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58 MATERIALS MAY/JUN 2025 FDM ASIA | www.fdmasia.com

lev dolgachov lower than those obtained from the re-resinated panels.
The influence of tensile strength was analysed to assess
the effect of recycling re-resinated strands on the tensile
properties of the panels.

Although the random orientation of strands in the lower
mat limits the representativeness of absolute tensile strength
and stiffness values, the study provides valuable insights.
Panels made from re-resinated strands exhibited higher
average tensile strength compared to control panels, with the
strength increasing approximately by 40 percent along the
major axis and 11 percent perpendicular to it.
Equivalent average tensile strengths of the control panels
were also calculated to be 30 percent and three percent lower

than those of the re-resinated panels parallel and perpendicular
to the major axis, respectively.
by the variations in the panel densities. Similarly, modulus values were about 12 percent and
Additionally, the average densities of the panel types were 30 percent higher (5 percent and 23 percent higher than
further normalised to prove that the statistically significant the equivalent moduli) for re-resinated strand panels in the
variations were not driven by increased density in the panels respective directions. However, a single-factor ANOVA revealed
made from the re-resinated strands. that these variations were not statistically significant, with

The IB study demonstrated significantly improved strength p-values of 0.12 and 0.54 for the tests along the major and
in panels made with re-resinated strands compared to controls. perpendicular axes, respectively.
This improvement is directly linked to residual pMDI resin A cross-comparison between the tensile strength of recycled
retained in the strands even after 3–4 weeks of conditioning. panels perpendicular to the major axis and control panels
The higher resin content facilitated stronger interfacial bonding along the major axis also showed no statistical significance (p
during curing, likely due to increased adhesive distribution = 0.72). Higher variability in control panel data was attributed
per unit cross-sectional area of the strands. Further chemical to density fluctuations. Importantly, it was assumed that the
analysis of the strands might help establish the claim. strand length was not reduced during recycling, resulting in
Re-resinated strand panels exhibited a 107 percent increase no statistically significant variations in the tensile properties,

in the IB strength relative to the control panels. ANOVA as the strand length is known to significantly influence panel
confirmed these differences as statistically significant with an properties.
extremely low p-value (approximately 0). Overall, these findings indicate that recycling and re-
These results support the value of recycling the waste resinating strands had no statistically significant impact on
strands during panel processing by re-resinating and reusing the tensile properties of the panels in any direction.
the strands for composite panels. This approach offers a Nail withdrawal tests were conducted to evaluate the
sustainable pathway for optimising composite panel production withdrawal strength of the panels, a critical property for

without compromising quality. Equivalent IB strength in the applications in the built environment.
control panels was 0.81 ± 0.16 MPa, which was still significantly The result indicate that panels made from re-resinated