How and Why Polymer Glasses Lose Their Ductility Due to Plasticizers

Impact of lock solutions on the mechanical performance of polyurethane central venous catheters: A comparative study

The impact of ethanol locks on the mechanical performances of central venous catheters was compared to that of aqueous-based locks. Several mechanical tests were performed to evaluate catheter behavior: kinking radius measurements, burst pressure, and tensile tests. Different polyurethanes were studied to assess the impact of radio-opaque charge and polymer chemical composition on catheter behavior. The results were correlated to swelling measurements and calorimetric measurements. In particular, ethanol locks have a higher impact on long contact time than aqueous-based locks: stresses and strains at break were lower, and kinking radii were higher. However, for all catheters, the mechanical performances remain much higher than the normative requirements.

The Glass Transition Temperature of Heterogeneous Biopolymer Systems

Biopolymers are abundant, renewable, and biodegradable resources. However, bio-based materials often require toughening additives, like (co)polymers or small plasticizing molecules. Plasticization is monitored via the glass transition temperature versus diluent content. To describe this, several thermodynamic models exist; nevertheless, most expressions are phenomenological and lead to over-parametrization. They also fail to describe the influence of sample history and the degree of miscibility via structure-property relationships. We propose a new model to deal with semi-compatible systems: the generalized mean model, which can classify diluent segregation or partitioning. When the constant k_GM is below unity, the addition of plasticizers has hardly any effect, and in some cases, even anti-plasticization is observed. On the other hand, when the k_GM is above unity, the system is highly plasticized even for a small addition of the plasticizer compound, which indicates that the plasticizer locally has a higher concentration. To showcase the model, we studied Na-alginate films with increasing sizes of sugar alcohols. Our k_GM analysis showed that blends have properties that depend on specific polymer interactions and morphological size effects. Finally, we also modeled other plasticized (bio)polymer systems from the literature, concluding that they all tend to have a heterogeneous nature.

Polymer Nanocomposite Data: Curation, Frameworks, Access, and Potential for Discovery and Design

With the advent of the materials genome initiative (MGI) in the United States and a similar focus on materials data around the world, a number of materials data resources and associated vocabularies, tools, and repositories have been developed. While the majority of systems focus on slices of computational data with an emphasis on metallic alloys, NanoMine is an open source platform with the goal of curating and storing widely varying experimental data on polymer nanocomposites (polymers doped with nanoparticles) and providing access to characterization and analysis tools with the long-term objective of promoting facile nanocomposite design. Data on over 2500 samples from the literature and individual laboratories has been curated to date into NanoMine, including 230 samples from the papers bound in this virtual issue. This virtual issue represents an experiment of the flexibility of the data repository to capture the unique experimental metadata requirements of many data sets at one time and to challenge the authors to participate in the curation of their research data associated with a given publication. In principle, NanoMine offers a FAIR platform in which data published in papers becomes directly Findable and Accessible via simple search tools, with open metadata standards that are Interoperable with larger materials data registries, and allows easy Reuse of data, e.g. benchmarking against new results. Our hope is that with time, platforms such as this one could capture much of the newly published data on materials and form nodes in an interconnected materials data ecosystem which would allow researchers to robustly archive their data, add to the growing body of readily accessible data, and enable new forms of discovery by application of data analysis and design tools.