The aim of this study was to improve the water resistance of a soybean meal-based adhesive with a low-cost lignin-based resin (LR).

Combining in-depth neutron diffraction and systematic bulk studies, we discover that the √ 5 × √ 5 Fe vacancy order, with its associated block antiferromagnetic order, is the ground state with varying occupancy ratios of the iron 16𝑖 and vacancy 4𝑑 sites across the phase-diagram of K𝑥Fe2−𝑦Se2. The orthorhombic order, with one of the four Fe sites vacant, appears only at intermediate temperatures as a competing phase. The material experiences an insulator to metal crossover when the √ 5 × √ 5 order is highly developed. Superconductivity occurs in such a metallic phase.

Five surfactants [sodium dodecyl benzene sulfonate (SDBS), sodium deoxycholate (NaDC), Triton X‐100 (TX10), Arabic gum (AG), and cetyltrimethyl ammonium bromide (CTAB)] were employed separately or jointly as superficial active agents (SAAs), to enhance solubilization/dispersion of multi‐walled carbon nanotubes (MWNTs) in aqueous solution and cement matrix. The stabilizations of MWNTs in 12 SAAs solutions were estimated through sedimentation time of each suspension with centrifugation or sitting in 60 days. The mechanical and electrical properties as well as microstructures of MWNTs/cement composites (MNT/CCs) using the SAAs of SDBS, NaDC, AG, or the mixture of SDBS and TX10 were investigated. It was found that the capability of SAAs in dispersing MWNTs roughly decreases in the order as SDBS&TX10, SDBS, NaDC&TX10, NaDC, AG, TX10, and CTAB. The SAA of SDBS and TX10 with a mixing ratio of 3:1 by weight exhibits the best solubilization/dispersion capability. The delaminating time of the suspension of the above SAA with or without centrifugation is 80 min and 60 days, respectively. The microscopy observation indicates that the nanotubes form a stable network in the MNT/CC using SDBS&TX10 SAA. In addition, compared to the Plain/C, the corresponding MNT/CC increases in flexural strength, compressive strength, and the electrical conductivity by 29.10%, 20.8%, and two orders of magnitude, respectively. The enhancements are attributed to the uniform and stable distribution of MWNTs with the suitable surfactants and the ultrasonic dispersion method.

A sufficiently large supercurrent can close the energy gap in a superconductor and create gapless quasiparticles through the Doppler shift of quasiparticle energy caused by finite Cooper pair momentum. In this gapless superconducting state, zero-energy quasiparticles reside on a segment of the normal state Fermi surface, whereas the remaining Fermi surface is still gapped. Here we use quasiparticle interference to image the field-controlled Fermi surface of Bi2Te3 thin films proximitized by the superconductor NbSe2. A small applied in-plane magnetic field induces a screening supercurrent, which leads to finite-momentum pairing on the topological surface states of Bi2Te3. We identify distinct interference patterns that indicate a gapless superconducting state with segmented Fermi surface. Our results reveal the strong impact of finite Cooper pair momentum on the quasiparticle spectrum.

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The primary goal of this study is to improve the water resistance of a soybean meal-based bioadhesive and its resultant plywood with water-soluble 5,5-dimethyl hydantoin polyepoxide (DMHP). DMHP is welldistributed in the adhesive system and the water resistance of the adhesive/resultant plywood increases with increased DMHP addition from 5 to 13 wt%. This improvement is attributed to the following: (1) DMHP reacts with active groups on protein molecules to form a dense cross-linking network, improving the cross-linking degree of the cured adhesive; (2) adding DMHP decreases the adhesive viscosity, which helps the adhesive to penetrate into the wood surface and interlock; (3) the wettability of the adhesive increases after incorporating DMHP; (4) the adhesive with DMHP creates a smooth surface with fewer holes and cracks to prevent moisture intrusion. Incorporating 13 wt% DMHP effectively improves the moisture resistance of the resultant adhesive by 38.7% and the wet shear strength of the resultant plywood by 182.9%, up to 1.16 MPa, well within interior-use plywood requirements. Adding DMHP also increases the adhesive solid content by 26.6% and decreases adhesive viscosity to 13 610 mPa s, which is beneficial for industrial-use plywood adhesives. Further increasing the DMHP addition to 17 wt%, the wet shear strength of the plywood with the resultant adhesive decreases by 40.5%, however, this is attributed to the significant penetration of the adhesive into the wood surface caused by the low viscosity.

The goal of this study is to employ bio-based dialdehyde starch (DAS), derived from in situ polymerization and the resultant microphase separation structure, to improve the strength of melamine–urea–formaldehyde (MUF) resin, as well as enhance the properties that affect its adhesive performance. Thus, we evaluated the effects of DAS on the chemical structure, toughness, curing behavior, thermal stability, and micromorphology of the MUF resin. Furthermore, the wet shear strength and formaldehyde emissions of a manufactured, three-layer plywood were also measured. Results indicate that DAS was chemically introduced into the MUF resin by in situ polymerization between the aldehyde group in the DAS and the amino group and hydroxymethyl group in the resin. Essentially, polymerization caused a DAS soft segment to interpenetrate into the rigid MUF resin cross-linked network, and subsequently form a microphase separation structure. By incorporating 3% DAS into the MUF resin, the elongation at break of impregnated paper increased 48.12%, and the wet shear strength of the plywood increased 23.08%. These improvements were possibly due to one or a combination of the following: (1) DAS polymerization increasing the cross-linking density of the cured system; (2) DAS modification accelerating the curing of the MUF resin; and/or (3) the microphase separation structure, induced by DAS polymerization, improving the cured resin’s strength. All the results in this study suggest that the bio-based derivative from in situ polymerization and microphase separation can effectively toughen and enhance the properties that affect adhesive performance in highly cross-linked thermosetting resins.