Industrial Polymer Production Research Articles

Increasing 1,4-Diaminobutane Production in Escherichia coli by Optimization of Cofactor PLP and NADPH Synthesis.

1,4-diaminobutane is widely used in the industrial production of polymers, pharmaceuticals, agrochemicals and surfactants. Owing to economic and environmental concerns, there has been a growing interest in using microbes to produce 1,4-diaminobutane. However, there is lack of research on the influence of cofactors pyridoxal phosphate (PLP) and NADPH on the synthesis of 1,4-diaminobutane. PLP serves as a cofactor of ornithine decarboxylase in the synthesis of 1,4-diaminobutane. Additionally, the synthesis of 1 mol 1,4-diaminobutane requires 2 mol NADPH, thus necessitating consideration of NADPH balance in the efficient synthesis of 1,4-diaminobutane by Escherichia coli. The aim of this study was to enhance the synthesis efficiency of 1,4-diaminobutane through increasing production of PLP and NADPH. By optimizing the expression of the genes associated with synthesis of PLP and NADPH in E. coli, cellular PLP and NADPH levels increased, and the yield of 1,4-diaminobutane also increased accordingly. Ultimately, using glucose as the primary carbon source, the yield of 1,4-diaminobutane in the recombinant strain NAP19 reached 272 mg/L·DCW, by increased 79% compared with its chassis strain.

A Versatile Disorder-to-Order Technology to Upgrade Polymers into High-Performance Bioinspired Materials.

Biodegradable polymeras traditional material has been widely used in the medical and tissue engineering fields, but there is a great limitation as to its inferior mechanical performance for repairing load-bearing tissues. Thus, it is highly desirable to develop a novel technology to fabricate high-performance biodegradable polymers. Herein, inspired by the bone's superstructure, a versatile disorder-to-order technology (VDOT) is proposed to manufacture a high-strength and high-elastic modulus stereo-composite self-reinforced polymer fiber. The mean tensile strength (336.1MPa) and elastic modulus (4.1GPa) of the self-reinforced polylactic acid (PLA) fiber are 5.2 and 2.1 times their counterparts of the traditional PLA fiber prepared by the existing spinning method. Moreover, the polymer fibers have the best ability of strength retention during degradation. Interestingly, the fiber tensile strength is even higher than those of bone (200MPa) and some medical metals (e.g., Al and Mg). Based on all-polymeric raw materials, the VDOT endows bioinspired polymers with improved strength, elastic modulus, and degradation-controlled mechanical maintenance, making it a versatile update technology for the massive industrial production of high-performance biomedical polymers.

Embedding Peptides into Synthetic Polymers: Radical Ring-Opening Copolymerization of Cyclic Peptides.

Biopolymers such as proteins and nucleic acids are the key building blocks of life. Synthetic polymers have nevertheless revolutionized our everyday life through their robust synthetic accessibility. Combining the unmatched functionality of biopolymers with the robustness of tailorable synthetic polymers holds the promise to create materials that can be designed ad hoc for a wide array of applications. Radical polymerization is the most widely applied polymerization technique in both fundamental science and industrial polymer production. While this polymerization technique is robust and well controlled, it generally yields unfunctional all-carbon backbones. Combinations of natural polymers such as peptides, with synthetic polymers, are thus limited to tethering peptides onto the side chains or chain ends of the latter. This synthetic limitation is a critical restraint, considering that the function of biopolymers is programmed into the sequence of their main chain (i.e., primary structure). Here, we report the radical copolymerization of peptides and synthetic comonomers yielding synthetic polymers with defined peptide sequences embedded into their main chain. Key was the development of a solid-phase peptide synthesis (SPPS) approach to generate synthetic access to peptide conjugates containing allylic sulfides. Following cyclization, the obtained peptide monomers can be readily copolymerized with N,N-dimethylacrylamide (DMA)─controlled by reversible addition-fragmentation chain transfer (RAFT). Importantly, the developed synthetic strategy is compatible with all 20 standard amino acids and uses exclusively standard SPPS chemicals or chemicals accessible in one-step synthesis─prerequisite for widespread and universal application.

Natural Polymers and Their Processing: Bottlenecks to Overcome Their Limitations in Medical Applications

Natural polymers are widely known and extensively studied, especially for applications involving biomaterials and medical devices. Such a market has a high-growth potential, associated with the increase in people's average lifetime and the crescent concern for health and prevention by the population worldwide. In spite of this, few products within the medical field made from natural polymers are manufactured on large scale and commercialized. This review aims to provoke a reflection on why there is a missing chain link between the study of these materials and their large-scale production. If there are plenty of research papers published about biopolymers, why are they not available in the market? Initially, we present general statistics about the most commonly studied natural polymers and their applications in the medical field. We then review and analyze the three main processes (in our opinion) involving the production of biomaterials: 3D printing, drying, and sterilization. We present a description of the main processing methods, focusing on the major difficulties and bottlenecks that these processes may present during their use and scale-up. Our main conclusion is that more effort and focus are needed from scientists, in particular chemical and material engineers, to integrate material science with unit operations and close the gap between research and industrial production of natural polymers. This way, we can finally bring decades of development in biopolymers to real-life applications.

Recent Advances in Biofluid Mechanics and Bio- and Hemorheology Collating Recent Advances in Predicting Complex Behavior of Human Blood With Thixo-Elasto-Visco-Plastic Models and Sequence of Physical Process

For years industrial polymer production has driven the development of rheological models to characterize the flow of materials. With the evolution of these models has come a corresponding advancement in the understanding of the complex mechanical properties. Recent efforts have been focused on modeling the behavior of complex fluids such as blood, whose microstructure leads to has simultaneous characteristics such as: thixotropy; elasticity; plasticity; and an evolving viscosity (part of which originates with the rouleaux’s evolution). The specific complex behavior of human blood can be analyzed via the analysis of Large-Amplitude-Oscillatory-Shear (LAOS) and Small-Amplitude-Oscillatory-Shear (SAOS) response tests. Unique features of human blood cannot be replicated in legacy steady-state models and, thus, have required the development of more comprehensive models capable of accurately fitting both steady state, transient flow and oscillatory shear flow. Expanding upon prior transient models, collaboration between the Chemical Engineering departments of the United States Military Academy and the University of Delaware has produced a new model, tensorial enhanced structural stress thixotropic-viscoelastic model (t-ESSTV). This model can capture the timescales contained within the plasma and individual red blood cells viscoelasticity and the thixotropic timescales associated with rouleaux breakdown and aggregation. The efficacy of t-ESSTV is demonstrated with a single Donor before consolidating the best fit model parameters of twelve Donor sets of rheological data. We then show the parametric correlations between model and physiological parameters and with the models’ prediction of microstructure, we correlate microstructure with the “elastic, solid-like” metrics as computed by Sequence of Physical Processes (SPP).

Exploiting the tuneable density of scCO2 to improve particle size control for dispersion polymerisations in the presence of poly(dimethyl siloxane) stabilisers

The dispersion polymerisation of methyl methacrylate (MMA) is a widely employed method for producing discrete, spherical PMMA particles from traditional solvents, which cover a broad particle size range. With environmental impact becoming an ever more widespread concern, there is increasing demand for greener solvents with advantageous characteristics. Supercritical carbon dioxide (scCO2) offers the potential of a greener solvent for dispersion polymerisations, with uniquely tuneable solvent properties and the ability to avoid energy and cost intensive drying steps. In this work, the tuneable density of scCO2 was exploited to influence the solubility of poly(dimethyl siloxane) stabilisers in the dispersion polymerisation of methyl methacrylate as a proof-of-concept. By varying the reactor pressure at the start of polymerisation, the final particle size was altered, without the need for cosolvent systems used in traditional solvents. Finally, this additional particle size control mechanism was exploited to achieve a PMMA particle size range far beyond what was previously attainable with this stabiliser. Thus, further enhancing the potential use of scCO2 as a green solvent for industrial polymer production.

Identification of bisphenols and derivatives in greenhouse dust as a potential source for human occupational exposure

Bisphenol A (BPA) and alternative bisphenols are widely used in the industrial production of polycarbonates and resin polymers. Adverse effects on human health have been described for BPA and owing to the structural similarity of alternative bisphenols and derivatives, a similar toxicity profile is expectable. Dust can act as a sink for bisphenols owing to the large surface area to mass ratio. Human risk exposure to bisphenols via indoor dust has been widely assessed in the last decade. The environmental conditions inside greenhouses, among other factors, facilitate that chemicals are released from greenhouse building materials to dust. This study aims to explore for the first time the potential of greenhouse dust as a new source of bisphenols for human exposure. For this purpose, a supramolecular solvent-based method was applied to the extraction of twenty-one bisphenols from greenhouse dust, prior to their determination by liquid chromatography–tandem mass spectrometry. Nineteen bisphenols were found in the five greenhouse dust samples analysed, with concentrations ranging from 5275 ng g−1 (BPA) to 0.25 ng g−1 (trichlorobisphenol A). The average daily dose (ADD) via dust ingestion for bisphenol compounds was calculated, in order to estimate the occupational exposure for inadvertent dust ingestion. Despite the calculated ADD value for BPA (47.81 ng kg−1 day−1) being below the tolerable daily intake proposed by EFSA (4·103 ng kg−1 day−1), this value was considerably higher than those previously reported for indoor dust, which brings to light the importance of considering greenhouse dust as bisphenols source of exposure for greenhouse workers.Graphical abstract

Fast and easy quantification of semi-crystalline microplastics in exemplary environmental matrices by differential scanning calorimetry (DSC)

Microplastics can be quantified with the thermoanalytical method of differential scanning calorimetry (DSC). It is a standard method for quality testing in industrial production and processing of polymers. This study shows that DSC can be used for the quantification of semi-crystalline polymers in environmental matrices. A significant improvement of detection accuracy and limit was achieved with defined pre-heating and cooling steps. The pre-heating reduced the signals of organic impurities and harmonized polymer crystallinity in particles of different origins. This study introduces the method and presents limits of quantification for polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP) and polyamide6 (PA6) as well as accuracy in environmental samples, demonstrating the feasibility of this method for the first time.

High-Velocity Stretching of Renewable Polymer Blends

We evaluated the influence of blending various renewable polymer grades and amounts to allow for high stretchability during stretching at 800 mm/s to produce polymer tapes with high Young’s moduli E and yield stress σy similar to industrial production of non-degradable synthetic polymers. Renewable polymer blends based on TPS, PBAT, and PLA with high stretchability as well as high E and σy of stretched tapes comparable to high-density polyethylene (PE-HD) and isotactic polypropylene were identified. High stretchability (up to 380%) was facilitated with TPS-PBAT tapes and comparably high E (up to 5000 MPa) and σy (up to 160 MPa) of stretched tapes were obtained for mixtures of different PLA grades resulting in E-moduli exceeding that of PE-HD. A balance of these properties approaching those of synthetic polymers was achieved with PLA-PBAT blends (stretchability: 340%, E: 4500 MPa, σy: 120 MPa).

КОМПЬЮТЕРНАЯ СИСТЕМА ДЛЯ ОПТИМАЛЬНОГО ПЛАНИРОВАНИЯ ПОЛИМЕРНЫХ ПРОИЗВОДСТВ

The development of a specialized computer system for optimal planning of production activities of large-scale multi-assortment polymer enterprises and corporations is described. The system is designed to form the optimal placement of orders for equipment within the planning interval. The computer system includes a module for representing knowledge about the scheduled object, a database of orders, production lines, types and recipes of polymer materials, a base of equipment reconfiguration rules, mathematical models of various optimization methods, including a problem-oriented genetic algorithm, and a solution visualization module. During the development, methods of mathematical modeling, methods of designing databases and knowledge bases, as well as technologies for creating automated information systems were used. The proposed computer system improves the efficiency of the scheduling process for industrial polymer production

Recovery of Residues from Olive Industry: Characterization of Simple and Acetylated Lignin

Lignin is a renewable material obtained in large quantities as a by-product of the olive industry. In this context, this study aims to examine lignin as macro-monomers in the synthesis of rigid polyurethane foam after chemical modification. Indeed, the lignin extracted from the olive residue is used by chemical treatment according to the organosolv process. Comparison by characterization of the single isolated lignin and the acetylated lignin according to the physicochemical analysisTGA, DSC, FTIR, C-13 NMR, 1-H NMR, and molar mass distribution (sec) shows its value as biomass capable of being transformed into polyol afterchemical modification. acetylation increases the weight and the number of molar masses by 25-50% was also determined. Acetylation has a greater effect on the short chains which are probably richer in free phenolic groups. Mass distribution analyzes reveal a relatively high molar mass in organosolv lignin moreover, polydispersity values are very high (20 >> 1). The characterization of spent olive cake reflects the interest of using this biomass as a source of renewable energy for the production of industrial polymers.

From alkylarenes to anilines via site-directed carbon-carbon amination.

Anilines are fundamental motifs in various chemical contexts, and are widely used in the industrial production of fine chemicals, polymers, agrochemicals and pharmaceuticals. A recent development for the synthesis of anilines uses the primary amination of C-H bonds in electron-rich arenes. However, there are limitations to this strategy: the amination of electron-deficient arenes remains a challenging task and the amination of electron-rich arenes has a limited control over regioselectivity-the formation of meta-aminated products is especially difficult. Here we report a site-directed C-C bond primary amination of simple and readily available alkylarenes or benzyl alcohols for the direct and efficient preparation of anilines. This chemistry involves a novel C-C bond transformation and offers a versatile protocol for the synthesis of substituted anilines. The use of O2 as an environmentally benign oxidant is demonstrated, and studies on model compounds suggest that this method may also be used for the depolymerization of lignin.

Atomically Precise Strategy to a PtZn Alloy Nanocluster Catalyst for the Deep Dehydrogenation of n-Butane to 1,3-Butadiene

The development of on-purpose 1,3-butadiene (BDE) technologies remains an active area in catalysis research due to the importance of BDE in industrial polymer production. Here, we report on a non-oxidative dehydrogenation catalyst for the production of BDE prepared by atomically precise installation of platinum sites on a Zn-modified SiO2 sup-port via Atomic Layer Deposition (ALD). In situ reduction x-ray adsorption spectroscopy (XAS) experiments, X-ray photoelectron spectroscopy (XPS), CO chemisorption, and high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) imaging of activated PtZn/SiO2 material, revealed the formation of a uniform, well-distributed sub-nano to nanometer PtZn (1.2 ± 0.3 nm) alloy as the active catalytic species.

ENDOCRINE DISRUPTORS: BISPHENOL A AND ITS RELATION WITH OBESITY

The prevalence of obesity is, worldwide, in wide intensification. This increase stimulates the search for new hypotheses that explain the genesis of the metabolic syndrome. This article seeks to clarify the obesogenic hypothesis of bisphenol A (BPA), based on its endocrine disrupting potential. Methodology: For the development of the present study, the Scopus and PubMed databases were used, from descriptors generated by the DeCS: Endocrine Disruptors; Foods; Obesity; Bisphenol A and its correspondents in English. Randomized and controlled trials were considered eligible, focusing on publications in English and Portuguese. The survey was conducted on April 11, 2017, with publications of the last five years being leaked. Based on this, 87 articles were obtained and, from the reading of the title and its abstracts, 26 publications were selected. After the complete reading of the 26 articles selected, 18 articles were obtained that served as a basis for this bibliographic review. Bisphenol A appears as an important agent that causes obesity in the contemporary world, interfering in the signaling mechanism of the endocrine system, being its high exposure linked to many of the habits present in the current context. Conclusion: Based on the possible consequences of bisphenol A, the reduction of human exposure to the compound should be considered. Based on this, alternatives to BPA in the production of industrial plastic polymers have to be considered since increased exposure to the endocrine disruptor is closely related to industrial production. Keywords: Endocrine Disruptors, Obesity, Bisphenol A

Metal Free Reversible-Deactivation Radical Polymerizations: Advances, Challenges, and Opportunities.

A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable control of polymerization reactions on a molecular level. Contrary to conventional radical polymerization, reversible-deactivation radical polymerization (RDRP) techniques provide the possibility to prepare polymers with well-defined structures and functionalities. The review provides a comprehensive summary over the development of the three most important RDRP methods, which are nitroxide mediated radical polymerization, atom transfer radical polymerization and reversible addition fragmentation chain transfer polymerization. The focus thereby is set on the newest developments in transition metal free systems, which allow using these techniques for biological or biomedical applications. After each section selected examples from materials synthesis and application to biomedical materials are summarized.

Melt index prediction with a mixture of Gaussian process regression with embedded clustering and variable selections

ABSTRACTIn this study, a penalized mixture of the Gaussian process regression model was proposed for the prediction of melt index (MI) in industrial polymer production. MI plays an important role in detecting the grade of a product. It is difficult to measure directly and is characterized by a large number of variables and multigrades. Because of multigrade products, in the development of soft sensors for MI prediction, it is not valid to assume unimodal Gaussian distribution of the data. To this end, the proposed method is capable of the simultaneous identification of significant variables and determination of important clusters of multigrade products. It is based on the shrinkage methods that have been shown to provide stable models that are more interpretable. Case studies are presented to show the features of the proposed method and its applicability to industrial MI prediction. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45237.

Bacterial exopolysaccharides for corrosion resistance on low carbon steel

ABSTRACTCorrosion is a global issue that affects safety and economics. There is an increasing demand for bio‐based polymers for industrial applications and production of polymers by micro‐organisms is especially attractive. This work reports on the electrochemical and physical properties of exopolysaccharides produced from lactic acid bacteria and their suitability as anti‐corrosive coatings. Bacterial exopolysaccharide coatings protected low carbon steel from corrosion by reducing ionic diffusion rates and maintaining a relatively passive metal‐coating interface. The data suggest the kinetics of film deposition are fast (<5 min) and there is little excess (loosely bound) material when hydrated. Measurements show thin (50 nm) coatings that when exposed to water exhibit self‐repairing phenomenon. The corrosion protection offered by the coatings is reported as the corrosion rate calculated from the corrosion current obtained by electrochemical impedance and polarization spectroscopy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45032.

Heterologous expression and characterization of Klebsiella oxytoca lysine decarboxylase

Cadaverine is a biogenic amine that has the potential to become an important platform chemical for the production of industrial polymers, such as polyamides and polyurethanes. We reported here a lysine decarboxylase from Klebsiella oxytoca. The lysine decarboxylase from Klebsiella oxytoca was cloned to Escherichia coli to get the strain LN18. The specific activity of the crude protein from LN18 reached 30 000 U. The molecular weight was about 80 kDa. The optimum temperature and pH of the crude protein were 55 ℃ and 5.5 respectively. The specific activity could keep over 30% at pH 8.0 compared the one at pH 5.5, much difference from Escherichia coli lysine decarboxylase CadA. Mg²⁺ was positive to the specific activity, whereas Fe²⁺, Zn²⁺ and Ca²⁺ were negative.

Automated targeting model for aggregate planning in production and energy supply chains

Aggregate planning aims to maximize profit for a supply chain while satisfying its demand. In this work, the automated targeting model (ATM) that was originally developed for resource conservation network is extended for use in aggregate planning for production and energy supply chains. The ATM is an optimization framework that is based on the insight-based technique of pinch analysis, with the philosophy in setting target(s) ahead of detailed planning. Being an optimization framework, the ATM offers other advantages than conventional pinch analysis technique by incorporating more case-specific constraints, and is able to handle more complex optimization problems. Three literature examples and an industrial polymer production case study are solved to show the robustness of ATM.

Stability engineering of the Geobacillus stearothermophilus alcohol dehydrogenase and application for the synthesis of a polyamide 12 precursor.

The thermostable NAD(+)-dependent alcohol dehydrogenase from Geobacillus stearothermophilus (BsADH) was exploited with regard to the biocatalytic synthesis of ω-oxo lauric acid methyl ester (OLAMe), a key intermediate for biobased polyamide 12 production, from the corresponding long-chain alcohol. Recombinant BsADH was produced in Escherichia coli as a homogeneous tetrameric enzyme and showed high activity towards the industrially relevant substrate ω-hydroxy lauric acid methyl ester (HLAMe) with K M=86μM and 44Umg(-1). The equilibrium constant for HLAMe oxidation to the aldehyde (OLAMe) with NAD(+) was determined as 2.16×10(-3) from the kinetic parameters of the BsADH-catalyzed forward and reverse reactions. Since BsADH displayed limited stability under oxidizing conditions, the predominant oxidation-prone residue Cys257 was mutated to Leu based on sequence homology with related enzymes and computational simulation. This substitution resulted in an improved BsADH variant exhibiting prolonged stability and an elevated inactivation temperature. Semi-preparative biocatalysis at 60°C using the stabilized enzyme, employing butyraldehyde for in situ cofactor regeneration with only catalytic amounts of NAD(+), yielded up to 23% conversion of HLAMe to OLAMe after 30min. In contrast to other oxidoreductases, no overoxidation to the dodecanoic diacid monomethyl ester was detected. Thus, the mutated BsADH offers a promising biocatalyst for the selective oxidation of fatty alcohols to yield intermediates for industrial polymer production.