Alexander Pfriem

Alexander Pfriem
Hochschule für nachhaltige Entwicklung Eberswalde · Faculty of Wood Science and Technology

Professor
Research in Wood Science

About

94
Publications
33,816
Reads
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631
Citations
Introduction
Our goal is to give special properties to wood and to make it more resistant to thermal, chemical and physical loads. Developing new ways of transformation and modification of wood leads to highly sustainable products made of wood. Treated wooden products must have a minimized environmental impact. This opens up new areas of industrial and entrepreneurial application with a considerable potential for innovation.
Additional affiliations
October 2010 - present
Hochschule für nachhaltige Entwicklung Eberswalde
Position
  • Professor (Full)
October 2010 - present
Hochschule für nachhaltige Entwicklung Eberswalde
Position
  • Professor (Full)
Description
  • Wood Chemistry, Wood Physics, Chemistry, Non-Metall Materials
September 2006 - September 2010
Technische Universität Dresden
Position
  • Research Assistant
Description
  • Wood Physics, Wood Drying, Wood Modification
Education
September 2003 - December 2006
Technische Universität Dresden
Field of study
  • PhD Study
October 1998 - August 2003
Technische Universität Dresden
Field of study
  • Process Engineering

Publications

Publications (94)
Conference Paper
Full-text available
Aufgrund von Rohstoffknappheit auch bei nachwachsenden Rohstoffen kann das Recyceln von Holz und Holzwerkstoffen auch im Möbelsektor nur an vor-letzter Stelle, vor der thermischen Verwertung, stehen. Davor gilt es, schon bei der Produktion den Materialeinsatz zu reduzieren bzw. Möbel so zu gestalten, dass eine verlängerte Nutzung möglich ist. Insge...
Article
Full-text available
Celtis mildbraedii sawdust (CMS) from Ghana was characterised to investigate its suitability with polyethylene terephthalate (PET) for syngas production via co-pyrolysis. The physical and chemical properties assessed include proximate and ultimate compositions, pH value, higher heating value (HHV), and lignocellulosic composition. Also, the thermal...
Article
The PyroForCE research project investigated the extent to which the fire behaviour of façade timbers can be changed by the creation of a surface pyrolysis layer alone in such a way that the requirements for classification as a flame-retardant building material are permanently fulfilled. For this purpose, a continuously operating wood pyrolysis syst...
Technical Report
Full-text available
Background / Scope Wood has been used as a sustainable material for facade cladding for centuries. The classification as ‘normally flammable building material’, according to German building code, only allows the use of wood as facade material for buildings up to and including building class three of the code. With surface pyrolysis, a method is sh...
Article
Journal: Holztechnologie (IHD gGmbH) Lap shear tests were carried out on fibre-reinforced epoxy resin with cellulose regenerated fibres (CRF). The strengths of CRF with and without sizing agents were compared. At the boundary layer between CRF and epoxy resin, insufficient bonding seems to be developed. A permanent stable structure could not be fo...
Article
Similar to a normal wave, a shock wave travels as energy through matter but it causes an abrupt rise of pressure, temperature and density. In this study, the influence of shock waves on wood structure were investigated in the light of possible future industrial utilization e.g. timber impregnating treatment. The constructed autoclave is capable of...
Article
Full-text available
The springback effect in molded wood laminations within the elastic range has, to date, not yet been mathematically described. Once cured, residual internal stresses within the laminations cause the final form to deviate from that of the die. Test pieces of beech laminations of 1 mm, 2 mm and 4 mm thicknesses and stack sizes of between 2 and 16 lam...
Article
The dynamic-mechanical behavior of phenol-formaldehyde-impregnated beech wood (Fagus sylvatica L.) veneers was evaluated at various relative humidities. The aim was to identify the plasticizing effects of moisture on phenol-formaldehyde-impregnated veneers. Thin beech veneer samples were impregnated with a low and a medium molecular weight phenol-f...
Article
Full-text available
Wood and wood-based products are widely used for structural building elements, but due to their composition, they are susceptible of combusting if exposed to fire. Fire safety is an important issue of building safety, especially when the building's fireload contents enhance the risks of fire spread. Therefore, the involved materials arevery importa...
Conference Paper
Full-text available
The springback effect of materials is well known but there are no reliable formulas to predict it. Mostly a FEM model is used which complicates the solution for simple forms. Wood lamellas can be bent and laminated into quite complex forms. The simplest form would be the shape of an arc. Gluing a number of wooden layers together the result differs...
Poster
Full-text available
Side and back parts of a guitar body are typically made of tropical wood species listed on CITES Annexes I and II. To substitute these protected wood species the thermal modification of European wood species becomes an important method to improve acoustical properties and dimensional stability. Different parts of a guitar body have specific functio...
Conference Paper
Within the present study, measurements by digital image correlation (DIC) were conducted to determine the effect of phenol-formaldehyde (PF) modification on the shape stability of moulded beech veneers (Fagus sylvatica L.) exposed to changing climatic conditions. For this purpose, thin beech veneers were impregnated with a low (lmwPF), a medium (mm...
Article
Full-text available
Forest-based industries have been continuously developing advanced processes, materials and wood-based solutions, to meet evolving demands and increase competitiveness. Engineered wood products (EWPs) constitute one emerging group of materials aiming at improved property profiles of wood, and provide desired shapes and functionality. In this paper,...
Poster
Full-text available
Part of this study is an acoustical comparison of two different guitars, one traditionally made of tropical wood and another made of thermally modified wood. The used frequency response analysis which was developed at the IfM (institute for musicalinstrument making) enables a substantial proposition of the acoustical performance of string instrumen...
Poster
Full-text available
The presented poster does not show results of an experiment or test setup. Instead, it provides a comprehensibly introduction to bioeconomy and its added value in funding proposal of any kind with a focus on lingo-celluloses-material. The importance of this topic is apparent in a climate changing world and a shift to environmentally friendly techno...
Conference Paper
Thermal modification changes wood's chemical composition and enhances its biological durability and dimensional stability. The aim of this study was to validate findings from laboratory studies following EN 113 (1996) with field tests according to EN 252 (1990, 2015) after five years of exposure. Thermally modified European beech and Norway spruce...
Article
Full-text available
Two phenol–formaldehyde resols, namely a low and a medium molecular weight phenol–formaldehyde, were investigated for their applicability as plasticizers in moulding of European beech veneer (Fagus sylvatica L.). Therefore, beech veneers specimens were impregnated with both phenol–formaldehyde resol types in various concentrations. Subsequently, tw...
Conference Paper
Full-text available
Different processes of thermal modification (TM) were compared by means of vibrational investigations of the modified wood. It was reviewed how the thermal treatment influences the sound properties of Sitka spruce samples for guitar soundboards. Therefor natural frequencies and damping were measured by acoustic resonance analysis. With this data, e...
Article
Wood in outdoor applications undergoes various degradation processes such as biological degradation as well as weathering. However, since carbon black is a very effective photostabilizer, it is hypothesised that wood surfaces can be protected from weathering by a layer of carbon (charcoal). Norway spruce (Picea abies) samples were pyrolised to crea...
Article
Full-text available
Three phenol-formaldehydes with varying molecular weight are investigated according to their suitability to improve the dimensional stability of beech wood (Fagus sylvatica L.). Focus of the work is to investigate the relation of the bulking effect of the wood caused by the varying phenol-formaldehydes treatments to the corresponding dimensional st...
Article
Seven different coating systems were tested regarding their suitability for application on bicycle frames made of wood. Since bicycles are ridden throughout the year, the coating system has to withstand different outdoor climate conditions and, especially in winter, the salt brines from the roads. For this reason, an artificial weathering test with...
Poster
Full-text available
Similar to a normal wave, a shock wave travels as energy through matter but it causes an abrupt raise of pressure, temperature and density. In this study the influence of shock waves on wood structure were investigated in the light of possible future industrial utilization e.g. timber impregnating treatment. On that account, an autoclave containing...
Conference Paper
Full-text available
Dynamic Mechanical Analysis (DMA) is not very common in wood research. For testing wood, no standards are given. Therefore researchers make up their own test setups which makes a comparison of different measurements difficult if not impossible. In this study the development of a method to manufacture the specimens was one goal that had to be achiev...
Conference Paper
Wood modification with phenolic resin is widely and commercially used to improve certain wood properties such as durability, certain mechanical properties or dimensional stability due to hydrophobic properties of the resin. Depending on the phenolic resin formulation (e.g. used catalyst, molecular weight or pH value) different characteristics are n...
Conference Paper
Full-text available
The aim of the study is to examine the potential of Phenol/formaldehyde for a plasticizing effect of wood veneer and the treatability of thin veneer stripes (0.6 mm thickness) with Phenol/formaldehyde for moulding applications. Swelling of the cell walls can serve as indicator for plasticizing effects. Thus, swelling of cell walls of beech veneer (...
Conference Paper
Full-text available
There is a growing need and market for temporary buildings for various purposes, including large construction projects in the tourism and events sectors or in civil protection. This paper gives an overview about the use of reusable lightweight materials in temporary buildings. Based on a project proposal submitted to the 7th framework, a new concep...
Conference Paper
Full-text available
Drei verschiedene Phenolharze wurden auf ihre Witterungsbeständigkeit in einem künstlichen Bewitterungstest in Anlehnung an DIN 927-6:2006 geprüft. Die Phenolharze wurden aufgrund des unterschiedlichen Molekulargewichts ihrer Vorkondensate ausgewählt. Anschließend wurde Buchenfurnier (Fagus sylvatica) mit den Phenolharzen bei 100 mbar Unterdruck fü...
Article
In dieser Arbeit wurde ein Prüfverfahren angewendet, das statische, zyklische Belastung von Klebstofffugen infolge Quellen und Schwinden des Holzes simuliert und plastische Verformungen im niedrigen Lastbereich aufzeigt. Es wurde das elastische Verhalten von Zugscher-Prüfkörpern, welche aus Buchenholz verklebt mit drei verschiedenen Holz-Klebstoffa...
Conference Paper
Full-text available
Waxes, oils, and other liquids change thermodynamic properties in porous systems. Due to observations from wax impregnated wood products, the effect of a melting point decrease of wax inside wood has been be analysed. Furthermore, it has been analysed whether or not the wood species used for impregnation has an effect on the melting behaviour of th...
Article
Full-text available
The unique mechanical and acoustical properties of wood and its aesthetic appeal still make it the material of choice for musical instruments. Here tropical hardwoods are typically used in musical instruments. This paper gives an overview of how the use of thermally modified wood can contribute to the use of raw materials for musical instruments. I...
Conference Paper
High-value wood veneer is used in furniture and automobile interior industry for decorative purposes. Due to mechanical restrictions veneer application on surfaces is limited to simple shapes. During the last centuries, many approaches were developed to improve the moulding behaviour of veneer. Yet, all processes face several difficulties. So far,...
Conference Paper
This study focuses on the effects of UV radiation and water spray on different types of modified wood. Therefore, thermally modified samples (T), wax impregnated samples (W) as well as thermally modified and subsequently wax impregnated samples (TW) of hard- and softwood were prepared. During the thermal treatment, for a specific period of time, th...
Article
Dynamic mechanical thermal analysis has been used to monitor the change in wood veneer stiffness due to furfuryl alcohol impregnation and plasticization of wood components and subsequent polymerization of furfuryl alcohol within wood material. This explains the improvement in the moulding ability of wood veneer where furfuryl alcohol aids in wood p...
Article
Full-text available
The aim of the cooperative research project was the development of a wood-cement in-situ concrete used as local fi ller and stiffening element in wooden ceiling elements. For further processing, only water should be added to the mineralized particles, whereby the amount of added water is relevant to the adjustment of the consistence and flowing cha...
Article
Full-text available
The mechanical properties of thermally modified wood are discussed with regard to toughness. The molecular origins of the mechanical properties and, in particular, the role of the hemicelluloses are considered. The important role of water and its interaction with the cell wall components is also examined. The properties are discussed from the point...
Article
This paper deals with the determination of the pore-size distribution of untreated and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.) and sycamore maple (Acer pseudoplatanus L.) by means of mercury intrusion porosimetry. The investigations considered oven-dried and at 22 °C and 95 % relative humidity-conditioned samples....
Conference Paper
Bound water states in small wood samples were investigated by means of time-domain nuclear magnetic resonance. A bench-top low-field NMR instrument (Bruker minispec mq20) with a proton resonance frequency of 20 MHz was employed. The mobility of the water molecules depends on the environment they exist in. This is reflected in the observed relaxatio...
Conference Paper
Wood as a natural material contains volatile organic compounds (VOCs) like formaldehyde and carboxylic acids. For this reason, wood is not suitable for applications in contact with precious and heavy metals which could react with the VOCs leading to corrosion. In this context, ancient exhibits in museums and displays containing these metals are at...
Conference Paper
The natural durability of wood refers to the resistance to attacks by wood-destroying organisms, e.g. fungi, insects and marine organisms. In this study the durability of thermally modified timber (TMT) was investigated. In field test (DIN EN 252, 1990) a variety of wood-dwelling and wood-destroying organisms occur simultaneously, while in lab test...
Article
Furfuryl alcohol modification of wood is a well-known process for wood property enhancement. The present project focuses on veneer molding for high-value applications using the plasticizing effect of furfuryl alcohol. Adding maleic anhydride to furfuryl alcohol leads to an acid-catalyzed polymerization of furfuryl alcohol at elevated temperatures,...
Article
Sound absorbers for acoustic panels made of wood particles and sodium water glass For the production of a highly porous and flame retardant sound absorber made of wood particles and sodium water glass as binder three methods for foaming and curing the water glass have been developed. The chemical foaming and curing method was not successful. With t...
Article
Der vorliegende Bericht beschreibt die Untersuchung von thermisch modifizierten Hölzern (TMT) hinsichtlich ihrer Flammbeständigkeit nach DIN 4102 an der Hochschule für Nachhaltige Entwicklung Eberswalde (FH). Ziel der Untersuchung war es, die von einem Hersteller zur Verfügung gestellten Proben verschiedener Thermohölzer ihrer Entflammbarkeit nach...
Article
The aim of this paper was to investigate pore-size distributions in the nano-diameter range of wood and their alteration due to thermal modification of wood using thermoporosimetry, and to find out what consequences can be derived regarding the biological durability. Thermoporosimetry is a technique that is based on the measurement using differenti...
Article
Full-text available
High-value wood veneer is used in the furniture and automobile interior industries for decorative purposes. Due to mechanical restrictions, veneer application on surfaces is limited to simple shapes. In the last century, many approaches were developed to improve the moulding behaviour of veneer. However, all of these processes face several difficul...
Article
Full-text available
The polymerization kinetics of furfuryl alcohol in wood veneer were studied using differential scanning calorimetry (DSC) and were compared with weight gains of treated wood veneers. Maleic anhydride was used as the reaction initiator. DSC data were obtained for samples of the veneers that had been impregnated with neat furfuryl alcohol or with fur...
Article
The main objective of this study was to evaluate the effect of sample preparation on cell-wall density and porosity using gas pycnometry. Native and thermally modified twin samples of Norway spruce (Picea abies (L.) Karst.), sycamore maple (Acer pseudoplatanus L.), and European ash (Fraxinus excelsior L.) were analyzed. The samples differed in term...
Article
The aim of the present investigation was to detect the change of density of oak (Quercus robur L.), due to the influence of a thermal modification. The reduction of the density was recorded by High- Frequency Densitometry and compared to measurements based on the Gravimetric Method. To achieve a comparison of the initial density before and the dens...
Article
In the present study, correlations between the dynamic and sound behaviour of bass guitar necks depending on the used wood species were investigated. The vibration behaviour was (objective characterization) examined using three manufacturing stages of the bass necks using the experimental modal analysis. To characterize the subjective sound of the...
Conference Paper
The aim of the present investigation was to detect changes, and make statistical simulation, of oak (Quercus robur) density, due to the influence of thermal modification parameters. The reduction of the density was recorded by High-Frequency Densitometry. To achieve a comparison of the initial density before and the density in result of thermal tre...
Article
Mithilfe der Hochfrequenz-Densitometrie lassen sich lokale Dichteunterschiede innerhalb eines Jahresringes von Holz analysieren. Beispielhaft wird die Vorgehensweise zur Nutzung dieser Methode zur Analyse von Dichteänderungen infolge einer thermischen Modifikation im Eichenholz vorgestellt. Um einen Vergleich der anfänglichen Dichte vor und der Dic...
Article
Full-text available
Due to mechanical restrictions veneer application on surfaces is limited to simple shapes. To enhance the moulding performance veneer samples were impregnated with furfuryl alcohol for improved plasticization. The plasticizing effect of furfuryl alcohol was determined according to the Erichsen cupping test and results were compared to control sampl...
Article
Full-text available
In the present study the influence of wood fibre morphology and shape factor (aspect ratio) as well as fibre content on the basic mechanical properties of injection mouldable Wood-Polypropylen (PP)-Composites was investigated. In order to feed the fibre fractions into the extruder in a technically feasible way, a method was developed to convert the...
Conference Paper
For evaluating the physical and mechanical properties, several tests were conducted on furfurylated and densified wood. For this purpose beech wood was impregnated with furfuryl alcohol and maleic acid anhydrite and additionally with acetone to reach different weight percentage gain (WPG) values. The impregnated samples were densified with a compre...
Article
Full-text available
Compression tests were conducted with veneers in the thickness direction. Thereby differences between the stress-strain curves of veneers and other known stress-strain curves were observed. Based on microscopic studies during the compression, it was possible to describe the deformation behaviour of the veneer, and deviations from known, typical str...
Article
The densification of wood leads to better mechanical properties, e.g., an increased hardness and dimensional stability. However, densified or shaped wood in contact with water springs back into its original shape without fixation. Hence, the aim of this study was the development of a combined densification and fixation procedure. Beech wood samples...
Article
Full-text available
The aim of the investigations was to evaluate the infl uence of a thermal modifi cation on the water absorption behaviour of spruce (Picea abies(L.) Karst.). After recording the water uptake of wood samples by partial immersion, a water absorption coefficient of the material could be determined according to EN ISO 15148:2002. The thermal modificati...
Article
Full-text available
The aim of this investigation was to compare the mechanical behaviour of lengthwise and plain sliced veneer of the species beech (Fagus sylvatica L.). Therefore, tension tests parallel and perpendicular to the grain were carried out. The results were evaluated using the variance analysis (ANOVA). As a result it can be stated that lengthwise sliced...
Article
Full-text available
The aim of this work was to analyse the material behaviour of thermally modified and native spruce by load applied perpendicularly to the grain. Therefore, thermally modified and native samples were prepared for bending tests with the load in tangential direction. The bending strength in radial direction decreases significantly with the thermal tre...
Article
The quantification of wax and remaining voids filled with air in wax-treated wood has not been described in detail in the literature, although such products are commercially available. In this paper, Scots pine ( Pinus sylvestris L.) and beech ( Fagus sylvatica L.) samples were impregnated with a hot melting amide wax and characterized. The apparen...
Article
The aim of the present investigation was to evaluate the influence of a thermal modification on the kinetics of the water vapour sorption of maple (Acer pseudoplatanus L.) and spruce [Picea abies (L.) Karst. x based on the assumption that the Fickian equation can be applied in this regard in the first approximation. The unsteady-state sorption proc...
Article
The characterization and removal of odorous substances caused by thermal treatment of wood were investigated using chromatographic and spectroscopic methods. Emissions of pentanal and hexanal, probably formed by oxidation of unsaturated fatty acids, were the prevailing aldehydes in untreated wood samples. Their amount decreased during thermal treat...
Article
The pore size distribution in wood affects sorption and transport of moisture. In the present paper, the pore structure of spruce and maple was examined in untreated and thermally modified samples. The relative humidities of the specimens were 33%, 43%, 53%, and 76%. Tests were carried out by helium pycnometry and mercury intrusion porosimetry. The...
Article
Full-text available
Certain extractives from thermally modified beech have fungicidal properties. Methanol extracts, resolubilized in propanone, caused a significant retardation of fungal growth on native beech specimen. Beech specimen impregnated with these extractives could be assigned to the durability class 4, i. e. not permanent. Other extracts of thermally modif...
Article
Abstract The milling process of Arboform was analysed by cutting force measurements and compared with experiments on MDF and chipboard. Under similar and practice-specific conditions, the specific cutting forces of Arboform were slightly higher than the ones of MDF and chipboard but below the values for HDF taken from literature.