No abstract

Polyols with the hydroxyl value OHV from 290 to 318 mg KOH/g are synthesized from rapeseed, sunflower seed, flaxseed, or coconut oils by the way of their: (1) transesterification with triethanolamine or (2) amidization with diethanolamine. The influence of water as the blowing agent on the storage stability of the polyol premix system is assessed from values of the polyol premix system pH, acid value, and variations in such parameters as cream and gel time. Water-blown polyisocyanurate (PIR) foams (150 · II × 300; II—isocyanate index) characterized by good mechanical characteristics, dimensional stability at 70°C and at relative humidity RH = 95% as well as by a very low water absorbance, are obtained. The optimal physical and mechanical properties of water-blown PIR foams are achieved at the isocyanate index values 150—200. The values of the solubility parameter δ and normalized cohesion energy Ecoh.norm. for the groups and blocks, incorporated in the polymer matrix, are calculated. A detailed experimental analysis has proved that the water-blown PIR foams from vegetable oil polyols possess competitive physical and mechanical properties to those exhibited by the traditional petrochemical origin foams. The optimal physical and mechanical properties suitable for practical applications, are achieved at the isocyanate index values 150<II<200.

A series of polyurethane-polyisocyanurate (PU-PIR) foams synthesized from PET-waste-derived aromatic polyester polyols (APP) was studied using thermogravimetric analysis, Cone calorimeter and burning tests. The effect of chemical structure of the APP containing fragments of glycerol, adipic acid, poly(propylene glycol) or hexanediol on thermal stability and flame resistance of the PU-PIR foams was elucidated. PU-PIR foams prepared from APP containing fragments of glycerol and/or adipic acid had higher thermal stability and lower weight loss at 330 °C. The foams based on APP derived from industrial PET waste were characterized by relatively low heat release and low smoke production. The presence of the fragments of the functional additives glycerol and/or adipic acid in the structure of APP used for production of PU-PIR foams, marginally decreased the heat release and slightly increased the smoke production.

http://dx.doi.org/10.5755/j01.ms.17.3.588

Polyols were synthesized from castor oil with diethanolamine and triethanolamine at the molar ratios from 1:1 M to 1:3 M with the total hydroxyl value and amino value in the range from 291 to 512 mg KOH/g. Bio-based rigid polyurethane foams with good mechanical properties, a high closed-cell content and the renewable content in the range from 25.0 to 35.6 wt% were obtained. Polyurethane coatings’ tensile strength and modulus of elasticity are higher for the samples obtained from castor oil/diethanolamine polyols, but the highest elongation at break is for the polyurethane from castor oil/triethanolamine polyols. In the temperature range from 150°C to 350°C, the polyurethanes from castor oil/triethanolamine have lower weight losses than the polyurethane from castor oil/diethanolamine polyols. The presence of polyethylene glycol enhances the degradability of the bio-based polyurethane foams in the presence of fungi.

Studies on the effect of the foams’ polymeric matrix’ properties on the tension and compression properties of pour rigid polyurethane (PUR) foams, apparent core density 65—70 kg/m3, at 296 and 77 K were carried out. PUR foams were produced by the hand mixing method from polyol systems that comprised polyether, polyester polyols, and chain extenders. To produce PUR foams, crude MDI was used, and Solkane 365 mfc/227 ea was used as a blowing agent. The molecular weight per branching unit (Mc) of the polymeric matrix of PUR foams was varied in the range 300—1150. Cohesion energy densities of the blocks forming the polymeric matrix were calculated. The effect of Mc on the formation of hydrogen bonds between the urethane groups was estimated from FTIR spectroscopy data and ratio NHbonded /NHfree. It has been found that, with increasing polymeric matrix’ Mc, the tensile strength and elongation at break of PUR foams at 296 and 77 K increases, while Young’s modulus decreases. The increase in the parameter Mc promotes the decrease in the compressive strength and modulus of elasticity of PUR foams at 296 K, while compressive strength indices at 77 K are higher for the foams, whose polymeric matrix has the highest Mc. With increasing polymeric matrix’ M c, the concentration of the urethane groups bonded with hydrogen bonds increases. Structural and mechanical properties of layered spray polyurethane foams, apparent core density approx. 48 kg/m3, having two layers and polymeric matrix’ Mc = 740 were investigated.