Higher Tensile Shear Strength Research Articles

Synthesis and properties of fluorine‐containing epoxy(meth)acrylate resins

Ten fluorinated epoxyacrylate and epoxymethacrylate resins were synthesized to achieve effective photocurability as well as good refractive index controllability. The resins are suitable as adhesives for fabricating optical communications devices since they show high adhesive tensile shear strength and can match the refractive indices of optical glasses

クラフトリグニン樹脂接着剤の製造

The preparation of kraft lignin-based wood adhesives with high tensile shear strength and water resistance was investigated. Softwood and hardwood kraft lignins (NKPL and LKPL) were isolated from industrial concentrated waste liquors in yields of 15.8% and 15.0% based on solids, respectively. A mixture of lignin and phenol (85 : 1570 : 30) was hydroxymethylated by reacting with formaldehyde in an alkaline aqueous methanol for 2 hours at 80°C. The reaction products. hydroxymethylated was named a lignin-phenol resin (LP). Walnut powder was added to LP for a lignin-based adhesive (LPA). LPAs produced from NKPL or LKPL containing over 20% of phenol had high dry tensile shear strength bonds when hot-pressed for 615 minutes at 140°C, but their wet strengths after 48-hour boil deteriorated strikingly. Alternative lignin-based adhesives (LPRA) which consisted of 8070% LP, 2030% resorcinol and so forth developed satisfactory bonds in either dry or wet strength when hot-pressed for 615 minutes at only 75100°C. All of 3-ply shinanoki plywoods bonded with LPRAs provided higher wood failure in the wet test than in the dry test. Ether soluble fractions (LP-2) from acidified LP contained hydroxymethylated phenols such as 2, 4, 6-trihydroxymethylphenol, so the resorcinol together with paraformaldehyde was found to be used as crosslinking agents between ether insolubles (LP-1) such as hydroxymethylated lignin-phenol copolymers and LP-2 to form water-insoluble macromolecule for adhesion. LPRA required less energy for bonding and yielded high-quality bonds, indicating that it may be useful as wood adhesives for various kinds of wood products.

Synthesis and conformational study of cuticle collagen models and application as a bioadhesive

The synthesis of models of marine cuticle collagens, conformational aspects of native and model proteins and bonding strengths on substrates are investigated. Based on the amino acid composition of acid-soluble cuticle collagen of the Polychaete Nereis japonica, two random-sequence copolypeptides and two repeating-sequence polypetides have been synthesized using N-carboxyanhydride and active-ester methods. Native marine cuticle collagen exhibited a thermally induced conformational transition at a melting temperature (Tm) of 28 °C. Sequential (Ala-Gly-Glu-Hyp-Gly-Gly)21 and (Hyp-Gly-Gly-Glu-Ala-Gly)19 exhibited Tm at 33 and 28 °C, respectively, while no critical Tm was observed in the cases of the random copolypeptides A and B, suggesting that the amino acid sequence plays an important role in the marine cuticle collagen. Adhesive formulations consisting of copoly(Lys10Tyr1), native and synthetic model collagens added by oxidase, were found to have the highest tensile shear strength of 5.1 N mm–2 on iron, while the value for copoly(Lys10Tyr1) itself was 2.6 N mm–2. Mixed adhesive formulations consisting of copoly(Lys10Tyr1) and collagens (native and synthetic) showed tensile shear strengths of 3.2–3.9 N mm–2 on iron. The effect of oxidase to increase the bonding strength was observed in general but the bonding strengths of the adhesive formulation consisting of both native and synthetic cuticle collagens were weaker on alumina, skin and bone than those on iron. The results of this study have been compared to those for bonding strengths of commercial gelatin from cattle bone.