Opacification Kinetics of PLA during Liquid Water Sorption.

When in contact with water, poly(lactic acid), PLA, undergoes several physical changes. A very evident one is opacification, namely the change from the typical transparent appearance to a white opaque color. This phenomenon is particularly significant for many applications, including packaging, since opacity hinders the possibility of a clear look of the packed goods and also worsens the consumers' perceptions.

A Comparative Study between Beeswax and Glycerol Monostearate for Food-Grade Oleogels.

With the aim to produce solid fats with a high percentage of unsaturated fatty acids, oleogels based on olive and peanut oil with different concentrations of beeswax (BW) and glycerol monostearate (GMS) as oleogelators were studied and compared. The critical oleogelator concentration for both BW and GMS was 3%. Thermal properties of the developed GMS-based oleogels pointed to a polymorphic structure, confirmed by the presence of two exothermic and endothermic peaks.

Morphology Distribution in Injection Molded Parts.

A more sustainable use of plastic parts makes it necessary to replace current plastic parts with recyclable components, also allowing the modulation of the part properties through the process. Injection molding is one of the most widely used technologies for obtaining rigid plastic parts, so it is crucial to understand how to tailor properties by adopting the correct processing conditions. One way is to perform annealing steps directly inside the mold: in-mold annealing improves the structural integrity and durability of the material, reduces defects, increases the resistance of parts against certain chemicals, reduces wear and tear, increases ductility, and lowers brittleness.

Modulating poly(lactic acid) degradation rate for environmentally sustainable applications.

The huge amount of plastics generated by the massive use of packaging makes it difficult to manage waste safely. Introducing biodegradable polymers, such as poly(lactic acid) (PLA), can at least partially reduce the environmental pollution from plastic waste. Biodegradable polymers must have a degradation rate appropriate for the intended use to replace durable plastics.

Analysis of Weld Lines in Micro-Injection Molding.

Micro-injection molding (µIM) is a widespread process for the production of plastic parts with at least one dimension, or feature, in the microscale (conventionally below 500 µm). Despite injection molding being recognized as a robust process for obtaining parts with high geometry accuracy, one last occurrence remains a challenge in micro-injection molding, especially when junctions are present on the parts: the so-called weld lines. As weld lines are crucial in determining mechanical part performances, it is mandatory to clarify weld line position and characteristics, especially at the industrial scale during mold design, to limit failure causes.

Modeling and Analysis of Morphology of Injection Molding Polypropylene Parts Induced by In-Mold Annealing.

It is generally recognized that high-temperature treatments, namely annealing, influence the microstructure and the morphology, which, in turn, determine the mechanical properties of polymeric parts. Therefore, annealing can be adopted to control the mechanical performance of the molded parts. This work aims to assess the effect of annealing on the morphology developed in isotactic polypropylene (iPP) injection-molded parts.

Production of Mesoglycan/PCL Based Composites through Supercritical Impregnation.

The development of targeted therapies for wound repair is knowing a growing interest due to the increasing aging of the population and the incidence of chronic pathologies, mainly pressure ulcers. Among molecules recruiting cell populations and promoting the formation of new vital tissue, sodium mesoglycan (MSG) has been proven to be effective in wound healing. In this work, MSG impregnation of polymer matrices has been attempted by a supercritical carbon dioxide-based process.

Multi-Scale Simulation of Injection Molding Process with Micro-Features Replication: Relevance of Rheological Behaviour and Crystallization.

The possibility of tailoring key surface properties through the injection molding process makes it intriguing from the perspective of sustainability enhancement. The surface properties depend on the replication accuracy of micro and nanostructures on moldings; such an accuracy is enhanced with cavity temperature. The simulation of the injection molding process is very challenging in the presence of micro and nanostructures on the cavity surface; this does not allow for the neglect of phenomena generally considered not to influence the overall process.

Fused Filament Deposition of PLA: The Role of Interlayer Adhesion in the Mechanical Performances.

A set of criteria to enhance mechanical performances of standard specimens (Type V, ANSI D368) made of polylactic acid (PLA) were proposed. Fused PLA deposition was conducted with nozzle temperature ranging from 180 to 230 °C and deposition plate temperature ranging from 70 to 110 °C. Optical microscopy, elastic modulus analysis and density measurement allowed emphasizing the effect of temperature field, also measured during the process, on the morphology and the mechanical characteristics of the specimen.

Alginate hydrogel: The influence of the hardening on the rheological behaviour.

Alginate based gels are widely adopted in many pharmaceutical and biomedical fields. The main rheological characteristics of the alginate-based gels are important design parameters for gel preparation. A new methodology for rheological tests on the alginate-based gels has been assessed in order to obtain reliable and reproducible results in terms of loss and storage moduli.

Correction: Speranza, V. et al. Hierarchical Structure of iPP During Injection Molding Process with Fast Mold Temperature Evolution. 2019, , 424.

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Hydrophobicity Tuning by the Fast Evolution of Mold Temperature during Injection Molding.

The surface topography of a molded part strongly affects its functional properties, such as hydrophobicity, cleaning capabilities, adhesion, biological defense and frictional resistance. In this paper, the possibility to tune and increase the hydrophobicity of a molded polymeric part was explored. An isotactic polypropylene was injection molded with fast cavity surface temperature evolutions, obtained adopting a specifically designed heating system layered below the cavity surface.

Process Induced Morphology Development of Isotactic Polypropylene on the Basis of Molecular Stretch and Mechanical Work Evolutions.

It is well known that under high shear rates polymers tend to solidify with formation of morphological elements oriented and aligned along the flow direction. On the other hand, stretched polymer chains may not have sufficient time to undergo the structuring steps, which give rise to fibrillar morphology. In the last decades, several authors have proposed a combined criterion based on both a critical shear rate and a critical mechanical work, which guaranties adequate time for molecular structuring.

Hierarchical Structure of iPP During Injection Molding Process with Fast Mold Temperature Evolution.

Mold surface temperature strongly influences the molecular orientation and morphology developed in injection molded samples. In this work, an isotactic polypropylene was injected into a rectangular mold, in which the cavity surface temperature was properly modulated during the process by an electrical heating device. The induced thermo-mechanical histories strongly influenced the morphology developed in the injection molded parts.

Replication of Micro- and Nanofeatures in Injection Molding of Two PLA Grades with Rapid Surface-Temperature Modulation.

The production by injection molding of polymeric components having micro- and nanometrical surfaces is a complex task. Generally, the accurate replication of micro- and nanometrical features on the polymeric surface during the injection-molding process is prevented by of the low mold temperature adopted to reduce cooling time. In this work, we adopt a system that allows fast heating of the cavity surface during the time the melt reaches the cavity, and fast cooling after heater deactivation.

Mechanical Properties Distribution within Polypropylene Injection Molded Samples: Effect of Mold Temperature under Uneven Thermal Conditions.

The quality of the polymer parts produced by injection molding is strongly affected by the processing conditions. Uncontrolled deviations from the proper process parameters could significantly affect both internal structure and final material properties. In this work, to mimic an uneven temperature field, a strong asymmetric heating is applied during the production of injection-molded polypropylene samples.

Design and production of gentamicin/dextrans microparticles by supercritical assisted atomisation for the treatment of wound bacterial infections.

In this work, the supercritical assisted atomisation (SAA) is proposed, for the first time, for the production of topical carrier microsystems based on alginate-pectin blend. Gentamicin sulphate (GS) was loaded as high soluble and hygroscopic antibiotic model with poor flowability. Particularly, different water solutions of GS/alginate/pectin were processed by SAA to produce spherical microparticles (GAP) of narrow size (about 2 μm).