Bioactive and Biodegradable Polycaprolactone-Based Nanocomposite for Bone Repair Applications

This study investigated the relationship between the structure and mechanical properties of polycaprolactone (PCL) nanocomposites reinforced with baghdadite, a newly introduced bioactive agent. The baghdadite nanoparticles were synthesised using the sol-gel method and incorporated into PCL films using the solvent casting technique. The results showed that adding baghdadite to PCL improved the nanocomposites' tensile strength and elastic modulus, consistent with the results obtained from the prediction models of mechanical properties. The tensile strength increased from 16 to 21 MPa, and the elastic modulus enhanced from 149 to 194 MPa with fillers compared to test specimens without fillers. The thermal properties of the nanocomposites were also improved, with the degradation temperature increasing from 388 °C to 402 °C when 10% baghdadite was added to PCL. Furthermore, it was found that the nanocomposites containing baghdadite showed an apatite-like layer on their surfaces when exposed to simulated body solution (SBF) for 28 days, especially in the film containing 20% nanoparticles (PB20), which exhibited higher apatite density. The addition of baghdadite nanoparticles into pure PCL also improved the viability of MG63 cells, increasing the viability percentage on day five from 103 in PCL to 136 in PB20. Additionally, PB20 showed a favourable degradation rate in PBS solution, increasing mass loss from 2.63 to 4.08 per cent over four weeks. Overall, this study provides valuable insights into the structure-property relationships of biodegradable-bioactive nanocomposites, particularly those reinforced with new bioactive agents.

Cold plasma treatment to prepare active polylactic acid/ethyl cellulose film using wheat germ peptides and chitosan

In this study, the surface of the polylactic acid/ethyl cellulose (PLA/EC) blend film was modified by dielectric barrier discharge (DBD) plasma treatment to facilitate the spin-coating of chitosan (CH) and wheat germ bioactive peptides (PEP) obtained from enzymatic hydrolysis of defatted wheat germ protein isolate on the surface of the film. The suitable plasma treatment condition was 5 min at 20 kV according to ATR-FTIR, AFM, SEM, water angle contact, and water solubility results. Increasing the surface roughness and oxygen-containing functional groups (CO and -OH) improved coating by PEP and CH. The PEP-coated film had better antioxidant activity than CH-PEP and CH-coated films. The results of antimicrobial activity demonstrated that PEP-coated film could reduce the growth of gram-negative bacteria (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). The PEP-coated film had competitive antibacterial properties with CH-coated. Hence, the obtained PEP-coated PLA/EC film could be a promising candidate for antioxidant and antibacterial food packaging.

Toward the development of polyethylene photocatalytic degradation

In this research, the photocatalytic degradation performance in a commercial low-density polyethylene (LDPE) film was investigated in the presence of zinc oxide (ZnO) nanoparticles grafted with two amounts of polyacrylamide. Fourier-transform infrared spectroscopy (FTIR) besides thermogravimetric analysis (TGA) test results reinforced the successful grafting of polyacrylamide to the extent of 10 and 39 wt.% on the ZnO nanoparticles. The photocatalytic degradation of the films under ultraviolet (UV) radiation was evaluated by characterizing the mechanical properties, weight loss, and morphology. The UV absorption and emission for ZnO nanoparticles were increased after grafting with 10% polyacrylamide. The tensile strength of the nanocomposite films increased with the incorporation of nanoparticles. The presence of ZnO nanoparticles in LDPE films increased the rate of degradation after 200 h of irradiation. The polyacrylamide grafting improved the dispersion of ZnO particles in LDPE matrix, whereas the increase of grafting extent from 10 to 39 wt.% reduced the photocatalytic performance of ZnO nanoparticles.

Using the Equivalent Fiber Approach in Two-Scale Modeling of the Elastic Behavior of Carbon Nanotube/Epoxy Nanocomposite

In this study, the mechanical behavior of epoxy/carbon nanotubes (CNTs) nanocomposite is predicated by a two-scale modeling approach. At the nanoscale, a CNT, the interface between the CNT and the matrix and a layer of the matrix around the CNT are modeled and the elastic behavior of the equivalent fiber (EF) has been identified. The CNT/epoxy interface behavior is modeled by the Park⁻Paulino⁻Roesler (PPR) potential. At the microscale, the EFs are embedded in the matrix with the extracted elastic properties from the nanoscale model. The random pattern has been used for the dispersing of EFs in the representative volume element (RVE). The effect of CNTs agglomeration in the epoxy matrix has also been investigated at the micro level. The Young's modulus of the nanocomposite was extracted from simulation of the RVE. CNT/epoxy nanocomposites at four different volume fractions were manufactured and the modeling results were validated by tensile tests. The results of the numerical models are in good agreement with the experiments and micromechanics theory, and by considering agglomeration of CNT in the model, the modeling results match with the experiments.