Tensile strength estimation of paper sheets made from recycled wood and non-wood fibers using machine learning

Figures & data

Figure 1. Fiber morphology of bleached kraft softwood pulp.

Figure 2. Cell of LSTM RNN.

Figure 3. Methodology flowchart.

Table 1. Fiber length during recycling processes (mm)

Recycling times		0	1	3	5
Reed Pulp	Arithmetic mean	0.30	0.31	0.31	0.30
	Weighted average	0.59	0.55	0.55	0.56
	Weighted Weighted average	0.91	0.84	0.80	0.85
Wood Pulp	Arithmetic mean	1.52	1.49	1.48	1.50
	Weighted average	2.28	2.25	2.20	2.26
	Weighted Weighted average	0.71	0.68	0.71	0.71

Table 2. Properties of reed fibers during recycling

Recycle Number
	0	1	2	3	4
Properties
Zero-span tensile strength (kg/15 mm)	7.95	7.63	7.80	7.69	7.58
Zero-span tensile index (Nm/g)	808.7	793.0	775.1	760.2	748.6
Basis weight (g/m^2)	73.57	64.33	65.61	64.65	63.69
Degree of polymerization	644	549	545	542	536
Fiber length (mm)	0.91	0.84	0.81	0.80	0.82
Degree of crystallinity (%)	77.34	77.89	79.91	80.62	81.33
Crystalline indices (%)	70.71	71.62	74.86	75.97	77.08
WRV (g/g)	2.02	1.80	1.65	1.60	1.56
RBA	0.23	0.20	0.18	0.18	0.16
Tensile index (Nm/g)	28.14	25.35	23.12	21.95	20.22

Figure 4. Effect of recycling on tensile strength of different pulps.

Figure 5. Effect of recycling on WRV.

Figure 6. Effect of recycling on RBA.

Figure 7. Correlation coefficients of properties and tensile strength.

Figure 8. Different stresses on paper with different damage states.

Figure 9. Damage index and tensile strength after each recycling.

Figure 10. Damage index estimation based on curve fitting and neural network.