This paper depicts characteristics of degradation of walls of bioreactors made of polymethylmethacrylate (PMMA) which was used to culture algae. The degradation processes take place stimulated by lighting of external surface and interaction with cultured species on internal surface. Results presented are representative for degradation of a bioreactor tube after the 4-year cultivation of Chlorella sp. Microscopic observations, roughness and transmission tests showed that changes have occurred on the inner surface. The result of use is a decrease in transmission and an increase in roughness. Microscopic observations showed that particles remained after culture, especially in cracks.

This research introduces a new hydroxyapatite-based composite, designed as a bone-implant scaffold—easy, quick, economical, and closely mimicking the structure of natural bone. Additive manufacture was used to print bioactive material to form a scaffold structure. Thus, during the experimental research, three different composite materials were made to examine both their mechanical and morphological properties. Numerical modeling was used to maximize and prove the mechanical and biological performance of the HA-polymer grafts. The obtained results indicated that incorporating HA and Mg particles into a polymeric matrix allows the structure to be used in tissue engineering. Best results were obtained using a structure, designed from PLA and PHA at 30%, PHB at 25%, Mg at 5%, and HA at 10%. The composite was distinguished by its lightness, strength, and biocompatibility, making it suitable for tissue engineering.

Transparent polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET) are widely used as glass alternatives in algal bioreactors, where optical clarity and mechanical stability are crucial. However, their long-term use is limited by surface degradation processes. Photodegradation, hydrolysis, and biofilm accumulation can reduce light transmission in the 400–700 nm range essential for photosynthesis. This study examined the aging of PMMA, PC, and PET under bioreactor conditions. Samples were exposed for 70 days to illumination, culture medium, and aquatic environments. Changes in their optical transmittance, surface roughness, and wettability were analyzed. All polymers exhibited measurable surface degradation, characterized by an average 15% loss in transparency, significant increases in surface roughness, and reduced contact angles. PMMA demonstrated the highest optical stability, maintaining strong transmission in key blue and red spectral regions, while PET performed the worst, showing low initial clarity and the steepest decline. The most severe surface degradation occurred in areas exposed to the receding liquid interface, highlighting the need for targeted cleaning and/or a reduction in the size of the liquid–vapor transition zone. Overall, the results identify PMMA and recycled PMMA (PMMA_R) as durable, cost-effective materials for transparent bioreactor walls.

The structural, processing, and mechanical response of a multiphase poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) matrix to two distinct glass fillers was investigated. Glass fibers and hollow glass spheres were incorporated by melt compounding and injection molding, while the unfilled blend served as the reference. Differential scanning calorimetry, X-ray diffraction, melt-flow-rate measurements, helium pycnometry, scanning electron microscopy with deep-learning-based segmentation, tensile, and Charpy impact tests were applied. At higher filler contents, the composite-level XRD-based crystallinity index decreased to approximately 47%, whereas the Scherrer-derived PHBV (110) coherent-domain size remained within approximately 21–24 nm. Preferred orientation, assessed independently from the PHBV reflection-intensity ratio, varied with filler type and content. Glass fibers progressively reduced melt flow and were associated with an increase in tensile modulus from 2.06 to 3.45 GPa and maximum tensile stress from 23.46 to 27.32 MPa at the highest investigated fiber content. Hollow glass spheres produced a non-monotonic melt-flow response, while the reduction in tensile performance at higher contents coincided with decreasing interparticle spacing and increasing specific external polymer–glass interfacial area. Within the analyzed SEM fields, no pronounced filler-rich clustering was evident. Notched specimens remained brittle, whereas unnotched specimens retained impact strength above 10 kJ × m⁻². Overall, the two filler geometries exhibited distinct relationships among apparent melt flowability, crystalline organization, quantitative microstructural descriptors, and mechanical response.

Hemp-based mycelium composites are promising bio-based materials, but their heterogeneous structure may strongly affect mechanical performance and stability under water exposure. Six hot-pressed composites based on hemp hurds and chopped hemp straw, colonized with Pleurotus ostreatus or Ganoderma applanatum, were investigated. Depending on formulation, spent coffee grounds, thermoplastic or plasticized starch, and polymeric components introduced as granules, film flakes, or poly(ε-caprolactone) meshes were incorporated. Apparent density, water absorption, dimensional changes during immersion, compression, and three-point bending were evaluated. Mean apparent density ranged from 0.69 to 0.96 g × cm⁻³ and showed a positive specimen-level association with maximum compressive stress within the investigated plates (Spearman’s ρ = 0.845, n = 30). Because only one plate was manufactured per formulation, the observed formulation-specific property profiles represent exploratory observations within the investigated manufactured plates rather than population-level estimates of formulation effects or manufacturing reproducibility. The highest mean maximum compressive stress was 5.7 ± 1.2 MPa, whereas the highest mean maximum flexural stress and flexural modulus were 4.6 ± 2.1 MPa and 627 ± 285 MPa, respectively. Water uptake, dimensional swelling, and retention of measurable integrity followed different formulation-dependent trends; the greatest through-thickness swelling did not necessarily correspond to the fastest loss of cohesion. Overall, density, mechanical response, water uptake, dimensional deformation, and wet-state integrity were related but distinct descriptors of material performance, highlighting the need for multi-property optimization.