One-step synthesis and characteristics of LiOH-castor oil based stable polyurethane foam

Bio-based polyester-polyurethane foams: synthesis and degradability by Aspergillus niger and Aspergillus clavatus

In this article, the degradability by Aspergillus niger and Aspergillus clavatus of three bio-based polyurethane (PU) foams is compared to previous degradability studies involving a Pseudomonas sp. bacterium and similar initial materials (Spontón et al. in Int. Biodet. Biodeg. 85:85-94, 2013, https://doi.org/10.1016/j.ibiod.2013.05.019 ). First, three new polyester-polyurethane foams were prepared from mixtures of castor oil (CO), maleated castor oil (MACO), toluene diisocyanate (TDI), and water. Then, their degradation tests were carried out in an aqueous medium, and employing the two mentioned fungi, after their isolation from the environment. From the degradation tests, the following was observed: (a) the insoluble (and slightly collapsed) foams exhibited free hydroxyl, carboxyl, and amine moieties; and (b) the water soluble (and low molar mass) compounds contained amines, carboxylic acids, and glycerol. The most degraded foam contained the highest amount of MACO, and therefore the highest concentration of hydrolytic bonds. A basic biodegradation mechanism was proposed that involves hydrolysis and oxidation reactions.

Review on disposal, recycling and management of waste polyurethane foams: A way ahead

With the burning issue of air, land and water pollution, the premonition of looking forward towards a future devoid of any kind of oil and gas reserves has caused a paradigm shift towards recycling, recovery of any synthetic polymer and also to dispose them off environmentally. Among them are plastics such as polyethylene terephthalate and poly vinyl chloride. Polyurethane (PU) is also under the scanner to dispose of or recycle it environmentally and sustainably. PU is at present the sixth most utilized polymer all over the world with a production of nearly 18 million tonnes per annum, which roughly estimates a daily production of PU products of greater than a million of cubic metres. Its thermostable nature is one of the major reasons for its higher preference over other polymers. This review article discusses the current disposal and technologies available to recycle waste PU foams and also sheds some light on some additional work being done in the field to upgrade the existing technology. Interestingly, some methods mentioned here are probably undergoing scale-up trials runs by now. Currently, the most researched and studied ones are mechanical recycling and glycolysis. But microbial and enzymatic disposal methods can be turned into full-scale industrial recycling processes in the near future. Additionally, we can see an archetypal shift from traditional oil-based sources to the agrarian sources.

Experimental Studies of the Effective Thermal Conductivity of Polyurethane Foams with Different Morphologies

Polyurethane foam (PUF) is actively used for thermal insulation. The main characteristic of thermal insulation is effective thermal conductivity. We studied the effective thermal conductivity of six samples of PUF with different types and sizes of cells. In the course of the research, heat was supplied to the foam using an induction heater in three different positions: above, below, or from the side of the foam. The studies were carried out in the temperature range from 30 to 100 °C. The research results showed that for all positions of the heater, the parameter that makes the greatest contribution to the change in thermal conductivity is the cell size. Two open-cell foam samples of different sizes (d = 3.1 mm and d = 0.725 mm) have thermal conductivity values of 0.0452 and 0.0287 W/m⸱K, respectively, at 50 °C. In the case of similar cell sizes for any position of the heater, the determining factor is the type of cells. Mixed-cell foam (d = 3.28 mm) at 50 °C has a thermal conductivity value of 0.0377 W/m⸱K, and open-cell foam (d = 3.1 mm) at the same temperature has a thermal conductivity value of 0.0452 W/m⸱K. The same foam sample shows different values of effective thermal conductivity when changing the position of the heater. When the heater is located from below the foam, for example, mixed-cell foam (d = 3.4 mm) has higher values of thermal conductivity (0.0446 W/m⸱K), than if the heater is located from above (0.0390 W/m⸱K). There are different values of the effective thermal conductivity in the upper and lower parts of the samples when the heater is located from the side of the foam. At 80 °C the difference is 40% for the open-cell foam (d = 3.1 mm).

A study on coconut fatty acid diethanolamide-based polyurethane foams

The possibility of using coconut fatty acid diethanolamide, a derivate from coconut oil as a bio-based polyol for the synthesis of polyurethane foam was explored. The intrinsic tertiary amine moiety in this polyol (p-CFAD) endowed an auto-catalytic effect in the synthesis process of polyurethane foams, combined with a shorter cream and gelation time compared to the fossil-based polyol 3152. H-nuclear magnetic resonance (¹H-NMR) and Fourier transform infrared spectrometry (FTIR) were conducted to characterize the chemical structural features of the p-CFAD, and rheology measurement showed the shear-thinning behavior due to the branched structure. A thermal conductivity comparable to the commercial rigid polyurethane foam was achieved when 40wt% fossil-based polyol 3152 was substituted with the bio-based p-CFAD. With the increased content of the p-CFAD, a transition of the physical properties from rigid PU foam to soft PU foam was observed. Scanning electron microscopy (SEM) revealed the occurrence of the interconnected pores on the cell walls with the increase of the added p-CFAD, implying the possibility of regulating the cellular structure and foam properties via the incorporation of the p-CFAD. Results showed the feasibility of using p-CFAD as a potential polyol in the development of bio-based polyurethane foams with high performance.