Critical Role of Spherulite Structure on Behavior of Stabilizers in Poly(propylene) Stabilization

Abstract

Summary: We found that the spherulite structure of polypropylene (PP) significantly influences the stability of PP by affecting the behavior of stabilizers. Smaller spherulites resulted in more homogeneous dispersion of stabilizers and their slower release into air, so as to elongate the lifetime of PP. Moreover, chemically and physically weak spherulite boundaries were selectively oxidized in the presence of stabilizers. The significance to control higher order structures on the stabilization of PP is reported.

Mechanical Recycling of Packaging Plastics: A Review

“…[ 122,137 ] The spherulitic structure focuses degradation at these spherulite boundaries, segregating catalyst residue and additives in the amorphous phase ( Figure ). [ 137,141 ] Macroradicals produced combine or undergo β‐scission. [ 91,119,122 ] As the methine proton is more reactive, the formation of peroxyradicals is enhanced but the resultant radical is stabilized versus PE.…”

“…[ 143 ] PPs spherulitic structure impacts the distribution of stabilizers and antioxidants (Figure 11). [ 141,143 ] Smaller spherulites allow a uniform distribution of stabilizers throughout the polymer matrix, improving radical capture reactions and thus efficacy. [ 141,143 ] Taniike et al.…”

“…[ 141,143 ] Smaller spherulites allow a uniform distribution of stabilizers throughout the polymer matrix, improving radical capture reactions and thus efficacy. [ 141,143 ] Taniike et al. reported that the distribution of the stabilizer within the PP polymer matrix is independent of the type of antioxidant or stabilizer.…”

“…reported that the distribution of the stabilizer within the PP polymer matrix is independent of the type of antioxidant or stabilizer. [ 141 ] Bio‐derived agro‐wastes include tannin wine seed extracts, seed polyphenol extracts and virgin wine wastes can stabilize the product and delay the onset of MFI oxidation degradation for up to 100 h. [ 144 ] Lignin, a natural phenolic polymer, can also successfully stabilize PP and recycled PP (rPP) at concentrations between to 2–5 wt%. The lignin acts as both an anti‐oxidant and as a filler to increase the rigidity of the polymer matrix.…”

“…A high number of entanglements and increased polymer block size positively affects the mechanical properties of the material. [ 141,152 ]…”