Highly functional lactic acid ring‐opened soybean polyols applied to rigid polyurethane foams

Abstract

We synthesized polyols with high hydroxyl functionalities (F OH s), between 9.0 and 12.6, and characterized them with differential scanning calorimetry, thermogravimetric analysis, and size exclusion chromatography after we parametrically studied the ringopening reaction of epoxidized soybean oil with lactic acid (LA) as a function of the reaction temperature and lactic acid equivalent fraction (f LA ). An increase of only 20 C in the reaction temperature (from 80 to 100 C) caused changes in the hydroxyl number (+17.8%), F OH (-25%), viscosity (-14.0%), and oligomeric content (-24.1%). f LA mostly affected the ring-opening yield, and only for f LA values above 0.4 was possible to achieve values higher than 80%. Rigid polyurethane foams (rPUFs) were synthesized and characterized with scanning electron microscopy, dynamic mechanical analysis (DMA), and compressive mechanical tests. rPUFs with a very high specific compressive strength (7.8 kPa kg -1 m 3 ) were synthesized solely with biobased soybean oil. DMA revealed a compromised relationship between the specific compressive strength and its temperature dependence. To increase the first one, the most relevant method was to increase F OH . Instead, to increase the latter one, the OH number had to be maximized.

Nanostructured rigid polyurethane foams with improved specific thermo‐mechanical properties using bacterial nanocellulose as a hard segment

“…This behavior is similar to what the author has found in other PUF formulations. 23,32,45 On the other hand, as it can be deduced from Figure 2, this tendency was not found for the ISO route. In fact, the ΔT MAX decreased to a less extent (8.1 C) and it was not dependent of BNC concentration.…”

Polyurethane Hybrid Composites Reinforced with Lavender Residue Functionalized with Kaolinite and Hydroxyapatite

“…Increasingly stringent environmental requirements for polymeric materials have led to the development of research to improve their mechanical and physical properties by adding ingredients of natural origin [ 11 ]. Due to the low price and ecological aspects, special attention is paid to materials of wood and plant origin [ 12 ]. One of the methods of modification of rigid PUR foams is the use of bio-fillers which affect their environmentally friendly character.…”

Compressive behavior of rigid polyurethane foams nanostructured with bacterial nanocellulose at low and intermediate strain rates

“…Several studies have also emphasized that the use of nanostructured foams could improve the specific mechanical properties of the material . In this regard, nanocellulose is a promising candidate in the development of sustainable, nontoxic, and low density RPUFs with enhanced mechanical properties . Most of the aforementioned studies have been aimed at investigating the synthesis of the nanostructured RPUFs with little focus on the strain‐rate dependence of the mechanical properties.…”