Lightweight lignocellulosic foams for thermal insulation

Foams are mainly composed of dispersed gas trapped in a liquid or solid phase making them lightweight and thermally insulating materials. Additionally, they are applicable for large surfaces, which makes them attractive for thermal insulation. State-of-the-art thermally insulating foams are made of synthetic polymeric materials such as polystyrene. This work focuses on generating foam from surfactants and renewable lignocellulosic materials for thermally insulating stealth material. The effect of two surfactants (sodium dodecyl sulphate (SDS) and polysorbate (T80)), two cellulosic materials (bleached pulp and nanocellulose), and lignin on the foaming and stability of foam was investigated using experimental design and response surface methodology. The volume-optimized foams determined using experimental design were further studied with optical microscopy and infrared imaging. The results of experimental design, bubble structure of foams, and observations of their thermal conductivity showed that bleached pulp foam made using SDS as surfactant produced the highest foam volume, best stability, and good thermal insulation. Lignin did not improve the foaming or thermal insulation properties of the foam, but it was found to improve the structural stability of foam and brought natural brown color to the foam. Both wet and dry lignocellulosic foams provided thermal insulation comparable to dry polystyrene foam. Graphical abstract

The Properties of OPEFB Cellulose Nanofibrils Produced by A Different Mode of Ultrafine Grinding

Cellulose Nanofibrils (CNFs) was resulted from deconstruction of the hierarchical structure of cellulose. CNFs are commonly obtained by mechanical fibrillation, such as ultrafine grinding processes and its variation. Nevertheless, the influence of different treatments on the properties of the resulting CNF especially from variety of ultrafine grinding mode has not been reported. This study investigates the properties of cellulose nanofibrils (CNF) produced from bleached pulp oil palm empty fruit bunch (OPEFB) Kraft pulp through an ultrafine grinder with two different treatments in the fibrillation process. These two treatments were: 1) ultrafine grinder with increasing gaps distances; -30, -50, -70, and -90 µm with five cycles in every gap, 2) ultrafine grinder on constant gaps (-30µm) with increasing grinding cycles: 5, 10, 15, 30, and 40 cycles through the grinder. The influence of the treatment was evaluated through particle size distribution, crystallinity index, and morphological properties. The result showed that the increasing gaps treatment efficiently improved the size uniformity of CNFs, length 147-139.5 nm, and scanning electron microscope micrograph confirmed that the diameter of CNF was smaller with the increasing grinding gaps than increasing grinding cycles. However, the increasing cycle’s treatment produced CNF with a higher crystallinity index. The crystallinity index (CrI) of the CNF decreased from 71.27 to 62.25% with increasing gaps, whereas the CrI of the CNF from increasing cycles was 69.35%. This study provides a valuable guideline for determining the appropriate process to produce CNF especially by mechanical grinding using ultrafine grinder from OPEFB according to the desired result.

Effect of bleaching using sodium hydroxide on pulp derived from Sesbania grandiflora

World demand for paper is increasing. Short rotation pulpwood is needed. Sesbania grandiflora also known as Turi, is a fast growing and straight log species. The scholarly information of Turi as pulpwood are still limited. This paper aims to provide information of sodium hydroxide effect on the paper made from pulp derived from Turi. Sodium hydroxide is a common chemical using as part of full stage chemical bleaching in pulp industrial. Kraft pulp that produced using Turi, was bleached with sodium hydroxide at 3%, 6% and 9% based on pulp weight, respectively. Unbleached pulp was served as blank test. The optical and mechanical properties of handsheet paper made from bleached kraft pulp were evaluated according to TAPPI standard. The brightness and opacity of handsheet made from bleached pulp were improved with increasing the concentration of sodium hydroxide. The mechanical properties of handsheet were improved with using 3% sodium hydroxide and gradually decreased after 3% sodium hydroxide. In conclusion, sodium hydroxide is potential to improve optical properties of Turi pulp and improve the mechanical properties of paper made from Turi pulp at certain level. Excessive usage of sodium hydroxide brings adverse effect to mechanical properties of paper made from Turi pulp.

A Method to Reduce Steam Consumption of ECF Bleaching Based on Operation Optimizing

Development of paper industry has been restricted by resources, energy and environment deeply; further reducing energy consumption becomes an urgent problem to be solved. In this paper, the calculating model of steam consumption in bleaching process is established under the premise of ensuring product quality and controlling bleaching cost. Then, an optimization model for minimizing steam consumption is constructed. Compared with before optimization, the steam consumption of the optimized bleaching system reduced by 19.48% (0.5014 t/adt) at a loss of 0.11% brightness (0.1 ISO%) and 5.17% viscosity (33 mL/g). The amount of chemicals should be increased to ensure the quality of the pulp while decreasing the bleaching temperature to reduce steam consumption, the cost of bleaching pulp has decreased by 1.62% (3.19 USD/adt) after optimization. The verification experiments showed all the pulp quality indices can meet the requirements of bleached pulp.

Mild enzymatic treatment of bleached pulp for tissue production

Effects of cellulase enzymatic treatment followed by mechanical beating were evaluated relative to the properties of cellulase-derived tissue pulps and handsheets. When different cellulase concentrations (0.0012 FPU/g, 0.0018 FPU/g, and 0.0024 FPU/g) of oven dried pulp (a 65/35 w/w ratio of beech to eucalyptus) were used for tissue production, a slight deterioration of the morphological characteristics was observed. Thus, a possibility of controlling the changes in the degree of polymerization of cellulose, as well as the fiber properties (in particular the length and coarseness) appeared. With an increased treatment time and enzyme concentration, these effects increased. The enzyme activity did not affect the apparent density of the paper, but the porosity drastically increased. The zero-span strength of the enzymatically treated pulps decreased with an increase in treatment time and amount of cellulase. However, mechanical beating improved the bonding between the cellulase fibers, which helped prevent the eventual decrease in mechanical properties of the handsheets. With the use of cellulase, the proposed moderate changes to fiber structure were achieved, giving the possibility of predicting and controlling the properties of tissue paper.

Dynamic-head space GC-MS analysis of volatile odorous compounds generated from unbleached and bleached pulps and effects on strength properties during ageing

Mixed hardwood unbleached (UB) and final bleached (FB) pulp along with the pulp of intermediate bleaching stages from an integrated paper mill have been undertaken for this study. Headspace GC-MS analysis of these pulps was made to identify the odorous compounds which are volatile organic compounds (VOCs), generated during ageing for 60 days. The result showed that a number of pre-generated VOCs such as aliphatic hydrocarbons and aldehydes are observed in the pulp sample which might be came from the process and it has been observed that upon ageing at ambient conditions, some acid functionalized VOC were generated in the pulp. The generation of these VOCs were established by ATR-FTIR analysis and the results showed that intensity of peak absorbance near 3340 cm − 1 {\text{cm}^{-1}} and 1641 cm − 1 {\text{cm}^{-1}} which represents the –OH stretching of acidic functional group and C=O stretch of aldehyde and acidic functional groups increased after ageing. Generation of acid functionalized volatile compounds were observed more in bleached pulp than in unbleached pulp. Degree of polymerization (DP) is pretty much related to the strength of paper. DP of both unbleached and bleached pulp gets reduced upon ageing while more reduction were observed in bleached pulp. Bleached pulps are more prone to degrade as compared to the unbleached pulp in terms of strength properties such as tensile index, breaking length, burst and double fold were observed. 12.3 % and 21.8 % reduction in tensile index was observed for UB and final bleached FB pulp respectively. Burst index of UB and FB pulp were found reduced to 23.8 % and 41.9 % respectively due to ageing. Reduction in the mechanical and optical properties was also observed in intermediate bleaching stages. There is much evidence for the contribution of VOCs to the degradation of paper. The results are strongly suggested that acid functionalized volatile compounds can have strong effects on degradation of cellulosic paper.

CHARACTERISATION OF MORINGA OLEIFERA (DRUMSTICK) WOOD FOR PULP AND PAPER MAKING

"Moringa oleifera (drumstick) wood was evaluated in terms of its chemical composition, morphological features, Kraft pulping behavior, ECF bleaching and mechanical strength properties – important parameters for pulp and paper making – in comparison with Acacia mangium. Moringa oleifera was found to have the following composition: holocellulose 65.5%, lignin 20.5%, pentosan 11.6%, -cellulose 40.5% and extractives content of 5.15%, which made it comparable with the Acacia mangium wood sample. The alkali prehydrolysis of Moringa oleifera was carried out using 2% NaOH at 150 °C. The prehydrolysis liquor (PHL) was found to contain 50.9 mg/kg of calcium, 5140 mg/kg of potassium and 312 mg/kg of iron content. The prehydrolysis step was followed by Kraft pulping in order to obtain chemical grade pulp of kappa number 15-16 under optimized conditions. The Moringa oleifera pulp was bleached using the DEpD bleaching sequence to reach 85% brightness (ISO). The bleached pulp had an average fiber length of 1.21 mm, which was higher than that of Acacia mangium – 0.782 mm. The mechanical strength properties of the unbleached and bleached pulps, such as tear, tensile and burst indices, were also determined to show their suitability for pulp and paper production."