The role of polymeric nanofibers on the mechanical behavior of polymethyl methacrylate resin

Effect of poly (ethylene glycol) on 3D printed PLA/PEG blend: A study of physical, mechanical characterization and printability assessment

The growing popularity of additive manufacturing in the science, industry is associated with high-quality products for futuristic applications. This study presents an in-depth characterization and analysis of the effect of poly (ethylene glycol) (PEG) having molecular weight 6000 g/mol used with various concentrations (1%,3%,5%) to modify the 3D printed Polylactide (PLA) part. The influence of PEG on the morphology, structure, thermal, wettability and mechanical properties of the 3D-printed PLA/PEG part was investigated. Herein, the mechanical property of injection moulding, 3D printed specimens, and finite element analysis (FEA) simulation results were also compared. The structure and properties of PLA/PEG blends were different from those of virgin PLA. By DSC analysis, it was found that the glass transition temperature (T_g) and cold crystallization temperature decreased in the case of the PLA/PEG blend. From TGA it was observed that PLA/PEG blend was thermally stable. It was shown that with the addition of PEG into PLA the tensile strength and young's modulus decrease, whereas elongation percentage and impact strength increase predominantly. The contact angle results indicate that the addition of PEG lowers the contact angle value of the PLA/PEG blend (from 69.32 ± 1.4° to 45.67 ± 1.2°) and increases surface wettability. With 5% PEG loading, PLA/PEG blend showed optimum structural and mechanical properties together with simple processibility.

Dual-jet electrospun PDLGA/PCU nonwovens and their mechanical and hydrolytic degradation properties

A dual-jet electrospinning was used to mix a different hydrophilicity poly(carbonate urethanes) (PCUs) nanofibers with a biodegradable poly(D,L-lactide-co-glycolide) (PDLGA) copolyester microfibers. As a result, PDLGA/PCU partially degradable nonwovens consisting of an interlaced of both components fibers were obtained. In order to examine the hydrolytic degradation process of polyester fraction, as well as changes that occurred in the mechanical properties of the whole nonwovens, gel permeation chromatography, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry and scanning electron microscopy as well as static tensile test were performed. Obtained results showed that for the introduction of more hydrophobic PCU nanofibers (ChronoSil), the process of copolyester chain scission slowed down and the erosion mechanism proceeded in bulk. Unexpectedly, even greater deceleration of PDLGA fibers degradation was observed in case of more hydrophilic PCU (HydroThane), and erosion mechanism changed to surface. Enhancement the affinity of the whole nonwoven to the water, manifested by strong water uptake, facilitated the diffusion processes of both: water and acid degradation by-products, which limited autocatalysis reactions of the hydrolysis of ester bonds. On the other hand, strength tests showed the synergy in the mechanical characteristics of both components. Presented method allows influencing the mechanism and rate of polyester degradation without changing its chemical composition and physical properties, affecting only the physical interactions between the nonwoven and the degradation environment, and thus, on diffusion processes. Obtained partially degradable materials possessed also time prolonged functional properties, compared to the copolyester-only nonwoven itself, thus could be considered as promising for biomedical applications e.g. in drug release systems, implants or surgical meshes for supporting soft tissues.