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Solid dispersion materials of abietic acid (ABA) were prepared with methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), and sodium carboxymethylcellulose (CMC-Na) using a conventional solvent evaporation method. In these materials, ABA was incorporated in an amorphous form. During dissolution tests, ABA from ABA/MC and ABA/HPMC solid dispersion materials initially rapidly dissolved, followed by a decrease in the dissolution rate before eventually plateauing. The dissolution of ABA from ABA/CMC-Na solid dispersion materials was similar, although it increased slightly with an increased shaking time over a long period. ABA from ABA/MC solid dispersion materials exhibited a higher dissolution rate compared with ABA from both ABA/HPMC and ABA/CMC-Na solid dispersion materials. The amount of undissolved material from ABA/cellulose derivative solid dispersion materials was lower compared with ABA/cellulose nanofiber and ABA/TEMPO-oxidized cellulose nanofiber solid dispersion materials. In addition, both ABA/MC and ABA/HPMC solid dispersion materials exhibited good growth-inhibitive effects against Trametes versicolor, a representative of white-rot fungus, compared with ABA/CMC-Na, ABA/cellulose nanofiber and ABA/TEMPO-oxidized cellulose nanofiber solid dispersion materials. Consequently, MC proved to be the most effective water-soluble carrier for ABA in water among the cellulose derivatives tested. [ABSTRACT FROM AUTHOR]

In this study, rosin polyethylene glycol ester was prepared by the reaction of natural rosin with PEG-400. It was modified with acrylic acid to prepare water-based ink binders. The results show that the reaction is carried out for 3 h at a molar ratio of rosin to PEG-400 of 1:4 and a catalyst and filler (Al2O3) of 30 wt%/RO. Products with high fixed content (83.4 wt%), low acid value (27.0 mg NaOH/g), high esterification rate (83.0%), good printability, and fast drying and flow rates are obtained. The key steps of the study include preparing polymers using natural rosin and PEG-400, esterification reaction, and modifying rosin polyethylene glycol ester emulsions. The focus of the study is to analyze the effect of the molar ratio of rosin to PEG-400, the type and content of the catalyst (filler), and the reaction time on the product to obtain the optimum process conditions. This study proposes a new method for the production of environmentally friendly water-based inks and provides valuable insights into future ink production and environmental technology. [ABSTRACT FROM AUTHOR]

Abstract The tomb of Marquis Yi of Zeng was unearthed in 1978 at Leiguudun in Suizhou City, Hubei Province, China. This is the largest wooden coffin in rock pit and vertical cave in the Warring States period in China. The large wooden coffin components provide reliable material data for the study of the feudal burial system in the pre-Qin period and have high value. In this paper, the wooden coffin excavated from the tomb of Marquis Yi of Zeng was studied. By understanding the composition of wood, studying the weight gain rate, shrinkage rate, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and compression resistance, the wood reinforced by rosin and epoxy resin was compared, and the reinforcement effect and principle of the two reinforcement methods were discussed. The study found that the wood properties of rosin reinforced group were better than those of epoxy reinforced group in the aspects of compressive strength, weight gain rate and volume shrinkage rate, and the mechanical properties of wood were significantly improved. In addition, methanol or ethanol can be used to dissolve the rosin shellac in this strengthening process, which can achieve reversible strengthening treatment. The results provide valuable examples and research ideas for the selection of different conservation techniques of large wooden cultural relics unearthed in the middle and lower reaches of the Yangtze River during the Warring States Period.

In the paper, five quaternary ammonium salts derived from rosin were synthesized, characterized and their antifungal activities against different molds were studied. Choline quaternary ammonium salt and tetramethylammonium hydroxide were synthesized from dehydroabietic acid and the rosin ethanolamine ester quaternary ammonium salts which are new compounds were synthesized from propylene pimaric acid. Their structures were confirmed by FTIR, 1HNMR, 13CNMR, and high resolution mass spectrometry. The antifungal activities of the synthesized quaternary ammonium salts from rosin acid were tested by Oxford cup method, and their minimum inhibitory concentration was determined. The results show that quaternary ammonium salts derived from rosin acid have inhibitory effects on bamboo slices to some extent. Among them, propylene pimaric acid ethanolamine ester quaternary ammonium salts (A1 and A2) showed obvious antifungal activity in the Oxford cup test. The Oxford cup activity test and anti-mildew effect of quaternary ammonium salts (B1 and B2) synthesized from rosin acid are significant, and there are almost no mould growth on bamboo slices. It can be inferred that A1, A2, B1 and B2 are expected to be used as bamboo mildew inhibitors. Five quaternary ammonium salts derived from rosin were synthesized and characterized; and their antifungal activities against different molds were studied. [ABSTRACT FROM AUTHOR]

BACKGROUND: To further develop potential natural fungicides, two series of new acrylopimaric acid triazole derivatives were synthesized, and their antifungal activities were tested and evaluated. RESULTS: In vitro antifungal activity results indicated that compound 5m exhibited significant inhibitory activity against Rhizoctonia solani with an half maximal effective concentration (EC50) value of 1.528 mg/L. Its antifungal effect was comparable to that of the commercially available fungicide fluconazole, epoxiconazole and propiconazole (EC50 values of 1.441, 0.815 and 1.173 mg/L). Subsequently, in vivo studies were conducted on compound 5m, which revealed its significant protective and curative effects against R. solani. In addition, physiological and biochemical studies showed that compound 5m could disrupt the morphology and ultrastructure of R. solani mycelium, increase cell membrane permeability, inhibit ergosterol synthesis, and enhance the activity of defense enzymes in rice plants. Three‐dimensional quantitative structure–activity relationship (3D‐QSAR) studies revealed that the molecular structure significantly influenced the binding of compound 5m to the receptor, thereby enhancing its antifungal activity. CONCLUSION: Compound 5m exhibits excellent antifungal activity against R. solani, making it a promising candidate fungicide for the prevention and control of R. solani. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The tomb of Marquis Yi of Zeng was unearthed in 1978 at Leiguudun in Suizhou City, Hubei Province, China. This is the largest wooden coffin in rock pit and vertical cave in the Warring States period in China. The large wooden coffin components provide reliable material data for the study of the feudal burial system in the pre-Qin period and have high value. In this paper, the wooden coffin excavated from the tomb of Marquis Yi of Zeng was studied. By understanding the composition of wood, studying the weight gain rate, shrinkage rate, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and compression resistance, the wood reinforced by rosin and epoxy resin was compared, and the reinforcement effect and principle of the two reinforcement methods were discussed. The study found that the wood properties of rosin reinforced group were better than those of epoxy reinforced group in the aspects of compressive strength, weight gain rate and volume shrinkage rate, and the mechanical properties of wood were significantly improved. In addition, methanol or ethanol can be used to dissolve the rosin shellac in this strengthening process, which can achieve reversible strengthening treatment. The results provide valuable examples and research ideas for the selection of different conservation techniques of large wooden cultural relics unearthed in the middle and lower reaches of the Yangtze River during the Warring States Period. [ABSTRACT FROM AUTHOR]

In Mexico, there is a deficit in the production of pine resin, because it relies on natural forests only. Therefore, it is necessary to select provenances and phenotypes of potential species such as P. oocarpa. The objective was to determine the difference between provenances and the variation in resin components and quality, as well as the effect of geographic and climatic factors. Resin from five provenances was collected from southern Mexico. The percentage of rosin, turpentine and water was obtained, as well as the acidity and saponification index. P. oocarpa resin had 80.94% rosin, 7.7% turpentine and 11.49% water. The saponification and acidity index was 125.47 and 117.49 mg KOH.g−1, respectively. All variables showed differences (p ≤ 0.0001) between provenances. The provenance contributed between 6.44 and 11.71% to the total variance, the error contributed between 88.29 and 93.56%. Geographic and climatic variables only had an effect on the percentage of turpentine; the correlation was negative with altitude and longitude, but positive with temperature and precipitation. The results allow defining seed collection sites for resin plantations and orienting the selection for a P. oocarpa improvement program. [ABSTRACT FROM AUTHOR]

Glycerol rosin ester (GRE) is extensively used in paint, coating, and adhesives. This study investigated the impact of reaction time, temperature, zeolite-type catalysts, dose and rosin-to-glycerol ratio on esterification of pine rosin. FTIR spectroscopy and acid number measurements confirmed the rosin ester. The highest conversion of 98 % was achieved by natural zeolite catalyst at 250 °C, reaction time 6 hours, catalyst dose of 0.5 %-mass, and rosin to glycerol ratio of 1:1. A higher proportion of strong acid sites in the natural zeolite produced higher conversion compared to ZSM-5, and the catalyst was separable from GRE by high temperature filtration.

Sonya Jamal Hamalaw, Fadil Abdulla Kareem, Arass Jalal Noori Department of Pedodontics and Community Oral Health, College of Dentistry, University of Sulaimani, Sulaymaniyah, IraqCorrespondence: Sonya Jamal Hamalaw, Sulaimaniyah, 46001, Iraq, Tel +9647705049108, Email sonya.hamalaw@univsul.edu.iqPurpose: Antibacterial and antibiofilm properties of magnesium oxide nanoparticles (MgONPs) mixture assessed against Streptococcus mutans (S. mutans), in addition to examining MgONPs varnish impact on the preservation of the tooth color and inhibition of methylene blue diffusion to the enamel.Methods: MgONPs mixture was prepared in deionized water (DW), absolute ethanol (E), and rosin with ethanol (RE), named varnish. The antibacterial and antibiofilm capacities of MgONPs mixtures were tested by agar well diffusion, colony-forming unit (CFU), and biofilm inhibition microtiter methods in triplicate and compared to sodium fluoride varnish (NaF) and chlorhexidine mouthwash (ChX). A spectrophotometer was used to record basic tooth color. The artificial demineralization was initiated for 96 h. Then, experimental materials were applied to the corresponding group, and 10-day pH cycles proceeded. Then, the color was recorded in the same ambient environment. The methylene blue diffusion was evaluated by staining the samples for 24 h. After that, the diffusion test was calculated by a digital camera attached to the stereomicroscope.Results: The agar well diffusion test expressed a significant inhibition zone with all MgONPs mixtures (p = 0.000), and maximum inhibition zone diameter associated with MgONPs-RE. The same finding was observed in the CFU test. Additionally, 2.5%, 5%, and 10% MgONPs-RE varnish showed strong biofilm inhibition capacity (p = 0.039) compared to NaF and ChX groups that inhibit biofilm formation moderately (p = 0.003). The study shows that the 5% MgONPs-RE varnish maintains basic tooth color with minimal methylene blue diffusion compared to NaF varnish (p = 0.00).Conclusion: Evaluating MgONPs as a mixture revealed antibacterial and antibiofilm capacity against S. mutans with a higher effect of MgONPs-RE varnish. Also, examining the topical effect of MgONPs-RE varnish on the preservation of the tooth color after pH cycle challenges and methylene blue diffusion to enamel confirmed the high performance of MgONPs-RE varnish at 5%. Keywords: fluoride, chlorhexidine, methylene blue, rosin, biofilms, dental enamel

Background: Allergic contact dermatitis (ACD) has been reported as an adverse effect from the use of several glucose sensors and insulin pumps from different manufacturers. Isobornyl acrylate (IBOA) has been identified as a major culprit sensitizer, but also other acrylates and (modified) colophonium have been reported as causes of ACD. Objectives: To report the two first cases diagnosed with ACD caused by the Dexcom G7 (DG7) glucose sensor. Patients and Methods: Two children with suspected ACD from DG7 were patch tested with our medical device series with an addition of selected test preparations including two variants of modified colophonium – methyl hydrogenated rosinate (MHR) and glyceryl hydrogenated rosinate (GHR). Both patients were also tested with acetone extracts made from different parts of the DG7 sensor. The extracts were analysed by gas chromatography–mass spectrometry (GC–MS). Results: Both patients tested positive to IBOA, hydroabietyl alcohol and GHR. In addition, patient 1 had a positive reaction to MHR and patient 2 had a positive reaction to colophonium. The GC–MS analyses showed the presence of IBOA and colophonium‐related substances in the DG7 extracts. Conclusions: Both patients were diagnosed with contact allergy to well‐known medical device‐related sensitizers. The presence of IBOA and (modified) colophonium in a newly introduced (on the Swedish market in 2023) glucose sensor is remarkable and indicates an inadequate toxicological assessment of the materials used in the sensor. [ABSTRACT FROM AUTHOR]

Iso-amyl ester rosin was synthesized and investigated for its potential utilization in medium density fiberboard (MDF) production. The isoamyl alcohol, the main starting material for the synthesis of isoamyl ester rosin, was obtained through the fractional distillation of fusel oil, a byproduct of bioethanol production. The optimum condition for the iso-amyl ester rosin synthesis was determined as: rosin (165 mmol), isoamyl alcohol (413 mmol), P-TSA/rosin 1.5% (w/w), and commercial additive/rosin 0.15% (w/w). The esterification reaction was followed by FT-IR and mass analysis. For MDF production, a water-repellent material, commercial paraffin (1.5% w/w relative to the dry fiber weight), iso-amyl ester rosin (1.5% and 2.0%; w/w), and unmodified rosin (1.5% and 2.0% w/w) were separately used. In addition, fresh wood fibers, 10% w/w urea formaldehyde (UF) adhesive (relative to the total dry fiber weight), and a 25% aqueous solution of ammonium chloride (as the hardening agent for the UF adhesive, at 0.5% w/w based on the solid adhesive content) were used. MDFs underwent various physical and mechanical tests. Isoamyl ester rosin showed promising results based on the analysis. The results showed that the isoamyl ester rosin can be considered as an alternative to paraffin in sustainable and environmentally friendly MDF production. [ABSTRACT FROM AUTHOR]

Herein, a phenomenological kinetic modeling of the disproportionation of rosin with a well-known antioxidant and bleaching agent, antioxidant 300, also known as 4,4′-thio-bis(3-methyl-6-tert-butylphenol) under thermal conditions adequate for rosin esterification with polyols such as glycerol or pentaerythritol, is studied. The temperature was varied in the 260–280 °C range, while the catalyst was either absent or added till a 2% w/w amount relative to rosin. The composition of the reaction liquid was followed by GC-MS to identify the rosin acids present in each sample and GC-FID to quantify them. Gas chromatography analyses indicated that abietic acids were involved in dehydrogenation, isomerization and disproportionation reactions, while pimaric acid underwent a number of isomerization reactions, dehydroabietic acid being the main product of the disproportionation process, while abietic acid almost disappeared in the more reactive conditions. Several kinetic models featuring direct hydrogenation, disproportionation, isomerization, and dehydrogenation reactions were proposed and fitted, step by step, to all relevant data. Physicochemical and statistical discrimination allowed for the selection of the most adequate model, which includes abietic, neoabietic and palustric acid dehydrogenation to dehydroabietic acid, abietic acid disproportionation to di- and dehydroabietic acid, and pimaric acid isomerization. In any case, a model with isomerization of all abietic-type acids towards abietic acid before its further transformation via dehydrogenation and disproportionation reactions seems statistically valid as well. [ABSTRACT FROM AUTHOR]

African swine fever virus (ASFV) causes a severe hemorrhagic disease in pigs, leading to up to 100% case fatality. The virus May persist on solid surfaces for long periods; thus, fomites, such as contaminated clothing, footwear, farming tools, equipment, and transport vehicles, May contribute to the indirect transmission of the virus. Here, a plastic surface functionalized with tall oil rosin was tested against ASFV. The rosin-functionalized plastic reduced ASFV infectious virus titers by 1.3 log10 after 60 min of contact time and killed all detectable viruses after 120 min, leading to a ~ 6 log10 reduction. In contrast, the infectious virus titer of ASFV in contact with low-density polyethylene (LDPE) plastic reduced

Iso-amyl ester rosin was synthesized and investigated for its potential utilization in medium density fiberboard (MDF) production. The isoamyl alcohol, the main starting material for the synthesis of isoamyl ester rosin, was obtained through the fractional distillation of fusel oil, a byproduct of bioethanol production. The optimum condition for the iso-amyl ester rosin synthesis was determined as: rosin (165 mmol), isoamyl alcohol (413 mmol), P-TSA/rosin 1.5% (w/w), and commercial additive/rosin 0.15% (w/w). The esterification reaction was followed by FT-IR and mass analysis. For MDF production, a water-repellent material, commercial paraffin (1.5% w/w relative to the dry fiber weight), iso-amyl ester rosin (1.5% and 2.0%; w/w), and unmodified rosin (1.5% and 2.0% w/w) were separately used. In addition, fresh wood fibers, 10% w/w urea formaldehyde (UF) adhesive (relative to the total dry fiber weight), and a 25% aqueous solution of ammonium chloride (as the hardening agent for the UF adhesive, at 0.5% w/w based on the solid adhesive content) were used. MDFs underwent various physical and mechanical tests. Isoamyl ester rosin showed promising results based on the analysis. The results showed that the isoamyl ester rosin can be considered as an alternative to paraffin in sustainable and environmentally friendly MDF production.

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Rosin-based polyurethane microspheres (5-Fu / RPUMs) are prepared by suspension polymerization using 5-fluorouracil (5-Fu) as the model drug rosin-based polyurethane (RPU) synthesized by prepolymerization, and extension and neutralization method as the carrier single factor experiment is used to optimize drug-loaded conditions. Infrared spectrometer X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive spectrometer are used to characterize drug-loaded microspheres. The in-vitro release performance and drug release kinetics model of drug-loaded microspheres are studied. The results show that 5-Fu / RPUMs are successfully prepared with an average particle size of 35. 0 μm and a smooth, rounded surface with holes. The optimal loading conditions are ρ5-Fu = 120 mg / mL and n-butanol / toluene as pore-forming agent. Under these conditions, the encapsulation rate of RPU to 5-Fu reaches 63. 35% and the drug loading is 7. 60%. 5-Fu / RPUMs is pH sensitive showing different sustainable release at different pH. In PBS buffer solution with pH= 6. 8, the cumulative release rate after 264 h is 65. 80%, showing a long-acting sustainable release effect. [ABSTRACT FROM AUTHOR]

Aim Hospital-acquired infections (HAIs) caused by antimicrobial-resistant ESKAPE pathogens are a significant concern for the healthcare industry, with an estimated cost of up to $45 billion per year in the US alone. Clostridioides difficile is an additional opportunistic pathogen that also poses a serious threat to immunocompromised patients in hospitals. Infections caused by these pathogens lead to increased hospital stays and repeated readmission, resulting in a significant economic burden. Disinfectants and sporicidals are essential to reduce the risk of these pathogens in hospitals, but commercially available products can have a number of disadvantages including inefficacy, long contact times, short shelf lives, and operator health hazards. In this study, we evaluated the effectiveness of Rosin (a natural substance secreted by coniferous trees as a defence mechanism against wounds in tree bark) and its commercial derivative Rosetax-21 as disinfectants and sporicidal against the six ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa , and Enterobacter species) and spore preparations from C. difficile. Methods and Results Both Rosin and Rosetax-21 were tested under simulated clean and dirty conditions [with Bovine Serum Albumin (BSA)] against the ESKAPE pathogens, and C. difficile spore preparations. In clean conditions, Rosin (5% weight/volume: w/v) demonstrated significant efficacy against five of the ESKAPE pathogens, with A. baumannii and Enterococcus faecium being the most susceptible, and K. pneumoniae the most resistant, showing only a 1-log reduction after a 5 min treatment. However, in dirty conditions, all pathogens including K. pneumoniae exhibited at least a 3-log reduction to Rosin within 5 min. Rosetax-21 (5% w/v) was found to be less effective than Rosin in clean conditions, a trend that was exacerbated in the presence of BSA. Additionally, both Rosin and Rosetax-21 at 2.5% (w/v) achieved complete eradication of C. difficile spores when combined with 0.5% glutaraldehyde, though their standalone sporicidal activity was limited. Conclusions The findings from this study highlight the potential of Rosin and Rosetax-21 as both bactericidal and sporicidal disinfectants, with their efficacy varying based on the conditions and the pathogens tested. This presents an avenue for the development of novel healthcare disinfection strategies, especially against HAIs caused by antimicrobial-resistant ESKAPE pathogens and C. difficile. [ABSTRACT FROM AUTHOR]

Dehydroabietyl polyethylene glycol glycidyl ether-grafted hydroxyethyl cellulose (HEC) polymer surfactant (DA (EO)5GE-g-HEC) was prepared using ring-opening polymerization with biobased rosin and hydroxyethyl cellulose as feedstocks. Dehydroabietyl polyethylene glycol glycidyl ether (DA(EO)5GE) was formed by condensation of dehydroabietyl alcohol polyoxyethylene ether (Rosin derivative: DA(EO)5H) and epichlorohydrin. The grafting degree of DA(EO)5GE-g-HEC was manipulated by adjusting the mass ratio of HEC and DA(EO)5GE and confirmed by EA. According to the formula, when m(HEC)/m(DA(EO)2GE) was 1:1~1:5, the grafting rate of DA(EO)5GE in DA(EO)5GE-g-HEC varied from 34.43% to 38.33%. The surface activity and foam properties of DA(EO)5GE-g-HEC aqueous solution were studied. The results showed that with the increase in grafting rate, the critical micellar concentration (CMC) in aqueous solution changed from 1.28 to 0.96 g/L. The results of the thermogravimetric analysis showed that the temperature range of the main stage of mass loss of DA(EO)5GE-g-HEC was 310°C~410°C, and the thermal decomposition processes of the samples with five mass ratios were similar. An oil in water emulsion was prepared by choosing cyclohexane as the oil phase and DA(EO)5GE-g-HEC as the emulsifier. The effect of DA(EO)5GE-g-HEC mass fraction on emulsion particle size and stability was analyzed. The results suggested that when the oil-water ratio was 8:2 with 0.4% emulsifier, the emulsion droplets were the smallest in terms of particle size and were the most stable. The rheological test results showed that the apparent viscosity decreased with the increase in shear rate and showed a typical elastic gel phenomenon. [ABSTRACT FROM AUTHOR]

Objective: Pine resin is a product obtained from plants belonging to the Pinaceae family and traditionally used in the treatment of wounds. The aim of this study is to determine the effectiveness of pine resin in corneal wounds. Material-Methods: In this study, three groups of 7 male Wistar Albino rats (n=7), each 2 months old, were established. To create the corneal wound model, the rats were anesthetized and the borders of the wound to be created on the corneal surface were determined using a 3 mm punch biopsy, then the first two layers of the cornea were removed with a corneal knife. Then, the first group was considered as the control group and no treatment was performed. The second group was determined as the pine resin group and applied once a day. The third group was considered as the drug group and was administered once a day. Fluorescein staining was performed every day for three days and the results were recorded. Results: Pine resin group showed the fastest recovery. On the third day, the rats were euthanized, and their eyes were enucleated. The collected eyes were sent for histopathologic examination and stained with hematoxylin-eosin. The lesions in the examined specimens were evaluated under microscope for hyperemia, vascularization, cellular infiltration and corneal edema. Conclusion: As a result of the study, ulceration was observed in the pine resin group. The study concluded that pine resin reduces clinical symptoms and promotes healing in corneal wounds. [ABSTRACT FROM AUTHOR]

Gum rosin is an important agricultural commodity which is widely used as a raw material for various industries. However, gum rosin has low stability, crystallizes easily, and tends to oxidize. This is due to carboxyl groups and conjugated double bonds in gum rosin’s structure. Therefore, to reduce these weaknesses, it is necessary to modify the rosin compound to achieve better stability via the esterification process. This paper surveys esterification agents such as glycerol, pentaerythritol, methanol, ethylene glycol, polyethylene glycol (PEG), allyl group, and starch Rosin ester. The product is used in the manufacture of pressure-sensitive adhesives, drug delivery, solder flux for electronic devices, as a plasticizer, and as a coating agent in fertilizers. In general, the esterification reaction between alcohols and carboxylic acids is very slow without a catalyst. Heterogeneous catalysts have the advantage of controlling size, structure, spatial distribution, surface composition, thermal-chemical stability, and selectivity. Among the catalysts for gum rosin esterification are ZSM-5, Fe3O4, ZnO, Calcium, TiO2, Kaolin, and Al2O3, among others. Different catalysts and esterification agents can produce various physical and chemical properties of rosin ester and will result in specific rosin ester products, such as glycerol ester, pentaerythritol ester, methyl ester, glycol ester, allyl ester, and acid starch-based rosin.

Pinus pinaster forestry occupies >20% of the forest ecosystem area in the continental territory of Portugal with a high impact on the national economy. This species' major derived non-wood product is oleoresin, the raw material for rosin production. Rosin comprises mainly a blend of resin acids and has broad industrial and pharmaceutical applications. Oleoresin production in Portugal has been progressively reduced due to low-cost producers in other countries; currently, it reaches only 2% of the existing P. pinaster trees. To support this value chain, the chemical fingerprint of rosin derived from the national forest requires focused analysis. In the present study, we collected oleoresin within seven geographically distinct pure P. pinaster forests in two consecutive collection years. A high-resolution nuclear magnetic resonance (NMR) method was used to quantify the diversity of resin acids in the corresponding rosin samples. Overall, the acquired data highlighted that the profile of resin acids in P. pinaster rosin produced in Portugal is highly regular, regardless of the forest location, having as the major constituents abietic acid and dehydroabietic acid. The diversity of resin acids is possibly influenced, to a minor extent, by some edaphoclimatic factors. [ABSTRACT FROM AUTHOR]

This study aims to reveal the effects of flexible chain lengths on rosin-based epoxy resin's properties. Two rosin-based epoxy monomers with varying chain lengths were synthesized: AR-EGDE (derived from ethylene glycol diglycidyl ether-modified acrylic acid rosin) and ARE (derived from acrylic acid rosin and epichlorohydrin). Diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) with different flexible chain lengths were used as curing agents. The adhesion, impact, pencil hardness, flexibility, water and heat resistance, and weatherability of the epoxy resins were systematically examined. It was found that when the flexible chains of rosin-based epoxy monomers were grown from ARE to AR-EGDE, due to the increased space of rosin-based fused rings, the toughness, adhesion, and water resistance of the rosin-based epoxy resins were enhanced, while the pencil hardness and heat resistance decreased. However, when the flexible chains of curing agents were lengthened, the resin's performance did not change significantly because the space between the fused rings changed little. This indicates that the properties of the rosin-based resins can only be altered when the introduced flexible chain increases the space between the fused rings. The study also compared rosin-based resins to E20, a commercial petroleum-based epoxy of the bisphenol A type. The rosin-based resins demonstrated superior adhesion, water resistance, and weatherability compared to the E20 resins, indicating the remarkable durability of the rosin-based resin. [ABSTRACT FROM AUTHOR]

Bio‐based alternatives for petroleum‐based epoxy resin curing agents, such as maleopimaric acid (MPA), are indispensable for sustainable fiber reinforced polymer composites with thermosetting matrices. However, previous investigations disregarded the importance of choosing the right stoichiometric ratio R between the anhydride groups in the rosin‐based curing agent and the epoxy groups in the resin. Therefore, the influence of R on the curing kinetics and mechanical properties of an epoxy resin cured with a rosin‐based anhydride is studied. Here, Fourier‐transform infrared spectroscopy (FT–IR) indicates that for R ⩾ 0.9 unreacted anhydride groups are present in the thermoset. Consequently, the network density decreases and the glass transition temperature Tg drops by about 40 °C. On the other hand, the steric hindrance of unreacted functional groups for R ⩾ 0.9, increases the flexural modulus and the reduced network density improves fracture toughness. The results indicate that the best R for overall high mechanical performance and good processability is preferably low (R ⩽ 0.7). Here, a low R results in a high Tg and good processability due to a low viscosity. However, the latency of the mixtures is low and therefore, the mixtures are not fit for processing via prepreg technology. [ABSTRACT FROM AUTHOR]

Solid dispersion materials of abietic acid (ABA) in mechanically fibrillated cellulose nanofiber (CNF), TEMPO-oxidized cellulose nanofiber (TOCNF), and partially deacetylated chitin nanofiber (ChNF) without or with aluminum sulfate (Alum) were prepared using a conventional solvent-evaporation method. ABA was retained in basically an amorphous form in the solid dispersion materials. The interactions between ABA and the nanofibers (NFs) were different between anionic NFs (CNF and TOCNF) and cationic NF (ChNF)-containing solid dispersion materials. The ABA dissolved in water from CNF- and ChNF-containing solid dispersion materials increased with an increase in shaking time and leveled off, whereas the amount released from TOCNF-containing solid dispersion materials increased rapidly, reached a maximum at the initial stage and then decreased gradually. The different behaviors might be presumed to depend on the narrowness of the NF fiber width rather than the ionic nature of the NFs. Alum basically inhibited ABA dissolution from CNF-containing solid materials, whereas it promoted ABA dissolution from TOCNF and ChNF-containing solid materials unless Alum addition was excessive. The former might correspond to a decrease of dissolved colloidal substances by Alum in acidic papermaking systems. [ABSTRACT FROM AUTHOR]

Pine rosin acid or Gondorukem is a solid resin obtained from pine sap. It is yielded as residue from a high temperature distillation process. In industry, rosin acid is widely used and modified as raw material in paint, ink, adhesive, resin, thermoplastic, and thermosetting polymer. Modification process generally is undergone to generate rosin acid with specific properties and for certain purposes. This paper report, potassium permanganate oxidation reaction of pine rosin acid under acidic process at low temperature. Product identified as 13,14-seco-13-oxoabiet-7-ene-dioic acid (0.52%), 7,8-dihydroxy-abietic acid (6.62%), and 7-oxo-dehydroabietic acid (1.49%). The crude product was isolated as a pale to white solid. Under high temperature a yellowish product was resulted. In overall, the yield isolated in between 46.4% and 86.0%

In Mexico, there is a deficit in the production of pine resin, because it relies on natural forests only. Therefore, it is necessary to select provenances and phenotypes of potential species such as P. oocarpa. The objective was to determine the difference between provenances and the variation in resin components and quality, as well as the effect of geographic and climatic factors. Resin from five provenances was collected from southern Mexico. The percentage of rosin, turpentine and water was obtained, as well as the acidity and saponification index. P. oocarpa resin had 80.94% rosin, 7.7% turpentine and 11.49% water. The saponification and acidity index was 125.47 and 117.49 mg KOH.g−1, respectively. All variables showed differences (p ≤ 0.0001) between provenances. The provenance contributed between 6.44 and 11.71% to the total variance, the error contributed between 88.29 and 93.56%. Geographic and climatic variables only had an effect on the percentage of turpentine; the correlation was negative with altitude and longitude, but positive with temperature and precipitation. The results allow defining seed collection sites for resin plantations and orienting the selection for a P. oocarpa improvement program.

Abstract Bio‐based alternatives for petroleum‐based epoxy resin curing agents, such as maleopimaric acid (MPA), are indispensable for sustainable fiber reinforced polymer composites with thermosetting matrices. However, previous investigations disregarded the importance of choosing the right stoichiometric ratio R between the anhydride groups in the rosin‐based curing agent and the epoxy groups in the resin. Therefore, the influence of R on the curing kinetics and mechanical properties of an epoxy resin cured with a rosin‐based anhydride is studied. Here, Fourier‐transform infrared spectroscopy (FT–IR) indicates that for R ⩾ 0.9 unreacted anhydride groups are present in the thermoset. Consequently, the network density decreases and the glass transition temperature Tg drops by about 40 °C. On the other hand, the steric hindrance of unreacted functional groups for R ⩾ 0.9, increases the flexural modulus and the reduced network density improves fracture toughness. The results indicate that the best R for overall high mechanical performance and good processability is preferably low (R ⩽ 0.7). Here, a low R results in a high Tg and good processability due to a low viscosity. However, the latency of the mixtures is low and therefore, the mixtures are not fit for processing via prepreg technology.

Pinus pinaster forestry occupies >20% of the forest ecosystem area in the continental territory of Portugal with a high impact on the national economy. This species’ major derived non-wood product is oleoresin, the raw material for rosin production. Rosin comprises mainly a blend of resin acids and has broad industrial and pharmaceutical applications. Oleoresin production in Portugal has been progressively reduced due to low-cost producers in other countries; currently, it reaches only 2% of the existing P. pinaster trees. To support this value chain, the chemical fingerprint of rosin derived from the national forest requires focused analysis. In the present study, we collected oleoresin within seven geographically distinct pure P. pinaster forests in two consecutive collection years. A high-resolution nuclear magnetic resonance (NMR) method was used to quantify the diversity of resin acids in the corresponding rosin samples. Overall, the acquired data highlighted that the profile of resin acids in P. pinaster rosin produced in Portugal is highly regular, regardless of the forest location, having as the major constituents abietic acid and dehydroabietic acid. The diversity of resin acids is possibly influenced, to a minor extent, by some edaphoclimatic factors.

The emergence of vitrimer, a new class of polymer materials can address the problem of recyclability, reprocess ability and recyclability of thermosetting plastics. Rosin, a natural product, is an ideal raw material for the preparation of polymers in a more sustainable way. Nevertheless, due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure, the cross-link density of materials is frequently lowered. In this study, hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids, which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers. It was completely characterized by differential scanning calorimetry test, thermogravimetric analysis, shape memory test and self-healing test. The prepared vitrimers exhibited good self-healing properties, excellent heat resistance (Td = 352 °C) as well as high mechanical properties (tensile strength of 46.75 MPa). The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton. Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy. Moreover, our work expanded the application field of rosin, increased the added value of rosin, and provided a novel method for preparing rosin-based vitrimers with ideal properties. [ABSTRACT FROM AUTHOR]

Rosin-based fluorescent polyurethane emulsion (FPU) was prepared using isophorone diisocyanate, ester of acrylic rosin and glycidyl methacrylate, 1,5-dihydroxy naphthalene (1,5-DN), and 1,4-butanediol as the raw materials. Then, rosin-based fluorescent polyurethane microspheres (FPUMs) were successfully prepared by suspension polymerization method using FPU as the main material, azodiisobutyronitrile as the initiator, and gelatin as the dispersant. FPUMs were characterized by Fourier transform infrared spectra, thermogravimetric analysis, optical microscopy, scanning electron microscopy and fluorescence spectra, and the response performance of FPUMs to pH was studied. The results showed that FPUMs were successfully prepared. With the increase of the level of 1,5-DN, the particle size of FPUMs increased gradually, and the fluorescence intensity increased first and then decreased. When the level of 1,5-DN was 3 wt.%, the average particle size was 49.3 μm, the particle distribution index (PDI) was 1.05, and the fluorescence intensity was the largest (3662 a.u.). The fluorescence intensity of FPUMs increased linearly with the decrease of pH, which can be used for pH detection in solution. Furthermore, the FPUMs exhibited good thermal stability, anti-interference and recoverability. [ABSTRACT FROM AUTHOR]

The effect of pine rosin (RO) was studied relative to the biodegradation of poly(lactic acid) (PLA), starch-based polymer (Mater-Bi), and PLA-flax composites. It was hypothesized that rosin can alter – either speed up or slow down – biodegradation in plastics depending on the specific species of polymer. The biodegradation was brought about by soil burial over 56 days. First, the effect of rosin was studied alone without any effects of soil burial. Second, the effects of soil burial were studied in terms of biodegradation. The results showed that RO increased the degree of crystallinity (+100%) and Young’s modulus (+14%) of PLA. For Mater-Bi, RO decreased the strength by 22% and led to brittleness (56% lower ultimate strain) of the specimens. After 56 days of soil burial, the presence of RO in PLA was found to speed up the degradation when compared to pure PLA (the decrease of strength was 9.3% and 6.6%, respectively). For Mater-Bi, the RO blending led to 2.1% slower biodegradation of strength during 56 days of soil burial. The effect of RO, in terms of affecting the biodegradation, was comparable in flax-reinforced and non-reinforced PLA. The strength of the fiber-matrix bonding remained equal for RO-impregnated fibers compared to the as-received flax fibers.

Epoxy resins are widely used as insulation materials for power systems and are mainly prepared from petrochemical materials, which have the disadvantage of being non-recyclable and environmentally harmful. In this paper, the maleopimaric acid (MPAc) curing agent was prepared from a renewable resource, rosin, and blended with a petroleum-based curing agent (methylhexahydrophthalic anhydride) to cure bisphenol A epoxy resin. The effects of the blending ratio on the curing characteristics as well as on the thermal, mechanical, and electrical properties of the epoxy resins were examined. From the results obtained, as for thermal properties, the introduction of MPAc enhanced the rigidity, glass transition temperature, and thermal decomposition temperature. As for mechanical properties, the brittleness was increased while the tensile strength and bending strength were weakened. When the mass fraction of MPAc was 20–30 wt%, the electrical properties reached the optimum, meeting the application requirements of electrical equipment. This study shows that using rosin-based curing agent maleicpine acid (MPAc) as a partial replacement for petroleum-based curing agents can make electrical equipment environmentally friendly, demonstrating the potential application prospects of rosin-based epoxy resins.

Zinc oxide nanoparticles (ZnO NPs) were successfully synthesized by a green method using rosin and zinc chloride as salt precursors. The phase structure, morphology, and particle size of ZnO were determined by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The fabricated ZnO NP samples are crystalline with a grain size of 30–100 nm. The ZnO NPs were used as catalysts for the photodegradation of methylene blue (MB) and methyl orange (MO) under visible and UV light. The results indicate that the prepared ZnO material excellently removed MB and MO (cinitial = 10 mg/L) with efficiencies of 100% and 82.78%, respectively, after 210 min under UV radiation with a ZnO NP dose of 2 g/L. The photocatalyst activity of the synthesized material was also tested under visible light radiation with the same conditions; however, it achieved lower efficiencies. In addition, ZnO NPs were also tested regarding their antibacterial activity, and the results showed that the prepared ZnO samples had the highest (i.e., 100%) antibacterial efficiency against E. coli.

Objective. In oral histopathology teaching and research, there is a need for high-quality undemineralized tooth sections that are easy to handle, have controlled thickness, allow the observation of intact microstructures, and can be preserved for long periods of time. Methods. Teeth were collected under non-demineralizing conditions. Tooth sections (15-25 μm) were prepared using a diamond knife, then randomly divided into three groups: (1) stained with rosin, (2) stained with hematoxylin and eosin, or (3) not stained. The prepared tooth sections were evaluated by microscopy for clarity and microstructure visibility. Results. The use of a diamond knife in the sectioning and grinding process yielded high-quality ground sections of teeth. Rosin-stained ground sections allowed better identification of microstructures within the teeth, compared with unstained or hematoxylin and eosin-stained ground sections. Conclusion. The best results were obtained in the ground sections of teeth that were stained with rosin. Ground sections of teeth prepared using this staining method could be useful in oral histopathology teaching and research. [ABSTRACT FROM AUTHOR]

BACKGROUND: RNA interference (RNAi) technology has been considered as a promising pest control strategy due to its species selectivity. One of the popular RNAs is exogenous double strand RNA (dsRNA). However, dsRNA is easily degraded by nucleases and is difficult to pass through the insect body walls, and these factors restrict the application of RNAi technology in pest management. Here, the brown planthopper (BPH, Nilaparvata lugens), a major hemipteran pest of rice in Asia countries was used as a model insect, and a dsRNA topical delivery system was constructed. RESULTS: The carrier part of the delivery system was composed of rosin‐modified polyethylene glycol and chitosan, termed ROPE@C. When the N/P ratio was greater than 1:1.25, the dsRNA/ROPE@C complex encouraged full binding of the dsRNA. The gel electrophoresis results showed that ROPE@C improved the stability of dsRNA in the presence of nucleases in gut and lumen contents for at least 6 h and in the temperature range from 4 °C to 37 °C. The dsNlCHSA/ROPE@C/alkyl polyglycoside (APG) nano‐formulation directly penetrated the body walls reaching hemocoel within 6 h, and consequently, the relative expression of chitin synthetase A (CHSA) in BPH was reduced by 54.3% and the mortality rate was 65.8%. CONCLUSION: We developed an appropriate delivery method for dsRNA application in BPH, which is helpful for a large‐scale application of RNAi pesticides. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This paper includes the curing of previously synthesized multifunctional bio-based epoxy resins (PEMPAE/TMPAE) with rosin-based imidoamine curing agents (IAMDK/IASDK/IAEDK) which are nucleophilic addition reaction products of diamino diphenyl ether (DDE) and dimaleopimaryl ketone (DMPK), a dehydrodecarboxylated derivative of MPA. Curing dynamics of rosin-based epoxy resins (PEMPAE/TMPAE) with rosin-based imidoamine curing agents (IAMDK/IASDK/IAEDK) were evaluated using differential scanning calorimetry. For comparison, the bio-based epoxy resins were also cured with rosin derivative dimaleopimaryl ketone (DMPK) and commercial-based diamino diphenyl ether (DDE). The universal testing machine and thermogravimetric analyzer) were used to measure the mechanical properties and thermal stability of the cured epoxy samples. The samples' chemical resistance was assessed by calculating the weight loss in percent after they were submerged in solutions of NaOH, HCl, and NaCl. We also used scanning electron microscopy (SEM) to examine the morphological changes. Rosin-based epoxy cured with imidoamine curing agents outperformed the commercial epoxy in terms of performance. [ABSTRACT FROM AUTHOR]

The increasing concern for the protection of the environment, through the use of renewable natural resources, has led in the last decades to the realization of a number of natural polymers or hybrids to be able to replace petroleum-based polymeric materials. Rosin is a low-cost wood resin extracted from conifers. In this paper, based on FTIR and Raman analyses, the spectra of natural Rosin resin and some hybrid resins with volume proportions of 45, 55 and 65% Rosin were studied. Some mechanical properties such as modulus of elasticity, elongation at break, tensile strength were determined from stress-strain diagrams obtained from tensile stress. Increasing the volume proportion of Rosin leads to a decrease in stiffness and strength properties and obtaining a visco-elastic behavior. [ABSTRACT FROM AUTHOR]

Over the last 20 years, many polymer-based additives have been used in asphalt modification. The extensive utilization of these additives and their inability to biodegrade create environmental concern for humans. Therefore, discovering affordable and naturally occurring asphalt polymers has become prominent. In this study, a new asphalt modifier was produced under laboratory conditions by synthesizing boron oxide with rosin (colophony resin), which is naturally produced from pine trees. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC)/thermogravimetric (TG), and X-ray powder diffraction (XRD) analyses were used to determine the microstructural characteristics of the produced modifier. The SEM analysis showed that the new modifier was distributed homogeneously the asphalt matrix, the FTIR and XRD analyses showed that a chemical synthesis had taken place, while the DSC and TG analyses determined the thermal structure characterization and temperature range of the modifier. The rheological properties of the modified asphalts were investigated by conducting penetration, softening point, ductility, flash point test, rotational viscosity (RV), and dynamic shear rheometer (DSR) tests. The results showed that the new modifier could be produced in a laboratory environment, the temperature sensitivity of the original asphalt was reduced by 48% with a 3% additive rate, and the modified asphalt provides a wide range of usage in hot climates. Conclusively, the boron-added resin compound (BARC) additive did not adversely affect the workability and pumpability properties and the BARC-modified asphalt binders significantly increased the rutting resistance. [ABSTRACT FROM AUTHOR]

Hydrogels have been widely applied in agricultural drought-resistance, pollution regulation, drug delivery and so on. Acrylamide (AM) is usually used as raw material to synthesize acrylamide hydrogels. However, inherently low mechanical strength greatly limits their applications in some special areas. Therefore, it is necessary to choose suitable functional monomers to optimize acrylamide hydrogels and improve their mechanical performances. In this paper, a novel acrylamide monomer modified by rosin was synthesized, and then polyacrylamide/rosinbased acrylamide (RAM) composite hydrogels were prepared via free radical polymerization using potassium persulfate as initiator, N, N'-methylene-bisacrylamide (MBA) as a crosslinker. The influence of RAM monomer was investigated in detail. The chemical structure, pore structure, swelling properties, thermal performances and mechanical properties of composite hydrogels were characterized by Fourier Transform Infrared spectrometer (FT-IR), thermogravimetric analysis (TG), scanning electron microscope (SEM), and universal testing, respectively. The results showed that the thermal stability and mechanical property of RAM hydrogels were improved significantly. The compressive strength of RAM hydrogels was increased to 3.5 times than that of AM hydrogels, and the tensile strength was 5.1 times compared with AM hydrogels as well. Moreover, RAM hydrogels exhibited a faster initial swelling rate due to the new pore structure formed after introducing the RAM monomer. [ABSTRACT FROM AUTHOR]

Environment friendly and intelligent surfactants have attracted great attention in recent years. A bio-based CO2 responsive surfactant rosin acid dimaleimide choline (R-BMI-C) with an extremely rigid skeleton was prepared using rosin and choline as raw materials by Diels-Alder addition reaction and acid-base neutralization reactions. Its structure was confirmed by IR and 1H NMR spectra. The foams' properties of R-BMI-C could be adjusted by bubbling CO2/N2 to change the structure of the surfactant. At pH 10.4, R-BMI-C forms an unstable foam with a half-life of 1.5 h. When the pH was reduced to 7.4 by bubbling CO2, R-BMI-C forms an extremely stable foam with a half-life of 336 h. The surfactant R-BMI-C changed from bola type to conventional type when bubbling CO2. And the internal aggregation structure of R-BMI-C aqueous solution changed from spherical micelles to laminar micelles according to the cryogenic-transmission electron microscope. We know that the lamellar structure tends to adsorb at the air/water interface or is trapped in the foam film, which slows down the foam coarsening and agglomeration process, resulting in a significant increase in foam stability. R-BMI-C could be used in oil extraction, fire-fighting and chemical decontamination due to its excellent foaming, stabilization and defoaming properties. [ABSTRACT FROM AUTHOR]

BACKGROUND: The use of fungicides to protect crops from diseases is an effective method, and novel environmentally friendly plant-derived fungicides with enhanced performance and low toxicity are urgent requirements for sustainable agriculture. RESULTS: Two kinds of rosin-based acylhydrazone compounds were designed and prepared. Based on the antifungal activity assessment against Rhizoctonia solani, Fusarium oxysporum, Phytophthora capsici, Sclerotinia sclerotiorum, and Botrytis cinerea, acylhydrazone derivatives containing a thiophene ring were screened and showed an inhibitory effect on rice R. solani. Among them, Compound 4n, with an electron-withdrawing group on the benzene ring structure attached to the thiophene ring, showed optimal activity, and the EC50 value was 0.981 mg L−1, which was lower than that of carbendazim. Furthermore, it was indicated that 4n could affect the mycelial morphology, cell membrane permeability and microstructure, cause the generation of reactive oxygen species in fungal cells, and damage the nucleus and mitochondrial physiological function, resulting in the cell death of R. solani. Meanwhile, Compound 4n exhibited a better therapeutic effect on in vivo rice plants. However, the induction activity of 4n on the defense enzyme in rice leaf sheaths showed that 4n stimulates the initial resistance of rice plants by removing active oxygen, thereby protecting the cell membrane or enhancing the strength of the cell wall. Through the quantitative structure–activity relationship study, the quantitative chemical and electrostatic descriptors significantly affect the binding of 4n with the receptor, which improves its antifungal activity. CONCLUSION: This study provides a basis for exploiting potential rosin-based fungicides in promoting sustainable crop protection. [ABSTRACT FROM AUTHOR]

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The effect of pine rosin (RO) was studied relative to the biodegradation of poly(lactic acid) (PLA), starch-based polymer (Mater-Bi), and PLA-flax composites. It was hypothesized that rosin can alter - either speed up or slow down - biodegradation in plastics depending on the specific species of polymer. The biodegradation was brought about by soil burial over 56 days. First, the effect of rosin was studied alone without any effects of soil burial. Second, the effects of soil burial were studied in terms of biodegradation. The results showed that RO increased the degree of crystallinity (+100%) and Young's modulus (+14%) of PLA. For Mater-Bi, RO decreased the strength by 22% and led to brittleness (56% lower ultimate strain) of the specimens. After 56 days of soil burial, the presence of RO in PLA was found to speed up the degradation when compared to pure PLA (the decrease of strength was 9.3% and 6.6%, respectively). For Mater-Bi, the RO blending led to 2.1% slower biodegradation of strength during 56 days of soil burial. The effect of RO, in terms of affecting the biodegradation, was comparable in flax-reinforced and non-reinforced PLA. The strength of the fiber-matrix bonding remained equal for ROimpregnated fibers compared to the as-received flax fibers. [ABSTRACT FROM AUTHOR]