Analysis of Factors Influencing the Efficiency of Catalysts Used in Waste PU Degradation

Abstract

Polyurethane (PU) is an indispensable part of people’s lives. With the development of polyurethane, the disposal of polyurethane waste has become a significant issue around the world. Conventional degradation catalysts have poor dispersion and low degradation efficiency when used in the process of solid degradation into liquid. Therefore, this paper innovatively adopts self-made core–shell nanoscale titanium catalysis, traditional alkali metal catalyst (KOH), and polyol to carry out the glycolysis of waste polyurethane (PU) pipeline foam. The homogenized nanoscale titanium catalyst coated with alcohol gel has an obvious core–shell structure. The alcohol gel not only protects the catalyst but also dissolves with the alcoholysis agent in the process of glycolysis and disperses more evenly into the alcoholysis agent to avoid the phenomenon of nanocatalyst agglomeration, so as to facilitate catalytic cracking without reducing catalyst activity. In this study, investigated and compared the production of renewable polyurethane foam via a one-step method based on use of a homogeneous core–shell nanostructured titanium catalyst vs. a traditional alkaline catalyst in terms of the properties of regenerated polyether polyols as well as of the foams produced from these polyols. The physicochemical properties of regenerated polyether polyols that were analyzed included viscosity, hydroxyl value, and average molecular weight. The regenerated polyurethane foams were characterized based on water absorption, TG, SEM, and thermal conductivity analyses. The results show that, when the addition of homogeneous titanium catalyst was T2 0.050 wt.%, the viscosity of regenerated polyether polyols was the lowest, at 5356.7 mPa·s, which was reduced by 9.97% compared with those obtained using the alkali metal catalyst (KOH). When the amount of titanium catalyst was T3 0.075 wt.%, the hard foam made of regenerated polyurethane prepared by the catalyst showed the best properties, with a compressive strength of 0.168 MPa, which is 4.76% higher than that of the foam prepared using KOH catalyst.

Study on Virtual Evaluation of Far Side Occupant Protection Based on CNCAP

“…The range of sensitivity analysis of each factor is determined, but there are still more than 200 verification conditions. Therefore, the comprehensive sensitivity analysis of each factor is further analyzed by orthogonal experimental design and range analysis [12]. Four factors including impact condition, impact angle, seat adjustment and dummy type are selected.…”

Healable, degradable polyurethane elastomers with excellent mechanical properties based on multiple hydrogen bonds

“…25 However, many studies are still based on acid or base to achieve the degradation of polyurethane, but acid or base still has a negative impact on the environment. 3,[26][27][28] This paper used polycaprolactone diol as a soft chain segment to prepare prepolymers with isophorone diisocyanate, and the adipic dihydrazide was introduced for chain extension. Simultaneously, the U 2 -diol was introduced into the polyurethane molecular chain to give the material the structural characteristics of the quadruple hydrogen bond.…”

“…Zhong et al fabricated a degradable polyurethane elastomer with excellent mechanical properties based on multiple hydrogen bond motifs of imidazolyl‐urea (IU) 24 ; Wang et al studied the degradation conditions of polyurethane by adjusting the ratio of polymer to depressor, glycol to ethanolamine, and reaction temperature 25 . However, many studies are still based on acid or base to achieve the degradation of polyurethane, but acid or base still has a negative impact on the environment 3,26–28 …”