A new chemically designed lignin leads to stronger, lighter carbon fiber and better recycled plastics
Germany's Lanxess generated net sales of E1.704 billion in the first quarter of 2020, down only 2% compared to the previous year despite the weak economic environment due to the COVID-19 pandemic. However, EBITDA pre-exceptionals declined by 9.9% to E245 million and net income from continuing operations fell more sharply, by 27.6%, to E63 million. The EBITDA margin pre-exceptionals amounted to 14.4% compared to 15.7% in 1Q 2019.
Polymer additives and colorants producer Milliken & Co reports that it has helped to produce essential medical personal protective equipment (PPE) amid the COVID-19 pandemic by boosting the plastic industry's ability to supply appropriate materials.
This article looks at the underlying chemistry of various types of additives, and antimicrobial films, which potentially could be used by the food-packaging industry, and the associated research work which seeks to make this technology commercially usable.
This chapter provides an overview of the coating of pharmaceutical dosage forms. The focus is on film coating, which has become the mainstay for modern pharmaceutical coating processes. From a materials standpoint the primary types of film-coating formulations are reviewed, as are problems associated with this technology. The types of equipment used in prior and current coating processes are described, and recent trends associated with film coating are described.
This article reports from Netherlands on the new company's enhanced plastic additives capacity.
The treatment of bacterial infections is increasingly complicated by the ability of bacteria to develop resistance to antimicrobial agents. Antimicrobial agents are often categorized according to their principal mechanism of action. Mechanisms include interference with cell wall synthesis (e.g., β-lactams and glycopeptide agents), inhibition of protein synthesis (macrolides and tetracyclines), interference with nucleic acid synthesis (fluoroquinolones and rifampin), inhibition of a metabolic pathway (trimethoprim-sulfamethoxazole), and disruption of bacterial membrane structure (polymyxins and daptomycin). Bacteria may be intrinsically resistant to ≥1 class of antimicrobial agents, or may acquire resistance by de novo mutation or via the acquisition of resistance genes from other organisms. Acquired resistance genes may enable a bacterium to produce enzymes that destroy the antibacterial drug, to express efflux systems that prevent the drug from reaching its intracellular target, to modify the drug’s target site, or to produce an alternative metabolic pathway that bypasses the action of the drug. Acquisition of new genetic material by antimicrobial-susceptible bacteria from resistant strains of bacteria may occur through conjugation, transformation, or transduction, with transposons often facilitating the incorporation of the multiple resistance genes into the host’s genome or plasmids. Use of antibacterial agents creates selective pressure for the emergence of resistant strains. Herein 3 case histories—one involving Escherichia coli resistance to third-generation cephalosporins, another focusing on the emergence of vancomycin-resistant Staphylococcus aureus, and a third detailing multidrug resistance in Pseudomonas aeruginosa—are reviewed to illustrate the varied ways in which resistant bacteria develop.
The cardanol-derived plasticizers cardanol acetate (CA) and epoxidized cardanol acetate (ECA) were prepared from a renewable resource, cashew nut shell liquid (CNSL), and their plasticization efficiencies were investigated. The thermal decomposition temperatures of the cardanol derivatives were higher than that of the common petroleum-based plasticizer di-2-ethylhexyl phthalate (DOP) in the order ECA > CA > DOP. The tensile strains of the PVCs containing CA and ECA were ca. 705–810%, and the tensile strengths were ca. 17.4–19.1 MPa, which were higher than those of PVC containing DOP. The results of a Fourier transform infrared spectroscopy (FT-IR/ATR) and dynamic mechanical analysis (DMA) showed that the compatibility of ECA with PVC was excellent, and the Tg of PVC containing 50 phr of ECA decreased to 27.4 °C. In studies on the combination of a primary plasticizer with epoxidized soybean oil (ESBO), it has been shown that the addition of small amounts (5 phr) of ESBO to ECA improves not only the thermal stability but also the mechanical properties, despite the insufficient compatibility of ESBO and PVC. It can be inferred that the mixture of ECA and ESBO improves the affinity of ESBO and PVC, thereby reducing the polymer chain interactions. Finally, in the leaching tests, the weight loss of PVC containing 50 phr of ECA was reduced to 2%, confirming that ECA is highly resistant to migration to water. As a result, the combination of two biobased plasticizers, ECA and ESBO, could be a good candidate to replace DOP.
Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.
The synthesis of a new bisperoxycarbamate based on a reaction between hexamethylene-1,6 diisocyanate and tertiary butyl hydroperoxide was undertaken. In addition, studies were carried out on an earlier research bisperoxycarbamate based on methylene bis(4-cyclohexylisocyanate) and tertiary butyl hydroperoxide. The equation showing the preparation of the new material is shown below: [Equation not shown] The new material - hexamethylene-N,N' bis (tertiary butyl peroxycarbamate) is shown to be able to crosslink a wide range of elastomers, namely -BIIR, NR, SBR, NR/BR, CR, FKM, NBR, Q, ECO, GPO. However, it has been found to give best results in fluorocarbon rubber which was examined in further detail. The material is shown to be versatile by using it to cure different grades of fluorocarbon rubber (mainly copolymers of vinylidene fluoride and hexafluoropropylene). The physical properties obtained with the new material as curing agent are comparable with those obtained using standard crosslinking agents for fluoroelastomers. Since carbon dioxide is evolved when bisperoxycarbamates are heated, calcium hydroxide was included in most formulations to act as an absorber system. Calcium oxide and magnesium oxide were found to be suitable metallic oxides to react with any acidic gases (such as hydrogen fluoride) evolved during curing of fluoroelastomer compounds. It was ii observed that the state of cure was- poorer when lead oxides were used (e.g. litharge PbO); also, the use of dibasic lead phosphite as acid acceptor appeared to interfere with HBTBP cure. Compounding studies, solvent extraction methods and nitrogen tests, and crosslink density measurements were used to postulate possible routes of crosslink formation. These routes of crosslink formation were based on homolytic decomposition of the bisperoxycarbamate, radical abstraction, interaction of a reactive intermediate, and radicalradical interaction. Additional information was obtained from stress relaxation measurements which indicated that new crosslinks were formed during postcuring of fluorocarbon vulcanizates and that this process continued in the initial stages of heat-ageing of postcured FKM vulcanizates.
The decision as to which chemical entity should progress to development as a drug candidate has, in the past, been based on relatively expensive preclinical efficacy and safety studies that have been performed in animals. This review presents a proposal to improve the efficiency of human drug development and increase the ‘hit rate’ of clinical candidates. The proposal is based on the concept that human drug metabolism strategies established early on in the drug development/drug discovery paradigm could lead to untenable candidates being discarded at an early stage in the drug development process. This strategy would tend to reduce costs and provide greater focus on those agents more likely to be successful as drug candidates.
This review aims at highlighting on recent developments in preparation, characterization, properties, crystallization behaviors, melt rheology, processing, and future applications possibilities of biodegradable polymers and their layered silicate nanocomposites. These materials are attracting considerable interest in materials science research. Montmorillonite and hectorite are among the most commonly used smectite-type layered silicates for the preparation of nanocomposites. In their pristine form they are hydrophilic in nature, and this property makes them very difficult to disperse into biodegradable polymer matrices. The most common strategy to overcome this difficulty is to replace the interlayer clay cations with quarternized ammonium or phosphonium cations, preferably with long alkyl chains.A wide range of biodegradable polymer matrices is described in this review with a special emphasis on polylactide because of more eco-friendliness from its origin as contrast to the fully petroleum-based biodegradable polymers and control of carbon dioxide balance after their composting.Preparative techniques include (i) intercalation of polymers or prepolymers from solution, (ii) in situ intercalative polymerization method, and (iii) melt intercalation method.This new family of composite materials frequently exhibits remarkable improvements of mechanical and material properties when compared with virgin polymers or conventional micro- and macro-composites. Improvements can include a high storage modulus both in solid and molten states, increased tensile and flexural properties, a decrease in gas permeability and flammability, increased heat distortion temperature and thermal stability, increase in the biodegradation rate, and so forth.
Some of the unsolved problems and unanswered questions in the flame retardance of polymers are reviewed. They include, durable flame-retardant systems for cotton; FR treatment of cotton–PET blends; durable, weatherable, non-water-leachable, FR treatment of lignocellulosic products, especially wood; better understanding of gas phase and condensed phase mechanisms of flame retardance; flame retardance by sulfur derivatives; weatherable flame-retardant coatings; lowering smoke from styrenic polymers; catalysis in flame retardance; and nanocomposites in flame retardance.
A new approach to produce biodegradable low-temperature greases, based on cellulose acetate butyrate (CAB) that dissolves in the medium of acetyl tributyl citrate (ATBC) at high temperatures and produces a gel during cooling because of phase separation, is proposed. Rheological properties of CAB solutions and gels in a wide temperature range from −80 °C to 160 °C were investigated with characterization of their viscoelasticity and viscoplasticity that arise because of the sol-gel transition of CAB/ATBC systems at 55 °C. CAB gelation reduces the wear coefficient tenfold when using ATBC as a lubricant but leads to a noticeable increase in the friction coefficient. To improve tribological properties of gel greases, additives of various solid particles were used: hexagonal boron nitride, graphite, and polytetrafluoroethylene (PTFE). The introduction of 10% to 30% additives in a gel grease containing 10% CAB has shown the preference of PTFE at a concentration of 10% for improving grease tribological characteristics.
Short carbon fibre filled polychloroprene compounds were prepared by mill mixing and by a making a cement in a solvent before being vulcanized by a thermovulcanisation technique, that is by heating at an elevated temperature (160°C) in absence of any vulcanizing agent
To assess the effects of exposure to Cd and Zn on rat testicular development, offspring, from mothers receiving either tap water, Cd, Zn or Cd + Zn during gestation and lactation periods, were observed on gestational day (GD) 20 and on postnatal days (PND) 12, 21 and 35. During gestation, Cd induced maternal hypozincemia and less transfer of Zn to the fetus. During lactation, progressive Cd accumulation and Zn depletion in testis at PND12 and PND21 were noted. An increase of abnormal seminiferous tubules and a decrease in testis weight and plasmatic testosterone concentration were also observed at PND21 and PND35 respectively. Interestingly, Zn supply induced a significant protection against Cd toxicity. These results suggest that the toxic effects of Cd observed during development are mediated by the disruption of Zn metabolism, which is established in mothers during pregnancy causing Zn deficiency in fetuses and continues to become more pronounced during lactation.
European demand for glass filled reinforced polyolefins continues to show significant growth rates. The main drive behind this is material replacement within the automotive and household appliance markets. In particular the automotive industry is turning towards glass filled polypropylene components both to reduce weight and increase recyclability. One route by which the performance of glass filled composites can be improved is by incorporating chemical coupling agents. In this paper the property enhancement achievable with POLYBOND 3002, supplied by BP Chemicals, is described. In addition development work with glass filled polymer alloys is presented.
