bioresources. com
PEER-REVIEWED ARTICLE
0.0920
0.0781
0.0651
0.0488
0.0279
10 15 20 25 30 35 40 45
7000
6000
MOR II(L) MOE II(R) MOR ^(L) MOE ^(R)
5000
4000
3000
2000
1000
0.0279
0.0488
0.0651
0.0781
0.0920
RC [g/m 2 ]
Fig. 5. The effect of resination coefficient on modulus of rigidity and modulus of elasticity The highest IB was reported for the CC board, which was the board in which the chips in the external layer were those intended for the core layer of furniture particle boards that were also used in the manufacturing of MFP boards (Table 5). The value of this parameter was similar to the investigated MFP panel. Internal bond was strongly related to chip thickness and susceptibility of the mat to pressing. Although the average thickness of CC chips was similar to that of DD and EE chips, they also comprised about 20% of thicker chips, while in the other groups the share of chips with 1 mm or similar thickness was only a few percent. Therefore, assuming the same susceptibility of the core layer chips to pressing, CC chips were probably the most resistant during mat pressing, which translated into high IB of the boards made of this type of chips. This study demonstrated that chips significantly shorter than strand chips, or even fine chips, may be successfully used in the manufacturing of external layers of OSB. Core layers made of strand chips provided high IB, whereas modulus of rigidity and modulus of elasticity strongly depended on the type of chips used in the external layers. Nevertheless, the boards made of the finest chips met all the relevant requirements for OSB/3 except for the requirements for modulus of elasticity for the longer axis set out in EN 310 (1993). The properties of the experimental boards were highly favorable when the chips in their external layers were the chips intended for MFP boards or for the core layer of furniture particle boards. Boards of this type met the requirements for P5 particle boards and, despite much lower density, they were only slightly less durable than MFP. High internal bond indicated that the resin content of the experimental boards was too high. It can be successfully lowered to 14.40 kg/m 3 , and when accompanied by an increase in the gluing of external layers, a modulus of elasticity of 3500 N/mm 2 would probably be achieved. As far as the linear dimensions of the chips were concerned, the chips slightly longer than BB, i . e ., those with a computational length of 10.34 mm, should be enough to produce P2 boards in these experimental conditions. The chips suitable for OSB/3 production should be characterized by the computational length of about 25 mm. The characterization of chips by both their linear dimensions and shape factors was found to be very cumbersome and did not provide an accurate description of the specific chip batch if they were not screened into a homogeneous dimension group. This was due to the fact that the dimensions of the chips retained on screens during screening for
8351
Mirski et al . (2016). “Non - strand chips OSB,” B io R esources 11(4), 8344-8354.
Made with FlippingBook Annual report maker