𝔖 Bobbio Scriptorium
✦   LIBER   ✦

The modification of lactic acid based poly(ester-urethane) by copolymerization

✍ Scribed by Janne Kylmä; Mika Härkönen; Jukka V. Seppälä

Publisher
John Wiley and Sons
Year
1997
Tongue
English
Weight
171 KB
Volume
63
Category
Article
ISSN
0021-8995

No coin nor oath required. For personal study only.

✦ Synopsis

Copolymers of L-lactic acid (LLA) with DL-mandelic acid (DLMA), 4-hydroxybenzoic acid, 4-acetoxybenzoic acid, DL-malic acid, or anhydrous citric acid were synthesized via direct copolycondensation in the presence of 1,4-butanediol, using stannous octoate as catalyst. The effect of the comonomer and the comonomer ratio on polycondensation and the glass transition temperature were investigated. The glass transition temperature of amorphous poly(L-lactic acid-co-DL-mandelic acid) increased linearly from 33Њ to 56ЊC as the mandelic acid composition was increased from 0 to 45 mol %. For urethane synthesis, prepolymers of LLA and DLMA were condensation polymerized with compositions of 100/0, 90/10, and 80/20 (mol % in feed). The preparation of poly(ester-urethane) (PEU) was carried out in a stirred glass reactor, using 1,6-hexamethylene diisocyanate and isophorone diisocyanate in melt. The glass transition temperature of poly(L-lactic acid-co-DL-mandelic acid-urethanes) showed a marked increase with increased mandelic acid composition. The molecular weights of these urethanes were lower than for PEU based on poly(L-lactic acid). Such a depression in the degree of polymerization is attributed to the steric hindrance of the bulky phenyl group as a side chain of mandelic acid.

📜 SIMILAR VOLUMES

Impact modification of lactic acid based
Impact modification of lactic acid based poly(ester-urethanes) by blending
✍ Mari Hiljanen-Vainio; Janne Kylmä; Kari Hiltunen; Jukka V. Seppälä 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 336 KB 👁 1 views

Branched biodegradable poly(ester-urethane) (PEU) was blended with two elastic biodegradable copolymers in proportions 5, 10, 15, and 20 wt % to investigate their effect on this hard and brittle polymer. Copolymer of L-lactide and 1-caprolactone, P(L-LA50/CL50), was synthesized by ring-opening polym

Hydrolysis of lactic acid based poly(est
Hydrolysis of lactic acid based poly(ester-urethane)s
✍ Hiltunen, Kari; Tuominen, Jukka; Seppälä, Jukka V. 📂 Article 📅 1998 🏛 John Wiley and Sons 🌐 English ⚖ 237 KB 👁 2 views

The hydrolysis behaviour of lactic acid based poly(ester-urethane)s has been studied in a bu †er solution of pH 7É00 at 37 and 55¡C. Samples were prepared using a straight two step lactic acid polymerization process. The lactic acid was Ðrst polymerized by condensation with a low molecular weight by

Lactic acid based poly(ester-urethanes):
Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis
✍ Kari Hiltunen; Jukka V. Seppälä; Mika Härkönen 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 223 KB 👁 1 views

We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender

Lactic acid based poly(ester-urethane)s:
Lactic acid based poly(ester-urethane)s: The effects of different polymerization conditions on the polymer structure and properties
✍ Kari Hiltunen; Jukka V. Seppälä; Mika Härkönen 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 198 KB 👁 1 views

A two-step process for lactic acid polymerization is studied: in the first step the lactic acid is condensation-polymerized to a low-molecular-weight hydroxylterminated prepolymer; and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender.