Modeling vertical density profile formation for strand-based wood composites during hot pressing: Part 1. Model development

Zhou, Cheng; Dai, Chunping; Smith, Gregory D.

doi:10.1016/j.compositesb.2011.05.036

Cited by 12 publications

(7 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3b the average surface density for pure aspen boards was 976.7 kg/m 3 , and for bamboo surface boards it was 878.3 kg/m 3 , while average core density for pure aspen boards was 648.5 kg/m 3 and for bamboo surface boards, 660.8 kg/m 3 . Virtually all mechanical properties of OSB including IB are linked to board density and distribution of density through the thickness of the board (Andrews 1998; Dai et al 2002;Zhou et al 2011). One reason aspen is used for OSB is that the material is very low in density-285 to 410 kg/m 3 , but mostly between 300 and 350 kg/m 3 (Peters et al 2002, with a high compaction ratio.…”

Section: Thickness Density and Vertical Density Profilementioning

confidence: 99%

“…One reason aspen is used for OSB is that the material is very low in density-285 to 410 kg/m 3 , but mostly between 300 and 350 kg/m 3 (Peters et al 2002, with a high compaction ratio. The board surface layers in particular are very effectively densified during hot pressing to give a composite of small elements and fissures that is similar in strength properties to undamaged solid parent material (Zhou et al 2009(Zhou et al , 2011. Semple et al (2007) compared the performance of clonal aspen wood of different density (from 328 to 408 kg/m 3 ) in OSB and found that mat compaction and densification was greater for lower density wood strands leading to superior board properties.…”

Section: Thickness Density and Vertical Density Profilementioning

confidence: 99%

See 1 more Smart Citation

Hybrid oriented strand boards made from Moso bamboo (Phyllostachys pubescens Mazel) and Aspen (Populus tremuloides Michx.): species-separated three-layer boards

2015

View full text Add to dashboard Cite

Five sets of three-layer OSB were made from aspen and/or Moso bamboo strands in the following three configurations: Aspen strands in the surface and core layers; Moso strands in the surface and core layers; and Moso strands in the surface and aspen strands in the core. Boards containing Moso strands in the surface layers had two sub groups: (1) all strands contain a node in the middle, and (2) all strands are node free (internode). All 30 boards were comprised of 50 % w/w surface furnish and 50 % core furnish, fabricated to 737 mm 9 737 mm 9 11.1 mm. Standard mechanical (thickness, density, surface and core density) and strength properties [internal bond (IB), flexure, lateral nail withdrawal resistance (LNR)], and water resistance [2 and 24 h thickness swell (TS) and water absorption (WA)] were assessed. Complete replacement of the aspen in the surface layers with internode Moso strands resulted in over 45 % greater MOR. Panels made with Moso surface layers met CSA O437.0 (2011) minimum requirements TS/WA without the need for wax addition, possibly because no densification of the surface material was observed. Due to high variance in LNR, effects of board type and core composition were not statistically significant, but LNR of boards exceeded CSA O437.0 minimum requirements. Moso bamboo surface OSB were low in MOE which is consistent with unadulterated tissue being high in bending strength and fracture toughness but low in specific stiffness. The presence of nodes in the bamboo strands significantly reduced the strength properties of OSB, a problem which could be mitigated by minimising the incidence of nodes in the strands, particularly those used in the surface layers.

show abstract

Section: Thickness Density and Vertical Density Profilementioning

confidence: 99%

Section: Thickness Density and Vertical Density Profilementioning

confidence: 99%

Hybrid oriented strand boards made from Moso bamboo (Phyllostachys pubescens Mazel) and Aspen (Populus tremuloides Michx.): species-separated three-layer boards

2015

View full text Add to dashboard Cite

show abstract

“…With this approach, along with increasing computational power, the foundation was laid to develop process models based on fundamental principles. Some analytical models of the hot-pressing process have been presented during the last decades [3,[13][14][15][16][17]. Based on these works, analytical models are now used for online prediction of the density profile in continuously operating, wood-based panel presses.…”

Section: Introductionmentioning

confidence: 99%

Influence of Pressing Schedule and Adhesive Content on the Rheological Behavior of Wood Fiber-Furnish Mats

Shalbafan

Thoemen

2022

Materials

View full text Add to dashboard Cite

In this study, for a better understanding of the hot-pressing process, the influence of adhesive content (AC) on various features of a typical pressing schedule for medium-density fiberboard (MDF) production, including fiber mat compressibility, heat transfer during hot-pressing, density profile and board properties, were evaluated. It was found that increasing the AC (urea formaldehyde) leads to faster heat transfer towards the mat’s central plane, mainly due to higher heat release from the adhesive polycondensation reaction. Moreover, the results indicate that the time needed to reach the critical mark of 100 °C in the central plane of the mat depends on the duration of the first densification level (FD). Importantly, the pressure peaks (pmax and p2nd) needed for mat densification are significantly reduced when increasing the AC, which might be attributed to the slippery effect created by the adhesive on the fiber surfaces. The duration of the FD also showed obvious effects on the intermediate density maxima (ρinter) and the core layer density (ρcore). In general, the physical and mechanical properties of MDF panels are significantly impacted by the pressing schedule and AC. All in all, the results of this study are valuable information for refining existing rheological models to improve their accuracy and their ability to simulate the vertical density profile during industrial production.

show abstract

“…Greater density variation in the hand-formed mat necessitates greater overall compaction and densification in order to achieve acceptable bonding strength in the lower-density regions. While greater compaction leads to higher strength properties of BFC [ 14 ] and wood composite materials in general [ 15 , 16 ], it can also cause processing problems such as delamination due to gas pressure build-up during hot pressing [ 17 , 18 , 19 ]. Volume and thickness loss are also greater with higher mat densification, creating a trade-off between product density and culm material recovery [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Characterizing Mat Formation of Bamboo Fiber Composites: Horizontal Density Distribution

Semple

et al. 2021

Materials

Self Cite

View full text Add to dashboard Cite

Bamboo fiber composite (BFC) is a unidirectional and continuous bamboo fiber composite manufactured by consolidation and gluing of flattened, partially separated bamboo culm strips into thick and dense panels. The composite mechanical properties are primarily influenced by panel density, its variation and uniformity. This paper characterized the horizontal density distribution (HDD) within BFC panels and its controlling factors. It revealed that HDD follows a normal distribution, with its standard deviation (SD) strongly affected by sampling specimen size, panel thickness and panel locations. SD was lowest in the thickest (40 mm) panel and largest-size (150 × 150-mm2) specimens. There was also a systematic variation along the length of the BFC due to the tapering effect of bamboo culm thickness. Density was higher along panel edges due to restraint from the mold edges during hot pressing. The manual BFC mat forming process is presented and found to effectively minimize the density variation compared to machine-formed wood composites. This study provides a basic understanding of and a quality control guide to the formation uniformity of BFC products.

show abstract

Modeling vertical density profile formation for strand-based wood composites during hot pressing: Part 1. Model development

Cited by 12 publications

References 27 publications

Hybrid oriented strand boards made from Moso bamboo (Phyllostachys pubescens Mazel) and Aspen (Populus tremuloides Michx.): species-separated three-layer boards

Hybrid oriented strand boards made from Moso bamboo (Phyllostachys pubescens Mazel) and Aspen (Populus tremuloides Michx.): species-separated three-layer boards

Influence of Pressing Schedule and Adhesive Content on the Rheological Behavior of Wood Fiber-Furnish Mats

Characterizing Mat Formation of Bamboo Fiber Composites: Horizontal Density Distribution

Contact Info

Product

Resources

About