| 1. |
- Adamopoulos, Stergios, et al.
(author)
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Adhesive bonding of beech wood modified with a phenol formaldehyde compound
- 2012
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In: European Journal of Wood and Wood Products. - : Springer Science and Business Media LLC. - 0018-3768 .- 1436-736X. ; 70:6, s. 897-901
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Journal article (peer-reviewed)abstract
- Untreated (controls) and phenol–formaldehyde (PF)-modified beech wood (10 and 25 % solid content) were glued with phenol resorcinol formaldehyde (PRF) and polyvinyl acetate (PVAc). Shear strength of PRF-bonded specimens was higher than that of PVAc-bonded ones under dry and wet conditions irrespective of the pre-treatment. Under dry conditions, only PVAc-bonded specimens exhibited reduction in shear strength due to PF-modification with 25 % PF concentration as compared to the controls. PF treated wood provided inferior bonding under wet conditions with the exception of 25 % PF concentration specimens glued with PRF adhesive. Modification with PF resulted in a decrease of adhesive penetration into the porous network of interconnected cells, especially at 25 % PF concentration.
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| 2. |
- Adamopoulos, Stergios, et al.
(author)
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CARACTERISTICILE MATERIALULUI FIBROS ŞI PROPRIETĂŢILEHÂRTIEI RECICLATE FOLOSITE ÎN FABRICAREA CARTONULUIONDULAT : Morphology and identification of fibre furnish components of papers used in the production of corrugated board
- 2013
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In: 7th International Symposium on Advanced Technologies for the Pulp, Paper and Corrugated Board Industry.
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Conference paper (peer-reviewed)abstract
- Fabricarea de ambalaje din carton ondulat (cutii, tăvi, etc) presupune un lanț de producțieintegrat, format din producătorii de hârtie, producătorii de carton ondulat și producătorii decontainere, dintre care, în Europa, majoritatea sunt IMM-uri. În prezent, containerele de cartonondulat sunt în mare parte realizate cu hârtie recuperată. Cea mai mare amenințare cu care seconfruntă lanțul de producție menționat este legat de lipsa de calitate și de disponibilitate a hârtieireciclate ca materie primă. Concret, una dintre cele mai importante proprietăți ale hârtiei deambalaj este rezistența mecanică, care depinde, în principal, de lungimea fibrelor din care estealcătuita hârtia. Aceste fibre sunt mai lungi în celuloza virgină (celuloza obţinută din lemn, adicănereciclată). Cu toate acestea, presiunea mare asupra cererii - precum și restricțiile economice șiecologice actuale referitoare la utilizarea lemnului ca materie primă - a condus la situația în caredoar o foarte mică cantitate de fibre naturale intră în lanțul de reciclare. Acest lucru înseamnă cărezistenţa fibrelor reciclate – si prin extindere – a hârtiilor – scade în mod constant, odată cuciclurile de reciclare aflate în desfăşurare. Suplimentar, hârtia reciclată prezintă o variabilitatefoarte mare, ceea ce constituie un obstacol atunci când vine vorba de a fabrica ambalaje cuproprietăţi omogene, cerute de către clienţi, la costuri fixe.Dificultatea de predicţie a proprietăților produselor din hârtie obţinute din surse eterogenepune mai multe limitări, care, din acest motiv, conduc la pierderi economice grave și numai ocaracterizare completă va permite mai buna lor folosire. Proiectul "RF-CORRUG - Controlulcalității materiilor prime din fibre recuperate pentru producția de carton ondulat", Cadrul NaționalStrategic de referinţă 2007-2013 Arhimede III, tratează această problemă tehnică comună aindustriei de carton ondulat. Concret, obiectivul principal al proiectului este de a sprijinicompetitivitatea companiilor producătoare de carton ondulat (în special IMM-uri), prin creareaunui instrument software bazat pe modele practice, care pot prezice proprietăţile sortimentului dehârtie de ambalaj, pornind de la proprietăţile fibrelor (calitative, cantitative, de structură) utilizateîn producția lor.Această lucrare prezintă informații referitoare la fibre (analiza cantitativă și calitativă,morfologia) și hârtiile de ambalaj (proprietățile fizice și mecanice) folosite în obţinereaambalajelor din carton ondulat. Au fost examinate diferite categorii de hârtii (miez şi capac),utilizate pentru producția de carton ondulat în Grecia. Principalele tehnici de analiză a fibrelor aufost: analiza masei fibroase, analiza morfologica a fibrei, microscopia optică, microscopiaelectronică de baleiaj (SEM). Suplimentar, a fost determinată rezistenţa la tracţiune (zero-spantensile test), pentru a măsura astfel rezistenţa medie a fibrei. Proprietăţile solicitate pentru hârtie au fost măsurate folosind testere şi standarderecunoscute pe plan internaţional. Informaţiile obţinute vor fi folosite pentru a dezvolta modelepredictive, bazate pe metode statistice avansate, pentru proprietăţile şi performanţele hârtiilor deambalaj, în funcţie de informaţiile furnizate de fibrele componente.
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| 3. |
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| 4. |
- Adamopoulos, Stergios, et al.
(author)
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Effect of cambium age and ring width on density and fibre length of black locust and chestnut wood
- 2010
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In: Wood research. - 1336-4561. ; 55:3, s. 25-36
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Journal article (peer-reviewed)abstract
- The relationship between wood density (WD) and fibre length (FL) with cambium age (CA) and ring width (RW) was studied in two ring-porous species, black locust and coppice-grown chestnut, collected in the Sithonia Peninsula, Chalkidiki, Greece. Using regression analysis methods, models of WD and FL in relation to CA and RW were obtained. It was found that the effect of CA and RW on WD and FL was similar for both species examined. WD of black locust and chestnut was predicted better through a model using CA and RW. A model for FL variations was also obtained with CA and RW and was more accurate than the simple models based on the two factors, CA and RW, separately. The multiple regression models suggested that the use of cambial age of growth rings together with their width might explain better their effects on WD and FL of black locust and chestnut.
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| 5. |
- Adamopoulos, Stergios, et al.
(author)
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Effect of hot-water extractives on water sorption and dimensional changes of black locust wood
- 2012
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In: Wood research. - 1336-4561. ; 57:1, s. 69-78
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Journal article (peer-reviewed)abstract
- The hygroscopicity and the dimensional changes of black locust heartwood were investigated in relation to the progressive removal of hot-water extractives. Extraction in the original specimen form removed only part of the total 8.434 % hot-water extractives, 3.601 % in first extraction and 4.642 % in second extraction. As a result, the adsorption and desorption behaviour of black locust wood was little affected by the extraction and only a small increase was observed in dimensional changes at every RH from 0 % to 97 %. The mean hysteresis coefficient was also little affected by extraction and increased from 0.75 at the unextracted stage to 0.77 at the second extraction. The initial dimensional change 3.76 % of unextracted black locust wood corresponding to RH changes between 43 % and 80 % increased after the first and second extraction to the respective values of 3.96 % and 3.97 %. Extraction had no effect on the significant, very strong linear relationships between swelling or shrinkage and equilibrium moisture content (EMC).
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| 6. |
- Adamopoulos, Stergios, et al.
(author)
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Effect of laser drilling on mechanical properties of fir (Abies borisii regis) and spruce (Picea excelsa) wood
- 2014
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In: Wood Structure, Properties and Quality – 2014. - : Moscow State University Press. - 9785813506253 ; , s. 7-12
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Conference paper (peer-reviewed)abstract
- Fir and spruce wood specimens, 2×2 cm in cross section and 34 cm long, were pre-pared with true radial and tangential surfaces. All lateral surfaces of the wood specimens were drilled by laser beams to a depth of 0,4 cm (1/5 of specimen thickness) with two drilling pat-terns (distance between holes 1 × 1 cm and 1 × 2 cm). After drilling, static bending (MOR, MOE), axial compression strength and toughness were determined and compared with non-drilled control specimens. The effects of the two laser drilling patterns on mechanical proper-ties of fir and spruce wood specimens were measured and assessed. The results showed that the two drilling patterns created by laser beams on all lateral surfaces of fir and spruce wood specimens at 0,4 mm depth did not practically affect the mechanical properties of wood.
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| 7. |
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| 8. |
- Adamopoulos, Stergios, et al.
(author)
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Grammage and structural density as quality indexes of packaging grade papers manufactured from recycled pulps
- 2014
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In: Drewno. - 1644-3985. ; 57:191, s. 145-151
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Journal article (peer-reviewed)abstract
- Corrugated packaging production is currently facing the challenge to ensure a satisfactory strength of packaging despite the continuous increase in recycled paper as the main fibrous component. This research addresses a very common technical problem for the corrugated board industry – the difficulty of predicting the properties of paper products produced from heterogeneous sources. Grammage and structural density, being easily available data, were examined as quality parameters of the most common categories of packaging paper in Europe. Grammage, ranging from 100 to 225 g/m2, has been found to be a dominant parameter for estimating the strength properties of paper.
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| 9. |
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| 10. |
- Adamopoulos, Stergios, et al.
(author)
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Mathematical approach for defining juvenile-mature wood transition zone in black locust and chestnut
- 2011
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In: Wood and Fiber Science. - 0735-6161. ; :3, s. 336-342
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Journal article (peer-reviewed)abstract
- This article defines age of transition from juvenile to mature wood in two ring-porous species, black locust (Robinia pseudoacacia L.) and chestnut (Castanea sativa Mill.). A logistic function was proposed using fiber length and ring width data of three black locust trees, aged 35-37 yr, and five chestnut coppice trees, aged 25-27 yr, from Sithonia Peninsula, Chalkidiki, Greece. The approach proved to be practical and objective in delineating maturity zones, and it was based on rate of change of yearly fiber length. The juvenile wood zone spread to the sixth growth ring from the pith in both species, whereas the demarcation of juvenile and mature wood was at age 12 and 14 yr in chestnut and black locust, respectively. Transition zone width comprised rings 7-12 in chestnut and rings 7-14 in black locust.
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