epoxidized soybean oil, castor oil, cardanol, citrate, and isosorbide have been broadly investigated. The synthesis of biobased plasticizers derived from renewable feedstocks and their impact on packaging material performance have been emphasized. Moreover, the effect of biobased plasticizer concentration, interaction, and compatibility on the polymer properties has been examined. Recent developments have resulted in the replacement of synthetic plasticizers by biobased counterparts. Particularly, this has been the case for some biodegradable thermoplastics-based packaging applications.

Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition

Plastics contain a complex mixture of known and unknown chemicals; some of which can be toxic. Bioplastics and plant-based materials are marketed as sustainable alternative to conventional plastics. However, little is known with regard to the chemicals they contain and the safety of these compounds. Thus, we extracted 43 everyday bio-based and/or biodegradable products as well as their precursors, covering mostly food contact materials made of nine material types, and characterized these extracts using in vitro bioassays and non-target high-resolution mass spectrometry. Two-third (67%) of the samples induced baseline toxicity, 42% oxidative stress, 23% antiandrogenicity and one sample estrogenicity. In total, we detected 41,395 chemical features with 186-20,965 features present in the individual samples. 80% of the extracts contained >1000 features, most of them unique to one sample. We tentatively identified 343 priority compounds including monomers, oligomers, plastic additives, lubricants and non-intentionally added substances. Extracts from cellulose- and starch-based materials generally triggered a strong in vitro toxicity and contained most chemical features. The toxicological and chemical signatures of polyethylene (Bio-PE), polyethylene terephthalate (Bio-PET), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyhydroxyalkanoates (PHA) and bamboo-based materials varied with the respective product rather than the material. Toxicity was less prevalent and potent in raw materials than in final products. A comparison with conventional plastics indicates that bioplastics and plant-based materials are similarly toxic. This highlights the need to focus more on aspects of chemical safety when designing truly "better" plastic alternatives.

Enhancement of mechanical, thermal and water uptake performance of TPU/jute fiber green composites via chemical treatments on fiber surface

Chopped jute fiber (JF) surfaces were modified using alkaline, silane and eco-grade epoxy resin. Surface characteristics of jute fibers were confirmed by FTIR and EDX analyses. JF filled polyurethane elastomer (TPU) composites were prepared via extrusion process. The effect of surface modifications of JF on mechanical, thermo-mechanical, melt-flow, water uptake and morphological properties of TPU-based eco-composites were investigated by tensile and hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) test, water absorption measurements and scanning electron microscopy (SEM) techniques, respectively. Mechanical test results showed that silane and epoxy treated JF additions led to increase in tensile strength, modulus and hardness of TPU. Glass transition temperature (Tg) of TPU rose up to higher values after JF inclusions regardless of treatment type. Si-JF filled TPU exhibited the lowest water absorption among composites. Surface treated JFs displayed homogeneous dispersion into TPU and their surface were covered by TPU according to SEM micro-photographs.

Fate of Hexabromocyclododecane (HBCD), A Common Flame Retardant, In Polystyrene-Degrading Mealworms: Elevated HBCD Levels in Egested Polymer but No Bioaccumulation

As awareness of the ubiquity and magnitude of plastic pollution has increased, so has interest in the long term fate of plastics. To date, however, the fate of potentially toxic plastic additives has received comparatively little attention. In this study, we investigated the fate of the flame retardant hexabromocyclododecane (HBCD) in polystyrene (PS)-degrading mealworms and in mealworm-fed shrimp. Most of the commercial HBCD consumed by the mealworms was egested in frass within 24 h (1-log removal) with nearly a 3-log removal after 48 h. In mealworms fed PS containing high HBCD levels, only 0.27 ± 0.10%, of the ingested HBCD remained in the mealworm body tissue. This value did not increase over the course of the experiment, indicating little or no bioaccumulation. Additionally, no evidence of higher trophic level bioaccumulation or toxicity was observed when L. vannamei (Pacific whiteleg shrimp) were fed mealworm biomass grown with PS containing HBCD. Differences in shrimp survival were attributable to the fraction of mealworm biomass incorporated into the diet, not HBCD. We conclude that the environmental effects of PS ingestion need further evaluation as the generation of smaller, more contaminated particles is possible, and may contribute to toxicity at nanoscale.

Estimation of the Emission Characteristics of SVOCs from Household Articles Using Group Contribution Methods

The risk to humans from chemicals in consumer products is a function of both hazard and exposure. There is an ongoing effort to quantify chemical exposure due to household articles such as furniture and building materials. Polymers and plastic materials make up a substantial portion of these articles, which may contain chemical additives such as plasticizers. When these additives are not bound to the polymer matrix, they are free to diffuse throughout it and leach or emit from the surface. We have implemented a methodology to predict plasticizer emission from polyvinyl chloride (PVC) products, based on group contribution methods that consider a free volume effect to estimate activity coefficients for chemicals in polymer-solvent solutions. Using the estimated activity coefficients, we calculate steady-state gas phase concentrations for plasticizers in equilibrium with the polymer surface (y₀). The method uses only the structure of the chemical and polymer, the weight fraction, and physical-chemical properties, allowing rapid estimation of y₀ at different weight fractions in PVC. Using the predicted y₀ values and weight fraction data gleaned from public databases, we estimate plasticizer exposures associated with 72 PVC-containing articles using a high-throughput model. We also investigate potential exposures associated with plasticizer substitutions in these products.

Dihalohydration of Alkynols: A Versatile Approach to Diverse Halogenated Molecules

In this paper we outline how dihalohydration reactions of propargylic alcohols can be used to access a wide variety of useful halogenated building blocks. A novel procedure for dibromohydration of alkynes has been developed, and a selection of dichloro and dibromo diols and cyclic ethers were synthesized. The dihalohydration of homo-propargylic alcohols provides a useful route to 3-halofurans, which were shown to readily undergo cycloaddition reactions under mild conditions. Finally, a novel ring expansion of propargylic alcohols containing a cyclopropylalkyne provides access to halogenated alkenylcyclobutanes.

Designing Green Plasticizers: Linear Alkyl Diol Dibenzoate Plasticizers and a Thermally Reversible Plasticizer

Several linear alkyl diol dibenzoate compounds, ranging from C3 to C6 in central diol length, were evaluated for their plasticizing effectiveness in blends with poly(vinyl chloride) (PVC). The results were compared to blends of PVC/di(2-ethylhexyl) phthalate (DEHP), the most commonly used commercial plasticizer. DEHP has come under scrutiny, due to its suspected endocrine-disrupting behaviour, and the proposed diol dibenzoates have previously been shown to have the potential to be green, safe candidates for DEHP replacement. The thermal and mechanical properties of PVC/dibenzoate blends were determined, and include glass transition temperature (T_g), the elongation at break, maximum stress, apparent moduli, torsional modulus, and surface hardness. The C3, C5, and C6 dibenzoates performed as well as or better than DEHP, with the exception of torsional modulus, further supporting their use as green plasticizers. For blends with 1,4-butanediol dibenzoate, differential scanning calorimetry and torsional temperature sweeps suggested that the compound partly crystallizes within PVC blends over the course of two days, thereby losing the ability to effectively plasticize PVC. However, upon heating to temperatures above 60 °C, effective plasticization was again observed. 1,4-Butanediol dibenzoate is thereby a reversible heat-activated plasticizer or processing aid with excellent plasticizer properties at mildly elevated temperatures.

Processing Conditions, Thermal and Mechanical Responses of Stretchable Poly (Lactic Acid)/Poly (Butylene Succinate) Films

Poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) based films containing two different plasticizers [Acetyl Tributyl Citrate (ATBC) and isosorbide diester (ISE)] at three different contents (15 wt %, 20 wt % and 30 wt %) were produced by extrusion method. Thermal, morphological, mechanical and wettability behavior of produced materials was investigated as a function of plasticizer content. Filmature parameters were also adjusted and optimized for different formulations, in order to obtain similar thickness for different systems. Differential scanning calorimeter (DSC) results and evaluation of solubility parameter confirmed that similar miscibility was obtained for ATBC and ISE in PLA, while the two selected plasticizers resulted as not efficient for plasticization of PBS, to the limit that the PBS–30ATBC resulted as not processable. On the basis of these results, isosorbide-based plasticizer was considered a suitable agent for modification of a selected blend (PLA/PBS 80:20) and two mixing approaches were used to identify the role of ISE in the plasticization process: results from mechanical analysis confirmed that both produced PLA–PBS blends (PLA85–ISE15)–PBS20 and (PLA80–PBS20)–ISE15 could guarantee advantages in terms of deformability, with respect to the PLA80–PBS20 reference film, suggesting that the promising use of these stretchable PLA–PBS based films plasticized with isosorbide can provide novel solutions for food packaging applications.

Biotechnological route for sustainable succinate production utilizing oil palm frond and kenaf as potential carbon sources

Due to the world's dwindling energy supplies, greater thrust has been placed on the utilization of renewable resources for global succinate production. Exploration of such biotechnological route could be seen as an act of counterbalance to the continued fossil fuel dominance. Malaysia being a tropical country stands out among many other nations for its plenty of resources in the form of lignocellulosic biomass. To date, oil palm frond (OPF) contributes to the largest fraction of agricultural residues in Malaysia, while kenaf, a newly introduced fiber crop with relatively high growth rate, holds great potential for developing sustainable succinate production, apart from OPF. Utilization of non-food, inexhaustible, and low-cost derived biomass in the form of OPF and kenaf for bio-based succinate production remains largely untapped. Owing to the richness of carbohydrates in OPF and kenaf, bio-succinate commercialization using these sources appears as an attractive proposition for future sustainable developments. The aim of this paper was to review some research efforts in developing a biorefinery system based on OPF and kenaf as processing inputs. It presents the importance of the current progress in bio-succinate commercialization, in addition to describing the potential use of different succinate production hosts and various pretreatments-saccharifications under development for OPF and kenaf. Evaluations on the feasibility of OPF and kenaf as fermentation substrates are also discussed.

Human exposure, hazard and risk of alternative plasticizers to phthalate esters

Alternative plasticizers to phthalate esters have been used for over a decade, but data regarding emissions, human exposure and health effects are limited. Here we review 20 alternative plasticizers in current use and their human exposure, hazard and risk. Physicochemical properties are collated for these diverse alternatives and log KOW values range over 15 orders of magnitude and log KAW and log KOA values over about 9 orders of magnitude. Most substances are hydrophobic with low volatility and are produced in high volumes for use in multiple applications. There is an increasing trend in the total use of alternative plasticizers in Sweden compared to common phthalate esters in the last 10 years, especially for DINCH. Evaluative indoor fate modeling reveals that most alternatives are distributed to vertical surfaces (e.g. walls or ceilings). Only TXIB and GTA are predicted to be predominantly distributed to indoor air. Human exposure data are lacking and clear evidence for human exposure only exists for DEHT and DINCH, which show increasing trends in body burdens. Human intake rates are collected and compared with limit values with resulting risk ratios below 1 except for infant's exposure to ESBO. PBT properties of the alternatives indicate mostly no reasons for concern, except that TEHPA is estimated to be persistent and TCP toxic. A caveat is that non-standard toxicological endpoint results are not available and, similar to phthalate esters, the alternatives are likely "pseudo-persistent". Key data gaps for more comprehensive risk assessment are identified and include: analytical methods to measure metabolites in biological fluids and tissues, toxicological information regarding non-standard endpoints such as endocrine disruption and a further refined exposure assessment in order to consider high risk groups such as infants, toddlers and children.