An efficient and general method for the synthesis of stable isotope deuterium labeled phthalate esters.

An efficient and general synthetic route of deuterium-labeled phthalate esters is described with high isotopic enrichment and excellent chemical purities using inexpensive and readily available o-xylene-D10 as labeled starting material. The structures and isotope-abundance were confirmed via 1 H NMR and mass spectrometry. These deuterium labeled phthalate esters can be used as analytical reference standards for the detection of plasticizer residues in soil, water, food, plastic products, etc.

Kinetics and Gibbs Function Studies on Lipase-Catalyzed Production of Non-Phthalate Plasticizer.

Petroleum based phthalate plasticizers encounter enormous claims to prohibit their production due to their harmful health impacts when they are mixed with plastics. That is why efforts are being done to find safer natural alternatives. We have investigated the reaction kinetics of the esterification epoxidation of oleic acid and 2-ethylhexanol in the presence of hydrogen peroxide catalyzed using Candida antarctica lipase (Novozym 435, Novozymes, Kobenhavn, Denmark). The product of this reaction is epoxidized 2-ethylhexyl oleate, a non-phthalate green plasticizer. The kinetic model for this reaction follows a multi-substrate PingPong Bi-Bi mechanism with competitive inhibition by the alcohol. The reaction's kinetic parameters were found to be 0.76 M, 0.37 M, 0.08 M, and 37.20 mM/min for Michalis-Menten constant for oleic acid (Kmo), Michalis-Menten constant for alcohol (Kma), alcohol inhibition constant (Kia), and maximum reaction velocity (Vmax), respectively. Then the Gibbs function analysis of the transition state based on the Arrhenius and Eyring equations was carried out. The internal diffusional limitations were found to be negligible as the effectiveness factor took the value of almost unity. While the external mass transfer resistance had no effect on the reaction due to operating at relatively high agitation speed and high temperature. This investigation confirms that this reaction was only kinetically controlled.

Semi-continuous Production of 2-Ethyl Hexyl Ester in a Packed Bed Reactor: Optimization and Economic Evaluation.

The aim of this work was to investigate the technical as well as the economic feasibility of producing 2-ethyl hexyl oleate (2-EHO), a non-phthalate plasticizer in a solvent free medium. The esterification reaction between oleic acid and 2-ethyl hexyl alcohol was carried out in a packed bed reactor (PBR) using Candida antarctica lipase B (Novozym 435; Novozymes; Copenhagen-Denmark) as biocatalyst. RSM was employed to optimize the esterification reaction conditions. The optimum reaction conditions were found to be flow rate of 1.5 mL/min, No. of cycles of 12 and molar ratio of 4:1 2-ethyl hexanol to oleic acid. The maximum experimental and predicated conversions were found to be 95.8% and 95.61% respectively. Formation of 2-EHO was approved by FTIR, 1HNMR and 13CNMR. From the economic prospective, PBR was capable of producing 2-EHO with a purity of more than 94% over 480 h without remarkable reduction of enzyme activity. This revealed an economic production of 2-EHO at a yield of 2 tons kg-1 lipase. The manufacturing cost was found to be $ 1.88 /kg 2-EHO, this contributed to a profit of about 30% compared to the commercial price of 2-EHO. Such results approve the technical and economic feasibility for this sustainable method in esters production.

Effect of hyperbranched poly(trimellitic glyceride) paired with different metal ions on the physicochemical properties of starch.

The novel hyperbranched poly(trimellitic glyceride) (PTG) starch plasticizer synthesized in our previous study was neutralized with different alkaline metal hydroxides. Mixed with starch, the effects of different alkaline metal cations, M+, on gelatinization of starch suspensions and thermal behaviors of the films were analyzed using RVA and DMA, respectively. The structures of the starch suspensions, films and freeze-dried samples (S/PTG-M) were investigated using DSC, XRD and FTIR spectroscopy, respectively. M+ increased the gelatinization temperature of starch suspensions in the order of S/PTG-Li > S/PTG-Na > S/PTG-K. The formation of a complex between M+ and starch in the films observed using FTIR spectroscopy improved the stability of the starch paste and gel, and increased the gel temperature of starch dispersions. The corresponding starch gel was relatively thermostable, but not shear-resistant. PTG decreased the Tg of starch films with different paired M+. PTG-Li and PTG-K, but not PTG-Na, strengthened the mechanical properties of starch films.

Preparation, characterization and evaluation of glycerol plasticized chitosan/PVA blends for burn wounds.

Chitosan like natural polymers have been widely used in burn wound management. Novel low molecular weight chitosan-PVA soft membranes have been studied for antibacterial and wound healing properties. The effectiveness of antibacterial activity was carried against bacterial pathogens while wound healing nature of chitosan was conducted in second degree burns on rabbits as model animal. Rabbits were divided into three groups; control untreated, treated with commercial Fusidic acid (Fu-A) cream and chitosan-PVA membranes. Low molecular weight chitosan showed significant antibacterial property towards bacterial pathogens. Wound healing experiments on second degree burn exhibited chitosan as significant wound healing agent for wound dressings. In morphological studies, normal growth of epidermis was observed and chitosan exhibited more effective for wound healing. Morphological studies also showed that chitosan wound dressings accelerated the granule and fibrous connective tissues formation. Physical characteristics of chitosan-PVA membranes were evaluated by water uptake capacity, SEM analysis, mechanical and water barrier studies.

Preparation and characterization of thermoplastic starch composite reinforced by plasma-treated poly (hydroxybutyrate) PHB.

The present work aims to study the effect of the addition of poly (hydroxybutyrate) PHB as reinforcement in thermoplastic cornstarch (TPS) produced by the thermal compression molding method. Initially, the physical and chemical properties of TPS with different amounts of glycerol as the plasticizer (25, 30 and 35 wt%), are evaluated. Then, the composites, including 35% glycerol and different PHB contents (10, 20 and 30 wt%), are prepared. Additionally, the surface of the PHB granules is modified by plasma treatment using atmospheric air and sulfur hexafluoride (SF6) gas. In order to evaluate the influence of the PHB contents before and after the plasma treatment, the composites are characterized by FTIR, TGA, DSC, XRD, SEM, and mechanical tests. SEM showed a homogeneous distribution of PHB granules in the TPS matrix. On the other hand, the micrographs of the composites, using the high concentration of plasma-treated PHB, showed the agglomerated particles in the starch matrix, which represented stress concentrators, and showed weak interfacial adhesion leading to the poor mechanical properties. The thermogravimetric analysis of the composites with PHB treated by plasma showed a higher thermal stability compared to the composites of TPS and untreated PHB.

Comparing a Statistical Model and Bayesian Approach to Establish the Design Space for the Coating of Ciprofloxacin HCl Beads at Different Scales of Production.

The primary objective of this study was to compare two methods for establishing a design space for critical process parameters that affect ethylcellulose film coating of multiparticulate beads and assess this design space validity across manufacturing scales. While there are many factors that can affect film coating, this study will focus on the effects processing conditions have on the quality and extent of film formation, as evaluated by their impact coating yield and drug release. Ciprofloxacin HCl layered beads were utilized as an active substrate core, ethylcellulose aqueous dispersion as a controlled release polymer, and triethyl citrate as a plasticizer. Thirty experiments were conducted using a central composite design to optimize the coating process and map the response surface to build a design space using either statistical least squares or a Bayesian approach. The response surface was fitted using a linear two-factor interaction model with spraying temperature, curing temperature, and curing time as significant model terms. The design spaces established by the two approaches were in close agreement with the statistical least squares approach being more conservative than the Bayesian approach. The design space established for the critical process parameters using small-scale batches was tested using scale-up batches and found to be scale-independent. The robustness of the design space was confirmed across scales and was successfully utilized to establish process signature for the coating process.

Preparation and application of a magnetic plasticizer as a molecularly imprinted polymer adsorbing material for the determination of phthalic acid esters in aqueous samples.

A novel magnetic plasticizer molecularly imprinted polymer adsorbing material (MIP@mSiO2 -ß-CD@Fe3 O4 ) was successfully synthesized for the determination of six phthalic acid esters in water, milk, and wine samples. The molecularly imprinted polymers were prepared via precipitation polymerization and a surface molecular imprinting technique, using a cyclodextrin-modified magnetic meso-porous material (mSiO2 -ß-CD@Fe3 O4 ) as a magnetic supporter, dibutyl phthalate and butyl benzyl phthalate as the dual template molecules, methacrylic acid as the functional monomer, and ethyleneglycol dimethacrylate as the cross-linking agent. The polymers were characterized by scanning electron microscopy, IR spectroscopy, and X-ray powder diffraction. Thermogravimetric analysis and static and dynamic adsorption experiments were carried out to assay its stability and selectivity. Under optimal experimental conditions, a magnetic solid-phase extraction with MIP@mSiO2 -ß-CD@Fe3 O4 coupled to gas chromatography and mass spectrometry method was successfully developed for the determination of phthalic acid esters. The established method achieved a good linear range of 0.10∼8.00 µg/mL (R > 0.99) and a low detection limit within the range of 1.0∼5.0 µg/L. An average recovery rate of 80.2∼103% with relative standard deviation < 6.7% was obtained upon the application of the developed method to detect phthalic acid esters in actual aqueous samples.

High efficiency dry coating of non-subcoated pellets for sustained drug release formulations using amino methacrylate copolymers.

Dry coating utilizing a fluidized bed was evaluated in order to produce films with sustained drug release using amino methacrylate copolymers as film former. In contrast to other dry coating procedures using amino methacrylate copolymers, the described method enables an appropriate polymer adhesion by the selection of a plasticizer additive mixture in combination with the use of a three-way nozzle for simultaneous application. Well spreading fatty acid esters were found to increase the coating efficiency from 73% to approximately 86%, when they were used in conjunction with the plasticizer. Pellets were used as drug cores without previous treatment. After a curing step at 55 °C, the pellets exhibited a prolongation of the drug release over a period of about 6 h. Mainly the three parameters, coating level, composition of the polymers in the coating mixture, and the type of plasticizer, were found to exert distinct influence on the dissolution profile. Despite the differences in the coating procedure, the dissolution profiles of the coated pellets as well as the influencing parameters were similar to those known from conventional coating techniques.

Identifying Greener and Safer Plasticizers: A 4-Step Approach.

The health and economic burden of endocrine disrupting chemicals, such as the plasticizer di(2-ethylhexyl) phthalate (DEHP), is prompting industry to develop alternatives. However, the absence of requirements for manufacturers to ensure the safety of these alternatives has led to the generation of replacements that may have similar or worse effects than the original chemicals. Consequently, there is increasing recognition by scientists, regulators and industry that proactive approaches are needed to develop safe chemical substitutes. We propose a 4-step approach for the design, characterization and toxicological testing of responsible alternative chemicals that we illustrate with our ongoing studies on DEHP replacements. Our approach is comprised of: (1) the design and characterization of alternative chemicals based on innovative chemical structures and environmental considerations; (2) large-scale in vitro cell-based high throughput and selective ex vivo studies to preselect the most innocuous alternatives; (3) an acute toxicity in vivo study to rule out overt toxicity of the selected candidates; and (4) an in utero and lactational exposure study comparing the effects of selected candidates to those currently in use, emphasizing commonly described phenotypes after exposure to the latter. Using this 4-step approach, we have identified 2 alternative chemicals displaying good plasticizing properties, better biodegradability, and less leaching than DEHP without any apparent toxicity in vivo. This process has thus far proven useful in the proactive identification of responsible chemical replacements for DEHP.

Effect of amylose content and nanoclay incorporation order in physicochemical properties of starch/montmorillonite composites.

The effects of the amylose content and the preparation sequence in physicochemical properties of starch/montmorillonite (MMT) composites were studied in this work. Native (30%) and high amylose Hylon VII (70%) starches were considered for assessing the effects of amylose content. Glycerol and MMT were used as additives to evaluate the effects of the former as plasticizer and the latter as reinforcer. The glycerol was incorporated before (Method M1) and after (Method M2) the addition of MMT. FTIR studies indicated that water bonding was affected by amylose content. Sorption isotherms indicated that method M2 favoured water adsorption and method M1 reduced water adsorption due to competition for active sites for interaction. TGA showed that method M1 induced a higher degradation rate than method M2. Wettability analysis by contact angle measurements showed that plasticizer promoted the hydrophilicity of the film, whereas MMT promoted a hydrophobic surface for both cases of amylose content.

Physical and mechanical properties of PLA, and their functions in widespread applications - A comprehensive review.

Poly(lactic acid) (PLA), so far, is the most extensively researched and utilized biodegradable aliphatic polyester in human history. Due to its merits, PLA is a leading biomaterial for numerous applications in medicine as well as in industry replacing conventional petrochemical-based polymers. The main purpose of this review is to elaborate the mechanical and physical properties that affect its stability, processability, degradation, PLA-other polymers immiscibility, aging and recyclability, and therefore its potential suitability to fulfill specific application requirements. This review also summarizes variations in these properties during PLA processing (i.e. thermal degradation and recyclability), biodegradation, packaging and sterilization, and aging (i.e. weathering and hygrothermal). In addition, we discuss up-to-date strategies for PLA properties improvements including components and plasticizer blending, nucleation agent addition, and PLA modifications and nanoformulations. Incorporating better understanding of the role of these properties with available improvement strategies is the key for successful utilization of PLA and its copolymers/composites/blends to maximize their fit with worldwide application needs.

Thermoplasticization of euglenoid ß-1,3-glucans by mixed esterification.

We experimentally demonstrated that paramylon, a storage polysaccharide of Euglena gracilis, is efficiently thermoplasticized by adding acyl groups that differ in alkyl chain length. Glass transition temperature of mixed paramylon esters was higher than those of plant-based polylactic acid (PLA), poly 11-aminoundecanoic acid (PA11), and petroleum-based acrylonitrile-butadiene-styrene (ABS) resin and was comparable to that of cellulose acetate stearate (CAS). Their thermoplasticity was equivalent to or higher than those of these reference plastics. The bending strength and bending elastic modulus of injection molded test specimens made from mixed paramylon esters were comparable to those of the reference plastics. While their impact strength was lower than that of specimens made from ABS resin and CAS, it was comparable to those of PLA and PA11. Euglenoid ß-1,3-glucans are thus a potential component of thermoplastic materials.

Properties of polyvinyl alcohol/xylan composite films with citric acid.

Composite films of xylan and polyvinyl alcohol were produced with citric acid as a new plasticizer or a cross-linking agent. The effects of citric acid content and polyvinyl alcohol/xylan weight ratio on the mechanical properties, thermal stability, solubility, degree of swelling and water vapor permeability of the composite films were investigated. The intermolecular interactions and morphology of composite films were characterized by FTIR spectroscopy and SEM. The results indicated that polyvinyl alcohol/xylan composite films had good compatibility. With an increase in citric acid content from 10% to 50%, the tensile strength reduced from 35.1 to 11.6 MPa. However, the elongation at break increased sharply from 15.1% to 249.5%. The values of water vapor permeability ranged from 2.35 to 2.95 × 10(-7)g/(mm(2)h). Interactions between xylan and polyvinyl alcohol in the presence of citric acid become stronger, which were caused by hydrogen bond and ester bond formation among the components during film forming.

Synthesis of plasticizer ester using acid-functionalized ionic liquid as catalyst.

Several plasticizer esters were synthesized by using acid-functionalized ionic liquids as catalyst. The results indicated that HSO3-functionalized Brønsted acidic ionic liquids show better catalytic and reusable performance than non-functionalized ionic liquids. For each plasticizer ester examined, one or two ionic liquids with high catalytic activity were chosen. Especially, the ionic liquids could be separated easily from the products and be reused at least six times with the conversion of the acid not less than 95%. Therefore, an environmental friendly approach for the synthesis of plasticizer ester is provided.

Preparation and properties of plasticized poly(lactic acid) films.

Poly(lactic acid), PLA, was blended with monomeric and oligomeric plasticizers in order to enhance its flexibility and thereby overcome its inherent problem of brittleness. Differential scanning calorimetry, dynamic mechanical analysis, transmission electron microscopy, and tensile testing were used to investigate the properties of the blends. Monomeric plasticizers, such as tributyl citrate, TbC, and diethyl bishydroxymethyl malonate, DBM, drastically decreased the T(g) of PLA, but the blends showed no morphological stability over time since rapid cold crystallization caused a size reduction of the amorphous domains in PLA. Consequently, the ability of PLA to accommodate the plasticizer diminished with the increase in crystallinity and migration of the plasticizer occurred. Increasing the molecular weight of the plasticizers by synthesizing oligoesters and oligoesteramides resulted in blends that displayed T(g) depressions slightly smaller than with the monomeric plasticizers. The compatibility with PLA was dependent on the molecular weight of the oligomers and on the presence or not of polar amide groups that were able to positively interact with the PLA chains. Aging the materials at ambient temperature revealed that the enhanced flexibility as well as the morphological stability of the films plasticized with the oligomers could be maintained as a result of the higher molecular weight and the polar interactions with PLA.