Bioinspired Electropun Fibrous Materials Based on Poly-3-Hydroxybutyrate and Hemin: Preparation, Physicochemical Properties, and Weathering

The development of innovative fibrous materials with valuable multifunctional properties based on biodegradable polymers and modifying additives presents a challenging direction for modern materials science and environmental safety. In this work, high-performance composite fibrous materials based on semicrystalline biodegradable poly-3-hydroxybutyrate (PHB) and natural iron-containing porphyrin, hemin (Hmi) were prepared by electrospinning. The addition of Hmi to the feed PHB mixture (at concentrations above 3 wt.%) is shown to facilitate the electrospinning process and improve the quality of the electrospun PHB/Hmi materials: the fibers become uniform, their average diameter decreases down to 1.77 µm, and porosity increases to 94%. Structural morphology, phase composition, and physicochemical properties of the Hmi/PHB fibrous materials were studied by diverse physicochemical methods, including electronic paramagnetic resonance, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, elemental analysis, differential scanning calorimetry, Fourier-transformed infrared spectroscopy, mechanical analysis, etc. The proposed nonwoven Hmi/PHB composites with high porosity, good mechanical properties, and retarded biodegradation due to high antibacterial potential can be used as high-performance and robust materials for biomedical applications, including breathable materials for wound disinfection and accelerated healing, scaffolds for regenerative medicine and tissue engineering.

Material Monitoring of a Composite Dome Pavilion Made by Robotic Coreless Filament Winding

A hemispherical research demonstration pavilion was presented to the public from April to October 2019. It was the first large-scale lightweight dome with a supporting roof structure primarily made of carbon- and glass-fiber-reinforced composites, fabricated by robotic coreless filament winding. We conducted monitoring to ascertain the sturdiness of the fiber composite material of the supporting structure over the course of 130 days. This paper presents the methods and results of on-site monitoring as well as laboratory inspections. The thermal behavior of the pavilion was characterized, the color change of the matrix was quantified, and the inner composition of the coreless wound structures was investigated. This validated the structural design and revealed that the surface temperatures of the carbon fibers do not exceed the guideline values of flat, black façades and that UV absorbers need to be improved for such applications.

A spectrophotometric analysis of extraoral aging conditions on the color stability of maxillofacial silicone

Context:

Surveys have reported color fading as the most frequent reasons patients given for disliking their prostheses.

Aim:

The aim of the study is to compare the color variation between two maxillofacial silicone elastomers after subjecting them to extraoral aging conditions.

Subjects and Methods:

A total of 80 samples were made from M511 Maxillofacial Rubber (Part A: Part B = 10:1) and Z004 Platinum Silicone Rubber (Part A: Part B = 1:1) and divided into two main Groups A and B (40 each). These main groups were then subdivided into five subgroups (A₁B₁, A₂B₂, A₃B₃, A₄B₄, and A₅B₅) (n = 8); outdoor weathering, acidic perspiration, sebum (for 6 months), and neutral soap and disinfectant (for 30 h), respectively. Baseline L*a*b* values were recorded. The samples were subjected to the extraoral aging conditions, and the L* a*b* values were recorded after the aging period using a spectrophotometer.

Statistical Analysis:

The intergroup comparison was done by Kruskal–Wallis test, whereas the intragroup comparison was done by Mann–Whitney test.

Results

All groups exhibited visually detectable, mean color differences that ranged from 3.06–5.21, except for A₄B₄. There was no statistical significance between the two materials when subjected to extraoral aging conditions.

Conclusions:

Visually perceptible and clinically unacceptable color changes occur when exposed to various extraoral aging conditions except for neutral soap solution immersion, for which values of Δ E* were clinically acceptable (ΔE < 3). It can be said for all practical purposes, clinically, the choice between M511 Maxillofacial Rubber (Part A: Part B = 10:1) and Z004 Platinum Silicone Rubber (Part A: Part B = 1:1) would yield more or less the same results, with unacceptable norms in terms of color stability under extraoral aging conditions.