Abstract
We found the formation of "shish-like" fibril crystals of aliphatic polyesters such as poly(l-lactic acid) (PLLA), poly(ε-caprolactone) (PCL), poly(12-hydroxydodecanoic acid) (PHDA) and poly(16-hydroxyhexadecanoic acid) (PHHA) from the sheared melt with shear rate over(γ, ̇) = 5 s-1 observed by polarizing optical microscope (POM). The melting temperature Tms of obtained fibril crystals of PLLA and PCL were higher than those of spherulites and were close to the equilibrium melting temperature Tm0. The small angle X-ray scattering (SAXS) patterns from the bulk sample including fibril crystals, small amount of unoriented small crystals and amorphous showed no peaks arose from the existence of long periods in fibril crystals. These are the evidence that the observed fibril crystals consist of assemblies of a lot of extended chain crystals (ECCs). We observed the morphology of moderately extracted single strand of fibril crystals at the magnification of POM by means of scanning electron microscope. We found that macroscopic fibril crystals of PLLA with diameter d = 10 μm consist of the bundle structure of microscopic fibril crystals with d = 2 μm. From POM observation of the formation of fibril crystals of PLLA and PCL, we showed phase diagrams of molecular weight M and crystallization temperature Tc for the formation of fibril crystals. From these phase diagrams, we evaluated a critical M and Tc for the formation of fibril crystals. Moreover, from the sequential melting and crystallization experiments, it was implied that the entanglement and transesterification play an important role on the formation of fibril crystals of aliphatic polyesters.
| Original language | English |
|---|---|
| Pages (from-to) | 58-68 |
| Number of pages | 11 |
| Journal | European Polymer Journal |
| Volume | 46 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2010 |
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Keywords
- Aliphatic polyester
- Crystallization
- Fibril crystal
- Poly(l-lactic acid)
- Shear flow
- Shish-kebab
ASJC Scopus subject areas
- Polymers and Plastics
- Physics and Astronomy(all)
- Organic Chemistry
Cite this
Formation and morphology of "shish-like" fibril crystals of aliphatic polyesters from the sheared melt. / Yamazaki, Shinichi; Itoh, Manabu; Oka, Takuya; Kimura, Kunio.
In: European Polymer Journal, Vol. 46, No. 1, 01.2010, p. 58-68.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Formation and morphology of "shish-like" fibril crystals of aliphatic polyesters from the sheared melt
AU - Yamazaki, Shinichi
AU - Itoh, Manabu
AU - Oka, Takuya
AU - Kimura, Kunio
PY - 2010/1
Y1 - 2010/1
N2 - We found the formation of "shish-like" fibril crystals of aliphatic polyesters such as poly(l-lactic acid) (PLLA), poly(ε-caprolactone) (PCL), poly(12-hydroxydodecanoic acid) (PHDA) and poly(16-hydroxyhexadecanoic acid) (PHHA) from the sheared melt with shear rate over(γ, ̇) = 5 s-1 observed by polarizing optical microscope (POM). The melting temperature Tms of obtained fibril crystals of PLLA and PCL were higher than those of spherulites and were close to the equilibrium melting temperature Tm0. The small angle X-ray scattering (SAXS) patterns from the bulk sample including fibril crystals, small amount of unoriented small crystals and amorphous showed no peaks arose from the existence of long periods in fibril crystals. These are the evidence that the observed fibril crystals consist of assemblies of a lot of extended chain crystals (ECCs). We observed the morphology of moderately extracted single strand of fibril crystals at the magnification of POM by means of scanning electron microscope. We found that macroscopic fibril crystals of PLLA with diameter d = 10 μm consist of the bundle structure of microscopic fibril crystals with d = 2 μm. From POM observation of the formation of fibril crystals of PLLA and PCL, we showed phase diagrams of molecular weight M and crystallization temperature Tc for the formation of fibril crystals. From these phase diagrams, we evaluated a critical M and Tc for the formation of fibril crystals. Moreover, from the sequential melting and crystallization experiments, it was implied that the entanglement and transesterification play an important role on the formation of fibril crystals of aliphatic polyesters.
AB - We found the formation of "shish-like" fibril crystals of aliphatic polyesters such as poly(l-lactic acid) (PLLA), poly(ε-caprolactone) (PCL), poly(12-hydroxydodecanoic acid) (PHDA) and poly(16-hydroxyhexadecanoic acid) (PHHA) from the sheared melt with shear rate over(γ, ̇) = 5 s-1 observed by polarizing optical microscope (POM). The melting temperature Tms of obtained fibril crystals of PLLA and PCL were higher than those of spherulites and were close to the equilibrium melting temperature Tm0. The small angle X-ray scattering (SAXS) patterns from the bulk sample including fibril crystals, small amount of unoriented small crystals and amorphous showed no peaks arose from the existence of long periods in fibril crystals. These are the evidence that the observed fibril crystals consist of assemblies of a lot of extended chain crystals (ECCs). We observed the morphology of moderately extracted single strand of fibril crystals at the magnification of POM by means of scanning electron microscope. We found that macroscopic fibril crystals of PLLA with diameter d = 10 μm consist of the bundle structure of microscopic fibril crystals with d = 2 μm. From POM observation of the formation of fibril crystals of PLLA and PCL, we showed phase diagrams of molecular weight M and crystallization temperature Tc for the formation of fibril crystals. From these phase diagrams, we evaluated a critical M and Tc for the formation of fibril crystals. Moreover, from the sequential melting and crystallization experiments, it was implied that the entanglement and transesterification play an important role on the formation of fibril crystals of aliphatic polyesters.
KW - Aliphatic polyester
KW - Crystallization
KW - Fibril crystal
KW - Poly(l-lactic acid)
KW - Shear flow
KW - Shish-kebab
UR - http://www.scopus.com/inward/record.url?scp=70449640626&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=70449640626&partnerID=8YFLogxK
U2 - 10.1016/j.eurpolymj.2009.09.003
DO - 10.1016/j.eurpolymj.2009.09.003
M3 - Article
VL - 46
SP - 58
EP - 68
JO - European Polymer Journal
JF - European Polymer Journal
SN - 0014-3057
IS - 1
ER -