Effects of Physical and Chemical Modification of Sunflower Cake on Polyurethane Composite Foam Properties

Abstract

Sunflower cake (SC), which is waste during the production of sunflower oil, was selected as a modifier of properties in polyurethane (PUR) foams. The SC was chemically modified with triphenylsilanol (SC_S) and physically modified with rapeseed oil (SC_O). The influence of SC on the rheological properties of the polyol and the kinetics of foam growth were investigated. PUR foams were characterized by morphological, mechanical, and thermal analysis. The results show that the physical and chemical modification of SC contributes to the changes in the properties of the foams in different ways. Too high hydrophobicity of SC_O affects the structure deterioration, and thus the mechanical properties, and in turn, reduces the affinity for water. In turn, chemical modification with silane allows for obtaining foams with the best mechanical properties.

Waste Wood Particles from Primary Wood Processing as a Filler of Insulation PUR Foams

“…As a result, it increases the heat transfer and thus reduces the thermal insulation of this type of foam [6,34]. Similar observations in the case of the modification of closed-cell PUR foam with various types of lignocellulosic fillers were made by Strąkowska et al and Członka et al [24,39]. Additionally, as shown in the literature, such disturbances in the morphology of the PUR foam due to the introduction of the organic filler, such as straw particles, may result from poor interfacial adhesion between the polymer matrix and the filler surface, which consequently disrupts the foaming process and, as a result, the structure of modified PUR foams [40].…”

“…Moreover, the presence of the wood particles and their relatively large dimensions undoubtedly limited both the growth of the foam cells and the susceptibility of the composition to the foaming process. According to Strąkowska et al [24], the presence of fillers also limits the mobility of the polymer and the speed of the polymerization reaction. Moreover, as reported by Członka et al [39], hydroxyl groups present in lignocellulosic fillers can react with highly reactive isocyanate groups.…”

“…Authors observed that 30-60% incorporation of rapeseed cake significantly influenced the apparent density and mechanical properties. Modified sunflower cake was added to PUR foam, and it was found that the addition of plant waste had an impact on the improvement of the mechanical properties, while it did not cause a significant deterioration of the insulating properties [24]. Funabashi et al [21] researched the effect of filler types on mechanical properties of a rigid polyurethane composite.…”

Evaluation of the Performance of Bio-Based Rigid Polyurethane Foam with High Amounts of Sunflower Press Cake Particles

“…Compared to the neat PUR foam, the cream time increases by 24%, 60% and 112%, gel time by 19%, 36% and 68%, and tack-free time by 26%, 47% and 79%, all at 10 wt.%, 20 wt.% and 30 wt.% SFP filler, respectively. It was previously observed by [ 19 ] that the presence of hydroxyl groups of SFP filler can interrupt the stoichiometry of synthesis due to the reaction between OH groups of SFP filler and NCO groups of isocyanate. As a result, the higher content of NCO groups is consumed and a reduced amount of CO 2 is generated, thus slowing down the foaming process.…”

“…Disregarding the positive or negative impacts on apparent density and compression set or compressive strength of natural filler-reinforced polyurethane foams, the study [ 17 ] showed that the addition of hazelnut and walnut shells improved the thermal stability of the resulting products, while [ 18 ] revealed that chemically modified lignin used as a natural filler in polyurethane foams decreased thermal degradation at low temperatures but increased it at higher ones. Moreover, [ 19 ] highlighted that 2% of sunflower press cake particles (SFP) improved the thermal stability of polyurethane foam at all degradation stages but increased thermal conductivity by 4% and compressive strength and flexural strength by 8% and 3%, respectively. The authors thought it would be an interesting idea for press cakes to be used as natural fillers for the modification of polyurethane foams, since SFP is a by-product of sunflower oil production and it contains components which are insoluble in water.…”