Nuno Gama

Effect of unrefined crude glycerol composition on the properties of polyurethane foams

The aim of this study is to evaluate the possibility of using unrefined crude glycerol (CG), a byproduct of the biodiesel industry, in the production of polyurethane foams. In order to assess the suitability of this raw material for the production of polyurethane foams, two samples of crude glycerol with different compositions in glycerol, fatty acids, and methyl esters were used directly, without any pretreatment or purification. Additionally, one of these samples was also submitted to a pre-treatment step in order to evaluate the advantage of purifying the raw material and, for comparison, pure glycerol was also used to prepare polyurethane foams. Both chemical and structural characterizations of the produced foams, as well as the thermomechanical properties determined, showed that unrefined crude glycerol is a suitable ecopolyol for the production of polyurethane foams. Although the presence of fatty acids and esters affects their mechanical performance, this issue can be explored to tune the properties of the ensuing polyurethane foams. Furthermore, the evaluation of the impact of using unrefined CG on the sustainability of polyurethane foams production yielded promising results.

Polyurethane Foams: Past, Present, and Future

Polymeric foams can be found virtually everywhere due to their advantageous properties compared with counterparts materials. Possibly the most important class of polymeric foams are polyurethane foams (PUFs), as their low density and thermal conductivity combined with their interesting mechanical properties make them excellent thermal and sound insulators, as well as structural and comfort materials. Despite the broad range of applications, the production of PUFs is still highly petroleum-dependent, so this industry must adapt to ever more strict regulations and rigorous consumers. In that sense, the well-established raw materials and process technologies can face a turning point in the near future, due to the need of using renewable raw materials and new process technologies, such as three-dimensional (3D) printing. In this work, the fundamental aspects of the production of PUFs are reviewed, the new challenges that the PUFs industry are expected to confront regarding process methodologies in the near future are outlined, and some alternatives are also presented. Then, the strategies for the improvement of PUFs sustainability, including recycling, and the enhancement of their properties are discussed.

Enzymatic synthesis of poly(glycerol sebacate) pre-polymer with crude glycerol, by-product from biodiesel prodution

The biodiesel fuel technology has attracted researchers worldwide as a viable alternative to fossil fuel consumption. The biodiesel production increment has resulted in a severe waste disposal crisis, because to produce 10 Kg of biodiesel, around 1 Kg of crude glycerol is produced. Therefore, it is essential to find valuable applications for this by-product. The biodegradable polymers have attracted interest, since many of their building blocks can be obtained from renewable sources. Poly(glycerol sebacate) (PGS) is polyester elastomer with potential biomedical applications, such, the recovery of soft tissues and organs and the delivery of pharmaceutical drugs. In this study, we report the successful synthesis of pre-polymer of PGS with Candida antarctica lipase B free (CALB) and lipase B immobilized Novozym 435 (N435) with crude glycerol and pure glycerol. The pre-polymers were analyzed by mass spectrometry MALDI-Tof-MS and RMN.The biodiesel fuel technology has attracted researchers worldwide as a viable alternative to fossil fuel consumption. The biodiesel production increment has resulted in a severe waste disposal crisis, because to produce 10 Kg of biodiesel, around 1 Kg of crude glycerol is produced. Therefore, it is essential to find valuable applications for this by-product. The biodegradable polymers have attracted interest, since many of their building blocks can be obtained from renewable sources. Poly(glycerol sebacate) (PGS) is polyester elastomer with potential biomedical applications, such, the recovery of soft tissues and organs and the delivery of pharmaceutical drugs. In this study, we report the successful synthesis of pre-polymer of PGS with Candida antarctica lipase B free (CALB) and lipase B immobilized Novozym 435 (N435) with crude glycerol and pure glycerol. The pre-polymers were analyzed by mass spectrometry MALDI-Tof-MS and RMN.

Thermal Energy Storage and Mechanical Performance of Crude Glycerol Polyurethane Composite Foams Containing Phase Change Materials and Expandable Graphite

The aim of this study was to enhance the thermal comfort properties of crude glycerol (CG) derived polyurethane foams (PUFs) using phase change materials (PCMs) (2.5–10.0% (wt/wt)) to contribute to the reduction of the use of non-renewable resources and increase energy savings. The main challenge when adding PCM to PUFs is to combine the low conductivity of PUFs whilst taking advantage of the heat released/absorbed by PCMs to achieve efficient thermal regulation. The solution considered to overcome this limitation was to use expandable graphite (EG) (0.50–1.50% (wt/wt)). The results obtained show that the use of PCMs increased the heterogeneity of the foams cellular structure and that the incorporation of PCMs and EG increased the stiffness of the ensuing composite PUFs acting as filler-reinforcing materials. However, these fillers also caused a substantial increase of the thermal conductivity and density of the ensuing foams which limited their thermal energy storage. Therefore, numerical simulations were carried using a single layer panel and the thermal and physical properties measured to evaluate the behavior of a composite PUF panel with different compositions, and guide future formulations to attain more effective results in respect to temperature buffering and temperature peak delay.