Change in thermal transitions and water uptakes of poly(l-lactic acid) blends upon hydrolytic degradation

AbstractThis article reports experimental data related to the research article entitled “Poly(malic acid-co-l-lactide) as a Superb Degradation Accelerator for Poly(l-lactic acid) at Physiological Conditions” (H.T. Oyama, D. Tanishima, S. Maekawa, 2016) [1]. Hydrolytic degradation of poly(l-lactic acid) (PLLA) blends with poly(aspartic acid-co-l-lactide) (PAL) and poly(malic acid-co-l-lactide) (PML) oligomers was investigated in a phosphate buffer solution at 40°C. It was found in the differential scanning calorimetry measurements that upon hydrolysis the cold crystallization temperature (Tc) and the melting temperature (Tm) significantly shifted to lower temperature. Furthermore, the hydrolysis significantly promoted water sorption in both blends

Stereocomplex Poly(lactic acid) Alloys with Superb Heat Resistance and Toughness

Biobased, biocompatible, and biodegradable poly­(lactic acid), PLA, possesses unique properties that give it high potential for a wide range of applications. However, its low thermal stability and brittleness are major obstacles for its use. In this study, both the thermal stability and toughness of PLA were simultaneously improved via stereocomplexation and reactive blending, by generating alloys composed of two PLA enantiomers, PLLA and PDLA, together with poly­(ethylene-<i>ran</i>-methylacrylate–<i>ran</i>-glycidyl methacrylate), EMA-GMA. It was found that reactive blending at 200 °C was very effective in generating alloys with high degrees of stereocomplex (sc) crystallinity and that the interfacial reaction between PLA and EMA-GMA contributed to a significant improvement in toughness. Most importantly, a (40/40/20)­PLLA/PDLA/EMA-GMA film with high sc crystallinity exhibited both much higher tensile impact strength and thermal stability than neat PLLA, retaining high storage modulus up to 210 °C. The scPLA alloys also exhibited superior chemical resistance to neat PLA. Thus, it was demonstrated that simultaneous complexation and the interfacial reaction transform PLA to the level of high performance materials

In-Plane Anisotropic Thermally Conductive Nanopapers by Drawing Bacterial Cellulose Hydrogels

We developed flexible polymeric “heat-guiding materials” by simply drawing bacterial cellulose (BC) hydrogels to align the cellulose nanofibers and form “nanopapers” with anisotropic thermal conductivity. The in-plane anisotropy of thermal conductivity between the drawn and transverse directions increased as the draw ratio increased. For the drawn BC nanopapers, the coefficient of thermal expansion was found to be inversely correlated with the thermal diffusivity. We fabricated a planar spiral sheet by assembling the drawn BC strips to visualize the “heat flux controllability”. The coexistence of heat-diffusing and heat-insulating capacities within the single nanopaper plane could help to cool future thin electronics

Outcomes in Newly Diagnosed Atrial Fibrillation and History of Acute Coronary Syndromes: Insights from GARFIELD-AF

BACKGROUND: Many patients with atrial fibrillation have concomitant coronary artery disease with or without acute coronary syndromes and are in need of additional antithrombotic therapy. There are few data on the long-term clinical outcome of atrial fibrillation patients with a history of acute coronary syndrome. This is a 2-year study of atrial fibrillation patients with or without a history of acute coronary syndromes