Effect of Press-Drying Parameters on Paper Properties

Abstract

This study investigates alternatives that can improve the internal bond strength (IBS) of paper by pulp refining and paper press-drying (PD). The improvement mechanisms of IBS and their impact on the strength development of high-yield pulps are discussed. All experiments were conducted using a factorial design where the factors were four pulp types (one spruce thermomechanical (TMP) and three chemi-thermomechanical (CTMP) from spruce, birch, and aspen), three refining levels, three PD temperatures and three pressures. The effects of these treatments on the physical and mechanical properties of paper were studied using an analysis of variance. Refining changed the fibre surface, thereby promoting mechanical adhesion. PD temperature softened the fibres and changed their surface chemistry, while PD pressure improved the contact area between fibres. These changes led to an important improvement in IBS which explained, to a large extent, the variations in paper properties. Compared to air-dried paper, PD paper showed much higher properties for most tested pulps at all refining levels. These results were due to the increase in bonded areas. PD at 175°C substantially improved the wet tensile strength of paper due to the flow of lignin on the fibre surface, which protects the hydrogen bonds from moisture.

The impact of molded pulp product process on the mechanical properties of molded Bleached Chemi-Thermo-Mechanical Pulp

“…The initial mechanical test, without any specific condition given to the samples prior to their testing, shows that the process parameters tested have an impact on the resulting MPPs' Young Modulus. A lower amount and size of pores as well as longer fibers given by a shorter pulping time is beneficial for a higher Young's Modulus as observed by several studies [18,36] with a resulting higher tensile index. A higher mould B temperature improves the MPP's Young's Modulus for both initial and after water sorption.…”

The impact of molded pulp product process on the mechanical properties of molded BCTMP

“…shows that the process parameters tested have an impact on the resulting MPPs' Young Modulus. A lower amount and size of pores as well as longer fibers given by a shorter pulping time is beneficial for a higher Young's Modulus as observed by several studies [18,29] with a resulting higher tensile index.…”

Effects of Photo-oxidation on the Properties of Hemp Office Papers

“…From the tensile index results, it could be concluded that papers with hemp fibers only (Type 1 and Type 2) are stronger than papers in which a small percentage of hemp fibers were added (Type 3). Generally, long fibers provide papers with higher tensile strength than that provided by short fibers (Fagbemi et al 2014;Koubaa and Koran, 2018). The reasons for strength loss with aging are not completely known, but the property is unquestionably influenced by the intrinsic chemistry, morphology, and structure of individual fibers as well as the network structure of the paper.…”

“…Unlike paper made with short fibers, papers made from long fibers show much better resistance to tearing (Koubaa and Koran, 2018). Generally, hemp fiber pulp is characterized by high tear resistance (Danielewicz and Surma-Ślusarska, 2017).…”