AMÉLIORATION DE LA STABILITÉ DIMENSIONNELLE DES PANNEAUX DE FIBRE DE BOIS MDF PAR TRAITEMENTS PHYSICOCHIMIQUES

AUTOR(ES)

Rosilei Aparecida Garcia

DATA DE PUBLICAÇÃO

2005

RESUMO

The objectives of this study were 1) to improve the dimensional stability of medium density fiberboards (MDF) by three physical or chemical treatments: a) esterification, b) maleated polypropylene wax and c) heat treatment; 2) to determine the effect of these treatments on the mechanical properties, vertical density profiles and wetting properties of the panels and 3) to determine the chemical modification following treatments. MDF panels were produced from fibers esterified with 5 % maleic anhydride. The esterification treatment showed a reduction in thickness swelling and water absorption after 2 hours water soaking independently of reaction time. However, the treatment did not improve the physical properties after 24 hours water soaking or after relative humidity repeated cycles. The receding contact angle increased while wicking decreased following esterification. MDF panels were produced from two resin types (urea-formaldehyde and melamineurea-formaldehyde) and three maleated polypropylene contents (0, 3 and 5 %). Photomicrographs showed that maleated polypropylene forms agregates within the panels. The treatment showed an important reduction of thickness swelling and water absorption after water soaking. Linear expansion and contraction increased following treatment. Thickness swelling and shrinkage in adsorption and desorption conditions decreased following treatment. The treatment improved the mechanical properties. Advancing contact angles increased for panels treated and bonded with ureaformaldehyde. Receding contact angle increased with 5 % maleated polypropylene content while wicking decreased following the treatment independently of maleated polypropylene content. Infrared spectroscopy did not detect chemical reaction between the fibers and the maleated polypropylene. MDF panels were produced from untreated fibers and heat-treated fibers at 150 and 180oC for 15, 30 and 60 minutes. Heat treatment showed a reduction on thickness swelling and water absorption after water soaking. Thickness swelling increased after relative humidity repeated cycles. Linear expansion and contraction and springback were not improved by the treatment. The treatment showed no significant effect in the mechanical properties and vertical density profile of the panels. The advancing and receding contact angles increased while wicking decreased by the treatment. X-ray photoelectron spectroscopy showed slight decreases in O/C ratio and changes in C1/C2 ratio for heat-treated fibers.

ASSUNTO(S)

panneaux de fibre de bois mdf tecnologia de chapas de madeira heat treatment recursos florestais e engenharia florestal tecnologia da madeira medium density fiberboard - mdf anatomia da madeira fibre de bois de densité moyenne dimensional stability maleated polypropylene waxes esterification treatment

Documentos Relacionados

• Douleurs d'origine vertébrale et traitements par manipulations
• Traitements Hypophysosurrénaux des Polyarthrites Chroniques Évolutives et de la Spondylarthrite Ankylosante *: (En Dehors de la Cortisone et de L'acth)
• Etudes Sur La SuppressivitÉ Des Mutants a Deficience Respiratoire De La Levure. II. Etapes De La Mutation Grande En Petite Provoquee Par Le Facteur Suppressif
• Contribution a l'Etude de la Toxicologie du Trichlorethylene. II: Resultats des Etudes Experimentales Chez l'Animal Par
• Observations sur l'Influence Chimique des Milieux de Culture sur le Développement et la Production de l'Indol par les Coli-Bacilles et par les Bacilles Typhiques