Application of Walnut Shells-Derived Biopolyol in the Synthesis of Rigid Polyurethane Foams

Abstract

This study aimed to examine rigid polyurethane (PUR) foam properties that were synthesized from walnut shells (WS)-based polyol. The Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the liquefaction of walnut shells was successfully performed. The three types of polyurethane (PUR) foams were synthesized by replacement of 10, 20, and 30 wt% of a petrochemical polyol with WS-based polyol. The impact of WS-based polyol on the cellular morphology, mechanical, thermal, and insulating characteristics of PUR foams was examined. The produced PUR foams had apparent densities from 37 to 39 kg m−3, depending on the weight ratio of WS-based polyol. PUR foams that were obtained from WS-based polyol exhibited improved mechanical characteristics when compared with PUR foams that were derived from the petrochemical polyol. PUR foams produced from WS-based polyol showed compressive strength from 255 to 310 kPa, flexural strength from 420 to 458 kPa, and impact strength from 340 to 368 kPa. The foams that were produced from WS-based polyol exhibited less uniform cell structure than foams derived from the petrochemical polyol. The thermal conductivity of the PUR foams ranged between 0.026 and 0.032 W m−1K−1, depending on the concentration of WS-based polyol. The addition of WS-based polyol had no significant influence on the thermal degradation characteristics of PUR foams. The maximum temperature of thermal decomposition was observed for PUR foams with the highest loading of WS-based polyol.

Rigid Polyurethane Foams Reinforced with POSS-Impregnated Sugar Beet Pulp Filler

“…PUR composite foams were synthesized according to the procedure described previously [43]. The selected amount of beet pulp (BP) filler was added to the polyol system.…”

The Impact of Ground Tire Rubber Oxidation with H2O2 and KMnO4 on the Structure and Performance of Flexible Polyurethane/Ground Tire Rubber Composite Foams

“…Such a phenomenon is commonly observed and is driven by economic and ecological factors. The introduction of such materials could noticeably reduce the use of conventional, petroleumbased raw materials required to manufacture polyurethanes [7]. Among the potential filler candidates for polyurethane foams are the following: polyurethane foam scraps [8], waste lignocellulose fillers [9,10], textiles [11], eggshell waste [12] and rubber wastes [13].…”

Rigid Polyurethane Foams Based on Bio-Polyol and Additionally Reinforced with Silanized and Acetylated Walnut Shells for the Synthesis of Environmentally Friendly Insulating Materials

“…The properties of WS-based polyol have been widely discussed in our previous study [ 11 ]. The selected properties of bio-polyol and polyester polyol (STEPANPOL PS-2352) are shown in Table 2 .…”

“…Bio-polyols derived from certain types of cellulosic sources, such as spent coffee [ 8 ], cassava residue [ 9 ] or jute fibers [ 10 ] have been examined for the synthesis of PUR materials. In our previous work, PUR foams were prepared using the bio-polyol derived from lignocellulosic walnut shells (WS) [ 11 ]. It has been shown that due to the rich organic nature (~50% of lignin, ~24% of cellulose and ~24% of hemicellulose) [ 12 , 13 ], WS can be successfully applied for the production of bio-polyols for the synthesis of PUR foams.…”

“…Unfortunately, a common phenomenon observed after the synthesis of PUR foams from bio-polyols is the deterioration of mechanical parameters of these materials [ 11 ]. Many previous studies have shown that the incorporation of a selected amount of fillers with both, organic or inorganic nature, helps to improve the mechanical characteristic of polymeric composites [ 14 , 15 ].…”