Effect of Press Cycle Time on Application Behavior of Board Made from Chemically Modified Particles

Abstract

Utjecaj trajanja ciklusa prešanja na ponašanje u primjeni ploče izrađene od kemijski modificiranih čestica Received -prispjelo: 12. 12. 2014. Accepted -prihvaćeno: 29. 1. 2016. UDK: 630*863.215 doi:10.5552/drind.2016 mechanical behavior was investigated as well as the decay resistance of acetylated particleboards. Original scientifi c paper • Izvorni znanstveni rad MATERIALS AND METHODS MATERIJALI I METODE Acetylation AcetilacijaFlakes were prepared by using a laboratory ring fl aker (Pallmam pz8) from maple wood (Acer insigne). They were dried in the oven for 24h at 103±2 °C. After 12h soaking in the acetic anhydride, the fl akes were heated at 120 °C for 40 and 180 minutes to achieve 9 and 16 % weight gains, respectively, (based on pre-test results). Modifi ed fl akes were washed with distilled water to remove acetic acid as the reaction by-product and unreacted acetic anhydride. Acetylated particles were dried in the oven at 103±2 °C for 24 h. Weight percent gain (WPG) was calculated using the equation (1). (1) Where WPG indicates the weight percent gain (%), W act and W unt are oven dry weights after and before the acetylation (g), respectively. OH group's substitution was determined according to equation (2) mentioned in the paper of Li et al. (2011). (2) Where OH substd indicates substitution of OH with acetyl groups (mmol/g), W act and W unt are oven dry weights after and before the acetylation (g), respectively. M w is the molecular weight of the adduct acetyl (-C (O)-CH 3 ) group (g/mmol). FTIR analysis 2.2. FTIR analizaThe Fourier transform infrared (FTIR) spectra were measured by using a Bio-rad spectrometer FTS-40 incorporating a Spectra Tech diffuse refl ectance accessory unit. For FTIR analysis, dried acetylated fl akes were milled and passed through a 40 mesh sieve. Spectra were obtained directly from wood powder on a detector prism. Manufacture of boards 2.3. Proizvodnja pločaParticles with size of 20-40 mesh were used for making the particleboards. After being blended with melamine urea formaldehyde (MUF) resin (10 % based on the oven dry weight), the single layer mats were pre-

Statistical evaluation of the effect of urea-formaldehyde resins synthesis parameters on particleboard properties

“…Thickness swelling also varies with pressing time, however there are other factors that affect this parameter (p-value = 0.0085**). IB increases with increasing press time, as expected [27][28][29][30]. An increase in the pressing time causes an increase of heat transferred into the mattress, either by conduction from the press plates or by convection due to moisture evaporation, which will promote polymerization of the resin in the inner layers of the panels, allowing for an increase in IB.…”

Prediction of Mechanical Performance of Acetylated MDF at Different Humid Conditions

“…In acetylation process, acetic anhydride substitutes the hydroxyl (-OH) groups in the wood cells with acetyl groups, resulting in decreased hygroscopicity and increased dimensional stability; while reductions in some mechanical properties also occur depending on the extent of temperature and time of the modification reaction [18][19][20]. Several explanations of the strength loss were given, as for example the type of the adhesive [21], bondability [22], press pressure [23], etc. Higher bondability is required if the panels are used under severe conditions for a long time.…”