No abstract

The possibility of veneer bonding with recycled polystyrene was examined. Five pressing regimes were studied. It was shown that low-pressure pre-heating is a necessary step allowing for increasing final shear strength of the woodthermoplastic joints and avoiding indentation of thermoplastic particles to wood.

This study investigated the possibility of applying flat-pressed wood-polymer composites in conditions of high humidity. The experiment involved three variants of wood-polymer composite panels 16 mm thick, and 680 kg per m3 density. The wood particles were bonded with polyethylene. The share of polyethylene in the core layer was fixed at 50%, while in the face layers the content was varied (40%, 50%, or 60%). The following parameters were examined: modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), screw holding (SH), thickness swelling (TS), water absorption (WA), susceptibility to drilling and milling, wettability and surface free energy, and resistance to mold. The results were compared to particleboard glued with urea-formaldehyde resin. The wood-polymer composite had lower MOR and MOE values and similar IB and SH values. The panels indicated a remarkably higher water resistance (lower TS and WA values) with good surface wettability and high resistance to mold fungi. Additionally, the composites were easier to machine, e.g. drilling or milling, in comparison to standard particleboards.

Abstract. The objective of this work was to compound mineral wool with wood particles in the production of particleboards of reduced flammability. Three series of boards with various contents of mineral wool (10, 20, 30 wt%) were successfully manufactured using ureaformaldehyde resin as binder. Thickness swelling, mechanical and thermal properties as well as ignitability of the boards were assessed. It occurred that reduced ignitability is accompanied by a decrease in mechanical performance.

In this study, wood plastic composites (WPC) made of poly(lactic acid) PLA and a bark-filler were manufactured. Two degrees of bark comminution (10–35 mesh and over 35 mesh) and varied content of bark (40, 50 and 60%) were investigated. The studied panels were compared with analogically manufactured HDPE boards. The manufacture of composites involved two stages: at first, WPC granules with the appropriate formulation were produced using the extruder (temperatures in individual extruder sections were 170–180 °C) and crushing using a hammer mill after cooling the extruded composite; secondly, the obtained granulate was used to produce boards with nominal dimensions of 300 × 300 × 2.5 mm3 by flat pressing in a mold, using a single daylight press at a temperature 200 °C. The study proved that comminuted bark can be applied as a filler in PLA composites. However, an increase in bark content decreased mechanical properties (MOR, MOE) and deteriorated humidity resistance (high TS and WA) of the panels. Along with the increase in bark content, an increase in the contact angle of the composite surfaces and a decrease in the total surface energy were noted. It was also found that PLA composites have higher strength parameters and lower moisture resistance compared to HDPE composites with the same bark content. Graphical abstract

This study regards the effect of technological aspects on mat compression during the manufacturing of low-density particleboards made of two low density species -i.e. poplar and pine. Using these materials, three-layer low-density particleboards (500 kg/m 3 ) were prepared. Three series were manufactured: (1) neat pine, (2) poplar-pine (face layer and core layer, respectively) and (3) neat poplar boards. Measurements of real-time variations in mat core temperature, pressure, and mat thickness allowed for the analysis of the mat compaction. Selected mechanical properties (modulus of rupture, modulus of elasticity, and internal bonding) of the manufactured particleboards were determined. Raw material of lower density used for particleboard manufacturing required either prolonged pressing time or more intense heat transfer into the mat core. The highest strength values were obtained for the poplar-pine particleboards.

Influence of apple wood waste from the annual care cut on the mechanical properties of particleboards. As part of the work, the influence of the share of apple wood waste from the annual care cut on the mechanical properties of 3-layer particle boards was examined. Particleboards were prepared using two variants of the specific maximum pressing pressure of 1.5 MPa and 2.5 MPa and mass share of particles from apple wood waste at the level of 0%, 25%, 50% and 75%. The results of the tests show a decrease in the value of the modulus of rapture and modulus of elasticity with the increase of the share of the additive in particleboard. In spite of the decrease of the value of the modulus of rapture and modulus of elasticity, all produced particleboards with the application of specific pressing pressure at the level of 2.5 MPa, met the requirements for P2 type particle board included in the PN 312: 2011 standard.

No abstract