How much do nanoparticle fillers improve the modulus and strength of polymer foams?

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.

Section: Resultsmentioning

confidence: 79%

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

Herrán

Amalvy

Chiacchiarelli

2019

“…In a recent study by Gimenez et al ., it was found that the development of RPUFs from bacterial nanocellulose (BNC) may result in a relevant increase in its specific mechanical properties. 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 .…”

Section: Introductionmentioning

confidence: 99%

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

Chiacchiarelli

Cerrutti

Flores‐Johnson

2019

Nanocellulose reinforced foams are lightweight with improved mechanical properties; however, the strain‐rate effect on their mechanical response is not yet fully understood. In this work, rigid polyurethane foams (PUFs) nanostructured with bacterial nanocellulose at 0.2 wt % (BNCF) and without it (PUF) are synthesized and subjected to compression tests at different strain rates. The BNC acts as a nucleation agent, reducing the cell size but maintaining a similar apparent density of 40.4 ± 3.3 kg m−3. Both BNCF and PUF exhibit strain‐rate effect on yield stress and densification strain. The BNCF exhibits localized progressive crushing and reduced friability, causing a remarkable recovery in the transverse direction. Numerical simulations show that functionally graded foams subjected to impact could be designed using different layers of PUF and BNCF to vary energy absorption and acceleration rate. The results presented herein warrant further research of the mechanical properties of nanostructured foams for impact applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48701.

“…Our research group has already published several articles regarding the synthesis and functionalization of BNC nanoparticles . As noticed by a recent review, the formulation of PUFs reinforced with CNC has been previously studied. On the other hand, so far, no publication has dealt with the incorporation of BNC in a PUF formulation.…”

Section: Introductionmentioning

confidence: 99%

Improved specific thermomechanical properties of polyurethane nanocomposite foams based on castor oil and bacterial nanocellulose

Gimenez

Leonardi

Cerrutti

et al. 2017

Bacterial nanocellulose (BNC) was used to synthesize polyurethane foams (PUFs) prepared from castor oil polyol and MDI diisocyanate using water as the blowing agent. The BNC reacted with the isocyanate, increasing the weight content of urethane hard segments (HS). It did not behave as a nucleation agent, forming a nanometric distribution of cells within the struts followed by a reduction of the apparent density (−7.6%) and a relevant increase of cell size in the growth direction (+37.9%). An alignment of the BNC parallel to the cell walls was observed, producing a nanocomposite with a higher reinforcement weight fraction in that area. At only 0.2 wt %, the BNC behaved as a nanostructured reinforcement, improving the specific compression modulus and strength by +4.67% and +23.6%, respectively, as well as the thermomechanical properties, with an improvement of the specific E′ at 30 °C of +52.4%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44982.