Search results for "artificial aging"
showing 3 items of 3 documents
Redesign of the Geometry of Parts Produced from PBT Composite to Improve Their Operational Behavior
2021
Parts produced from PBT-GF30 (70% polybutylene terephthalate +30% fiberglass) are very often used in car construction, due to the properties of this material. The current trend is to make parts with a shape designed to be as complex as possible, to take over many functions in operation. During the research, a part that is a component of the structure of car safety systems, and that must be completely reliable in operation, was analyzed. This piece has a complex shape that involves the intersection of several walls. Thus, the research aimed at establishing the optimal radius of connection between the walls (R), the ratio between the thickness of the intersecting walls (K) and the angle of in…
Polymer aging affects the bioavailability of microplastics-associated contaminants in sea urchin embryos
2022
Microplastics (MPs) in the marine environment undergo complex weathering factors that can affect their ability to interact with different coexisting environmental contaminants (termed here co-contaminants). In this study, the influence of artificially aging using UV on the sorption of a complex mixture of co-contaminants onto MPs was investigated in order to provide meaningful hypotheses on their individual and combined toxicities on sea urchin embryos. A mixture of artificially aged MPs (PS particles and PA microfibers) combined with 2,2′ ,4,4′ - tetrabromodiphenyl ether (BDE-47), or Cd or Cu, both alone and in a mix, were used to expose embryos of Paracentrotus lividus. The effects of pol…
Influence of artificial aging and ZrO2 nanoparticle-reinforced repair resin on the denture repair strength
2019
Background The purpose of this study was to evaluate the effect of aging process on the tensile strength (TS) of repaired acrylic denture base using ZrO2 nanoparticles (nano-ZrO2)-reinforced autopolymerized resin. Material and Methods A total of 240 heat-polymerized acrylic resin specimens (n=10) were prepared and sectioned creating 2 mm-repair-gap. Autopolymerized acrylic resin, pure and modified with 2.5, 5, and 7.5wt% nano-ZrO2 were used for specimens repair. TS of repaired specimens were measured using the universal testing machine after water immersion at 37oC for 2, 7 and 30 days. At each time interval, half the immersed specimens underwent thermo-cycling aging process (5000 cycles at…