Miscibility and Properties of Low Molecular Mass Poly(L-lactide) and Poly(methyl methacrylate) Blends

Elvira Vidović,Ante Jukić,Fabio Faraguna

doi:10.15255/cabeq.2019.1630

Abstract

Modification of biobased PLLA properties by mixing with conventional PMMA via melt mixing in Brabender mixer was performed. Despite negative results of theoretical miscibility calculations by the group contribution approach of Coleman, Graf and Painter,<br /> homogeneous blend morphologies were prepared as recorded with scanning electron<br /> microscopy (SEM). All PLLA/PMMA blends displayed a single glass transition temperature. With increasing fraction of PMMA in blends, the increase in Tg from 58 °C to 93 °C was recorded by differential scanning calorimetry (DSC). Added PMMA improved<br /> mechanical properties, while the flexibility of PLLA/PMMA blends gradually decreased as revealed by DMA measurements.

Highlights

Polylactide (PLA) is the most important aliphatic polyester used for various applications in medicine and pharmacy for quite some time, in particular, due to its extraordinary characteristics of biocompatibility, nontoxicity, and processability
Miscible Poly(L-lactic acid) (PLLA)/poly(methyl methacrylate) (PMMA) blends were prepared with the latter over a whole composition range, which was confirmed by a single glass transition and a single α-relaxation transition determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), respectively
The obtained results are consistent with findings of Zhang et al.[36] who have shown for the PLA and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (EGA) blends that, the addition of EGA up to 20 % caused an increase in melting temperature, as well as an increase in the enthalpy of cold crystallization, i.e., added EGA induced a larger non-isothermal crystallization in PLA

Summary

Introduction

Polylactide (PLA) is the most important aliphatic polyester used for various applications in medicine and pharmacy for quite some time, in particular, due to its extraordinary characteristics of biocompatibility, nontoxicity, and processability. Miscible PLLA/PMMA blends were prepared with the latter over a whole composition range, which was confirmed by a single glass transition and a single α-relaxation transition determined by DSC and DMA, respectively. 350000 prepared from solution displayed two glass transition temperatures and melting endotherm of PLLA phase. It was established that atactic and syndiotactic PMMA (aPMMA and sPMMA) mixed with PLLA by casting from chloroform solution displayed similar behavior, UCST type, and a clarifying point in the range 210 – 255 °C depending on the composition. MMA and iPMMA was explained by the difference in solubility parameters (aPMMA and sPMMA: 19.43 and 19.53 (MPa)1/2, which is close to PLLA (20.66 (MPa)1/2) relative to iPMMA (18.98 (MPa)1/2) These findings on the PLLA/PMMA blends indicate that their miscibility depends on the preparation method and structural characteristics of polymers. The obtained blends were pressed in a laboratory compression molder for 5 min at 200 °C, and films for testing were obtained

Characterization methods

Results and discussion g

Findings

Conclusions