Effect of a Novel Family of N,N′-Diphenyl Bisamides on the Formation of β Crystalline Form in Isotactic Polypropylene

Abstract

In this paper, a family of eight N,N 0 -diphenyl bisamide compounds were synthesized and characterized by fourier transform infrared (FT-IR) and 1 H nuclear magnetic resonance (NMR) technologies. The influence of different compounds on the formation of crystalline form in iPP had been investigated by means of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized light microscopy (PLM). N,N 0 -diphenyl succinamide (DPS), N,N 0 -diphenyl glutaramide (DPG) and N,N 0 -diphenyl adipamide (DPA) are -nucleating agents for iPP among these compounds. The results also indicate that DPS and DPA have higher ability to induce the -form than DPG. The analysis of the cell parameters of three efficient -nucleating agents shows that they all have approximate periodic length of b-axis of 0.65 nm. And it is also suggested that two-dimensional lattice matching relationships exist between the crystal structures of the -nucleating agents and that of -iPP.

Structural Relationships between Zinc Hexahydrophthalate and the β Phase of Isotactic Polypropylene

“…The structural correlation between iPP and β-nucleating agent crystals has drawn wide attention of researchers. ,− Stocker and Dou − studied the mechanism of amide-nucleating agents inducing the formation of β-iPP, and they all confirmed the lattice matching in the nucleation. A periodicity of about 6.5 Å existed in all crystallizations of the β-nucleating agents and iPP.…”

Morphological Characteristics of β-Nucleating Agents Governing the Formation of the Crystalline Structure of Isotactic Polypropylene

“…The formation mechanism of the β-crystal of iPP induced by DCHT/DCHN is well explained by epitaxial crystallization, which defines a favorable dimensional match with a mismatch less than ±15% on the contact plane between the deposit and substrate. − A two-dimensional match between the β-crystal and DCHT/DCHN crystal, including the chain axis and interchain directions, has been proposed to be a premise to readily induce the formation of β - nuclei. ,− Importantly, the β-nucleation efficiency of aromatic amide β-NAs is determined by the epitaxial match between the growth planes of β-crystal and the specific surfaces of β-NA crystal, which is profoundly influenced by the chemical structure and crystal structure of NAs . Several studies demonstrated that the K β value in iPP is remarkably affected by the chemical structure of aromatic/aliphatic amide-based β-NAs, including the symmetry of the molecules, type and length of the central alkyl group, and type and size of the peripheral substitution. − The dominant role of the crystal structure of NAs was reported by Zhou et al, who found that 2,6-naphthalenedicarboxamide and 1,4-naphthalenedicarboxamide show different crystal structures, and the former selectively induces the formation of β - crystals, while the latter exhibits a very weak α-nucleation effect . Interestingly, aromatic bisamide-based β-NAs can be dissolved to different extents in the iPP melt, depending on the final heating temperature ( T f ) and their content, and can subsequently crystallize to form different morphologies, including dotlike, needle-like, and dendritic morphologies, in the following cooling process. ,− Accordingly, the K β value is indispensably influenced by the recrystallized morphology of β-NAs in the iPP melt.…”

Effect of Metallic Salts of Phenylmalonic Acid on the Crystallization of Poly(L-lactide)

“…1c), no obvious crystallization peak was observed for the pure PLLA, which showed that the crystallization rate of the pure PLLA was The epitaxial nucleation mechanism based on the dimensional lattice matching rules [26,27] was used to explain the nucleation mechanism of carboxylates in polypropylene [28][29][30][31][32][33][34] . It was also adopted to explain the superior nucleation ability of some carboxylates in a PLLA matrix, such as zinc phenylphosphonate [23] , zinc citrate complex nanoparticles [35] and cadmium phenylmalonate [36] .…”