جستجوی مقالات مرتبط با کلیدواژه "آهاردهی سطحی" در نشریات گروه "صنایع چوب و کاغذ"

Surface sizing of historical papers by starch sizing was performed with the aim of investigating the effect of this material on the aesthetic and mechanical properties of historical papers. For this purpose, starch sizing with a weight concentration of 3% were used and pH, colorimetric, angle of contact and tensile strength tests were performed before and after aging of the samples. The results showed that the pH of samples non-sizing and samples containing starch sizing decreased after aging but it is still in the alkaline range. The brightness of the samples was slightly reduced after sizing with starch before and after aging and the color of the samples tends to darken. Tensile strength of paper samples containing starch sizing before and after aging increased compared to samples non-sizing. The results of measuring the angle of contact also showed that starch sizing no effect on increasing the resistance of paper to wetting and does not prevent the surface of the paper from getting wet.

Surface sizing of paper by anionic starch were carried out with the aim of its concentration effect on physical and strength properties of recycled paper. For this, hand sheets (100 GSM) of mixed recycled pulp containing 1% cationic starch were prepared and were treated by the sizing agent on the sheet surface at various concentration (0, 3-10%). Application and concentration increment of the starch solution caused its higher retention on the surface and lesser penetration into the paper structure (Z direction), contributed to the better hydrophobicity of sized paper and significantly reduction in water absorption of the paper, with the highest reduction in the Cobb test up to the solution concentration of 5%. Also, the results revealed that regarding to absorption and its increment into the paper surface combined to penetration to the paper thickness, strength properties of bending stiffness, burst and tensile indices have been increased which the improvement rate were more predominant up to the 5% cons. Penetration of a part of sizing agent into the porous structure of paper and resulted improvement in fiber bonding are possible and probable, that higher concentration and viscosity of the starch solution contributed to the lesser penetration and bonding formation with higher retention on the paper surface which resulted in continuous improvement in paper smoothness. With the sizing solution thickening, tear index decreased due to starch film formation on the paper surface with brittle character. In general, increasing of the anionic starch solution up to the 5% could be reported as an optimum level.