Selective Cleavage of the Aryl Ether Bonds in Lignin for Depolymerization by Acidic Lithium Bromide Molten Salt Hydrate under Mild Conditions

The present study demonstrates that the concentrated lithium bromide (LiBr) solution with acid as catalyst was able to selectively cleave the β-<i>O</i>-4 aryl ether bond and lead to lignin depolymerization under mild conditions (e.g., in 60% LiBr with 0.3 M HCl at 110 °C for 2 h). Four industrial lignins from different pulping and biorefining processes, including softwood kraft lignin (SKL), hardwood kraft lignin (HKL), softwood ethanol organosolv lignin (EOL), and acid corncob lignin (ACL), were treated in the LiBr solution. The molecular weight, functional group, and interunit linkages of the lignins were characterized using GPC, FTIR, and NMR. The results indicated that the β-<i>O</i>-4 aryl ether bonds of the lignins were selectively cleaved, and both LiBr and HCl played crucial roles in catalyzing the cleavage of the ether bonds

Synthesis and Application of Polyepoxide Cardanol Glycidyl Ether as Biobased Polyepoxide Reactive Diluent for Epoxy Resin

Polyepoxide cardanol glycidyl ether (PECGE), a novel cardanol derivative, was synthesized and used as reactive diluent for petroleum-based epoxy resin in this work. The synthetic condition was first optimized, and the resultant PECGE diluent was characterized using Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR. The influence of addition of this diluent on the viscosity of the diluent epoxy resin was also studied. Mechanical and heat-resistant properties of the cured epoxy resin containing PECGE were especially evaluated. By the addition of PECGE into the petroleum-based epoxy resin, the viscosity of the obtained epoxy resin was reduced. The tensile strength, elongation at break, and heat-resistant property of the obtained resin were all improved, while the flexural and compressive strengths of the resin only slightly decreased, implying the potential of PECGE as a very promising biobased reactive diluent for epoxy resin

Tung Oil-Based Unsaturated Co-ester Macromonomer for Thermosetting Polymers: Synergetic Synthesis and Copolymerization with Styrene

A novel unsaturated co-ester (co-UE) macromonomer containing both maleates and acrylates was synthesized from tung oil (TO) and its chemical structure was characterized by FT-IR, ¹H NMR, ¹³C NMR, and gel permeation chromatography (GPC). The monomer was synthesized via a new synergetic modification of TO, by introducing maleic groups first and acrylic groups subsequently onto TO molecules. The influence of experimental factors on thermomechanical properties of the cured bioresins was evaluated to better understand structure–property relationships of the biomaterials and optimize experimental conditions. The obtained TO-based co-UE monomer possessed a highly polymerizable CC functionality, consequently resulting in rigid bioplastics with high cross-link densities (ν_e) and excellent mechanical properties. For instance, the bioplastic prepared under the optimal synthesis conditions demonstrated a ν_e of 4.03 × 10³ mol/m³, storage modulus at 25 °C of 2.40 GPa, and glass transition temperature (<i>T</i>_g) of 127 °C, as well as tensile strength and modulus at 36.3 MPa and 1.70 GPa, respectively. A new theory for determining optimal comonomer concentration was further developed according to the copolymerization equation. The proposed theory accurately predicted the best styrene dosage for the co-UE monomer. At last, the hydroxyethyl acrylate (HEA)-modified TO-based resin was compared with the unmodified one in thermomechanical properties, thermal stability, microstructural morphologies, and curing behaviors. The new co-UE bioresin showed higher CC functionality and cross-link density, superior properties including <i>T</i>_g and thermal stability, and similar curing behaviors. The developed eco-friendly rigid biomaterials provide potential application in structural plastics such as sheet molding compounds

Self-Plasticization of PVC Materials via Chemical Modification of Mannich Base of Cardanol Butyl Ether

The internally plasticized PVC materials by displacement of chlorine with mannich base of cardanol butyl ether, that is, the covalent attachment of the cardanol-based internal plasticizer to the PVC matrix, is descried for the first time. The chemical structure and properties of cardanol-based internal plasticizer and internally plasticized PVC materials was characterized. The results showed that the <i>T</i>_g of self-plasticization PVC material decreased from 85.6 to 49.3 °C when chlorine atoms in PVC were substituted with mannich base of cardanol butyl ether, tensile strength decreased from 30.33 to 18.86 MPa, and the elongation at break increased from 180.37% to 357.20%, which illustrated that mannich base of cardanol butyl ether played internally plasticized effect on PVC. The internal plasticization mechanism was also studied. Self-plasticization PVC films showed no migration in <i>n</i>-hexane, but 15.7% of DOP leached from the DOP/PVC system into <i>n</i>-hexane. The PVC materials were expected to be commercial application in producing food packing, toys, and medical devices with high requirements in migration resistance

Highly Functional Unsaturated Ester Macromonomer Derived from Soybean Oil: Synthesis and Copolymerization with Styrene

A highly functional unsaturated ester macromonomer was synthesized from soybean oil (SBO), and its chemical structure was confirmed by FT-IR, ¹H NMR, ¹³C NMR, and gel permeation chromatography. The monomer was prepared through modifying epoxidized soybean oil (ESO) first with a synthesized precursor, hydroxyethyl acrylated maleate (HEAMA), and then employing maleic anhydride (MA) to modify the produced ESO-HEAMA. The obtained SBO-based monomer (ESO-HEAMA-MA) possessed a CC bond functionality of 6.75–8.15 per ESO. Effects of styrene concentration, feed ratio, and initiator concentration on the dynamic mechanical properties of the cured bioresins were investigated carefully. When the monomer with the highest CC bond functionality was used, the cured resins with 20–60 wt % styrene demonstrated cross-link densities of 5.07–9.52 (10³ mol)/m³, storage moduli at 25 °C of 1.32–2.16 GPa, glass transition temperatures of 69.9–114.1 °C, and tensile strengths and moduli of 19.7–33.1 MPa and 1.17–2.11 GPa, respectively. Microstructural morphologies of tensile-fractured surfaces of the cured resins were studied by scanning electron microscopy. Finally, curing behaviors of the resultant resin was studied by differential scanning calorimetry. The developed eco-friendly biomaterials have potential applications in the industry of unsaturated polyester resins

Additional putative toxin transcripts identified by similarity searches.

<p>^a Full-length and not full-length open reading frames (ORFs) are indicated by “F” and “N”, respectively.</p><p>^b Transcripts with or without a signal peptide are indicated by “Y” and “N”, respectively; transcripts in which the presence of a signal peptide was unclear are indicated by “U” (Unknown).</p><p>Additional putative toxin transcripts identified by similarity searches.</p

Alignment of translationally controlled tumor protein (or histamine-releasing factor).

<p>The aligned sequences are as follows: <i>Rhipicephalus microplus</i> histamine release factor (AAY67698), <i>Amblyomma americanum</i> histamine release factor (AAY67700), <i>Latrodectus hesperus</i> histamine release factor (ADV40083), <i>Saccoglossus kowalevskii</i> TCTP (XP_002740226) and <i>Ixodes scapularis</i> TCTP (AAY66972). Black and gray indicate amino acids that are identical or highly conserved across all aligned sequences, respectively.</p

Epoxy Monomers Derived from Tung Oil Fatty Acids and Its Regulable Thermosets Cured in Two Synergistic Ways

A novel biobased epoxy monomer with conjugated double bonds, glycidyl ester of eleostearic acid (GEEA) was synthesized from tung oil fatty acids and characterized by ¹H and ¹³C NMR. Differential scanning calorimeter analysis (DSC) and Fourier transform infrared spectroscopy (FT-IR) were utilized to investigate the curing process of GEEA with dienophiles and anhydrides. DSC indicated that GEEA could cross-link with both dienophiles and anhydrides through Diels–Alder reaction and epoxy/anhydride ring-opening reaction. Furthermore, Diels–Alder cross-link was much more active than the ring-opening of epoxy and anhydride in the curing process. FT-IR also revealed that GEEA successively reacted with dienophiles and anhydrides in both cross-linking methods. Dynamic mechanical analysis and mechanical tensile testing were used to study the thermal and mechanical properties of GEEA cured by maleic anhydride, nadic methyl anhydride and 1,1′-(methylenedi-4,1-phenylene)­bismaleimide. Due to the independence between the curing agents, dienophile and anhydride, a series of thermosetting polymers with various properties could be obtained by adjusting the composition of these two curing agents

Alignment of the conserved sequence motifs of Kunitz-type inhibitors.

<p>The deduced amino acid sequences of unigenes 18473, 23096, 40962 and 40624 were aligned with known Kunitz-type inhibitors, including <i>Ixodes scapularis</i> Kunitz-domain protein (XP_002435213), <i>Crassostrea gigas</i> putative Kunitz-type proteinase inhibitor (EKC39386), <i>Latrodectus hesperus</i> Kunitz-like protease inhibitor (ADV40132), <i>Astyanax mexicanus</i> Kunitz-type protease inhibitor 1-like (XP_007252976) and <i>Danio rerio</i> Kunitz-type protease inhibitor 1 (AAI63937). The six highly conserved cysteine residues are indicated by asterisks.</p

Categorization of unigenes into KEGG biochemical pathways.

<p>A total of 13,663 unigenes were assigned to 241 KEGG pathways belonging to six categories. (A) The percentage of the pathway amount in each category is shown. (B) The ten largest groups with KEGG database annotation. The x-axis indicates the number of annotated unigenes.</p