polyurethanes from vegetable oils
TRANSCRIPT
Polyurethanes from Vegetable OilsPolyurethanes from Vegetable Oils
polyurethanespolyurethanes• Polyurethane (PUR and PU) is a polymerPolyurethane (PUR and PU) is a polymer composed of a chain of organic composed of a chain of organic units joined units joined
by carbamate (urethane) links. by carbamate (urethane) links. • 2 Mechanical properties eg- high tensile strength & elongation.Mechanical properties eg- high tensile strength & elongation. Thermal properties:- 40-80Thermal properties:- 40-8000c ( both long & short term application).c ( both long & short term application). Hydrolytic stability:- highest resistanceHydrolytic stability:- highest resistance to water at elevated temperature .to water at elevated temperature . Oil,grease and solvent resistance Oil,grease and solvent resistance
The major application of polyurethanes are Coatings Adhesives & sealants Elastomers, etc
characteristics of polyurethane materialscharacteristics of polyurethane materials
Why vegetable oil based polymer ?Why vegetable oil based polymer ? Vegetable oils are excellent but very heterogeneous renewable raw
materials for polyurethanes It gaining popularity due to some attractive properties related to the
specific structure of oils It concerns about the environment and sustainability. Ready availability Inherent bio degradability Some oils like tung (wood) oil have conjugated double bonds, which
tend to polymerize easily when exposed to air. Its composition and price. Price wise, soybean oil, palm oil, and rapeseed oil are the most
attractive for large-scale industrial products.
Polyurethanes are based on:Polyurethanes are based on:
Castor oilCastor oil Soybean oil Soybean oil Fatty Acid Polyols. Polyfunctional Vegetable Oil-based Polyols. Fatty Acid Polyester. Sun flower, canola,corn,etc
Urethane polymer from soybean oilUrethane polymer from soybean oil Oils and fats are triacylglycerols (triglycerides) i.e., esters of glycerin
and different fatty acids. Soy fatty acids are useful for modification of polyurethanes.Soy fatty acids are useful for modification of polyurethanes. Fatty acids can easily be converted to reactive multifunctional Fatty acids can easily be converted to reactive multifunctional
N-alkanolamides.N-alkanolamides. This modification is achieved by base catalysis of oil with This modification is achieved by base catalysis of oil with
diethanolamine to give dialkanol soyamides.diethanolamine to give dialkanol soyamides. Heat resistant Pu foams are obtained from epoxidized soybean Heat resistant Pu foams are obtained from epoxidized soybean
oil ,diethylene glycol,MDI & polyethylene glycol.oil ,diethylene glycol,MDI & polyethylene glycol. Fire resistant & dimensionally stable Pu’s are epoxidized oil, Fire resistant & dimensionally stable Pu’s are epoxidized oil,
halogenated bis phenol, TDI & phenolic resins.halogenated bis phenol, TDI & phenolic resins.
Castor Oil-based Polyurethanes. Glass transition of castor oil/pure MDI may vary with the hydroxyl
number. it is around 5oc when the isocyanate index ([NCO]100/[OH]) was increased to 120, Tg
increased. Properties of polyurethane networks could be modified by
copolymerizing with different monomers to obtain interpenetrating networks.
carbodiimide modified MDI gives Tg with castor oil of around 8oc. Particularly active in the field of interpenetrating networks with
castor oil polyurethanes was the Sperling group. Casting electro-insulating compounds based on crude MDI and filled
castor oil have been used in the electrical industry for encapsulating dry transformers
Polyurethanes from Fatty Acid Polyols. It is It is prepared either from fatty acids by transesterification of the
polyols with glycols and removing glycerin. Such polyols may have lower viscosity but also lower functionality. Properties of a polyurethane from MDI and a polyol obtained by
epoxidation and ring opening with methanol having an OH number of 173 with those made by transesterification of polyol with ethylene glycol.
If one breaks up the triglyceride structure by transesterification with methanol and removes the glycerin.
Primary hydroxyls give more thermally stable urethane bonds but in the case of EG-fatty acid polyurethane, the break up and evaporation of ethylene glycol may have taken place catalyzed by the residual tin-based esterification catalyst.
Segmented PUs from Polyfunctional Vegetable Oil-based Polyols Addition of glycerin Increasing Tg and the rigidity of the vegetable oil-
based polyurethane networks. Glass transition of the soft phase (soy-based matrix) was found to
decrease with increasing soft segment concentration (SSC). Linear Segmented Polyurethane Elastomers from Fatty Acid
Polyester Soft Segments:
Thermoplastic polyurethane elastomers are block copolymers consisting of alternating soft and hard segments.
Hard segments consisted of mixed esters of terephthalic acid and/or dimeric acid with dimerol and ethylene glycol or butane diol.
Soft segments were polytetramethylene oxide diols of a MW weight of 2000.
Effect of the polyol OH number on Tg of PUs from different oils:
Properties of Vegetable Oil-based PUsElectrical Properties: Vegetable oils are fairly non-polar compounds and as such
could be used as a substitute for petrochemical electroinsulating oils.
Electrical and mechanical properties of castor oil and soy-based polyurethanes showed excellent properties, While castor oil gave rubbery polyurethanes, soy-based compounds were glassy.
Castor oil casting compounds displayed higher permittivity.Thermal Stability : It is not high primarily due to the presence of labile
urethane groups. Standard petrochemical polyurethanes based on propylene
oxide are very unstable in the oxidative atmosphere.
Polyurethanes from polyols with primary hydroxyls are more stable than those with secondary OH
Crosslinking density increases thermal stability Ethylene glycol extended polyurethanes from fatty acid
polyols are the least stable The thermal stability of polyurethanes decreased with
crosslinking density
Hydrolytic Stability: Vegetable oils have three ester bonds susceptible to
hydrolysis The urethane bonds also may hydrolyze when exposed to
high humidity to give an amine and carbon dioxide R-NH-COOR’ + HOH -> RNHCOOH + R’OH R-NH-COOH -> RNH2 + CO2
Biodegradability:
polyurethane foams and cast polyurethanes are biodegradable.
It is desirable for packaging materials and materials intended for short useful life.
It is undesirable in engineering materials with long service life.
Polyurethane prepared from polyols from soybean oil, triolein, and linseed oil by the epoxidation route and hydroformylation using respirometry, measures the evolution of CO2 as a result of bacterial activity on the exposed powdered material in soil.
ConclusionConclusion Vegetable oils offer a variety of new structures in polyols
depending on the method of synthesis, resulting in PUs with new properties, suitable for a range of applications.
Currently, vegetable oil polyols must be used in conjunction with petrochemical polyols in flexible foams, but they could be used as sole polyols in other applications.
New structures are continually being developed and properties are being improved.
With time we can expect a dramatic increase in the use of vegetable oil-based polyols in the polyurethane field.
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References:- Holcapek, M.; Jandera, P.; Zderadicka, P.; Hruba´, L.
“Characterization of triacylglycerol &diacylglycerol composition of plant oils using high-performance liquid chromatography atmospheric pressure chemical ionization mass spectrometry”, J. Chromatogr. A 2003, 1010, 195–215.
Pryde, E. H.; Gast, L. E.; Frankel, E. N.; Carlson, K. D. “Vegetable oils and animal fats as renewable resources for plastics and coatings applications”, Polym.-Plast. Technol. Eng. 1976, 7, 1–26.
D.L.KAPLAN(ED.)”Biopolymers from Renewable resources”,springer,Medford,USA,January 1998