Page 50 - FDMAsia May/Jun 2026

48 MATERIALS MAY/JUN 2026 FDM ASIA | www.fdmasia.com

Magnific PB2 demonstrated superior overall performance, combining
exceptional dimensional stability (Residual TS: 0.49%) with
strong retention of mechanical properties (MOR: 67%, MOE:
56–64%, IB: 75%).
Its homogeneous fine particle structure and lower core
density contributed to reduced internal stresses and improved

water resistance. For demanding outdoor environments requiring
In striking contrast, MDF showed a substantially lower both dimensional stability and structural integrity, PB2 is strongly
IB retention of only 30 percent (0.43 MPa), indicating much recommended.
higher sensitivity to moisture induced degradation (Table 5). PB1 exhibited intermediate performance, with good dimensional
The lower IB retention in MDF results from a combination stability (Residual TS: 1.58%) and adequate mechanical retention
of factors. MDF fibres have a substantially higher specific after aging (MOR: 66–74%, MOE: 56–58%, IB: 71%).
surface area than the wood particles used in particleboard. Its three layer structure performed adequately but was
Adhesive droplets, which cover only a limited portion of outperformed by the single layer fine particle board in thickness
the fibres’ surface, are distributed over a larger total surface swelling. PB1 remains suitable for semi protected exterior

area, leading to fewer and more widely spaced bond points applications or where a three layer structure is preferred for
per unit area. other manufacturing reasons.
Consequently, the fibre adhesive interface is more susceptible MDF showed comparatively lower resistance to accelerated
to moisture induced swelling and disruption. It is important to aging, characterised by excessive Residual TS (5.43%) and
note that MDF panels are generally designated for use with a substantial IB strength loss (retention: 30%).
surface finish (coating or paint), whereas the results presented While its MOR and MOE retention met or exceeded relevant
here are from tests on unfinished panels. The application of standards, the high thickness swelling and very low IB retention

finishes generally improves panel durability. indicate high sensitivity to moisture induced degradation under
unprotected exterior conditions.
Table 5. IB strength of PB1, PB2 and MDF under non aged
and aged conditions, with retention rates. Therefore, unfinished MDF is not recommended for
Non Aged IB unprotected outdoor use. However, with effective surface
Panel Type Aged IB (MPa) IB Retention (%)
(MPa) coatings (paint, laminate), its performance may be acceptable
PB1 1.47 (11.4) 1.05 (7.3) 71
PB2 1.18 (6.7) 0.89 (14.7) 75 because its bending properties remained strong.
MDF 1.28 (9.0) 0.43 (18.8) 30 Practical implications for the wood industry:
*All differences between non aged and aged were significant at α • For exterior siding applications, a single layer fine particle
= 0.05.*
particleboard (PB2) can achieve better dimensional stability

Comparative Performance than a three layer board (PB1), even though both use the
This study provides a comprehensive comparative evaluation same PF adhesive.
of three industrial exterior grade panels—two PF bonded This finding challenges the assumption that multi layer
particleboards (PB1: three layer; PB2: single layer) and one structures are always superior for moisture resistance.
pMDI bonded MDF—subjected to six accelerated aging cycles Manufacturers may consider simplifying their board structures
according to ASTM D1037 12. The results offer important for certain exterior products.
insights into their suitability for exterior applications. • PF bonded particleboards retained over 70 percent of IB