Non-Negligible Effect of Additives in the Application of Successive Self-Nucleation and Annealing Fractionation for Microstructure Characterization of Matrix Resin in Additive-Containing Samples

Abstract

Successive self-nucleation and annealing (SSA) is a convenient and versatile thermal fractionation technique that has been extensively used to characterize the chain microstructure of semicrystalline polymers. In practical applications, commercial products containing various additives are frequently tested by SSA to analyze the resin structure. In this case, whether the presence of additives affects the SSA result of matrix resin is worth considering. In this work, four additives including two nucleating agents (β-NA and α-NA), a lubricant, and an acid scavenger were purposefully added into the same polypropylene random copolymer (PPR) matrix resin, and SSA fractionation results of PPR with and without these additives were comparatively studied. It was found that SSA results of PPR containing diverse additives and pristine PPR are different. The results of small-angle X-ray scattering monitoring of the melting process of the "standard" crystal proved that additives altered the thermal stability of the ordered structure in the polymer upon heating. It is the variation in thermal stability that led to the change in the ideal self-nucleation temperature determined by the self-nucleation experiment, which is a crucial reason why different additives affected the SSA results of the same matrix resin. This work reminds that in the practical application of SSA to characterize the chain microstructure of the resin matrix for samples containing additives, the influence of additives cannot be ignored.

Effect of a Self-Assembled Nucleating Agent on the Crystallization Behavior and Spherulitic Morphology of Poly(lactic acid)

“…According to Figure e, the crystallization temperature ( T c ) of DDBH was about 182 °C during the first cooling run. The appearance of the viscosity step might be attributed to the crystallization of DDBH. , On crystallization of DDBH in the PLA melt upon cooling, the reassembly of DDBH resulted in an increase in the η* values …”

“…40,41 On crystallization of DDBH in the PLA melt upon cooling, the reassembly of DDBH resulted in an increase in the η* values. 36 The influence of DDBH on crystalline morphologies of PLA during PLA/DDBH blends was studied by POM. The morphological evolutions of pure PLA and PLA/DDBH samples upon cooling to 130 °C for 60 min are shown in Figure 4.…”

“…In actual processing, NAs usually show different structures from the original forms in PLA melts. , In the case of insoluble NAs, the NAs disperse in PLA and then aggregate together to induce the crystallization of PLA. , In the case of soluble NAs, the NA dissolves in the PLA during the heating process, after which the dissolved NAs would recrystallize into different structures, thus demonstrating their different nucleating effects. , The real structure of NA that induces PLA crystallization is often different from its original form and is determined from its dispersion state during heating and its recrystallization behavior during cooling. Therefore, the structural evolution and final recrystallization structure of NA in PLA under different experimental conditions were studied.…”

“…25 In actual processing, NAs usually show different structures from the original forms in PLA melts. 35,36 In the case of insoluble NAs, the NAs disperse in PLA and then aggregate together to induce the crystallization of PLA. 26,37 In the case of soluble NAs, the NA dissolves in the PLA during the heating process, after which the dissolved NAs would recrystallize into different structures, thus demonstrating their different nucleating effects.…”