Application of spruce wood flour as a cellulosic-based wood additive for recycled paper applications— A pilot paper machine study

This study gives a first insight into the use of wood flour as a plant-based and cellulosic-based alter-native additive for newsprint and paperboard production using 100% recycled fibers as a raw material. The study compares four varieties of a spruce wood flour product serving as cellulosic-based additives at addition rates of 2%, 4%, and 6% during operation of a 12-in. laboratory pilot paper machine. Strength properties of the produced newsprint and linerboard products were analyzed. Results suggested that spruce wood flour as a cellulosic-based additive represents a promising approach for improving physical properties of paper and linerboard products made from 100% recycled fiber content. This study shows that wood flour pretreated with a plant-based polysaccharide and untreated spruce wood flour product with a particle size range of 20 μm to 40 μm and 40 μm to 70 μm can increase the bulk and tensile properties in newsprint and linerboard applications.

Efficiency of Visual and Machine Strength Grading of Sawn Timber with Respect to Log Type

A batch of pine timber sawn from butt, middle and top logs was strength graded with the visual method (classification into grading classes KW—best quality, KS—medium quality, KG—inferior quality and Reject) and with the machine strength grading method—performed with the use of a mobile timber grader (classification into C strength classes). We compared the efficiency of grading classes and strength classes, depending on the type of log from which the material was obtained (butt, middle, top). Next, a strength grading machine was used to measure the modulus of elasticity in bending (MOE) and static bending strength (MOR). The ANOVA confirmed the influence of both the log type (butt, middle, top), the C strength class, and the visual strength grading class on the values of density (DEN) and MOR. Timber density and MOR decreased from the butt log section to the top log section. The ANOVA confirmed the influence of log type on MOE values, but only to a limited extent.

Mechanical Properties of Machine Stress Graded Sawn Timber Depending on the Log Type

This article presents the results of tests conducted on Scots pine timber from three different kinds of logs: butt, middle and top. A planed pine timber batch composed of 510 pieces, dried to ca. 12% humidity, was machine-graded using a portable MTG device, and classified into the following classes: C18, C24, C30, C35 and C40 (according to EN 338:2016). During the second stage of the study, the timber was tested to determine its density, MOE and MOR, in accordance with EN 408:2012. We analyzed the impact of the timber’s log of origin on the results of machine strength grading and on the values of correlation coefficients between the tested properties. The results show, among others, that there is a correlation between the C classes and MOR of the tested timber, as well as its origin from butt, middle or top logs.

Comparison of results between visual and machine strength grading of Polish-grown pine timber (Pinus sylvestris L.) from the Baltic Forestry Region

Comparison of results between visual and machine strength grading of Polish-grown pine timber (Pinus sylvestris L.) from the Baltic Forestry Region. The paper presents the analysis of results of strength grading of Scots pine wood (Pinus sylvestris L.) with two different methods: visual and machine strength grading, conducted on raw material from the Baltic Forestry Region. Visual strength grading was carried out in accordance with PN-D-94021:2013, while machine strength grading was performed with the use of the MTG device by a Dutch company, Brookhuis Electronics BV. The machine assisted method of timber strength grading proved to be more efficient, resulting in a higher amount of timber in the C30 class (28.7%) than in the best (KW) class after visual strength grading (3.3%). On the basis of the conducted tests, it has been confirmed that machine strength grading results in very few (6.0%) rejected timber pieces. At the same time, there have been cases of timber pieces that hadn't been classified in any of the classes or rejected during machine strength grading. Such pieces were treated as rejected.

Comparison results of visual and machine strength grading of Scots pine sawn timber from the Silesian Forestry Region in Poland

Comparison results of visual and machine strength grading of Scots pine sawn timber from the Silesian Forestry Region in Poland. The paper presents an analysis of the strength grading results performed by two methods – visual (appearance) and machine, carried out for sawn timber obtained from the Silesian Forestry Region in Poland. Visual strength grading was performed in accordance with PN-D-94021:2013, while the machine strength grading with the use of MTG device from Brookhuis Electronics BV. As a result of the tests, it was confirmed that the machine grading results in a very small share of sawn timber classified as rejects. At the same time, during machine strength grading there were some sawn timber pieces that were not classified for any class or a reject. Based on its visual appearance, such timber elements should be graded as rejects.

Visual and machine strength grading of European ash and maple for glulam application

Medium dense hardwoods (HWs) show higher tensile strength (TS) values than softwoods (SWs). These advantages cannot be utilised effectively because HW grading is not well developed. The aim of the present paper was to analyse the utilisation potential of European ash (Fraxinus spp.) and maple (Acer spp.) grown in Central Europe, which were graded by different methods. The visual grading characteristics of 869 HW boards were determined and the dynamic modulus of elasticity (MOEdyn) and X-ray attenuation (XRA) were measured by an industrial scanner. The specimens were subsequently tested in tension according to EN 408:2010 and according to German visual grading rules show strength values of 28 MPa and 30 MPa, respectively. Machine strength grading and for a combination of manually assessed boards and MOEdyn give rise to higher strength data. MOEdyn, in particular, results in lamella data with 62 MPa for ash and 42 MPa for maple. There is good agreement with recently presented HW tensile profiles. Machine grading with a multisensor system allows better strength prediction compared to the MOEdyn or visual strength grading. Best performance is achieved by a combined grading approach.

Modulus of elasticity as a criterion for strength grading of structural sawn timber

Modulus of elasticity as a criterion for strength grading of structural sawn timber. The paper presents an analysis that was performed on sawn timber originating from the Silesian Forest District in terms of parameters related to the elastic properties of the material. As part of the research, static modulus of elasticity (in accordance with EN 408: 2010 + A1: 2012) and dynamic modulus (using a portable device for machine strength grading) were determined. Both elasticity modulus were correlated with the density of the material, and compared with the database developed on the basis of previous research carried out at Faculty of Wood Technology of WULS- SGGW, including the results of strength grading of sawn timber from five natural Polish forest regions.