Investigation on the physical properties and internal bonding of HDF made of oxidized fiber

Current research was conducted to investigate the physical properties and internal bonding of High-Density Fiberboard (HDF) made from oxidized fibers and different amount of glue. In order to surface modification, fiber was treated with 40% nitric acid. After fibers gluing with urea-formaldehyde (7% and 9% based on the dry weight of fibers), the boards with a density of 0.9 g/cm3 were made by hot pressing at 175°C and 4 minutes. The results of spectroscopy were confirmed the reduction of hydroxyl functional groups and the increase of the carboxylic group due to oxidation. The results of short term immersion test in water showed that in boards containing oxide-modified fibers and 9% urea-formaldehyde glue were measured the minimum water absorption and thickness swelling with mean of 78.5 and 28.65%, respectively.Spring back of modified boards containing less glue was affected by the stresses release and debonding of the wood elements that resulted in internal bonding loss

The Impact of an Acidic Post-Treatment on Surface-Modified Old Corrugated Cardboard (OCC) with NaOH-Urea as a Reinforcing Agent

Chemical surface modification is one method for enhancing the mechanical and barrier properties of packaging paper. The NaOH/urea solvent system has been deemed an effective, inexpensive, and cost-effective solvent for paper modification and cellulose dissolution due to its unique self-reinforcing qualities and the fact that it can be utilized on an industrial scale, although it is ineffective for porous paper and requires pre- or post-treatment. This study examined the influence of acid as a post-treatment on the surface modification of paper with NaOH/urea to improve properties relative to packaging uses. The results indicated that NaOH/urea modification on OCC as a semi-crystalline material did not result in materials with superior resistance and barrier qualities. While acid treatment increased tensile and burst strength and air permeability, it was ineffective at increasing tear strength. Properties of control, NaOH/urea treatment, and acidic post treatment papers were respectively 33.31, 29.4, and 37.46 mn/g in the tensile index, 1.7, 1.58, and 1.74 Kpa.m2/g in burst index, 9.94, 9.07 and 8.87 mn.m2/g in tear index, 2.04, 1.34 and 1.32 s-1 in smoothness, 37.2, 38.2 and 45.4 s in air resistance, and 77.5, 90.8 and 80.5 water absorption. Therefore, with or without acidic post-treatment, the sheets became hydrophilic

Preparation of Filter Paper from Bamboo and Investigating the Effect of Additives

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size.This research received funding from the Basque Government (IT1498-22)