Vegetable oil-based polyurethanes

Key words vegetable oil-based polyurethane, preparation of polyurethane, curing of polyurethane, stmcture-property relationships of polyurethane, application of polyurethane. 

In the area of material science, polyurethane has captured a unique niche of its own, instigating research in industry and across the academic field in recent times. Following its inception in the mid-1930s, its popularity has reached a pinnacle with a huge variety of applications in coatings, leathers, elastomers, sealants, composites, biomedicals and so on.  

1 Scientific publications searched by Scopus as a function of publication year. 

The salient features of vegetable oil-based polyurethanes which make 

Polyurethane elastomers are a class of specialised polymers with high reversible deformation which are characterised by high abrasion and chemical resistance, mechanical and thermal properties. The primary and essential requirements for a polyurethane elastomer are a flexible long chain oligomeric macroglycol with a molecular weight -3000-5000 g moL,  

---

Fig. 22 Respirometry of vegetable oil-based polyurethanes made from the following polyols triolein-met arrowhead), soy-HF (filled square), soy-met 180 (open diamond), soy-met 206 (open circle), and linseed met (open square). Also shown is ESO/BF3 polymer (open triangle) and soybean oil control (filled circle). Temperature was increased from 30°C to 55°C on day 71. Note that hydroxyl number of 180 has the functionality of 3.3 and that of hydroxyl 206 is 4.0. Met refers to polyol made from ESO and methanol HF refers to polyol from hydroformylation and reduced ESO. Reproduced from [152] by permission of Journal of Polymers and the Environment...

Badri, K. H. Process for the production of vegetable oil-based polyurethane polyols. Malaysia Patent MY 145094-A (2012). 

Vegetable oil-based polyurethanes have good chemical and physical properties owing to the hydrophobic nature of the triglyceride moiety. 

Vegetable oil-based polyurethanes 151 Table 6.1 A few macroglycols used in polyurethane synthesis... 

Epoxidised and hydroformylated vegetable oil-based polyurethanes leave parts of the chain dangling, which may affect the properties of the final product. However, dangling chains are not present in polyols made by ozonolysis and can therefore be used effectively in the synthesis of polyurethanes (Fig. 6.7) ... 

Vegetable oil-based polyurethanes are soluble in hydrocarbon solvents as well as in commonly used solvents. This is due to the presence of long nonpolar hydrocarbon chains and polar urethane hnkages. However, with a decrease in oil length (as discussed in Chapter 4), mixtures of aliphatic and aromatic solvents are required. Resins with an oil length below 50 are soluble in aromatic solvents. 

Polyurethanes prepared via transesterification of soybean and linseed oils with n-butanol in the presence of lipozyme (a lipase), also possess these improved properties, particularly in the case of MDI-based polyurethanes. Mechanical properties such as tensile strength, percentage elongation, elastic modulus, wear resistance, tear resistance. Shore A hardness, and thermostability of vegetable oil-based polyurethane IPNs showed significant improvement at a critical vinyl or acrylic polymer level. 

The initial degradation of vegetable oil-based polyurethanes occurs at a faster rate than in synthetic poly(propylene oxide) (PPO)-based polyurethanes, although at relatively high temperatures, PPO-based polyurethanes display a faster loss. However, the situation is reversed in an oxygen atmosphere (air). Thus, vegetable oil-based polyurethanes exhibit better oxidative thermal stability than standard PPO-based polyurethane. ... 

What different types of vegetable oil-based polyurethanes are available in the market ... 

---