80797 Munchen, WinzererstraBe 45

Institutsieiter Prof.Dr.Dr.habil. G.Wegener

Telefon (089) 306 309 0; FAX (089) 306 309 11

Bewertung von "Date Palm Leaves' Midribs Blockboard"

nach deutschen Sperrhoiznormen

Gutachtliche Stellungnahme

Munchen, 4.9.1996

Institutsieiter Verfasser

Prof. Dr. G. Wegener Dipl.-HoIzwirt F. Troger

Quality Assessment of Palm Leaves' Midrib BIockboard

According to German Standards 

Fritz Troger, Institute for Wood Research, Munich University

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Summary

Early in 1996, the Institute for Wood Research of the University of Munich was commissioned by the GT2 office in Cairo to assess the quality of blockboard, developed as part of the GTZ project program, in orientation tests using German standards.

The institute's assessment report, in its introductory section, gives a description of the cross-sectional structure of blockboard as defined in German standards. Blockboard is considered a high-quality, very well reputed wood based panel material. For cost reasons alone, applications are restricted to fields with above average quality specifications, e.g. in high-quality interior decorating (wall and ceiling panels), high-quality furniture and equipment manufacture.

Six blockboard samples measuring 1,000 mm x 500 mm x 13 mm constituted the test material supplied by the Egyptian plant El-Kharga. "Date Palm Leaves' Midribs Blockboard", as this panel with a centre layer of palm leaves' midribs is officially called, has a cross-sectional structure according to the principles of cross-banded lumber veneered board. The block core consists of slats cut from palm leaves' midribs, with a cross section of 10 mm x 10 mm. Surface veneers from poplar wood, 1.5 mm thick, are glued onto both sides of the block core using urea formaldehyde resin.

Tests involved the investigation of the following material properties: Moisture content (DIN 52 375), thickness swelling (DIN 52 364), density (DIN 53 374), internal bond strength (DIN 53 255), bending strength (DIN 52 371) and specifications regarding surface veneer and core layer (DIN 68 705, part 2).

Overall, the investigation of the material properties of Date Palm Leaves' Midribs Blockboard led to consistently positive results.. Special attention is drawn to the following board characteristics:

1. The surfaces of the poplar wood veneers were evaluated class 1 and class 2 on top and underneath respectively. Some veneer surfaces proved excessively rough. This should be brought to the attention of the supplier.

2. The core of the blockboard is the centre layer which consists of slats made of the midribs of palm leaves. Emphasis is placed on the fact that this centre layer of palm leaves midribs fulfilled most specifications for centre layers made from wood. In future care should be taken to cut palm leaves' midribs in such a manner that slats with angles of 90° are achieved as well as being full edged. Grading for first and second choice could be considered.

3. The results of the internal bond test could not be better. The leverage-break tests gave excellent results regarding the gluing of surface veneers and core layer (No. 1 ranking according to DIN 53 255).

4. For surface veneers with the grain oriented in parallel to the longitudinal axis of the specimens bending strength was in the range of 37 to 43 N/mm2. As expected, the bending strength range for veneers with grain perpendicular to the longitudinal axis of specimens was, at 27 to 30 N/mm , considerably lower.

In summarizing the results, it can be confirmed that Palm Leaves' Midrib Bloclcboard can be considered a valuable wood-based materials panel. On account of its good mechanical properties this panel is suitable for a great number of applications such as furniture manufacture, interior fitting, container and equipment manufacture as well as wall and ceiling panelling.