diplomsko delo - visokošolski strokovni študij
Abstract
Ugotavljali smo vpliv hladnega predstiskanja na lastnosti težko gorljive vezane plošče. Bukov furnir smo tretirali z vodnimi raztopinami boraksa in borove kisline, ga zopet posušili ter iz njega izdelali z melamin-urea-formaldehidnim (MUF) lepilom zlepljene furnirne plošče. Pred vročim stiskanjem smo plošče različno dolgo (9,5 min ter 29,5 min) hladno predstiskali. Kasneje smo iz plošč izdelali preizkušance, katerim smo ugotavljali vprešek, gostoto in vlažnost, kakovost zlepljenosti ter upogibno trdnost in modul elastičnosti. Na osnovi rezultatov preizkušanja mehanskih lastnosti plošč smo ovrednotili vpliv hladnega predstiskanja na kakovost lepljenja. Ugotovili smo, da lahko vplivamo na mehanske lastnosti težko gorljive vezane plošče že z 9,5 minutnim hladnim predstiskanjem, saj se je strižna trdnost povečala za 5,7 % glede na plošče pri katerih nismo uporabili hladnega predstiskanja. Umetno staranim ploščam pa se je zaradi predstiskanja strižna trdnost povečala za 8,3 %. Upogibna trdnost se je v vzdolžni smeri povečala za 13,3 %, v prečni pa za 18,3 %. Modul elastičnosti se je v vzdolžni smeri povečal za 6 %, v prečni pa za 8,3 %. Pri daljšem hladnem predstiskanju (29,5 min) se je strižna trdnost lepilnega spoja namakanih preizkušancev zmanjšala za 8,6 % v primerjavi s preizkušanci iz plošč, izdelanih brez hladnega predstiskanja. Umetno starani preizkušanci so imeli za 12,5 % manjšo trdnost. Po 29,5 minutnem hladnem predstiskanju se je upogibna trdnost povečala, vendar je bilo to povečanje manjše kot pri 9,5 minutnem predstiskanju. Modul elastičnosti v vzdolžni smeri se je pri 29,5 minutnem hladnem predstiskanju povečal, vendar za samo 3,1 %, medtem ko se je v prečni smeri zmanjšal za 1,3 %.
Keywords
furnir;hladno predstiskanje;furnirna plošča;mehanske lastnosti;
Data
Language: |
Slovenian |
Year of publishing: |
2010 |
Source: |
Ljubljana |
Typology: |
2.11 - Undergraduate Thesis |
Organization: |
UL BF - Biotechnical Faculty |
Publisher: |
[F. Dolgan] |
UDC: |
630*832.282 |
COBISS: |
1818505
|
Views: |
822 |
Downloads: |
221 |
Average score: |
0 (0 votes) |
Metadata: |
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Other data
Secondary language: |
English |
Secondary title: |
Influence of cold pre-pressing on properties of heavily burnable plywood |
Secondary abstract: |
We observed the influence of cold pre-pressing on properties of heavily burnable plywood. Beech veneer was impregnated with Borax and Boric acid water solutions. Then it was dried again and veneer boards, glued with melamine-urea-formaldehyde glue, were produced. In the manufacture of plywood, 2 different periods of cold pre-pressing time (9.5 min and 29.5 min) were compared. To determine thickness loss, density and moisture content, bonding quality, bending strength and modulus of elasticity plywood specimens were prepared. Based on the results of testing of plywood mechanical properties, the impact of cold pre-pressing on the quality of adhesion was evaluated. We found out that we could influence mechanical properties of heavily burnable plywood already with 9.5 min cold pre-pressing, because the shear strength increased for 5.7 % regarding to the non-cold pre-pressed plywood. Due to cold pre-pressing of artificially aged plywood boards, the shear strength increased for 8.3 %. The bending strength in the longitudinal direction increased for 13.3 %, in transverse for 18.3 %. Modulus of elasticity in the longitudinal direction increased for 6 %, in the transverse for 8.3 %. At longer (29.5 min) cold pre-pressing time, the shear strength of adhesive bond of soaked specimens decreased for 8.6 %, compared to that of non-cold pre-pressing specimens. Strength of artificially aged specimens was 12.5 % lower. After 29.5 minutes, the cold pre-pressing of the bending strength increased, but the increase was less than at 9.5 minutes long cold pre-pressing. At 29.5 minutes long cold pre-pressing, the modulus of elasticity was 3.1 % higher in longitudinal direction, while in the transverse direction it decreased for 1.3 %. |
Secondary keywords: |
veneer;cold pre-pressing;heavily burnable plywood;mechanical properties; |
Type (COBISS): |
Undergraduate thesis |
Thesis comment: |
Univ. v Ljubljani, Biotehniška fakulteta, Odd. za lesarstvo |
Pages: |
X, 56 f., [12] f. pril. |
Keywords (UDC): |
applied sciences;medicine;technology;uporabne znanosti;medicina;tehnika;agriculture and related sciences and techniques;forestry;farming;wildlife exploitation;kmetijstvo ter sorodne vede in tehnologije;forestry;gozdarstvo;forest products and their utilization;gozdni proizvodi in njihova uporaba; |
ID: |
21882 |