Crystallization Kinetics and Morphology in Miscible Blends of Two Crystalline Polymers

Abstract

ABSTRACT:Miscibility, crystallization behavior and morphology of blends prepared from two crystalline polymers, poly(butylene succinate) (PBSU), and poly(vinylidene chloride-co-vinyl chloride) [P(VDC-VC)] have been examined by polarized optical microscopy and differential scanning calorimetry. It is found that PBSU is miscible with P(VDC-VC) since each blend showed a single glass transition temperature T •. Spherulitic morphology and the melting behavior of the blends were strongly dependent upon the crystallization kinetics and some unique phenomena were found out: (i) in contrast to the other results reported so far, growth rate G of low-Tm component (PBSU) was decreased greatly with increasing high-Tm component [P(VDC-VC)] content, (ii) for the PBSU/P(VDC-VC) (40: 60) blend crystallized at 90oC (i.e., the growth rate of the two components was appproximately the same) so called interlocked spherulites were formed, where PBSU spherulites grown through the interlamellar regions of P(VDC-VC) spherulites, (iii) for the blends crystallized during fast cooling conditions from the melt (e.g., faster than IOoC min-1 ), only one melting peak appeared corresponding to PBSU and no noticeable melting peaks of high-T m component P(VDC-VC) were observed. Hence, it is seen that the crystallization behavior of high-T m component is heavily affected by the low-T m component. Therefore, kinetic factors are the most important one in controlling the crystallization behavior and the morphology of the crystalline/crystalline blends.KEY WORDS Poly(butylene succinate) j Poly(vinylidene chloride-co-vinyl chloride) / Polymer Blend I Spherulitic Morphology j Crystallization Kinetics / Miscibility between two amorphous polymers have been studied intensively by many researchers, especially in relation to phase separation dynamics. Miscibility between crystalline and amorphous polymers has also been examined, and a number of miscible blends are known. 1 -9 On the other hand, few studies have been reported on the miscibility and crystallization behavior of polymer blends between two crystalline polymers. A miscible crystalline/crystalline polymer blend is a rare phenomenon and only a few pairs have been reported to form miscible systems [e.g., poly(c-caprolactone) (PCL)/poly(vinylidene chloride), 10 · 11 poly(3-hydroxybutyrate) (PHB)/poly(ethylene oxide) (PEO), 12 PHB/poly-(L-lactide)13]. This is because the crystalline polymer pairs having attractive interactions between the two components are very rare. Manley et a/. 14 -17 recently have reported a series of miscibility and crystallization behavior of poly(1,4-butylene adipate) (PBA) and poly-(vinylidene fluoride) (PVDF) where both constituents are crystalline polymers. In the PBA/PVDF blends, the melting points of the two components have been ca. 100°C apart, the crystallization behavior and morphology of the low-Tm component (PBA) are seriously influenced by the presence of the spherulitic microstructure of the high-Tm component (PVDF).Recently, we have reported miscibility and crystall...

Crystallization kinetical and morphological peculiarities in binary crystalline/crystalline polymer blends

“…39,41 That blend system is interesting in that the low T g component PCL enables the PC-whose high T g usually inhibits its crystallization-to crystallize to a remarkable extent. 36,37,41 Simultaneous crystallization (in the sense that the components crystallize at the same time) upon isothermal conditions, and the IPC as well as the ILC schemes, respectively, could be realized, for example, in the blend PBSU/ P(VDC-co-VC), [46][47][48][49][50][51][52][53] in the blend PESU/PEO 26,28 and in the blend PLA/P(BSU-co-BC). 44,45 The actual crystallization scheme-whether S-co-S, IPC, ILC, or IFC, whether one-step or two-step crystallization occurs-depends clearly on the composition and on the thermal conditions.…”

Nonisothermal Crystallization Kinetics of Poly(butylene succinate) and Poly(ethylene succinate)

“…PBSU was found to be miscible with poly(vinylidene fluoride), poly(vinylidene chloride-co-vinyl chloride), poly(ethylene oxide) (PEO) and poly(vinyl phenol). [5][6][7][8][9] On the other hand, PBSU was found to show no miscibility with PHB, poly(3-hydroxybutyrate-co-hydroxyvalerate) and poly("-caprolactone). [10][11][12] We also studied the subsequent melting behavior of PBSU crystallized nonisothermally from the melt.…”

Pattern Formation and Growth Kinetics in Eutectic Systems

“…Actually, in the literature, the studies of crystalline/crystalline polymeric systems are very scarce because a miscible polymeric mixture in which two components are crystalline is a rare phenomenon. Up to now, the reported miscible pairs include PVDF/PBA [61], PHB/PVDF [62][63], PHB/PEO [54,64], PEO/PES [65], PEO/PBSU [66], PBSU/P(VDC-VC) [67], Nylon66/Nylon48 [68] systems and PEO blends with two quite different molecular weights [69], etc. These mixtures showed different crystalline behaviors.…”