Stored-product pests attack cereal grains and legume seeds post-harvest. They not only damage the grain but also decrease its weight and quality. Therefore, the aim of the present study was to ...investigate the bioactivity of resin powders extracted from Pistacia lentiscus L. bark, Boswellia carterii birdwood bark, and Elettaria cardamomum seeds against two of the most important stored-product pests, Sitophilus granarius (L.) and Tribolium confusum Jacquelin du Val. We used three bioassay methods, repellent effect, reduction of progeny, and grain weight loss and investigated the effects of the powders on the life cycles of the insects. Wheat grains were mixed with the three botanical powders separately, at different concentrations (3, 5, 7, and 10 % w/w). Sitophilus granarius and T. confusum were fed these mixtures. Repellent activity was examined after 2, 4, 8, 12, and 24 h. The E. cardamomum powder displayed the maximum repellent activity (100 %) against both S. granarius and T. confusum after 24 h at 3 % concentration. The P. lentiscus powder reached maximum repellent activity (80 %) against S. granarius and T. confusum at 7 % concentration after 12 h and 24 h, respectively. The B. carterii powder achieved maximum repellent activity against S. granarius and T. confusum (73.3 % and 86.7 %) at 10 % concentration after 24 h and 12 h, respectively. No progeny was produced in grains treated with 3 % P. lentiscus powder, 7 % E. cardamomum powder, or 7 % B. carterii powder. Thus, protection against both beetles started from 3 % concentration when P. lentiscus powder was used and from 7 % and 10 % (against S. granarius and T. confusum, respectively) when E. cardamomum powder was used. A 7 % B. carterii concentration completely saved the grains from S. granarius damage, and a 10 % concentration offered 99.5 % protection against T. confusum. However, all tested powders significantly affected all the studied parameters (life cycle and grain weight loss). The results show that the three botanical powders provide high repellent activity against S. granarius and T. confusum, which might be useful in protecting stored grains from these insects.
Background
Colophonium (rosin) can cause allergic contact dermatitis, mainly due to autoxidation of abietic acid (AbA). Products containing ≥0.1% colophonium should be labeled with EUH208 — “Contains ...rosin; colophony. May produce an allergic reaction.” How should this be measured?
Objective
To compare the results from different strategies for estimating colophonium levels in consumer products: (a) from AbA, and (b) the sum of all major resin acids. To investigate the ratio of 7‐oxodehydroabietic acid (7‐O‐DeA)/AbA as indication of autoxidation.
Methods
Resin acids were extracted from consumer products, derivatized, and then separated by gas chromatography/mass spectrometry (GC/MS).
Results
Resin acids were detected in 9 of 15 products. No product contained colophonium ≥0.1%. Estimation based on AbA resulted in underestimation of the colophonium levels in four of nine products. For three products, the obtained levels from this strategy were only one of two compared to when estimating from the sum of all resin acids. The ratio 7‐O‐DeA/AbA varied from 74% to 1.4%.
Conclusions
We propose to measure colophonium based on the sum of all detectable major resin acids, including 7‐O‐DeA. The ratio of 7‐O‐DeA/AbA should be used as a marker of autoxidation, indicating an increased risk of sensitization. The presented analytical method is simple to use and suitable for further screening studies.
Colophonium is known to cause allergic contact dermatitis, and consumer products containing ≥0.1% must be labeled according to EU regulations, but how to measure this complex composition accurately?
Of the analyzed consumer products in this study, 9 of 15 were shown to contain resin acids, the main constituents of colophonium.
For an estimation as accurately as possible of the colophonium content, we suggest that all major resin acids, including a marker of autoxidation.
Epoxy resin (ER) is one of the most widely used synthetic resins, and the improvement of its toughness is an important issue. In this study, Epon 828 is used as ER resin, polytetramethylene ether ...glycol (PTMG) and liquefied wood (LW) are used as polyol, and IPDI, H12‐MDI, Desmodur N, and Desmodur L are used as isocyanate. The influence of polyurethane resin (PU) composition on the reactivity of ER/polyol/isocyanate blended resin and the properties of ER/PU composite are investigated. The results show that the mixture of ER/PTMG/IPDI has greater reactivity, followed by ER/PTMG/Desmodur N, while ER/PTMG/Desmodur L has lower reactivity. In the structure of ER/PU blended resin composites, ER and PU resins not only form a physical interpenetrating structure, but also undergo a copolymerization crosslinking reaction. The modulus of elasticity of ER/PU composites prepared with trifunctional Desmodur L and Desmodur N is greater than that of bifunctional IPDI and H12‐MDI, while those with LW as polyol is greater than that of PTMG as the raw material.
Different polyols (PTMG and LW) and isocyanate (IPDI, H12‐MDI, Desmodur N, and Desmodur L) are added directly to epoxy resin, the reactivity of epoxy/polyol/isocyanate blended resins and the properties of ER/PU composites are investigated. The results show that the ER resin and the PU not only form a physical interpenetrating structure, but also undergo a copolymerization crosslinking reaction.
The recycling of thermoset‐based composites is challenging. The replacement of thermosetting resins with thermoplastics is an initial step to address this issue, together with the use of green ...reinforcements. Owing to the recent development of low‐viscosity thermoplastic resins, it is possible to produce thermoplastic matrix composites using the resin transfer molding (RTM) technique, which was originally conceived for the production of thermosetting matrix composites. These resins are based on cyclic esters, methyl methacrylate, and cyclic (butylene terephthalate) oligomers. This review presents the state‐of‐the‐art works reported on the production of thermoplastic matrix composites via a thermoplastic RTM (TP‐RTM) process, from the in situ polymerization of the resins through the optimization of the TP‐RTM parameters for the evaluation of the composite properties.
Phenol-formaldehyde (PF) resin continues to dominate the resin industry more than 100 years after its first synthesis. Its versatile properties such as thermal stability, chemical resistance, fire ...resistance, and dimensional stability make it a suitable material for a wide range of applications. PF resins have been used in the wood industry as adhesives, in paints and coatings, and in the aerospace, construction, and building industries as composites and foams. Currently, petroleum is the key source of raw materials used in manufacturing PF resin. However, increasing environmental pollution and fossil fuel depletion have driven industries to seek sustainable alternatives to petroleum based raw materials. Over the past decade, researchers have replaced phenol and formaldehyde with sustainable materials such as lignin, tannin, cardanol, hydroxymethylfurfural, and glyoxal to produce bio-based PF resin. Several synthesis modifications are currently under investigation towards improving the properties of bio-based phenolic resin. This review discusses recent developments in the synthesis of PF resins, particularly those created from sustainable raw material substitutes, and modifications applied to the synthetic route in order to improve the mechanical properties.
Polymers from renewable resources are receiving tremendous attention due to the increasing concerns on the depletion of fossil oils and deteriorated environments. Cardanol, as an abundant and ...renewable chemical raw material, has been widely used for the production of renewable polymer
materials via converting into various of chemical monomers with active functional groups. This comprehensive review deals with various aspects of cardanol as a starting material the preparing various polymer and polymer composites such as benzoxazine resins, phenolic resin, polyurethanes,
epoxy resin, vinyl ester polymers, polyamide and cyanate ester resins. The assessment of the future prospects for the use of cardanol to synthesise novel and valuable renewable materials is presented.
Vinyl ester resins (VERs) are one of the main categories of polymeric matrices for fabrication of high-performance commercial composites. They have more desirable properties compared with unsaturated ...polyester resins. Inserting urethane functional groups in the structure of VERs and producing urethane vinyl ester resin (UVER) improve its impact and chemical resistance, enlongation and toughness. The use of isocyanate as the primary resource in urethane preparation, which is derived from phosgene toxic material, may be associated with environmental hazards; as a result, non-isocyanate polyurethane (NIPU) methods have been developed. Herein, we have described the preparation and characterization of UVER by isocyanate-free system. First, cyclic carbonates of epoxides, 2-hydroxy-3-(4-(oxiran-2-ylmethoxy)butoxy)propyl methacrylate (HOMBPM) and diglycidyl ether of bisphenol-A epoxy resin (DGEBA) were synthesized by treatment of the corresponding epoxides with atmospheric pressure of carbon dioxide and tetrabutylammonium bromide (TBAB) as a catalyst. Then, the as-prepared cyclic carbonates were reacted with ethylenediamine in the presence of different catalysts to produce non-isocyanate epoxy vinyl ester urethane prepolymer. UVER is a potential compound for curing with VERs and fabricating materials with superior mechanical features such as elongation and tensile strength in comparison to VERs. Characterization techniques such as FTIR,
1
H and
13
C NMR spectroscopy and titration methods for measurements of epoxy equivalent weight (EEW), acid number and amine value are used in the synthesis of the desired compounds.
Graphical Abstract
The replacement of synthetic and petroleum-based ingredients with greener alternatives of natural origin is an imperative issue in rubber technology for the tire industry. In this study, a ...glycerin-esterified maleated rosin resin, derived from natural resources, is examined as a potential tackifier in styrene-butadiene rubber (SBR) formulations. A comparison is made with two synthetic resins commonly used as tackifiers in tire manufacturing: a petroleum-derived aromatic resin and a phenolic resin. Specifically, this research investigates how these resins affect the structure, dynamics, and curing characteristics of SBR compounds, which are strictly related to the mechanical and technological properties of the final products. Moving die rheometer and equilibrium swelling experiments are employed to analyze vulcanization kinetics and crosslink density, which are differently influenced by the different resins. Information on the polymer-resin compatibility is gained by differential scanning calorimetry and dynamo-mechanical analysis, while solid-state NMR methods offer insights into the structure and dynamics of both cured and uncured SBR compounds at the molecular level. Overall, our analysis shows that the resin of vegetal origin has a comparable impact on the SBR compound to that observed for the synthetic resins and could be further tested for industrial applications.
Hyperbranched epoxy resins are efficient modifiers for epoxy resins but still require simultaneous improvements in terms of thermomechanical/mechanical properties and thermal stability. Herein, a ...novel resveratrol-based hyperbranched polyether epoxy resin (HBPEER) was designed for all-purpose epoxy resin modification. To this end, hyperbranched polyether with terminal phenolic hydroxyl groups was first synthesized from commercially available 1,6-dibromohexane (A2-type monomer) and resveratrol (B'B2-type monomer). Surface modification with epichlorohydrin was afterward implemented to produce hyperbranched polyether with terminal epoxy groups (HBPEER). Next, various HBPEER-modified epoxy thermosets were prepared and characterized. The results suggested that compared to the neat diglycidyl ether of bisphenol A (DGEBA) thermoset, the 6 wt% HBPEER-modified epoxy thermoset showed an increase in impact strength, elongation at break, critical stress intensity factor (KIC), critical crack propagation energy release rate (GIC), flexural strength, tensile strength, storage modulus, glass transition temperature (Tg), and initial thermal decomposition temperature (Td5%) by 69.6 %, 87.0 %, 32.0 %, 68.2 %, 29.3 %, 37.0 %, 8.1 %, 3.5 %, and 1.6 % respectively. Moreover, the dielectric constant and loss of 6 wt% HBPEER-modified epoxy thermoset decreased by 16.2 % and 16.5 %, respectively. Such comprehensive performance modifications were caused by the combined effects of crosslink density improvement, efficient intramolecular cavity, rigid stilbene units, and flexible aliphatic backbone of HBPEER.
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•A resveratrol-based hyperbranched polyether epoxy resin (HBPEER) was synthesized.•HBPEER was synthesized via A2 + B'B2 polycondensation strategy.•The toughness and strength of HBPEER-modified epoxy thermosets were significantly improved.•HBPEER is an efficient and all-purpose modifier for epoxy thermosets.
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