Phenolic Material Research Articles

Flavanoids of Dalea searlsiae: A plant under investigation for reintroduction to native habitats of the great basin

The plant genus Dalea (Fabaceae) has been a prolific source of phenolic metabolites. We report here an investigation of Dalea searlsiae, an herbaceous member of the genus, native to the Great Basin areas of the Western United States. D. searlsiae is the subject of current studies on the reintroduction of native flora, via seed distribution, to rangelands. Cattle that graze on these species avoid 'bloat,' which may be attributed to the high phenolic content of the plants. Methanolic extracts of aerial and root portions of the plants have undergone fractionation using standard open-column techniques of silica gel vacuum liquid chromatography, Sephadex LH-20, and linear gradient chromatographic techniques. To date, these studies have afforded a suite of isoflavones and rotenoids from the aerial portions of the plant and related phenolic materials from the roots. Structure determination of pure compounds was accomplished primarily by extensive 1D and 2D NMR spectroscopy, and mass spectrometry. Antimicrobial bioassays have revealed significant activity concentrated in the root portions of the plant. D. searlsiae is active against wild-type and penicillin-induced resistant strains of Staphylococcus aureus, and toward Streptococcus mutans and Bacillis subtilis. The results of antiinsectan assays of the rotenoid-containing aerial portions will also be presented.

Mechanical properties characterization of the skin and core of a novel composite sandwich structure

This study has investigated the mechanical properties of the constituent materials of a novel structural composite sandwich panel developed for structural applications. Properly designed and carefully conducted experiments using coupon specimens following ISO and ASTM test standards were performed to characterize the flexural, tensile, compressive and shear properties of the fiber composite skins and the modified phenolic core of the composite sandwich structure. As a general behavior, the glass fiber composite skins behaved linearly elastic up to failure in both tension and compression with the tensile strength much higher than the compressive strength. The modified phenolic core behaved linearly elastic in tension but exhibited non-linear behavior in compression. The modified phenolic core material exhibited higher strength and modulus in shear and compression compared to the traditional core material systems. The improved mechanical properties of the core structure combined with the high-strength and lightweight glass fiber composite skins suggest a high potential of the novel composite sandwich panel for structural applications. Furthermore, the results of this study provide an understanding of the fundamental behavior of the constituent materials of a novel sandwich structure providing a base knowledge from which further research could continue.

Polybenzoxazine alloys and blends: Some unique properties and applications

Polybenzoxazine (PBZ), a novel class of high performance thermosetting phenolic resin, has been developed in order to overcome many shortcomings of conventional phenolic materials from either novolac or resole type resins. The paper first provides the overview of this high temperature material including main types, chemical structure of each type, and properties of the polymer, especially the synergistic behavior in thermal properties. It then describes the manufacturing technique to produce the monomeric resin as well as some applications of the polymer.

Simulation and Experiment for the Ogive Affecting PELE Broken Finite-Thickness Reinforced Concrete Targets

In order to analyze the ogive effects PELE broken Finite-Thickness reinforced concrete (RC) targets, a variety of shape and materials ogive for PELE penetration 24 millimeters RC targets was analyzed using numerical simulation by LS-DYNA 3D finite element analysis software, the simulation results show that the PELE projectiles with a hollow cone shape and phenolic resin material ogive have better effect of broken RC. And the simulation model for the real experiment, the test results and simulation results agreed well, the simulation calculation model and parameters for PELE is credible, which can provide useful reference for design.

Behavior of Full-Scale Railway Turnout Sleepers from Glue-Laminated Fiber Composite Sandwich Structures

An experimental study on the flexural and shear behavior of the full-scale glue-laminated composite sandwich beams in three different layouts was conducted to evaluate the suitability of this construction system for railway turnout sleepers. The building block of this innovative beam is a novel composite sandwich structure made up of glass fiber composite skins and modified phenolic core material that has been specifically developed for civil engineering applications. The sandwich beam is produced by gluing layers of fiber composite sandwich structure together in flatwise (horizontal) and in edgewise (vertical) orientations. The glued sandwich beams with edgewise laminations presented appropriate strength and stiffness for replacement turnout timber sleeper. The mechanical properties of these glue-laminated sandwich beams are comparable with the existing timber turnout sleepers, demonstrating that the innovative composite sandwich beam is a viable alternative sleeper material for railway turnouts. From this study, it is concluded that the glue-laminated composite sandwich structures have the potential to be used for replacement railway turnout sleepers. An enhanced understanding of the behavior of fiber composite sandwich structures for potential civil engineering applications is also an outcome of this investigation.

Designing polyethylene terephthalate‐based barrier resins

AbstractWe have studied the efficiencies of commercially available barrier resins used for food packaging and beverage bottle applications and compared them with resins made using copolymer and blending approaches. The effects of various copolymer related parameters that influence oxygen barrier performance and the underlying mechanisms for these effects in PET‐based copolymers and blends were investigated. Using these approaches, it is possible to make highly effective PET‐based copolymers for gas barrier applications. Blending of PET with phenolic and other organic materials shows equivalent barrier performance in PET copolymers having comonomer levels of <8‐mole %. Reduction in oxygen permeation rates results from the reduction or elimination of short range molecular motion of polyethylene terephthalate molecules. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The antimicrobial effects of cranberry against Staphylococcus aureus

The antimicrobial effects of the American cranberry (Vaccinium macrocarpon) on a major food-borne pathogen, Staphylococcus aureus, were investigated using commercially obtained Lakewood® organic cranberry juice and Ocean Spray® cranberry juice cocktail and four other berry fruit extracts (acai berry, strawberry, raspberry, and blueberry). The results showed that cranberry is a potent antimicrobial against S. aureus and the most potent among the berries studied. The order of percentage inhibition of bacterial growth at the same concentration of phenolic materials as gallic acid equivalents was Lakewood cranberry juice > Ocean Spray cranberry juice ≫ blueberry > acai berry ≫ raspberry ≫ strawberry. The antimicrobial effect was not due to the acidity of the berries as NaOH-neutralized samples were almost as effective in terms of percentage inhibition of viable cell growth. Solid-phase extraction of cranberry juice using C18 solid phase showed that the antimicrobial effects reside exclusively with the C18-bound materials.

Behaviour of glued fibre composite sandwich structure in flexure: Experiment and Fibre Model Analysis

The behaviour of glued composite sandwich beams in flexure was investigated with a view of using this material for structural and civil engineering applications. The building block of this glue-laminated beam is a new generation composite sandwich structure made up of glass fibre reinforced polymer skins and a high strength phenolic core material. A simplified Fibre Model Analysis (FMA) usually used to analyse a concrete beam section is adopted to theoretically describe the flexural behaviour of the innovative sandwich beam structure. The analysis included the flexural behaviour of the glued sandwich beams in the flatwise and the edgewise positions. The FMA accounted for the non-linear behaviour of the phenolic core in compression, the cracking of the core in tension and the linear elastic behaviour of the fibre composite skin. The results of the FMA showed a good agreement with the experimental data showing the efficiency and practical applications of the simplified FMA in analysing and designing sandwich structures with high strength core material.

Phytochemical analysis and in vitro antioxidant activity of Uncaria gambir

The present research work was carried out to evaluate the antioxidant potential and antiradical property of methanolic extract of Uncaria gambir. Antioxidant and radical scavenging activity were determined by using different in vitro assays including reducing power assay, superoxide anion scavenging activity assay, hydroxyl radical scavenging activity assay, nitric oxide scavenging activity assay, DPPH free radical scavenging assay and hydrogen peroxide method. Preliminary phytochemical screening revealed that the extract of U. gambir possesses flavonoids, alkaloids and phenolic materials. In the present investigation, quantitative estimation of flavonoids content and phenolic content was also carried out by colorimetric methods, using aluminium chloride and Folin–Ciocalteu reagent method, respectively, to establish relationship between antioxidant activity and total phenolics and flavonoid contents. The total phenolic and flavonoid contents were found to be 18.37±2.79 mg gallic acid equivalents (GAE)/g dry weight and 5.82±2.23 mg rutin equivalents (RE)/g dry weight, respectively. The extract showed significant antioxidant activity in a dose-dependent manner in all the assays. The IC50 values of all parameters were determined. Ascorbic acid was used as standard. The results obtained in the present study indicated that U. gambir extract could be a potential source of natural antioxidant. Key words: Antioxidant, ascorbic acid, DPPH, hydroxyl radical, Uncaria gambir

Phytochemical Analysis and in vitro Antioxidant Activity of Zingiber officinale

Introduction: Antioxidant activity of the methanol extract of Zingiber officinale was determined by Reducing power assay, Superoxide anion scavenging activity assay, Hydroxyl radical scavenging activity assay, Nitric oxide scavenging activity assay, DPPH free radical scavenging assay, and hydrogen peroxide method. Methods: Preliminary phytochemical screening revealed that the extract of Z. officinale possesses flavonoids, volatile oil and phenolic materials. In the present investigation, quantitative estimation of flavonoids and phenols was carried out by colorimetric methods, using aluminum chloride method and Folin Ciocalteu reagent respectively. Result: The extract showed significant activities in all antioxidant assays compared to the standard antioxidant in a dose dependent manner and remarkable activities to scavenge reactive oxygen species (ROS) may be attributed to the high amount of hydrophilic phenolics. The IC50 values of all parameters were determined while ascorbic acid was used as standard. Conclusion: The results obtained in the present study indicate that Z. officinale extract is a potential source of natural antioxidant.

Self‐curable epoxide resins based on cardanol for use in surface coatings

PurposeThe purpose of this paper is to develop eco‐friendly coatings based on low‐cost epoxide resins prepared by using a natural phenolic material such as cardanol (non‐toxic), in place of ordinary phenol (toxic), which can be self‐curable at an optimum temperature.Design/methodology/approachCardanol‐formaldehyde novolac resins (CNs) were prepared by reacting cardanol with formaldehyde in different molar ratios varying from 1:0.6 to 1:0.9. Prepared CNs were epoxidised by reacting with epichlorohydrin to produce epoxide resins, which would be called as epoxidised CNs (ECNs). Further, ECNs were modified by reacting with diethanolamine (DEtOA), a secondary amine to introduce tertiary amino group(s) into the molecules, required for self‐curability of ECNs. These modified ECNs are referred to as MECNs. The molar ratio of ECNs to DEtOA was taken in accordance with epoxy functionality of epoxide resins (ECNs) which ranged from 0.5 to 2.9. Nine numbers of MECNs (MECN1 to MECN9) were prepared by using four epoxide resins. These resins viz. CNs, ECNs and MECNs were characterized by 1H NMR and FTIR spectroscopic methods for their structure elucidatation, and by gel permeation chromatography for determining their molecular weights.FindingsThe most suitable molar ratio of ECN:DEtOA for the preparation of MECNs was found to be 1:1. The CN prepared by using cardanol and formaldehyde in the molar ratio of 1:0.7 was used for the preparation of ECN2 and MECN2. Applied films of epoxide resins, designated as MECN2, had reasonably good physical and chemical resistance properties. With a wide cure window, the films of MECN2 were found to be self‐curable at an optimum cure schedule of 160°C/30 min. Owing to self‐curability of the developed epoxide resins, the coatings based on them did not require any additional/external crosslinker to be incorporated in the coating composition.Research limitations/implicationsThe prepared epoxide resins (MECNs) had good physical and chemical resistance properties, but demonstrated low stability and low resistance to xylene, in particular.Originality/valueThe paper shows how the epoxide resins were prepared by using a low‐cost phenolic material (cardanol) which is obtained from natural renewable resources, instead of petroleum, and is non‐toxic. These developed coatings can be applied as primer coat and top coat on metallic substrates. True self‐curability of the coating films has been achieved via anionic polymerization.

Phenylpropanoid Glycoside Analogues: Enzymatic Synthesis, Antioxidant Activity and Theoretical Study of Their Free Radical Scavenger Mechanism

Phenylpropanoid glycosides (PPGs) are natural compounds present in several medicinal plants that have high antioxidant power and diverse biological activities. Because of their low content in plants (less than 5% w/w), several chemical synthetic routes to produce PPGs have been developed, but their synthesis is a time consuming process and the achieved yields are often low. In this study, an alternative and efficient two-step biosynthetic route to obtain natural PPG analogues is reported for the first time. Two galactosides were initially synthesized from vanillyl alcohol and homovanillyl alcohol by a transgalactosylation reaction catalyzed by Kluyveromyces lactis β-galactosidase in saturated lactose solutions with a 30%–35% yield. To synthesize PPGs, the galactoconjugates were esterified with saturated and unsaturated hydroxycinnamic acid derivatives using Candida antarctica Lipase B (CaL-B) as a biocatalyst with 40%–60% yields. The scavenging ability of the phenolic raw materials, intermediates and PPGs was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) method. It was found that the biosynthesized PPGs had higher scavenging abilities when compared to ascorbic acid, the reference compound, while their antioxidant activities were found similar to that of natural PPGs. Moreover, density functional theory (DFT) calculations were used to determine that the PPGs antioxidant mechanism proceeds through a sequential proton loss single electron transfer (SPLET). The enzymatic process reported in this study is an efficient and versatile route to obtain PPGs from different phenylpropanoid acids, sugars and phenolic alcohols.

Synthesis of New Benzoxazine from Cardanol-Furfural Resin and the Properties of the Corresponding Polymer

A novel benzoxazine-based phenolic resin containing furan groups and long alkyl side-chain (CFB) was synthesized using cardanol-furfural resin as phenolic raw materials. The new benzoxazine-based cardanol-furfural resin derived from renewable resources was characterized by FTIR,1H NMR spectra and Differential scanning calorimeter (DSC) etc. The thermal ring-opening reaction of the benzoxazine ring and the polymerization of the double bond were demonstrated with FTIR measurement. The thermal behavior of the cured product was also investigated with thermogravimetric analysis. The corresponding polybenzoxazine showed Tgvalue higher than that of polybenzoxazine prepared from cardanol, ammonia and formaldehyde. The char yield value at 800°C of the corresponding polybenzoxazine is 46.2% in N2atmosphere. The results showed that the polybenzoxazine cured from CFB had good heat resistance and toughness.

Thiophosphate esters of cashew nutshell liquid derivatives as new antioxidants for poly(methyl methacrylate)

In this work, poly(methyl methacrylate) films 1% additivated with new thiophosphate esters antioxidants derived from technical Cashew Nutshell Liquid (CNSL), a byproduct of the cashew nut (Anacardium occidentale L.) industry, were investigated by thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) measurements under inert (N2) and oxidative (synthetic air) atmospheres. Three new products were synthesized and characterized by GC/MS, 1H and 31P NMR. The analyses were focused on the onset (T e) and offset temperature (T o) of degradation of the films, and on the maximum degradation temperature (T MAX). It was observed that the thermal stability of the films increased with the addition of the thiophosphate ester antioxidants, which indicates that CNSL could be used as a natural source of phenolic material for the synthesis of antioxidants.

The overexpression of AtPrx37, an apoplastic peroxidase, reduces growth in Arabidopsis

Understanding peroxidase function in plants is difficult because of the lack of substrate specificity, the high number of genes and their diversity in structure. In the present study, the relative expression of 22 genes coding putative peroxidases (E.C 1.11.1.x) in Arabidopsis was studied. The relative expression of AtPrx37 showed a correlation with the cessation of growth in rosette leaves as well as with the growth capacity along the flower stem. Using AtPrx37::GUS construction, its expression was associated with the vascular bundles. Furthermore, the overexpression of AtPrx37 under the control of CaMV 35S promoter rendered a dwarf phenotype with smaller plants and delayed development. The plants overexpressing AtPrx37 also showed an increase in the amount of esterified phenolic material associated with their walls. A role in the growth cessation and phenolic cross-linking during lignin deposition is postulated.

Hybrid TPS: A novel hybrid thermal protection system for atmospheric entry space probes based on SHS-Produced MgO/spinel refractories

A novel Hybrid Thermal Protection System (Hybrid TPS) for space probes entering planetary atmospheres at very high velocities has been designed and tested. The system mainly consists of a coarsely porous MgO/spinel refractory made by SHS and filled with a reinforced phenolic material creating a hybrid system. The two main constituents act synergistically protecting each other from the extreme heating developed during atmospheric entry and reduce the recession and irregularity at the front surface. The results of the investigation have shown that the hybrid system offers satisfactory protection at heat fluxes of more than 2000 kW/m2 and total heat loads of more than 200 MJ/m2 and is thus a promising material for high-speed atmospheric entry usages.

Environmental assessment of green hardboard production coupled with a laccase activated system

European consumption of wood-based panels reached record levels in recent years driven mostly by demand from end-use sectors: residential construction, furniture, cabinets, flooring and mouldings. The main panel types are composite boards such as particleboard, high density fiberboard (HDF), medium-density fiberboard (MDF) and other adhesively bonded composites such as plywood and wet-process fiberboard (hardboard). The synthetic resins used in their manufacture come from non-renewable resources, such as oil and gas. Several consequences are associated to this type of adhesives: variation in the availability and cost of these wood adhesives depends on raw materials, the formaldehyde emissions as well as the limited recyclability of the final product. Hence, in the search for alternatives to petroleum-based wood adhesives, efforts are being devoted to develop adhesives by using phenolic substitutes based on lignin, tannin or starch. In this context, the forest industry is increasingly approaching to enzyme technology in the search of solutions. The main goal of this study was to assess the environmental impacts during the life cycle of a new process for the manufacture of hardboards manufacture, considering the use of a two-component bio-adhesive formulated with a wood-based phenolic material and a phenol-oxidizing enzyme. This new product was compared to the one manufactured with the conventional phenol-formaldehyde resin. The study covers the life cycle of green hardboards production from a cradle-to-gate perspective, analysing in detail the hardboard plant and dividing the process chain in three subsystems: Fibers Preparation, Board Forming and Board Finishing. Auxiliary activities such as chemicals, bio-adhesive, wood chips, thermal energy and electricity production and transport were included within the system boundaries. Global warming (GW), photochemical oxidant formation (PO), acidification (AC) and eutrophication (EP) were the impact categories analysed in this study. Additionally, the cumulative energy demand was evaluated as another impact category. According to the results, four stages significantly influenced the environmental burdens of the production system: laccase production, on-site thermal energy and electricity production as well as wood chipping stage. Due to the environmental impact associated to the production of green bonding agents, a sensitivity analysis with special focus on the eutrophying emissions was carried out by evaluating the amount of laccase and lignin based phenolic material used. The combined reduction in both bonding agents may slightly reduce the contributions to this impact category. In addition, a hypothetical scenario with no laccase and with a higher concentration of the lignin based material (25% more) could improve the environmental profile in all impact categories with a reduction of 1.5% in EP. Further research should focus mainly on laccase production, in order to reduce its energy demand as well as on the amount of green adhesive required to obtain mechanical and swelling properties similar to those of conventional hardboard.

Complexation properties and synthesis of a novel Schiff base with triphenylene nucleus

We presented the synthesis of a novel Schiff base and its complexation properties with some transition metal ions in this work. For this, the 2,3,4,6,7,10,11 hexahydroxytriphenylene (HHTP) as starting material was synthesized according to known procedure. Moreover, the 2-((2-chloroethylimino)methyl) phenol material was prepared with reaction of salicylaldehyde and 2-chloroethylamine hydrochloride. To give the 2,3,4,6,7,10,11-hexakis(salicyliminoethoxy)triphenylene (HSE-TP) as a novel Schiff base, the HHTP were treated with 2-((2-chloroethylimino)methyl)phenol in acetone media. Complexation properties of this Schiff base were investigated towards Ni(II), Cu(II), Co(II), Zn(II), Pd(II) and Cd(II) as transition metals. The structures of these new compounds (ligand and complexes) were characterized with FT-IR, magnetic susceptibility measurement, thermal methods (TGA), 1H NMR and elemental analyses.

Response of a glass/phenolic composite to high temperatures

Determining the response of composite phenolic materials to fire remains a major unsolved problem that is important for high consequence safety analysis. Difficulties arise when thermophysical property measurements are obscured by decomposition reactions. This article presents several decomposition experiments and models for a phenolic resin impregnated into chopped 1.27-by-1.27 cm glass fabric. The thermal response of the material was measured using thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and laser flash diffusivity (LFD). The TG data was used to develop a 5-step decomposition mechanism describing mass loss due to reaction; the DSC data was used to describe the energy changes associated with these reactions; and the LFD data was used to describe energy flow into the decomposing material. An effective thermal conductivity model was used to partition energy transport by gas conduction, solid conduction, and diffusive radiation. The dynamic gas volume fraction is treated as a field variable to extrapolate thermal transport properties at high temperatures where decomposition is prevalent. These various models have been implemented into a finite element response model with an example calculation that includes uncertainty.

Carbon–phenolic ablative materials for re-entry space vehicles: Manufacturing and properties

Thermal protection systems (TPS) are designed to protect re-entry space vehicles from the severe heating encountered during hypersonic flight through a planet’s or the earth’s atmosphere. A carbon–phenolic ablative TPS was developed, manufactured and tested with the aim of fulfilling the thermal and mechanical requirements corresponding to the actual loads experienced by a vehicle during a moon-earth re-entry. Experimental activities were carried out on two different composite systems (a resole resin coupled with a graphitic felt and a graphitic foam), and were aimed to the optimization of the manufacturing procedure and to the characterization of the mechanical behaviour and of the insulation performance of the fabricated composites.