Cyanoethylation of several fiber materials and their utilization as adhesive in wood-based panels
This study examines the cyanoethylation and thermoplasticity of several cyanoethylated fiber materials. Cyanoethylated pulps with a degree of substitution of 1.43 have the lowest Vicat softening point. Cyanoethylated poplar with a weight gain of 18.2 % has the lowest melting temperature. Instead of traditional adhesives, cyanoethylated materials can be used to produce wood-based panels because of their good thermoplasticity. Plywood bonded with cyanoethylated pulp has a bonding strength of 2.06 MPa and an average wood failure of 62.7 %. Wheat straw particle board containing 40 % cyanoethylated pulp has an internal bonding strength of 0.49 MPa, a modulus of rupture (MOR) of 33 MPa, and a density between 0.5 and 0.6 g cm−3. Fiberboard containing 40 % cyanoethylated pulp has an internal bonding strength of 0.53 MPa, MOR of 38 MPa, modulus of elasticity of 4,200 MPa, and a density between 0.7 and 0.8 g cm−3. Its swelling in thickness is 41 %.
Centaurea solstitialis and Silybum marianum weeds conversion into value-added thermoplastic materials by benzylation process
Centaurea solstitialis and Silybum marianum are considered to be weeds in agricultural fields and forests. These annual herbaceous plants can be converted into value-added thermoplastics by means of benzylation. Products can be utilized in different applications where plastics are used. Substitution reaction was carried out with benzyl chloride under different alkaline conditions, 15, 25 and 35 %, respectively. Alkali concentration affects the substitution reaction. The chemical structure of modified materials was remarkably changed. In order to detect changes, crystallinity index of the materials and their thermal properties were analyzed. In FTIR spectra, the peaks appeared at 695 and 736 cm−1, indicating the aromatic C–C angular deformation. Multiple peaks appeared at 3050 cm−1 which were indications of benzylation of the materials. A peak increase was observed at 1596 cm−1 due to the aromatic substitution. Hydroxyl groups were replaced with benzyl groups which increased peak intensity. After modification, hydrogen bond energy changed and crystallinity of both materials was reduced. This substitution process on functional groups changed the decomposition temperature of the modified materials. It reduced to the decomposition temperature of the materials to a temperature range between 240 and 280 °C. Thermogravimetric analysis revealed that modified products were characterized by poorer thermal stability compared to raw materials.
Tensile properties of chemically modified ring- and rotor-spun cotton yarns
The effects of chemical treatments and modifications on the tensile properties of ring-and rotor-spun cotton yarns is discussed. The rotor-spun yarns treated with zinc chloride show a higher tenacity at low stretch levels compared to sodium hydroxide, whereas with sodium hydroxide, the rotor-spun yarns show higher tenacity at higher stretch levels compared with zinc chloride. The aqueous-treated rotor-spun yarns show a higher change in tenacity compared to ring-spun yarns. Sodium hydroxide-treated yarns before resin treatment show a higher retained tenacity compared to zinc chloride-treated yarns. The substitution treatment after swelling and stretching to 100% shows a higher tenacity than that of the slack substituted yarns. © 1995 John Wiley & Sons, Inc.