Effect of pressure on poly-L-Lactic Acid morphology

Christopher M. Baker; Aharon Azagury; Edith Mathiowitz

doi:10.1016/j.polymer.2016.07.028

Effect of pressure on poly-L-Lactic Acid morphology

Christopher M. Baker, Aharon Azagury, Edith Mathiowitz

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

When exposed to pressures below and above its glass transition temperature (T_g) over time, both the amorphous and crystalline regions of Poly-L-Lactic Acid (PLA) can be oriented. The most pronounced effect was the existence of an intense birefringence which lacked any sign of crystalline structure as observed by polarized light microscopy as well as the existence of a non-birefringent area in some of the same samples. Differential Scanning Calorimetry (DSC) analysis of the birefringent areas revealed decreased enthalpy of relaxation (ΔH_ER) and specific heat capacity (ΔC_P) values as well as the existence of at least two T_g’s when samples were treated at 63 °C and above, indicating increased orientation of the amorphous region. These same samples additionally displayed increased crystallinity which was depicted by an increased enthalpy of crystallization (ΔH). Additionally, X-Ray Diffraction (XRD) revealed a shift from an amorphous to a crystalline structure. Regions that did not display intense birefringence revealed minimal changes in T_g, ΔH_ER, and ΔC_P.

Original language	English
Pages (from-to)	250-262
Number of pages	13
Journal	Polymer
Volume	99
DOIs	https://doi.org/10.1016/j.polymer.2016.07.028
State	Published - 2 Sep 2016
Externally published	Yes

Keywords

Birefringence
Film cast
Polyester

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Materials Chemistry

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10.1016/j.polymer.2016.07.028

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title = "Effect of pressure on poly-L-Lactic Acid morphology",

abstract = "When exposed to pressures below and above its glass transition temperature (Tg) over time, both the amorphous and crystalline regions of Poly-L-Lactic Acid (PLA) can be oriented. The most pronounced effect was the existence of an intense birefringence which lacked any sign of crystalline structure as observed by polarized light microscopy as well as the existence of a non-birefringent area in some of the same samples. Differential Scanning Calorimetry (DSC) analysis of the birefringent areas revealed decreased enthalpy of relaxation (ΔHER) and specific heat capacity (ΔCP) values as well as the existence of at least two Tg{\textquoteright}s when samples were treated at 63 °C and above, indicating increased orientation of the amorphous region. These same samples additionally displayed increased crystallinity which was depicted by an increased enthalpy of crystallization (ΔH). Additionally, X-Ray Diffraction (XRD) revealed a shift from an amorphous to a crystalline structure. Regions that did not display intense birefringence revealed minimal changes in Tg, ΔHER, and ΔCP.",

keywords = "Birefringence, Film cast, Polyester",

author = "Baker, {Christopher M.} and Aharon Azagury and Edith Mathiowitz",

note = "Publisher Copyright: {\textcopyright} 2016 Elsevier Ltd",

year = "2016",

month = sep,

day = "2",

doi = "10.1016/j.polymer.2016.07.028",

language = "English",

volume = "99",

pages = "250--262",

journal = "Polymer",

issn = "0032-3861",

publisher = "Elsevier BV",

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TY - JOUR

T1 - Effect of pressure on poly-L-Lactic Acid morphology

AU - Baker, Christopher M.

AU - Azagury, Aharon

AU - Mathiowitz, Edith

PY - 2016/9/2

Y1 - 2016/9/2

N2 - When exposed to pressures below and above its glass transition temperature (Tg) over time, both the amorphous and crystalline regions of Poly-L-Lactic Acid (PLA) can be oriented. The most pronounced effect was the existence of an intense birefringence which lacked any sign of crystalline structure as observed by polarized light microscopy as well as the existence of a non-birefringent area in some of the same samples. Differential Scanning Calorimetry (DSC) analysis of the birefringent areas revealed decreased enthalpy of relaxation (ΔHER) and specific heat capacity (ΔCP) values as well as the existence of at least two Tg’s when samples were treated at 63 °C and above, indicating increased orientation of the amorphous region. These same samples additionally displayed increased crystallinity which was depicted by an increased enthalpy of crystallization (ΔH). Additionally, X-Ray Diffraction (XRD) revealed a shift from an amorphous to a crystalline structure. Regions that did not display intense birefringence revealed minimal changes in Tg, ΔHER, and ΔCP.

AB - When exposed to pressures below and above its glass transition temperature (Tg) over time, both the amorphous and crystalline regions of Poly-L-Lactic Acid (PLA) can be oriented. The most pronounced effect was the existence of an intense birefringence which lacked any sign of crystalline structure as observed by polarized light microscopy as well as the existence of a non-birefringent area in some of the same samples. Differential Scanning Calorimetry (DSC) analysis of the birefringent areas revealed decreased enthalpy of relaxation (ΔHER) and specific heat capacity (ΔCP) values as well as the existence of at least two Tg’s when samples were treated at 63 °C and above, indicating increased orientation of the amorphous region. These same samples additionally displayed increased crystallinity which was depicted by an increased enthalpy of crystallization (ΔH). Additionally, X-Ray Diffraction (XRD) revealed a shift from an amorphous to a crystalline structure. Regions that did not display intense birefringence revealed minimal changes in Tg, ΔHER, and ΔCP.

KW - Birefringence

KW - Film cast

KW - Polyester

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U2 - 10.1016/j.polymer.2016.07.028

DO - 10.1016/j.polymer.2016.07.028

M3 - Article

AN - SCOPUS:84978397887

SN - 0032-3861

VL - 99

SP - 250

EP - 262

JO - Polymer

JF - Polymer

ER -

Effect of pressure on poly-L-Lactic Acid morphology

Abstract

Keywords

ASJC Scopus subject areas

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