Resonance Fourier Research Articles

Novel organic glass with superior optical properties based on dimethyl itaconate and diethyl itaconate

Novel high light transmittance material was synthesized by dimethyl itaconic acid and diethyl itaconic acid via piecewise bulk polymerization, using benzoyl peroxide (BPO) as catalyst. Its chemical structure was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). The thermal performance of polymer was characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), showing its glass transition temperature (Tg) was between 52 °C and 72 °C, thermal decomposition temperature above 230 °C, suitable for processing. The transmittance of the polymer is as high as 92% and a density of 1.1 g/cm3, which has the optical device application potential. We also tested the hydrophilicity of the material surface by the contact angle test, combined with the data of simulated calculation to explore the influence factors of hydrophilic change on the material surface.

Comprehensive characterization of industrial wastewaters using EEM fluorescence, FT-IR and 1H NMR techniques

The organic matter present in six industrial wastewaters (pulp and paper mill, brewery, textile, dairy, slaughterhouse effluents and a municipal landfill leachate) has been studied in this work using three analytical techniques: excitation-emission matrix fluorescence (EEMF), proton nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FTIR).The pulp and paper mill effluent shows characteristic signals of the presence of lignins, carbohydrates and carboxylic acids, as well as sulfate, carbonate and sulfonates (coming from surfactants used in the cleaning of tanks). The main constituents of the brewery effluent are peptides and proteins coming mainly from spent yeast and diatomite filters (the presence of the latter was confirmed by SiO bands in the FTIR spectrum). The municipal landfill leachate is characterized by the majority presence of humic substances (typical of an old landfill) and a residual presence of small peptides, amino acids and carboxylic acids. Additionally, several inorganic compounds were identified by FTIR, such as nitrate, sulfate, phosphate and cyanide ions. The textile effluent from a cotton-based industry contains carbohydrates, carboxylic acids and sulfonates, which can act as auxochromes in the textile industry. The dairy effluent comprises amino acids and small peptides coming from the biodegradation of milk and whey in addition to carbohydrates (lactose) and carboxylic acids (mainly lactic acid). The presence of tyrosine-like peaks B in the EEMF spectrum of the slaughterhouse effluent indicates the existence of small peptides and amino acids coming from the biodegradation of blood proteins. Additionally, residual glucose, fatty acids, phosphate and sulfate were also identified in this effluent.

Hydrophilic PVDF membrane with versatile surface functions fabricated via cellulose molecular coating

Hydrophilic PVDF membrane was fabricated in single step via cellulose molecular coating prepared by homogeneous solution of cellulose oligomer synthesized by enzyme catalysis (EC)/Trifluoroacetic acid (TFA). Both smooth and rough coatings can be prepared by regulating the aggregative structure of cellulose molecular coatings. The chemical structures of the cellulose and its coating were confirmed by 1H Nuclear Magnetic Resonance Spectroscopy (1H NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The aggregation structure of the cellulose coating was characterized by wide-angle X-ray diffraction (WAXD). X-ray Photoelectron Spectroscopy (XPS) studies unveiled the strong binding of cellulose molecular to PVDF membranes at the interface. Scanning Electron Microscopy (SEM) morphologies show that the cellulose molecules were uniformly coated on the surface and cross section of the membranes. Water contact angle measurement suggested that cellulose molecular coating possessed high hydrophilicity and wetting rate, giving the PVDF membranes high water flux and excellent anti-fouling performances. The coated membranes also show excellent adsorption and desorption performances for crystal violet (CV). The superior performances of incompletely crystallized cellulose coating over amorphous cellulose coating were attributed to the increased specific surface area resulting from the surface roughness. The construction of cellulose molecular coating with controlled aggregation structure provides a novel efficient technology in the field of purification of wastewater, opening up a new approach to the microstructural manipulation of the hydrophilic coating.

Metabolomic Profiling of Fresh Goji (Lycium barbarum L.) Berries from Two Cultivars Grown in Central Italy: A Multi-Methodological Approach.

The metabolite profile of fresh Goji berries from two cultivars, namely Big Lifeberry (BL) and Sweet Lifeberry (SL), grown in the Lazio region (Central Italy) and harvested at two different periods, August and October, corresponding at the beginning and the end of the maturation, was characterized by means of nuclear magnetic resonance (NMR) and electrospray ionization Fourier transform ion cyclotron resonance (ESI FT-ICR MS) methodologies. Several classes of compounds such as sugars, amino acids, organic acids, fatty acids, polyphenols, and terpenes were identified and quantified in hydroalcoholic and organic Bligh-Dyer extracts. Sweet Lifeberry extracts were characterized by a higher content of sucrose with respect to the Big Lifeberry ones and high levels of amino acids (glycine, betaine, proline) were observed in SL berries harvested in October. Spectrophotometric analysis of chlorophylls and total carotenoids was also carried out, showing a decrease of carotenoids during the time. These results can be useful not only to valorize local products but also to suggest the best harvesting period to obtain a product with a chemical composition suitable for specific industrial use. Finally, preliminary studies regarding both the chemical characterization of Goji leaves generally considered a waste product, and the biological activity of Big Lifeberry berries extracts was also investigated. Goji leaves showed a chemical profile rich in healthy compounds (polyphenols, flavonoids, etc.) confirming their promising use in the supplements/nutraceutical/cosmetic field. MG63 cells treated with Big Lifeberry berries extracts showed a decrease of iNOS, COX-2, IL-6, and IL-8 expression indicating their significant biological activity.

Synthesis and application of indole esters derivatives containing acrylamide group as antifouling agents

Two new indole ester derivatives containing acrylamide group were synthesized by Michael addition reaction and Friedel-Crafts reaction based on 5-bromo-1H-indole. The synthesized compounds were characterized by 1H Nuclearmagnetic Resonance Spectroscopy (1HNMR) and Fourier Transform Infrared spectroscopy (FTIR). In the step of the Friedel-Crafts reaction, the optimum process conditions were determined as that the catalyst was AlCl3, the reaction time was 3 days and the reaction temperature was 25 °C. The results of minimal inhibitory concentration (MIC) of synthesized compounds showed that the two synthesized compounds have better antibacterial activity than reference. Algal inhibiting experiment shows that indole derivatives have better algae inhibition performance. Anti-protein adsorption experiment of antifouling paints with indole derivative and chlorothalonil as antifouling agents proves that indole derivatives exhibit better protein resistance behaviors. The antifouling paints using indole derivatives as antifouling agents have excellent antifouling properties after 24 months marine field test.

Physicochemical characterisation of Piptadeniastrum africana (Hook. F.) gum, a potential pharmaceutical excipient

Modern advances in dosage forms require innovative excipients that make them more efficient than conventional dosage forms. Natural excipients like gums are known to be cheap, biodegradable, and readily available. However several natural gums are yet to be fully characterized and utilized. This study sought to determine the physicochemical properties of Piptadiniastrum africana (Hook. F.) gum to establish a basis for its pharmaceutical application. The crude Piptadiniastrum africana gum (CPAG) was collected as the natural exudates from the tree bark and observed for its macroscopic features. Physicochemical characteristics such as the moisture content, insoluble matter, and ions as well as pH, swelling index, hydration capacity, solubility, viscosity, flow properties, and rheological behaviour were determined. To assess the chemical and morphological nature of the purified gum, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) imaging, X-ray diffractogram (XRD), and Fourier Transform Infrared (FT-IR) spectroscopy were employed. CPAG was a pale-dark brown color with an ammoniac smell and a biting taste while the purified Piptadeniastrum africana gum (PPAG) (yield 33.19%w/v) was off white-light brown color with a characteristic smell and bland taste. The moisture content of CPAG and PPAG was determined to be 13% and 8% respectively while the insoluble matter level was 0.31% and 0.12% respectively. Both CPAG and PPAG contained monovalent and divalent metal ions in the order Ca2+>Mg2+>Fe2+>Na+>Cu2+>K+>Zn2+. The swelling and hydration capacities of CPAG were found to be 1.35 and 4.24 respectively while values for PPAG were determined as 0.22 and 3.8 respectively. PPAG was soluble in both hot and cold water, HCl and chloroform. The gum was determined morphologically to be an amorphous carbohydrate with β-D-mannopyranosyl units attached to repeated units of α-D-galactopyranosyl. This study reveals that the purified gum possesses physicochemical features suitable as an excipient for pharmaceutical use.

Sustainable utilization of food waste: Production and characterization of polyhydroxybutyrate (PHB) from damaged wheat grains

Sizeable quantities of wheat grains are wasted or damaged every year either due to improper storage in warehouses or adverse environmental conditions that trigger insect and rodent infestations. As a result damaged wheat grain (DWG) is generated in substantial quantities which, if left alone, could cause environmental pollution. This work focuses on utilizing DWGs for the production of polyhydroxybutyrate (PHB), a biodegradable plastic, with ‘green’ applications. A two-step process involving acid hydrolysis followed by bacterial fermentation by Bacillus sp. NII2 was used at optimum hydrolysis conditions: 3 % acid concentration, 15 % substrate loading and 15 min hydrolysis time, which resulted in 102.47 mg/mL reducing sugars in the hydrolysate. Morphological analysis of the hydrolysis residue displayed pore formation in the substrate as seen in scanning electron micrographs, indicating localized release of sugars. Under optimal conditions, the bacterial culture exhibited 4.33 g/L biomass that accumulated 1.41 mg/L PHB. Produced PHB was characterized through nuclear magnetic resonance imaging (1H-NMR, 13C-NMR) and Fourier transform infrared spectroscopy to confirm the presence of the functional groups (–CH, –CH2, –CH3, –C=O, –C–O–C–) that are innate to the structure of PHB. Thermogravimetric analysis of PHB demonstrated the stability of the biopolymer up to a temperature of 256 °C. The PHB produced from DWG opens up a new opportunity for its sustainable utilization and application in the development of biodegradable biopolymer which could find applications in food packaging.

Click preparation and mechanism on amphiphilic oleophobic/hydrophilic behavior of fluorinated diblock copolymers

AbstractIn this article, amphiphilic fluorinated diblock copolymers of poly(perfluorohexylethyl acrylate)‐block‐allylpolyethyleneglycol (PF6A‐b‐APEG1200) are synthesized by reversible addition‐fragmentation transfer (RAFT) polymerization and sequential thiol‐ene click reaction. The molecular structure is characterized by 1H nuclear magnetic resonance (1H NMR) spectra and Fourier transform infrared (FTIR) spectra. Morphology and particle size of resultant copolymer micelles in aqueous solution are analyzed by transmission electron microscope (TEM) and dynamic light scattering (DLS). The wettability and relative element contents of PF6A‐b‐APEG1200 coatings are investigated with contact angle (CA) and X‐ray photoelectron spectroscopy (XPS). When PF6A‐b‐APEG1200 coating is stimulated by water, the fluorine content at the top fluoropolymer‐air interface decreases and the water contact angle of the surface decreases over time, showing the hydrophilicity. While stimulated by n‐hexadecane, the fluorine content of the film surface increases, showing the oleophobicity with a stable apparent oil contact angle of 72 ± 1°. According to the detailed analysis of XPS results, the stimuli‐responsive behavior of the amphiphilic polymers can be ascribed to the migration and rearrangement of the two blocks in PF6A‐b‐APEG1200, which might probably be one of the universally accepted oleophobic/hydrophilic mechanisms.

The investigation of optimum condition of natural rubber epoxidation reaction in latex phase

Natural rubber (NR) latex epoxidation is a chemical modifcation of natural rubber to produce natural rubber with higher polarity (oil resistant) which is commonly called epoxidized natural rubber (ENR). ENR is produced from the reaction of natural rubber latex with performic acid. Performic acid is formed from in situ reaction between formic acid and hydrogen peroxide. During epoxidation process, the carboxyl group of natural rubber is converted into epoxy group and various side reaction products such as carbonyl, hydroxyl, and hydro furan. These side products must be minimalized to optimize the epoxy level. The epoxidation reaction was carried out at 70 ° C for 6 hours using 2 types of latex: fresh latex (FL) and concentrated latex (CL). The addition of reactant was varied in two ways: dropwise (coded “1”) and poured all at once (coded “2”). The epoxy product and rate constant (k) were analyzed to obtain optimum reaction condition. The epoxy and side reaction content were determined by Attenuated Resonance Fourier Transform Infrared (ATR-FTIR). The slope of epoxy-time plotting curve was determined as ENR rate constant (k). The optimum NR epoxidation reaction was achieved in CL2, which exhibited lowest value of side reaction and highest value of k (2.8082x10 -5 L mol -1 sec -1 ).

Mechanical and microscopic properties of fly ash phosphoric acid-based geopolymer paste: A comprehensive study

Fly ash (FA) is a common industrial by-product, which is usually used as raw materials of alkali-activated geopolymer or cement additive. However, there are few studies on phosphoric acid-based geopolymer cement synthesized with FA. In this study, FA phosphoric acid-based geopolymer (FAPG) was prepared by using low-calcium FA as raw material and phosphoric acid (PA) as reactant at room temperature. Microscopic properties and geopolymerization mechanism were studied by X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry, nuclear magnetic resonance instrument and Fourier transform infrared spectroscopy. The hydration characteristics were studied by isothermal calorimetry, and the thermal properties were explored by thermogravimetric analysis. Additionally, the setting time, compressive strength, pH and electrical conductivity of FAPG were measured. The results indicated that room-temperature cured FAPG paste activated with 50% PA and 0.3 liquid–solid mass ratio (L/S) yielded a maximum compressive strength during 0–90 days of curing. As curing time increased, the strength increased for FAPG with 50% PA, but increased at first and then scarcely increased for other FAPG pastes. The compressive strength decreased with L/S increasing. As curing time increased, the pH increased and electrical conductivity decreased. The initial and final setting time, and fluidity decreased with increasing PA concentration but increased with L/S increasing. The FAPG paste was a composite structure composed of crystalline and amorphous phase. The crystalline phase was composed of Brushite, Monetite and Berlinite, and the amorphous phase was composed of -Al-O-P-, -Si-O-P- and Si-O-Al-O-P- units. The average pore diameter of FAPG ranged from 37.38 to 64.44 nm. Heating to 1200 °C, FAPG paste presented four stages of mass loss. The total hydration heat increased with PA concentration increasing.

Exploring the chemical space of white wine antioxidant capacity: A combined DPPH, EPR and FT-ICR-MS study

The chemical composition and functionality of molecular fractions associated with dry white wines oxidative stability remain poorly understood. In the present study, DPPH assay, electron paramagnetic resonance spectroscopy (EPR) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) were used to explore the chemical diversity associated with the antioxidant capacity (AC) of white wines. AC determined using the DPPH assay and EPR were complementary and enabled differentiation of wine samples into groups with low, medium, and high AC. Mass spectra variations associated with global DPPH- and EPR-derived indices enabled identification of 365 molecular markers correlated with samples with high AC, of which 32% were CHO compounds including phenolic and sugar derivatives, 20% were CHOS and 36% were CHONS compounds including cysteine-containing peptides. This study confirmed the importance of CHONS and CHOS compounds in the antioxidant metabolome of dry white wines. Knowledge about these compounds will enable better understanding of the oxidative stability of white wines and therefore aid in achieving optimum shelf life.

Extraction, purification, physicochemical properties and antioxidant activity of a new polysaccharide from Ocimum album L. seed

In this study, a novel polysaccharide fraction from Ocimum album seed was extracted and then purified by Cellulose DEAE-52 and Sephadex G-200 anion exchange chromatography. The structural, physicochemical and antioxidant properties of the main polysaccharide fraction (OAP-1A) were evaluated. The purified polysaccharide contained 94.3% carbohydrate, 3.56% moisture and 2.14% ash and result of gel permeation chromatography (GPC) showed average molecular weight of 593 kDa. The results of high-performance liquid chromatography (HPLC) showed that OAP-1A was a neutral hetero-polysaccharide composed of mannose (35.7%), glucose (33.32%), galactose (19.6%) and rhamnose (11.38%). In addition, GC–MS data, nuclear magnetic resonance (NMR) spectrum and Fourier transform infrared (FT-IR) analysis revealed that the backbone of OAP-1A consists of →3)-β-D-Manp-(1→, →3,4)-β-D-Manp-(1→, →3,6)-β-D-Manp-(1→, →3)-α-D-Glcp-(1→, →6)-β-D-Galp-(1→, →4)-α-L-Rhap-(1→ and α-D-Glcp-(1→. X-ray diffraction (XRD) analysis showed semi-crystalline structure in OAP-1A. Differential scanning colorimeter (DSC) and thermo-gravimetry analysis (TGA) indicated that OAP-1A had relatively high thermal stability. Moreover, OAP-1A showed strong scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

Mechanochemical synthesis of a novel eutectic of the antimicrobial nitazoxanide with improved dissolution performance

Background: Nitazoxanide (NTZ) is a broad spectrum antimicrobial agent with poor aqueous solubility and low bioavailability. Thus, the generation of new solid forms of NTZ is relevant to improve its unfavorable properties. The present study deals with the application of mechanochemistry for the preparation of alternate solid forms of NTZ, using saccharine (SAC) as coformer. Methods: NTZ-SAC mixtures were prepared by neat and liquid-assisted grinding (LAG) and characterized using differential scanning calorimetry (DSC), hot stage microscopy (HSM), X-ray Powder Diffraction (XRPD), 13C Solid-state Nuclear Magnetic Resonance (SSNMR) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. Powder dissolution (PD) profiles were obtained with USP apparatus 2 in buffer phosphate pH 6.5 with 0.25% Tween 80 - 0.25% triethanolamine and in 0.25% sodium lauryl sulfate, at 37 ºC ± 0.5 ºC and 75 rpm. Drug release was characterized in terms of dissolution efficiency (DE). Results: XRPD, SSNMR and DRIFT indicated that NTZ and SAC did not cocrystallize but DSC and HSM revealed that they formed a binary eutectic mixture which melted near 176 °C, a melting temperature lower than those of NTZ and SAC. PD data indicated that the 1:1 NTZ-SAC sample obtained by LAG exhibited a slightly higher DE than pure NTZ in the two assayed media. Conclusion: NTZ and SAC formed a eutectic, the first reported for this drug, which improved its dissolution rate and opened the pathway for studies searching for new eutectics with better biopharmaceutical attributes than NTZ and the NTZ-SAC eutectic reported herein.

A novel P/N-based flame retardant synthesized by one-step method toward cotton materials and its flame-retardant mechanism

A novel flame retardant containing phosphorus and nitrogen elements, ammonium salt of N,N-dimethylene p-benzenesulfonic phosphonic acid (ADBSPA), was prepared by one-step continuous chemical method. The chemical structure of the ADBSPA was determined by nuclear magnetic resonance spectrum (NMR) and Fourier transform infrared (FTIR), and ADBSPA was processed onto cotton materials by immersion method. The flame retardancy of coated cotton materials was analyzed by limiting oxygen index (LOI) and Vertical burning test. The LOI value of cotton coated with 350 g/L ADBSPA increased from the original 18.2 ± 0.2% to 31.7 ± 0.2%, and the damaged length of this sample reduced to 6.6 ± 0.1 cm, which proved that ADBSPA enhanced the anti-burning ability of cotton materials. Cone calorimetry was used to evaluate the combustion behavior of cotton materials before and after coating. Compared with original sample, ADBSPA changed the combustion path of cotton materials, and the intuitive performance was that the ADBSPA-cotton-4 reserved 25.1 ± 0.5% of char residue at 250 s, and its peak heat release rate (PHRR) greatly reduced to 17 ± 1 kW/m2. The surface morphology of uncoated and coated cotton materials was characterized by scanning electron microscopy (SEM). It was observed that the coated sample still maintained a complete fiber skeleton after burning. In addition, thermogravimetric (TG) analysis confirmed that the coated cotton materials had good thermo-oxidative and thermal stability. All results pointed out that the phosphorus and nitrogen elements contained in ADBSPA as well as cotton cellulose constituted the three basic conditions of intumescent flame-retardant system. The polyphosphoric acid compounds formed by phosphorus element at high temperature promoted the dehydration of cotton fibers into char layer. The non-flammable gases produced by the nitrogen element in the combustion process covered the surface of fabrics, thereby playing the role of shielding heat and diluting combustible gases. A novel phosphorus-nitrogen flame retardant was prepared by one-step continuous chemical method and applied to improve the thermal stability and anti-flammability of cotton materials.

Development of Low-Viscosity and High-Performance Biobased Monobenzoxazine from Tyrosol and Furfurylamine.

This work details the scalable and solventless synthesis of a potential fully biobased monobenzoxazine resin derived from tyrosol and furfurylamine. The structure of the monomer was studied by nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR). The curing of the precursors was characterized by differential scanning calorimetry (DSC), rheological measurements, and thermogravimetric analysis (TGA). The properties of the resulting biobased polybenzoxazine were then determined by thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMA). A thermally stable resin was obtained with 5% and 10% weight-reduction-temperature (Td5 and Td10) values of 349 and 395 °C, respectively, and a char yield of 53%. Moreover, the low melting temperature, low viscosity, and excellent thermomechanical behavior make this fully biobased resin a promising candidate for coating applications.

Facile fabrication of non-spherical thiol-functionalized organosilica particles and their adsorption of Ag(I)

Thiol-functionalized organosilica particles with bowl-like or golf ball-like morphology were successfully obtained through a facile sol–gel procedure. 3-mercaptopropyltrimethoxysilane (MPTMS) and tetraethoxysilane (TEOS) were copolymerized under the catalysis of ammonia. The morphology and the growth process of bowl-like and golf ball-like organosilica particles were observed using scanning electron microscopy (SEM). The results demonstrated that the morphology of the organosilica particles could be finely controlled by adjusting the amount of ammonia, the ratio of two silane precursors, the ratio of oil to water and the solvent system. 29Si nuclear magnetic resonance (29Si NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to detect the composition of the non-spherical particles. Moreover, the as-obtained thiol-functionalized organosilica particles performed high Ag(I) adsorption property with the maximum adsorption capacity of 465.0 mg/g.

Pressurized Liquid Extraction of a Phycocyanobilin Chromophore and Its Reconstitution with a Cyanobacteriochrome Photosensor for Efficient Isotopic Labeling.

Linear tetrapyrrole compounds (bilins) are chromophores of the phytochrome and cyanobacteriochrome classes of photosensors and light-harvesting phycobiliproteins. Various spectroscopic techniques, such as resonance Raman, Fourier transform-infrared and nuclear magnetic resonance, have been used to elucidate the structures underlying their remarkable spectral diversity, in which the signals are experimentally assigned to specific structures using isotopically labeled bilin. However, current methods for isotopic labeling of bilins require specialized expertise, time-consuming procedures and/or expensive reagents. To address these shortcomings, we established a method for pressurized liquid extraction of phycocyanobilin (PCB) from the phycobiliprotein powder Lina Blue and also the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis). PCB was efficiently cleaved in ethanol with three extractions (5 min each) under nitrogen at 125�C and 100 bars. A prewash at 75�C was effective for removing cellular pigments of Synechocystis without PCB cleavage. Liquid chromatography and mass spectrometry suggested that PCB was cleaved in the C3-E (majority) and C3-Z (partial) configurations. 15N- and 13C/15N-labeled PCBs were prepared from Synechocystis cells grown with NaH13CO3 and/or Na15NO3, the concentrations of which were optimized based on cell growth and pigmentation. Extracted PCB was reconstituted with a recombinant apoprotein of the cyanobacteriochrome-class photosensor RcaE. Yield of the photoactive holoprotein was improved by optimization of the expression conditions and cell disruption in the presence of Tween 20. Our method can be applied for the isotopic labeling of other PCB-binding proteins and for the commercial production of non-labeled PCB for food, cosmetic and medical applications.

A simple method to obtain ursolic acid

A simple method has been developed to obtain ursolic acid (UA) by crystallization and recrystallization of the ethanol extract of Clinopodium revolutum. Its structure was confirmed by 1D (1H-, 13C-, DEPT 45, 90 and 135) and 2D (COSY, HMBC and HSQC) nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The results provide a theoretical basis for considering the species Clinopodium revolutum with a source of UA.

Enhancing the flame retardancy of lyocell fabric finished with an efficient, halogen-free flame retardant.

A novel flame retardant (PNPG) containing phosphorus and nitrogen was synthesized through the reaction of neopentyl glycol, phosphoric acid and urea, and was then used for preparation of flame retardant lyocell fabric through a dip-dry-cure finishing process. The structure of the PNPG was confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT-IR). The flame retardancy and thermal stability of the treated fabric were evaluated by a cone calorimetry test and thermogravimetric analysis (TG), which showed that the char residue of the treated fabric at 800 °C was as high as 39.7% under a nitrogen atmosphere. At the same time, the peak heat release rate (PHRR) and total heat release (THR) were significantly reduced by 92.9% and 81.2%, respectively. Obviously, the presence of flame retardant can effectively improve the thermal stability and flame retardancy of lyocell fabrics. In addition, thermogravimetric analysis combined with Fourier transform infrared spectroscopy (TG-IR), scanning electron microscopy (SEM), and Raman spectroscopy indicated that the flame retardant mechanism was consistent with the condensed phase and gas phase mechanism. The limiting oxygen index (LOI) of the treated samples could reach 39.3%, moreover, even after 20 laundering cycles (LCs), the LOI values of the samples finished at 28.3% with 120 g L−1 flame retardant remaining, which confirmed the durability and high flame retardancy of the treated samples. In addition, the mechanical properties, whiteness, rigidity and flexibility of the fabrics treated with PNPG were insignificantly reduced within a more acceptable range than the original samples. In summary, the flame retardant described herein has excellent flame retardant properties and char-forming ability, and it is suitable for the preparation of flame retardant lyocell fibers.

Synthesis of Lactic Acid-Based Thermosetting Resins and Their Ageing and Biodegradability.

The present work is focused on the synthesis of bio-based thermoset polymers and their thermo–oxidative ageing and biodegradability. Toward this aim, bio-based thermoset resins with different chemical architectures were synthesized from lactic acid by direct condensation with ethylene glycol, glycerol and pentaerythritol. The resulting branched molecules with chain lengths (n) of three were then end-functionalized with methacrylic anhydride. The chemical structures of the synthesized lactic acid derivatives were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT–IR) before curing. To evaluate the effects of structure on their properties, the samples were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the tensile testing. The samples went through thermo-oxidative ageing and biodegradation; and their effects were investigated. FT-IR and 1H-NMR results showed that three different bio-based resins were synthesized using polycondensation and end-functionalization. Lactic acid derivatives showed great potential to be used as matrixes in polymer composites. The glass transition temperature of the cured resins ranged between 44 and 52 °C. Pentaerythritol/lactic acid cured resin had the highest tensile modulus and it was the most thermally stable among all three resins. Degradative processes during ageing of the samples lead to the changes in chemical structures and the variations in Young’s modulus. Microscopic images showed the macro-scale surface degradation on a soil burial test.