Coat Components Research Articles

Investigation in the pyrolysis of polyester coated on aluminum-based beverage: Thermodynamic properties, product and mechanism

Aluminum cans are typical solid waste. Polyester coatings not only polluted the environment, but also affected the quality of aluminum recycling. In this study, three common local polyester coatings on the surface of aluminum cans were selected as raw materials (PC-PB, PC-VY and PC-SG). Thermogravimetric analysis, elemental analysis, Fourier transform infrared spectrometer and pyrolysis gas chromatography/mass spectrometry (PY-GC/MS) were used to study the pyrolysis behavior and pyrolysis products of the polymer components coated on the aluminum cans. TG analysis showed that pyrolysis of the coatings mainly occurred at 250–540 °C, with a weight loss of about 25 % for the polyester coating PC-PB and PC-VG, and a lower weight loss of 15 % for polyester coating PC-SY. The effect of pyrolysis temperature on the pyrolysis products of polyester coatings was investigated using PY-GC/MS. The results showed that the main products of pyrolysis included four major groups: oxygenated compounds, aromatic compounds, nitrogenous compounds and aliphatic hydrocarbons. At 600 °C, the aromatic compounds, oxide-containing reached 57–67 % and 20–27 %, respectively. The main pyrolysis products include neopentyl glycol, phthalic anhydride, toluene, styrene and so on. The high content of aromatic compounds in the product can be used as chemical raw materials as well as alternative fuels. In addition, the pyrolysis principles of the three main components of polyester coatings (polyester resins, amino resins, and styrene-acrylic resins) were postulated.

Advancing protein display on bacterial spores through an extensive survey of coat components.

The profound stability of bacterial spores makes them a promising platform for biotechnological applications like biocatalysis, bioremediation, drug delivery, etc. However, though the Bacillus subtilis spore is composed of >40 proteins, only ∼12 have been explored as fusion carriers for protein display. Here, we assessed the suitability of 33 spore proteins (SPs) as enzyme display carriers by direct allele tagging at native genomic loci. Of the 33 SP investigated, 26 formed functional fusions with β-glucuronidase (GUS) - a ∼272 kDa homotetramer. This almost triples the number of SPs assessed for enzyme display and doubles the number of functional fusions documented in the literature. We quantitatively assessed the 1) SP promoter activation dynamics during growth, 2) supported GUS activity on spores, 3) surface availability, 4) protection from thermal and proteolytic degradation, and 5) compatibility of co-expression of many of these fusions. Multi-copy expression and pairwise co-expression of the most promising SP-GUS fusions highlighted the complexity of spore structure/assembly and difficulty in predicting compatibility between different SPs fusions. We also assessed the suitability of engineered spores to degrade PET (polyethylene terephthalate) films and found that surface exposed SPs were most effective. Beyond the broad survey, a key outcome of our work was the identification of SscA ( s mall s pore c oat assembly protein A ) as an effective spore display carrier. SscA supported enzyme activity at least fourfold higher than any other SP, including the well-established and popular anchor, CotY. We attribute this to the biochemical and genetic features of SscA; its promoter demonstrated early and sustained activation relative to other SPs and its small size (∼3 KDa) likely minimally interferes with enzyme folding, oligomerization, and activity. Although the specific localization of SscA within the spore coat has not been established, its hydrophobic nature and low surface availability suggests that it assembles internally within the spore coat, which makes it highly stabilizing and suitable for many biocatalytic applications. Overall, this work serves as a knowledgebase to advance the biotechnological utility of B. subtilis spores.

Study on the effect of film-forming agent composition on moisture and heat resistance of basalt fiber composites

Abstract Resistance to hygrothermal aging is the key to the popularization and application of basalt fiber composites in the field of electrical equipment, so it is crucial to develop fiber surface-modified coatings suitable for basalt fibers with excellent hygrothermal resistance. In this study, the performance changes of basalt fiber composite samples treated with four types of surface coatings under artificially accelerated hygrothermal aging test were comparatively analyzed, and the mechanism of different components in the surface coatings was further analyzed. The results showed that the use of epoxy resin emulsion co-mingled with acrylic emulsion as the film-forming agent could significantly improve the mechanical properties of the samples. The use of epoxy resin emulsion co-blended with polyurethane emulsion as the film-forming agent improved the insulating properties and moisture and heat resistance of the samples. Further, the use of 5:1:1 epoxy emulsion, acrylic emulsion, and polyurethane emulsion co-blended as the film-forming agent component can ensure the insulation and hygrothermal resistance of the samples while taking into account the mechanical properties. After 120 hours of wet-heat aging, the breakdown field strength was increased by 22%, leakage current and dielectric loss angle was increased by 10%, and the mechanical properties were also significantly improved compared with the sample with epoxy emulsion as the main film-forming agent. In summary, through the compounding of the film-forming agent emulsion components, the optimization of the moisture and heat resistance of basalt fiber composites can be achieved, and the use of the mass percentage of 5:1:1 for the three types of emulsions blended to prepare the fiber surface coatings is more suitable for the treatment of basalt fibers to prepare the electrician’s equipment.

Amide and amidoester fatty acid derivatives as multifunctional components of protective alkyd urethane coatings

Amide and amidoester fatty acid derivatives as multifunctional components of protective alkyd urethane coatings

Fracture mechanism of metallic film with nano to sub-micron thickness on polycrystalline substrate

Understanding the fracture behaviors of ultrathin metallic films on polycrystalline substrates is essential to preventing failures of extensive coated components. This study investigates the fracture mechanisms of niobium films with nano to sub-micron thickness deposited on stainless steels, serving as a model system. Cracks of the 100-nm films are demonstrated to be primarily induced by out-of-plane dislocation slips in the substrate. However, as the film thickness increases to 500 nm, our findings reveal that the deposited films no longer solely succumb to substrate plasticity. Instead, they influence substrate deformation by forming an interface-affected zone with intense heterogeneous interactions. In this zone, both the accumulation of geometrically necessary dislocations and a transition from dislocation to twinning accommodated plasticity occur. The extensive deformation twinning creates ultrahigh steps, ultimately resulting in film cracking. These in-depth microscopic insights pave the way for advancements in ultrathin coatings and offer valuable knowledge for future research.

VARP binds SNX27 to promote endosomal supercomplex formation on membranes.

Multiple essential membrane trafficking pathways converge at endosomes to maintain cellular homeostasis by sorting critical transmembrane cargo proteins to the plasma membrane or the trans-Golgi network (TGN). The Retromer heterotrimer (VPS26/VPS35/VPS29 subunits) binds multiple sorting nexin (SNX) proteins on endosomal membranes, but molecular mechanisms regarding formation and regulation of metazoan SNX/Retromer complexes have been elusive. Here, we combine biochemical and biophysical approaches with AlphaFold2 Multimer modeling to identify a direct interaction between the VARP N-terminus and SNX27 PDZ domain. VARP and SNX27 interact with high nanomolar affinity using the binding pocket established for PDZ binding motif (PDZbm) cargo. Specific point mutations in VARP abrogate the interaction in vitro. We further establish a full biochemical reconstitution system using purified mammalian proteins to directly and systematically test whether multiple endosomal coat complexes are recruited to membranes to generate tubules. We successfully use purified coat components to demonstrate which combinations of Retromer with SNX27, ESCPE-1 (SNX2/SNX6), or both complexes can remodel membranes containing physiological cargo motifs and phospholipid composition. SNX27, alone and with Retromer, induces tubule formation in the presence of PI(3)P and PDZ cargo motifs. ESCPE-1 deforms membranes enriched with Folch I and CI-MPR cargo motifs, but surprisingly does not recruit Retromer. Finally, we find VARP is required to reconstitute a proposed endosomal "supercomplex" containing SNX27, ESCPE-1, and Retromer on PI(3)P-enriched membranes. These data suggest VARP functions as a key regulator in metazoans to promote cargo sorting out of endosomes.

Evading the strength and toughness trade-off dilemma in Lu2Si2O7 environmental barrier coatings via micro-nano reinforcement

Lu2Si2O7 nanostructured environmental barrier coating was prepared using as–synthetic Lu2Si2O7 feedstock via atmospheric plasma spraying. The structure and mechanical performances of Lu2Si2O7 coatings were characterized in detail. Results indicate that nanostructured Lu2Si2O7 coating exhibits a bi-modal microstructure, lamella structure and unmelted particles. The phase components of nanostructured Lu2Si2O7 coatings consist of β-Lu2Si2O7 and a small number of X2-Lu2SiO5. Furthermore, the nanohardness and elastic modulus of Lu2Si2O7 coatings have the characterization of bi-modal properties via Weibull analysis, i.e., the large Weibull modulus and the small Weibull modulus represent molten lamella structure and unmelted particles, respectively. Meanwhile, the fracture toughness of nanostructured Lu2Si2O7 coatings is superior to conventional Lu2Si2O7 coatings, and the adhesion strength of Lu2Si2O7 coatings is about 22.6 MPa by pull-extend test. Results of research are helpful for the design and preparation of advanced thermal spray coating.

Research on the resistance of protective coatings for concrete to the effects of atmospheric moisture

The development of the construction industry has led to increased requirements for the operational properties of building materials in general and concrete in particular. Although concrete is designed primarily to withstand structural loads, it must also resist environmental influences to increase its durability. This article presents the results of the influence of the components of protective coatings on the hydro-physical properties of concrete. The edge wetting angle in concrete with a protective coating ranges from 95 to 101 degrees, which is about twice that of uncoated concrete. The mass of concrete under the influence of hygroscopic moisture increases, and after 30 days of exposure, it is 1.1–1.6 wt. % compared to 5.7–5.8 wt. % for control samples. The minimum increase (1.1–1.2 wt. %) is achieved when using coatings with the largest amount of heat-resistant varnish KO-08. The water absorption of the developed coating compositions decreases after 30 days of being in water from 5.2 to 1.6–2.2 wt. % for C20/25 concrete. Low temperatures negatively affect the hydrophysical properties of protective coatings, but only slightly. It has been found that water absorption increases by approximately 20 %.

Stability and Biaxial Behavior of Fresh Cheese Coated with Nanoliposomes Encapsulating Grape Seed Tannins and Polysaccharides Using Immersion and Spray Methods.

In the food industry context, where fresh cheese stands out as a highly perishable product with a short shelf life, this study aimed to extend its preservation through multi-layer edible coatings. The overall objective was to analyze the biaxial behavior and texture of fresh cheese coated with nanoliposomes encapsulating grape seed tannins (NTs) and polysaccharides (hydroxypropyl methylcellulose; HPMC and kappa carrageenan; KC) using immersion and spray methods, establishing comparisons with uncoated cheeses and commercial samples, including an accelerated shelf-life study. NT, HPMC, and KC were employed as primary components in the multi-layer edible coatings, which were applied through immersion and spray. The results revealed significant improvements, such as a 20% reduction in weight loss and increased stability against oxidation, evidenced by a 30% lower peroxide index than the uncoated samples. These findings underscore the effectiveness of edible coatings in enhancing the quality and extending the shelf life of fresh cheese, highlighting the innovative application of nanoliposomes and polysaccharide blends and the relevance of applying this strategy in the food industry. In conclusion, this study provides a promising perspective for developing dairy products with improved properties, opening opportunities to meet market demands and enhance consumer acceptance.

Identification of Novel Loci Precisely Modulating Pre-Harvest Sprouting Resistance and Red Color Components of the Seed Coat in T. aestivum L.

The association between pre-harvest sprouting (PHS) and seed coat color has long been recognized. Red-grained wheats generally exhibit greater PHS resistance compared to white-grained wheat, although variability in PHS resistance exists within red-grained varieties. Here, we conducted a genome-wide association study on a panel consisting of red-grained wheat varieties, aimed at uncovering genes that modulate PHS resistance and red color components of seed coat using digital image processing. Twelve loci associated with PHS traits were identified, nine of which were described for the first time. Genetic loci marked by SNPs AX-95172164 (chromosome 1B) and AX-158544327 (chromosome 7D) explained approximately 25% of germination index variance, highlighting their value for breeding PHS-resistant varieties. The most promising candidate gene for PHS resistance was TraesCS6B02G147900, encoding a protein involved in aleurone layer morphogenesis. Twenty-six SNPs were significantly associated with grain color, independently of the known Tamyb10 gene. Most of them were related to multiple color characteristics. Prioritization of genes within the revealed loci identified TraesCS1D03G0758600 and TraesCS7B03G1296800, involved in the regulation of pigment biosynthesis and in controlling pigment accumulation. In conclusion, our study identifies new loci associated with grain color and germination index, providing insights into the genetic mechanisms underlying these traits.

Research of the properties of protein hydrolysates obtained from the broiler chicken gizzards as a potential component of bioactive film coatings

Protein hydrolysates are a promising active component in the production of bioactive film coatings for food products. Some biopolymers can exert the biological activity. More often, however, it is necessary to select biologically active substances to impart these properties to films. On the other hand, not all components allow forming films with the required properties, and therefore there is a need to study the individual technological characteristics of the components used. The purpose of the research is to establish the antioxidant and technological properties of protein hydrolysates obtained by microbial fermenta- tion of poultry by-products in whey with bifidobacteria, propionic acid bacteria and acidophilic bacteria as a potential basis for bioactive film coatings of food products. The hydrolysate obtained by fermentation without the addition of the specified bacterial species was used as a control sample. The functional properties of protein hydrolysates were assessed: antioxidant capacity by coulometric titration on an Expert-006 coulometer using ascorbic acid as a standard, antiradical activity by the DPPH method on a Jenway 6405 UV/Vis spectrophotometer with determination of the IC50 value. The technological proper- ties, solubility, water-holding, fat-holding and fat-emulsifying capacities were also determined by the gravimetric method. In addition, the average hydrodynamic diameter of particles in protein hydrolysates was determined using a Microtrac FLEX particle size analyzer. The results of studies of the antioxidant properties showed that the DPPH antiradical activity was 14.7% higher in the experimental samples of hydrolysates obtained by fermentation with bifidobacteria compared to the control; samples of hydrolysates obtained by fermentation with propionic acid bacteria showed an antioxidant capacity 29.6% higher than that of the control sample. The IC50 value turned out to be the highest in the control hydrolysate sample (2.994 mg/ml), which was 45.5–53.3% higher than that in the experimental hydrolysate samples. The results of determining the technologi- cal properties showed that they differ significantly for protein hydrolysates obtained by fermentation with different types of bacteria. For example, the highest values of fat-holding and fat-emulsifying capacities were found in the hydrolysate obtained by fermentation with bifidobacteria (351.1% and 61%, respectively), which shows its potential for incorporation into the bio- composite in the form of a protein-oil emulsion. The high solubility of the experimental samples of hydrolysates (from 90.1 to 91.4%) suggests their uniform distribution in the aqueous phase when composing the biocomposite of the film. Thus, the research results have shown the prospects of using protein hydrolysates from the gizzards of broiler chickens in whey as an active component of bioactive film coatings. The antioxidant properties of protein hydrolysates allow slowing down oxidative processes in the main food nutrients, which will contribute to an increase in the shelf life of food products packaged in bioac- tive films with this component.

Self-healing epoxy coatings via microencapsulation of aromatic diisocyanate in lignin stabilized Pickering emulsions

Isocyanate-filled microcapsules are gaining increased attention for their role in developing self-healing materials, thereby reducing maintenance costs and increasing polymer durability. Nevertheless, microencapsulating highly reactive -NCO groups remains a challenging task in the literature. Likewise, considerable efforts have been directed towards developing polymers from renewable and biobased sources, which could also be applied to microcapsule synthesis. In this work, lignin, an abundant biopolymer, was used as a solid stabilizer for oil-in-water (O/W) interfaces, enabling the encapsulation of highly reactive isocyanate. Hybrid polyurethane/polyurea microcapsules containing reactive methylenediphenyl diisocyanate (MDI) were obtained via optimized O/W Pickering emulsions using lignin for system stabilization. This optimized process facilitated shell formation via the reaction of diisocyanate with lignin and water, eliminating the need for additional chain extenders. Scanning electron microscopy revealed the formation of spherical and rough microcapsules, while infrared spectroscopy confirmed the presence of residual free -NCO groups, indicating effective encapsulation of MDI. Additionally, a core -NCO concentration of 11 wt% was confirmed by titration. The microcapsules were further assessed as components in self-healing epoxy coatings. Their incorporation resulted in the retardation of corrosion on a low carbon steel panel after 72 h of submersion in a saline solution. Electrochemical impedance spectroscopy (EIS) confirmed a significant increase of approximated 620% in impedance modulus after 83 days of immersion in a 3.5 wt% NaCl solution, compared to the neat epoxy coating. These findings suggest a promising technological application of this material for the advancement of self-healing epoxy-based coatings and composites.

Exploring the Implications of Golgi Apparatus Dysfunction in Bone Diseases.

The Golgi apparatus is an organelle responsible for protein processing, sorting, and transport in cells. Recent research has shed light on its possible role in the pathogenesis of various bone diseases. This review seeks to explore its significance in osteoporosis, osteogenesis imperfecta, and other bone conditions such as dysplasias. Numerous lines of evidence demonstrate that perturbations to Golgi apparatus function can disrupt post-translational protein modification, folding and trafficking functions crucial for bone formation, mineralization, and remodeling. Abnormalities related to glycosylation, protein sorting, or vesicular transport in Golgi have been associated with altered osteoblast and osteoclast function, compromised extracellular matrix composition, as well as disrupted signaling pathways involved with homeostasis of bones. Mutations or dysregulation of Golgi-associated proteins, including golgins and coat protein complex I and coat protein complex II coat components, have also been implicated in bone diseases. Such genetic alterations may disrupt Golgi structure, membrane dynamics, and protein transport, leading to bone phenotype abnormalities. Understanding the links between Golgi apparatus dysfunction and bone diseases could provide novel insights into disease pathogenesis and potential therapeutic targets. Future research should focus on unraveling specific molecular mechanisms underlying Golgi dysfunction associated with bone diseases to develop targeted interventions for restoring normal bone homeostasis while decreasing clinical manifestations associated with these issues.

Cocoa butter and replacement in compound coatings and effect on the coatings rheological profile

Cocoa butter is a crucial component in chocolate and compound coatings, significantly influencing their physicochemical properties, which, in turn, affect the viscosity and cooling rate of the coatings. This impact is vital in the formulation and storage of coatings, affecting their flow behavior, texture, and stability. Research has shown that the inclusion of coconut oil as a cocoa butter substitute in chocolate results in a reduction in the chocolates viscosity. This is attributed to the lower viscosity of coconut oil, primarily due to its lauric acid content. This experiment utilized the Brookfield viscometer to measure the viscosity of chocolate. Three representative types of chocolate were selected: milk chocolate, white chocolate, and dark chocolate, all containing the same ingredient: coconut oil. The analysis of the measurement results allows the determination of the viscosity characteristics of chocolate, providing insights into which type of chocolate exhibits the most significant improvement in viscosity due to the presence of coconut oil. Experimental results indicate that milk chocolate with the addition of 4.5% coconut oil exhibits optimal physical characteristics, including gloss, texture, and overall acceptance by participants. In contrast, dark chocolate with coconut oil has higher viscosity and slower cooling rates, requiring more time to complete the coating or product preparation, which may affect production efficiency. White chocolate with coconut oil typically falls between milk chocolate and dark chocolate in terms of viscosity. This study delves deep into the impact of cocoa butter substitutes on various chocolate coatings, offering valuable insights into the application of coconut oil as a cocoa butter alternative in chocolate production.

Corrosion behavior and incorporation mechanism of Y2O3-TiO2 composite coatings fabricated on TC4 titanium alloy by plasma electrolytic oxidation

The anti-corrosion of titanium alloys is a topic of concern in many fields. In our work, the Y2O3-TiO2 composite coatings were fabricated on the TC4 titanium alloy by plasma electrolytic oxidation (PEO). The reaction was conducted in an electrolyte system made up of Na2SiO3, KOH, and (NaPO3)6. The effects of additive Y(NO3)3 in the electrolyte on the microstructure, chemical component, phase structure, thickness, hydrophobicity, and corrosion resistance of the composite coatings were studied. The results show that the composite coatings prepared by PEO reaction exhibit preferable corrosion resistance. The addition of Y(NO3)3 is beneficial for thickening the coatings, reducing their porosity and pore size, and further improving their hydrophobicity and corrosion resistance. Furthermore, the incorporation mechanism of Y2O3 was discussed based on thermodynamics theory.

Sheep's Second Cheese Whey Edible Coatings with Oregano and Clary Sage Essential Oils Used as Sustainable Packaging Material in Cheese.

Sheep's second cheese whey (SCW), the by-product resulting from whey cheese production, was used as a component of cheese coatings containing oregano (Origanum compactum) and clary sage (Salvia sclarea) essential oils (EOs). SCW powder was obtained by the ultrafiltration/diafiltration of SCW followed by reverse osmosis and freeze drying. The coatings were produced with a mixture of SCW and whey protein isolate (WPI) using glycerol as plasticizer. Model cheeses were produced with cow´s milk and those containing SCW:WPI coatings; those with and without EOs were compared to controls without coating and with a commercial coating containing natamycin. At the end of ripening (28 days), the cheeses containing EOs presented higher water activity (ca. 0.930) and moisture content, as well as lower titratable acidity. Concerning color parameters, significant differences were also observed between products and as a result of ripening time. However, the use of SCW:WPI coatings did not significantly influence the color parameters at the end of ripening. Regarding texture parameters, the cheeses containing SCW:WPI coatings presented significantly lower values for hardness, chewiness, and gumminess. Significant differences were also observed for all microbial groups evaluated either between products and as a result of ripening time. In all cases, lactobacilli and lactococci counts surpassed log 7-8 CFU/g, while the counts of yeasts and molds increased steadily from ca. log 3 to log 6 CFU/g. The lowest counts of yeasts and molds were observed in the samples containing natamycin, but nonsignificant differences between products were observed. In conclusion, SCW:WPI cheese coatings can successfully substitute commercial coatings with the advantage of being edible packaging materials manufactured with by-products.

The Types of Organic Compound in Living Body

Organic compound, any of a large class of chemical compounds in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen. carbon atoms provide the key structural framework that generates the vast diversity of organic compounds. All things on Earth (and most likely elsewhere in the universe) that can be described as living have a crucial dependence on organic compounds Foodstuffs—namely, fats, proteins, and carbohydrates—are organic compounds, as are such vital substances as hemoglobin, chlorophyll, enzymes, hormones, and vitamins. Other materials that add to the comfort, health, or convenience of humans are composed of organic compounds, including clothing made of cotton, wool, silk, and synthetic fibres; common fuels, such as wood, coal, petroleum, and natural gas; components of protective coatings, such as varnishes, paints, lacquers, and enamels; antibiotics and synthetic drugs; natural and synthetic rubber; dyes; plastics; and pesticides.

Gıda atıklarının bakteriyel selüloz üretiminde kullanımı

Cellulose is defined as a polymer that exists in the cell walls of plant tissues and is widely used in many industrial fields. However, the recent threat of deforestation has led researchers to find alternative wood sources for cellulose production. For this reason, literature studies have focused on certain types of bacteria known to be capable of producing cellulose, such as Acetobacter, Gluconobacter, Alcaligenes, etc. It is stated that cellulose of plant origin and bacterial origin have a similar structure. Bacterial cellulose possesses a big economic and commercial potential depending on the purpose and the production method and is generally used in food applications as a fat substitute, rheology modifier, immobilization material for probiotics and enzymes, stabilizer of pickering emulsions, component of food coatings and green packaging film. Recently, it has become more prominent to use food waste as production inputs, such as beet and sugar cane molasses, fruit waste, dairy industry waste, etc. So, the utilization of industrial by-products, agro-forestry, and food industry residues as carbon sources has been providing significant advantages, such as increasing yield and reducing cost. The objective of this study was to present a general look related to bacterial cellulose production in combination with the use of food waste and future trends.

Cyclic ether and anhydride ring opening copolymerisation delivering new ABB sequences in poly(ester-alt-ethers).

Poly(ester-alt-ethers) are interesting as they combine the ester linkage rigidity and potential for hydrolysis with ether linkage flexibility. This work describes a generally applicable route to their synthesis applying commercial monomers and yielding poly(ester-alt-ethers) with variable compositions and structures. The ring-opening copolymerisation of anhydrides (A), epoxides (B) and cyclic ethers (C), using a Zr(iv) catalyst, produces either ABB or ABC type poly(ester-alt-ethers). The catalysis is effective using a range of commercial anhydrides (A), including those featuring aromatic, unsaturated or tricyclic monomers, and with different alkylene oxides (epoxides, B), including those featuring aliphatic, alkene or ether substituents. The range of effective cyclic ethers (C) includes tetrahydrofuran, 2,5-dihydrofuran (DHF) or 1,4-bicyclic ether (OBH). In these investigations, the catalyst:anhydride loadings are generally held constant and deliver copolymers with degrees of copolymerisation of 25, with molar mass values from 4 to 11 kg mol-1 and mostly with narrow dispersity molar mass distributions. All the new copolymers are amorphous, they show the onset of thermal decomposition between 270 and 344 °C and variable glass transition temperatures (-50 to 48 °C), depending on their compositions. Several of the new poly(ester-alt-ethers) feature alkene substituents which are reacted with mercaptoethanol, by thiol-ene processes, to install hydroxyl substituents along the copolymer chain. This strategy affords poly(ether-alt-esters) featuring 30, 70 and 100% hydroxyl substituents (defined as % of monomer repeat units featuring a hydroxyl group) which moderate physical properties such as hydrophilicity, as quantified by water contact angles. Overall, the new sequence selective copolymerisation catalysis is shown to be generally applicable to a range of anhydrides, epoxides and cyclic ethers to produce new families of poly(ester-alt-ethers). In future these copolymers should be explored for applications in liquid formulations, electrolytes, surfactants, plasticizers and as components in adhesives, coatings, elastomers and foams.

Influence of the thermal expansion on the surface quality of coated and non-coated natural-fiber-reinforced composites

Natural fiber reinforced plastics (NFRP) are increasingly used as a sustainable material alternative to glass or carbon fiber reinforced plastics in lightweight solutions. Visible and/or decorative coated components must meet high surface qualities and defects such as fiber print-through due to different expansion behavior of fiber and matrix are not permitted. Various studies investigate the expansion behavior of NFRP under the influence of temperature and humidity on mechanical properties. In contrast, there are no studies that relate these properties to decoratively coated NFRP and the importance for surface quality. The present study aims to fill this gap using a flax fiber reinforced bio-based epoxy resin (FFRP) manufactured by resin transfer molding process (RTM). The surface roughness and the coefficient of thermal expansion (CTE) were determined as a function of the fiber mass fraction. Further, FFRP and carbon fiber reinforced plastics (CFRP) were decoratively coated and subjected to an alternating climate test. The results showed that reducing the fiber mass fraction of an FFRP to 40 % and using a glass-fiber non-woven on the surface, in combination with 50 % fiber mass fraction, were the most promising methods for reducing roughness in the uncoated state. In addition, the FFRP exhibited an increased CTE longitudinally of 11 ppmK−1 and transversely of 105 ppmK−1 to the fiber direction compared to the CFRP (5 and 79 ppmK−1), along with increased roughness of Ra 0.8 compared to 0.6. The effect of fiber print-through was shown for all variants by the stress in the alternating climate test.