Abstract
AbstractThe bulk polymerization of L,L‐dilactide was studied as a function of polymerization temperature (Tp), time and concentration of catalyst (tin 2‐ethylhexanoate). Poly(L‐lactide) (PLLA), with the highest value of intrinsic viscosity ([η] = 13 dl · g−1; M̄v ≈ 1 · 106) and heat of fusion (ΔHm = 64,7 J · g−1), was synthesized at a low catalyst concentration (0,015 wt.‐%) and at the lowest Tp studied (100°C), just above the melting point of L,L‐dilactide (98°C). The ceiling temperature of PLLA was found to be 275°C, as deduced from an M̄v max. − Tp curve. The M̄w/M̄n ratios of as‐polymerized PLLA samples ranged from 2 to 3. Fractions of PLLA with M̄v max. were already present at 50% conversion. The experimental results support a proposed nonionic insertion polymerization mechanism. Polymerization at 100–140°C resulted in early crystallization of PLLA leading to a rather untangled polymer and microporous (pores up to 100 nm) sample texture.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
