Effects of TS-1 zeolite structures on physical properties and enzymatic degradation of Poly (butylene succinate) (PBS)/TS-1 zeolite hybrid composites

Preparation of Titania-Silica Composite Aerogel at Atmospheric Pressure and Its Catalytic Performance in the Synthesis of Poly (Butylene Succinate)

Titanates are widely used in the synthesis of polyesters, such as Poly (butylene succinate) (PBS), due to their excellent catalytic activity for polycondensation. However, the hydrolysis sensitivity of titanate and side reactions at high temperatures restrict the further improvement of the molecular weight of polyesters and lead to the high content of end carboxyl group content in the products. In this work, we prepared titania-silica composite aerogels with resistance to hydrolysis and large specific surface area, which were further explored as an efficient catalyst for polycondensation reactions. A series of titania-silica composite aerogel catalysts for PBS polycondensation were successfully prepared by the sol-gel method. The influence of a Ti/Si ratio on the surface morphology and structure of the aerogels was examined. Titania-silica composite aerogel exhibits the surface characteristics of high specific surface area and high Lewis acid content. The specific surface area of titania-silica composite aerogels can reach 524.59 m²/g, and the Lewis acid content on the surface can reach 370.29 μmol/g. Furthermore, the catalytic performance for the polycondensation reaction of PBS was investigated. The intrinsic viscosity of PBS synthesized by catalysis with the composite catalyst with a Ti/Si ratio of 9/1 reaches 1.74 dL/g, with the M_n of 7.72 × 10⁴ g/mol. The hydrolysis resistance stability of the titania-silica composite aerogel is greatly improved compared with traditional tetrabutyl titanate (TBT), and the end carboxyl group content of PBS is effectively reduced to lower than 30 mol/ton.

A Review on Properties and Application of Bio-Based Poly(Butylene Succinate)

Researchers and companies have increasingly been drawn to biodegradable polymers and composites because of their environmental resilience, eco-friendliness, and suitability for a range of applications. For various uses, biodegradable fabrics use biodegradable polymers or natural fibers as reinforcement. Many approaches have been taken to achieve better compatibility for tailored and improved material properties. In this article, PBS (polybutylene succinate) was chosen as the main topic due to its excellent properties and intensive interest among industrial and researchers. PBS is an environmentally safe biopolymer that has some special properties, such as good clarity and processability, a shiny look, and flexibility, but it also has some drawbacks, such as brittleness. PBS-based natural fiber composites are completely biodegradable and have strong physical properties. Several research studies on PBS-based composites have been published, including physical, mechanical, and thermal assessments of the properties and its ability to replace petroleum-based materials, but no systematic analysis of up-to-date research evidence is currently available in the literature. The aim of this analysis is to highlight recent developments in PBS research and production, as well as its natural fiber composites. The current research efforts focus on the synthesis, copolymers and biodegradability for its properties, trends, challenges and prospects in the field of PBS and its composites also reviewed in this paper.

Evaluation efficiency of Iranian natural zeolites and synthetic resin to removal of lead ions from aqueous solutions

Heavy metal such as Pb2+ (lead ions) has high toxicity potential, and it can be dangerous for public health and environment. The ion exchange process is one of the methods that can be used for Pb2+ removal from aqueous solutions. The aim of this study was to investigate the removal efficiency of Pb2+ from the synthetic aqueous solutions using Iranian natural zeolite (INZ) (Clinoptilolite) in comparison with a synthetic resin (SR). In this study, the removal of Pb2+ from aqueous solution investigated by INZ and synthetic resin under different experimental conditions. Parameters like initial Pb2+ concentration, contact times, adsorbent dosage, pH and size particles of INZ, and best-fitted isotherm were studied. The results showed that the most removal efficiency of Pb2+ with INZ was obtained at pH 3–5, contact time 15–60 min, adsorbent dosage 20–50 g/L, Pb2+ initial concentration 25 mg/L, and the removal efficiency was increased with decreasing INZ particle size. The high removal of Pb2+ with SR was at pH 4–6, for 25 mg/L initial Pb2+ concentration at 15–60 min and 5–10 g/L SR. Isotherms study with ISOFT software indicates that the Freundlich and Langmuir isotherms expression provides the best fit for Pb2+ sorption by INZ and SR, respectively. This study indicated that for Pb2+ ion removal, the SR was more efficient than INZ for high concentration solutions; however, in low concentration of Pb2+, the removal efficiency was approximately equal.

Selection of the optimum 3D-printed pore and the surface modification techniques for tissue engineering tracheal scaffold in vivo reconstruction

The influences of pore sizes and surface modifications on biomechanical properties and biocompatibility (BC) of porous tracheal scaffolds (PTSs) fabricated by polycaprolactone (PCL) using 3D printing technology. The porous grafts were surface-modified through hydrolysis, amination, and nanocrystallization treatment. The surface properties of the modified grafts were characterized by energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The materials were cocultured with bone marrow mesenchymal stem cells (BMSCs). The effect of different pore sizes and surface modifications on the cell proliferation behavior was evaluated by the cell counting kit-8 (CCK-8). Compared to native tracheas, the PTS has good biomechanical properties. A pore diameter of 200 μm is the optimum for cell adhesion, and the surface modifications successfully improved the cytotropism of the PTS. Allogeneic implantation confirmed that it largely retains its structural integrity in the host, and the immune rejection reaction of the PTS decreased significantly after the acute phase. Nano-silicon dioxide (NSD)-modified PTS is a promising material for tissue engineering tracheal reconstruction. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 360-370, 2019.