The role of quinoid derivatives in the UV-initiated synergistic interaction mechanism of HALS and phenolic antioxidants

Effect of Stabilizers and Thermoplastic Polyurethane on the Properties of Three-Dimensional Printed Photochromic Wood Flour/Polylactic Acid Composites

This study was aimed at investigating the photofatigue resistance and mechanical properties of photochromic wood-plastic composites using a stabilizer complex-AH (antioxidant 1010 and hindered amine light stabilizer HALS 770)-with different contents of thermoplastic polyurethane (TPU), which was prepared by the melt-blending extrusion process and three-dimensional (3D) printing. Photofatigue resistance, mechanical property, microtopography, and thermal analyses of 3D printed samples were performed. The results showed that the difference in surface color of composites improved by 26.7% with addition of AH after 10 days of accelerated aging, whereas the mechanical strength decreased. Upon adding TPU, composites' impact strength significantly increased by 25.48% and 87.87% with 10% and 20% addition, respectively. Meanwhile, the interface compatibilities between the components were enhanced. The differential scanning calorimetry and thermogravimetric analysis results indicated that 10% TPU could improve the thermal stability of composites.

Equivalence study of extractables from single-use biopharmaceutical manufacturing equipment after X-ray or gamma irradiation

Single-use (SU) devices and assemblies used as manufacturing equipment in the biopharmaceutical industry require comprehensive qualifications. These qualifications include the assessment of compounds released from SU devices in contact with the process fluids, and how these leachable compounds potentially influence process performance, drug product quality, and patient safety. SU suppliers need to provide comprehensive qualification data for several parameters, for both new products and product changes, such as changes in the sterilization process applied to the SU device. The introduction of X-ray irradiation as an alternative to the currently used and established gamma irradiation of SU devices represents a situation where robust data is required to demonstrate equivalency between these two radiation technologies. Here, we present the results of a comprehensive extractables study for three SU components, bags, tubing, and sterilizing grade filters, evaluated after X-ray and gamma-ray irradiation. The selected study conditions were set up to allow a direct comparison of the results from the two sterilization methods, and to allow conclusions to be made on the impact of irradiation type on the polymers and their additives. Orthogonal analytical methods are applied to identify and quantify all organic compounds present. The data package provided here supports risk assessments for application of irradiated SU equipment in biopharmaceutical manufacturing. The formation of reaction products and the fundamental chemical pathways are discussed and found to be independent of the irradiation type. The results demonstrate the equivalency of both irradiation methods for extractables from plastic components used in pharmaceutical and biopharmaceutical manufacturing.

Co-intercalated layered double hydroxides as thermal and photo-oxidation stabilizers for polypropylene

An elegant and efficient approach consisting in the co-intercalation of stabilizing molecular anions is described here. The thermal stabilizer calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate] (Irganox 1425, MP-Ca) and a photo-oxidation stabilizer (hindered amine light stabilizer, HALS) are co-intercalated into the interlayer regions of layered double hydroxides (LDH) in a one-step coprecipitation. These hybrid organic-inorganic materials are successively dispersed in polypropylene to form H _n M _{n '}-Ca₂Al/PP composite films (with H = HALS and M = MP) through a solvent casting method. The corresponding crystalline structure, chemical composition, morphology as well as the resistance against thermal aging and photo-oxidation are carefully investigated by various techniques. The results show that the powdered H _n M _{n '}-Ca₂Al-LDHs hybrid materials have a much higher thermal stability than MP-Ca and HALS before intercalation. In addition, the H _n M _{n '}-Ca₂Al/PP composites exhibit a higher overall resistance against thermal degradation and photo-oxidation compared to LDHs intercalated with only HALS or MP. This underlines the benefit of the co-intercalation. The co-intercalated LDH materials pave a new way in designing and fabricating high-performance multifunctional additives for polymers.