Development of a rheological model for polymeric fluids based on FENE model

Rheological models for polymer solutions and melts based on the finitely extensible non-linear elastic (FENE) dumbbell theory are reviewed in this study. The FENE-P model that is a well-known Peterlin approximation of the FENE model, indicates noticeable deviation from original FENE predictions and also experimental results, especially in the transient flow. In addition, both FENE and FENE-P models have some shortcomings from the point of view of theory. To overcome these shortcomings, a new approximation of the FENE spring force has been established. It has been used to develop a modified constitutive rheological model for polymeric fluids. In the procedure of modeling, the effect of non-affine deformation is introduced into the new model. Comparison between the model predictions and experimental data presented in the literature for transient and steady shear flow of polystyrene indicates that this modified model can predict the rheological behavior of polymeric fluids with a great accuracy. The newly developed modified model could predict different slopes that can cover the behavior of most of the polymeric fluids

Photo-crosslinked gelatin-polyvinyl alcohol composite films : UV-riboflavin treatment for improving functional properties

In this study, physicochemical and structural properties of films based on gelatin (G), polyvinyl alcohol (PVA), and composite films (0PVA:1G, 1PVA:2G, 1PVA:1G, 2PVA:1G, 1PVA:0G) using photo-oxidation (in the presence of sensitizer riboflavin) were investigated. UV barrier of the UV-treated films was significantly improved as the light transmission at a wavelength of 200-350 nm was obtained from 0% to 0.7%. The photosensitizer-induced cross-linking significantly decreased water vapor permeability and solubility of the films. The results demonstrated that the mechanical properties of UV-treated films were significantly improved compared to the control sample. The tensile strength (TS) improved by increasing the gelatin content in composite films where the 1PVA:2G treatment showed the highest TS (61.13 MPa). SEM images also showed a dense and homogenous tissue in 1PVA:2G compared to the other composite films. According to DSC and FTIR results, the most efficient interactions were established for 1PVA:2G composite film. The obtained results showed the effectiveness of the photo-oxidation process in improving films' properties encouraging the use of this method in the production of biodegradable films. Practical applications In this study, according to the experiments, the photo-oxidation process with riboflavin as a sensitizer can increase the physicochemical properties of the biodegradable films by increasing the interaction between the ingredients even better than typical nylon films such as heat resistance, tensile strength, mechanical properties, and lack of UV and moisture permeability. This production technique can be tested in the industry to produce packaging with better properties

A novel biocompatible polymeric blend for applications requiring high toughness and tailored degradation rate

Finding the right balance in mechanical properties and degradation rate of biodegradable materials for biomedical applications is challenging, not only at the time of implantation but also during biodegradation. For instance, high elongation at break and toughness with a mid-term degradation rate are required for tendon scaffold or suture application, which cannot be found in each alpha polyester individually. Here, we hypothesise that blending semi-crystalline poly(p-dioxanone) (PDO) and poly(lactide-co-caprolactone) (LCL) in a specific composition will enhance the toughness while also enabling tailored degradation times. Hence, blends of PDO and LCL (PDO/LCL) were prepared in varying concentrations and formed into films by solvent casting. We thoroughly characterised the chemical, thermal, morphological, and mechanical properties of the new blends before and during hydrolytic degradation. Cellular performance was determined by seeding mouse fibroblasts onto the samples and culturing for 72 hours, before using proliferation assays and confocal imaging. We found that an increase in LCL content causes a decrease in hydrolytic degradation rate, as indicated by induced crystallinity, surface and bulk erosions, and tensile properties. Interestingly, the noncytotoxic blend containing 30% PDO and 70% LCL (PDO3LCL7) resulted in small PDO droplets uniformly dispersed within the LCL matrix and demonstrated a tailored degradation rate and toughening behaviour with a notable strain-hardening effect reaching 320% elongation at break; over 3 times the elongation of neat LCL. In summary, this work highlights the potential of PDO3LCL7 as a biomaterial for biomedical applications like tendon tissue engineering or high-performance absorbable sutures.</p

Efficient and Economic Heparin Recovery from Porcine Intestinal Mucosa Using Quaternary Ammonium-Functionalized Silica Gel

Heparin, usually isolated from porcine intestinal mucosa, is an active pharmaceutical ingredient of great material value. Traditionally, diverse types of commercial resins were employed as an adsorbent for heparin retrieval from biological samples. However, more recent years have encouraged the advent of new cost-effective adsorbents to achieve enhanced heparin retrieval. Inexpensive cationic ammonium-functionalized silica gels, monodispersed with larger surface area, porosity, and higher thermal stability, were chosen to evaluate the heparin recovery yield from porcine intestinal mucosa. We demonstrated that higher positively charged and less bulky quaternary modified silica gel (e.g., QDASi) could adsorb ~28% (14.7 mg g&minus;1) heparin from the real samples. In addition, we also determined suitable surface conditions for the heparin molecule adsorption by mechanistic studies and optimized different variables, such as pH, temperature, etc., to improve the heparin adsorption. This is going to be the first reported study on the usage of quaternary amine-functionalized silica gel for HEP uptake