Tension test data for PAGF from a previous study  are shown in the figure for comparison.
During welding, the glass fibers tend to orient themselves in the plane of the weld creating an interface whose properties are largely dictated by the properties of the thermoplastic polymer matrix [8, 12, 27], It should also be noted that the tensile strength of PIWGF specimens are ~20% lower than that of the PAGF specimens in both unwelded and welded conditions.
There are many possible reasons for the observed deterioration in tensile strength in recycled PIWGF compared to prime PAGF. First, micro-scratches caused by TiOa particles on the surface of reinforcing glass fibers [22, 24] could cause early fracture of the fibers and reduce their reinforcing effect.
It appears that recycling had rendered PIWGF more prone to cavitation under tensile loading, which resulted in a lower tensile strength than PAGF. Furthermore, it has been reported that the crystallinity of PIWGF is lower than that of PAGF , which translates to a weaker matrix because PA6 is a semicrystalline polymer.