Characterization and comparison of polyurethane networks prepared using soybean‐based polyols with varying hydroxyl content and their blends with petroleum‐based polyols

Abstract

Polyurethane Networks (PUNs) were synthesized using polyols derived from soybean oil, petroleum, or a blend of the two in conjunction with diisocyanate. The soybean-based polyols (SBPs) were prepared using air oxidation, or by hydroxylating epoxidized soybean oil. Some of the networks were subjected to several solvents to determine their respective swelling behavior and solubility parameters. Sol-fractions were also determined, and DMA experiments were utilized to monitor the changes in storage modulus and tan ␦ with temperature for networks with sol and with the sol extracted. A linear relationship was noted between the hydroxyl number of a SBP and the glass transition temperature of its corresponding unextracted PU network within the range of hydroxyl numbers (i.e., 55-237 mg KOH/g) and glass transition temperatures (i.e., Ϫ21-ϩ83°C) encountered in this work. This same linear relationship was realized between the weighted hydroxyl number of soy and petroleum-based polyol blends and the glass transition temperature of the resulting unextracted and extracted network PUs within the ranges utilized in this study (i.e., 44 -57 mg KOH/g, Ϫ54 -19°C).

Soy-Based Polyols and Polyurethanes

“…Normally, polyols with hydroxyl numbers <110 mg KOH/g can be synthesized via air oxidation (up to 5 days processing, no catalysts). Different methods of hydroxylation and catalytic air oxidation processes will increase the hydroxyl functionality of soy-based polyols produced from non-catalytic air oxidation described above Pechar et al, 2006). Induced air oxidation of soybean oil was also shown to produce a significant increase in the number of hydroxyl groups.…”

Synthesis and properties of multihydroxy soybean oil from soybean oil and polymeric methylene‐diphenyl‐ 4,4′‐diisocyanate/multihydroxy soybean oil polyurethane adhesive to wood

“…Recently, some works on synthesizing polyol with reactive groups have appeared in the literature. 8,9 Other efforts have been made to improve adhesion by using modified polyols, as demonstrated in a number of papers. 8,9 Somani et al 10 used cater oil to produce a PU resin for wood.…”

“…8,9 Other efforts have been made to improve adhesion by using modified polyols, as demonstrated in a number of papers. 8,9 Somani et al 10 used cater oil to produce a PU resin for wood. Kansara et al 10 refined vegetable oil into glycerol and fatty acids and then reacted it with isocyanate to evaluate its bond strength of PB.…”

“…Petrovic et al 11 mixed soybean oil with BrA, ClA, CH 3 OA, and HA to create polyols and used them to produce a PU resin. Pechar et al 9 reported PU foam from palm polyol obtained from kernel oil and glycol. Wilkes et al 9 used soybased polyol, which was prepared via oxirane ringopening reaction of epoxidized soy bean oil with methanol to make PU foam.…”

Thermal and mechanical properties of cast polyurethane resin based on soybean oil

“…These are raw materials from renewable resources, and with isocyanates they produce PUs that can compete in many aspects with those derived from petrochemicals. 1,2 Soybean oil is one of the many vegetable oils that can be converted into a polyol by various methods, such as epoxidation, 3,4 hydroformylation, 5 and ozonolysis. 6 Because of the high functionality, these polyols can also be crosslinked with diisocyanates to give rigid PUs.…”