Hierarchical structure and properties of rigid PVC foam crosslinked by the reaction between anhydride and diisocyanate

Rigid crosslinked poly(vinyl chloride) (c‐PVC) foams by forming semi‐interpenetrating network (SIPN) structure via the reaction of phthalic anhydride (PA) and diisocyanate were prepared. The influence of PA on hierarchical structure and mechanical properties of c‐PVC foam was studied. The Fourier transform infrared spectrometer results showed that the presence of PA resulted in the formation of imide structure in the SIPN of obtained c‐PVC foams, which introduced a structural defect of SIPN. Thus, the residue (gel) from tetrahydrofuran extraction of the foams decreased with the increase of PA content. Dynamic thermal analysis showed the presence of three aggregation state structures in the c‐PVC foams, depending on the loading of PA. The addition of PA in the formulations affected cellular structure and mechanical properties of the obtained foams. Furthermore, the influence of chemical environment of anhydride compounds on the formation of imide structure in the crosslinking network of c‐PVC foams was discussed. A strategy for reducing defect of crosslinking network and improving mechanical properties was put forward.