RIGID FOAM WITH IMPROVED INSULATING POWER

Abstract

A rigid foam or composition allowing a rigid foam to be obtained made from polyurethane and/or polyisocyanurate. The rigid foam or composition includes polyols selected from polyester polyols and polyether polyols; the polyols include: 5 to 50% of a polyester polyol A by weight relative to the total weight of the polyols; and a polyol B selected from polyester polyols B and polyether polyols B. The polyester polyol A is of general formula Rx-Ry-Z-Ry′-Rx′ in which Z is a C3 to C8 alcohol sugar chosen from glycerol, sorbitol, erythritol, xylitol, araditol, ribitol, dulcitol, mannitol and volemitol. Ry and Ry′ are diesters of formula —OOC—Cn-COO— in which n is between 2 and 34, and Rx and Rx′ are identical or different C2 to C12 monoalcohols.

Claims

1-15. (canceled)

16. A rigid foam or composition allowing a rigid foam to be obtained made from polyurethane and/or polyisocyanurate, said foam or composition comprising polyols selected from polyester polyols and polyether polyols; said polyols comprising: from 5 to 50% of a polyester polyol A by weight relative to the total weight of the polyols; and a polyol B selected from polyester polyols B and polyether polyols B; said polyester polyol A being of general formula Rx-Ry-Z-Ry′-Rx′ wherein, Z is a C3 to C8 alcohol sugar selected from glycerol, sorbitol, erythritol, xylitol, araditol, ribitol, dulcitol, mannitol and volemitol, Ry and Ry′ are diesters of formula —OOC—C.sub.n—COO— with n comprised between 2 and 34, and Rx and Rx′ are identical or different C2 to C12 monoalcohols.

17. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein the mass ratio of polyester polyol A over the polyol B is comprised between 5/95 and 50/50.

18. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein said polyester polyol A being obtained by: a first polycondensation (a) of a C3 to C8 alcohol sugar Z, selected from glycerol, sorbitol, erythritol, xylitol, araditol, ribitol, dulcitol, mannitol and volemitol; and of two identical or different C4 to C36 diacids Y and Y′ and a second polycondensation (b) of the product obtained in (a) with two identical or different C2 to C12 diols X and X′.

19. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein the diacids Y and Y′ are independently selected from butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid and mixtures thereof.

20. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein the diols X and X′ are independently selected from 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol and mixtures thereof.

21. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein said foam or composition has a cell size with a minimum diameter in the transverse direction comprised between 50 and 350 μm and/or a bulk density comprised between 22 to 60 kg/m.sup.3 and/or has a measurement of the lower thermal conductivity coefficient comprised between 18 and 30 mW/(m×K) and/or comprises 5 to 49% of a polyester polyol A by weight relative to the total weight of the polyol.

22. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein the polyester polyol A has a molecular weight comprised between 350 g/mol and 2,000 g/mol and/or a hydroxyl value from 300 to 900 mg KOH/g and/or a viscosity at 25° C. comprised from 4,000 to 25,000 mPa.Math.s

23. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein said foam has a cell size with a minimum diameter in the transverse direction comprised between 50 and 350 μm and/or a bulk density comprised between 22 and 60 kg/m.sup.3.

24. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein said foam comprises at least one reaction catalyst, at least one blowing agent, a stabiliser, at least one polyisocyanate having a functionality at least equal to 2 and, optionally, a flame retardant.

25. The rigid foam or composition allowing a rigid foam to be obtained according to claim 24, said foam being a polyisocyanate foam and comprising: 60 to 100 parts of polyols of which 5 to 50% by weight of polyester polyol A such as described in claim 1 on the weight of polyol, 100 to 700 parts of at least one polyisocyanate, 0.1 to 13 parts of at least one catalyst, 0.5 to 80 parts of at least one blowing agent, 0.2 to 8 parts of a stabiliser, and 0 to 30 parts of a flame retardant.

26. The rigid foam or composition allowing a rigid foam to be obtained according to claim 25, said foam being a polyisocyanate foam and comprising: from 70 to 100 parts of polyols of which 5 to 49% or 6 to 48% by weight of polyester polyol A such as described in claim 1 on the weight of polyol, from 120 to 650 parts of at least one polyisocyanate, from 0.5 to 12 parts of at least two catalysts, from 5 to 70 parts of at least one blowing agent, from 1 to 7 parts of a stabiliser, and from 5 to 25 parts of a flame retardant.

27. The rigid foam or composition allowing a rigid foam to be obtained according to claim 25, said foam being a polyisocyanate foam and comprising: between 80 and 100 parts of polyols of 5 to 49% or 6 to 48% by weight of polyester polyol A such as described in claim 1 on the weight of polyol, between 150 and 575 parts of at least one polyisocyanate, between 1 and 11 parts of at least two catalysts being an amine catalyst and a potassium carboxylate, between 10 and 60 parts of at least one blowing agent, between 1.5 and 6 parts of a stabiliser, and between 10 and 20 parts of a flame retardant.

28. The rigid foam or composition allowing a rigid foam to be obtained according to claim 24, said foam being a polyurethane foam and comprising: at least 1 to 100 parts of which 5 to 50% of a polyester polyol A such as described in claim 1 by weight relative to the total weight of the polyol, 150 to 500 parts of at least one polyisocyanate, 0.5 to 5 parts of at least one catalyst, 0.5 to 15 parts of at least one blowing agent, 0.2 to 5 parts of a stabiliser, and 0 to 30 parts of a flame retardant.

29. The rigid foam or composition allowing a rigid foam to be obtained according to claim 28, said foam being a polyurethane foam and comprising: from 40 to 100 parts of polyols of which 5 to 49% or 6 to 48% of a polyester polyol A such as described in claim 1 by weight relative to the total weight of the polyol, from 160 to 425 parts of at least one polyisocyanate, 0.5 to 5 parts of at least one catalyst, 0.5 to 12 parts of a chemical blowing agent and/or 0 to 60 parts of a physical blowing agent, 0.2 to 5 parts of a stabiliser, and 0 to 30 parts of a flame retardant.

30. The rigid foam or composition allowing a rigid foam to be obtained according to claim 28, said foam being a polyurethane foam and comprising: between 80 to 100 parts of polyols of which 5 to 49% or 6 to 48% of a polyester polyol A such as described in claim 1 by weight relative to the total weight of the polyol, between 180 and 375 parts of at least one polyisocyanate, 0.5 to 5 parts of at least one amine catalyst, 0.6 to 10 parts of a chemical blowing agent and/or 0.5 to 30 parts of a physical blowing agent, 0.2 to 5 parts of a stabiliser being a polyether-polysiloxane copolymer, and 0 to 30 parts of a flame retardant.

31. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein the polyol B has a hydroxyl value comprised between 80 and 800 mg KOH/g and/or a functionality greater than or equal to 2, and/or a molar mass (Mn) comprised between 50 and 4,000 g/mol and/or an acid value less than 10 mg KOH/g and/or a viscosity less than 50,000 mPa.Math.s at 25° C.

32. The rigid foam or composition allowing a rigid foam to be obtained according to claim 16, wherein: the at least one polyisocyanate is selected from toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate and mixtures thereof; and/or the at least one catalyst is selected from at least one tertiary amine, at least one potassium carboxylate and at least one triazine and mixtures thereof; and/or the at least one blowing agent is selected from chemical blowing agents selected from water, formic acid, phthalic anhydride and acetic acid and/or physical blowing agents selected from pentane, isomers of pentane, hydrocarbons, hydrofluorocarbons, hydrochlorofluoroolefins, hydrofluoro-olefins, ethers and mixtures thereof; and/or the at least one stabiliser is selected from silicone glycol copolymers, non-hydrolysable silicone glycol copolymer, polyalkylene siloxane colpolymer, methylsiloxane polyoxyalkylene colpolymer, polyether-polysiloxane colpolymer, polydimethylsiloxane polyether copolymer, polyethersiloxane, a polyether-polysiloxane copolymer, a polysiloxane-polyoxyalkylene block copolymer or mixtures thereof; and/or the at least one flame retardant is selected from Tris (1-chloro-2-propyl) phosphate, triethylene phosphate, triaryl phosphate esters, ammonium polyphosphate, red phosphorus, trishalogenaryl, and mixtures thereof.

33. The rigid foam or composition allowing a rigid foam to be obtained according to claim 32, wherein the at least one catalyst is selected from N, N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, 1,3,5-tris(3-[dimethylamino] propyl)-hexahydro-s-triazine, potassium 2-ethylhexanoate and mixtures thereof.

34. A panel or a block of rigid foam comprising a rigid foam according to claim 16.

35. A method of thermal or cryogenic insulation or a method for filling, waterproofing, sealing or improving the buoyancy of an object or of a building by the depositing or the introduction of rigid foam blocks or panels according to claim 34 or by the projection in situ of the rigid foam or of the composition allowing a rigid foam to be obtained made from polyurethane and/or polyisocyanurate, said foam or composition comprising polyols selected from polyester polyols and polyether polyols; said polyols comprising: from 5 to 50% of a polyester polyol A by weight relative to the total weight of the polyols; and a polyol B selected from polyester polyols B and polyether polyols B; said polyester polyol A being of general formula Rx-Ry-Z-Ry′-Rx′ wherein, Z is a C3 to C8 alcohol sugar selected from glycerol, sorbitol, erythritol, xylitol, araditol, ribitol, dulcitol, mannitol and volemitol, Ry and Ry′ are diesters of formula —OOC—C.sub.n—COO— with n comprised between 2 and 34, and Rx and Rx′ are identical or different C2 to C12 monoalcohols.

Description

FIGURES

[0247] FIG. 1: Change in (a) the temperature, (b) expansion profile, (c) standardised height (H/Hmax) as a function of time during the PIR foams.

[0248] FIG. 2: Change in the characteristic times (cream, thread and tack-free drying) of foaming of PIR foams according to the content of BASAB.

[0249] FIG. 3: SEM images of the PIR foam REF, magnification ×40: (a) in the direction transverse to the expansion of the foam, (b) in the direction of the expansion (from the bottom upwards).

[0250] FIG. 4: Cell diameters of PIR foam. FIG. 4A: minimum distribution of the diameter in the transverse direction; FIG. 4B: distribution of the maximum diameter in the transverse direction; FIG. 4C: minimum distribution of the diameter in the longitudinal direction; and FIG. 4D: distribution of the maximum diameter in the longitudinal direction.

[0251] FIG. 5: Distribution of the cell diameters in the direction transverse to the expansion of different PIR foams.

[0252] FIG. 6: FUR spectra of foams. FIG. 6A: REF, PU-90/10/0-KE, PU-75/25/0-KE, PU-65/35/0-KE, PU-55/45/0-KE; FIG. 6B: Reference, PU-45/55/0-KE, PU-65/35/0-KE.

[0253] FIG. 7: ATG curves of the PIR foams under reconstituted air.

[0254] FIG. 8: DTGA curves of the PIR foams under reconstituted air.

[0255] FIG. 9: Stress-strain curves of foams in the longitudinal direction from the REF to PU-35/65/0-KE.

[0256] FIG. 10: Stress-strain curves in the transverse direction for the foams REF to PU-35/65/0-KE.

[0257] FIG. 11: Change in Young's moduli in the longitudinal (at the top) and transverse (at the bottom) directions according to the content of BASAB.

EXAMPLES

I. Equipment and Method

[0258] a. Chemicals

[0259] The polyisocyanate used is 4,4′-polymeric methylenebis (phenylisocyanate) (called pMDI, commercial range Ongronat 2500 from BorsodChem). Various catalysts such as N, N-dimethylcyclohexylamine (called DMCHA) from BorsodChem, 1,3,5-tris(3-[dimethylamino] propyl)-hexahydro-s-triazine (called triazine, trade name Tegoamin C41 from Evonik), bis (2-dimethylaminoethyl) ether (called BDMAEE, trade name Lupragen N205 from BASF), 15% by weight. A solution of 2-potassium ethylhexanoate was used (called KE, trade name K-ZERO 3000 from Momentive). The flame retardant is the phosphate of tris (1-chloro-2-propyl) (TCPP) from Shekoy. The surfactant used has a polyether polysiloxane base (called PDMS, trade name TEGOSTAB® B84501 from the company Evonik). The ethylene glycol (EG) was obtained from Alfa Aesar (purity 99%). The isopentane from Inventec was used as a physical blowing agent. All of these chemicals were used as they were received without any other purification. The petrosourced polyol is an aromatic polyester polyol obtained from phthalic anhydride (Stepanpol® PS-2412, from Stepan). This polyol is used as a conventional reference and is also called petrosourced polyol in what follows. The biosourced polyester polyol (BASAB) was synthesised from sorbitol according to a protocol described hereinabove PCT/IB2017/055107. The polyester polyol BASAB results from an esterification in two steps between the sorbitol, adipic acid and 1,4-butanediol (1.4 BDO). The first step is the reaction of the sorbitol with two equivalents of adipic acid in relation to sorbitol. The second step consists of the adding of a molar equivalent of 1.4 BDO in relation to the adipic acid. The reaction was carried out in mass without a catalyst at 150° C. This specific process leads to a linear polyester-polyol. The properties of BASAB and of the petrosourced polyol are compared in Table 1.

TABLE-US-00001 TABLE 1 Comparison of the properties of the reference petrosourced polyol and of BASAB BASAB Hydroxyl Acid value Viscosity Surface Polyester value (mg (mg (25° C., Primary Secondary tension Polyol KOH/g) KOH/g) mPa .Math. s) hydroxyls hydroxyls (mN/m) Petrosourced 230-250 1.9-2.5 4,000 2 0 33.6 ± 0.9 polyol BASAB 490-510 Inf. 3 14,000 2 4 .sup. 40 ± 0.8

[0260] b. General Method for Obtaining BASAB

[0261] The reaction is carried out in a sealed Stainless steel reactor provided with a U-shaped stirring blade, a Dean Stark having an outlet at the top of the condenser in order to connect thereto a vacuum pump and a bottom outlet for recovering the condensates, an inlet and an outlet of inert gas. In the pure state sorbitol powder and adipic acid are introduced into the reactor in a molar ratio 1/2 (sorbitol/adipic acid). The reactor is placed under inert atmosphere then is launched for heating. When the temperature reaches 100° C., the stirring is progressively started up to 170 rpm. When the temperature reaches 150° C., the reaction is launched and continues for 3 h. After 3 h, 1,4 butanediol (called diol in what follows) is introduced into the reactor in a molar ratio (1,4 butanediol/sorbitol) 2.2/1. The temperature of the reaction medium returns to 150° C. (stirring still maintained at 170 rpm, inert atmosphere). 2 h30 after the return to 150° C. a partial vacuum passage is carried out under a partial vacuum for a duration of one minute then the atmospheric pressure is brought under inert atmosphere. 4 h30 after the adding of diols, a new partial vacuum flush is carried out for 2 minutes then the atmospheric pressure is brought under inert atmosphere. 6 h15 minutes after the introduction of the diol (which is a total reaction time of 9 h15 min at 150° C.), the reactor is stopped and the reaction product is recovered hot in order to have minimum loss during the transfer of material from the reactor to the conditioning of the product.

[0262] c. General Method for Preparing PIR Foams

[0263] The isocyanate/hydroxyl (NCO/OH) molar ratio was maintained at 3.2 in all the formulations of PIR. To determine the quantity of isocyanate, all the reactive hydroxyl groups are taken into account, i.e. polyols, water and certain solvents used in the composition of the catalysts. A mixture containing polyols, catalysts, a surfactant (PDMS), a flame retardant (TCPP), an expansion agent (isopentane) and water was prepared. In each formulation the quantities (Table 2), of water, TCPP and surfactants were maintained constant at 0.9, 15 and 2.5 parts by weight (pbw), respectively. The total quantity of polyol was maintained at 100 pp. The quantity of expansion agent was adjusted to obtain equivalent bulk densities of foam. The mixture was stirred mechanically until a fine white emulsion was obtained with the incorporation of the expansion agent. The temperatures of the different components were adjusted to 20° C. Then, the correct quantity of polyisocyanate was quickly added using a syringe in the emulsion. The entire reaction mixture was vigorously stirred for 5 s. Then, the foam expands freely in a 250 ml disposable beaker at room temperature (controlled at 20° C.) or in a Foamat. The main characteristic reaction times, i.e. the cream time, the thread time and the tack-free drying time, were recorded. Before a more thorough analysis, the foam samples were stored at room temperature for three days in order to obtain complete structural and dimensional stability, without shrinkage. Certain foams were prepared with a partial substitution of the petrosourced polyester polyols with biosourced polyol, BASAB. The substitution rate was 0 (reference, REF) at 65% by weight. The PIR foams were labelled according to the ratio of petrosourced polyol (% by weight of the polyols)/BASAB (% by weight of the polyols)/EG (% by weight) as REF, PU-90/10/0-KE, PU-75/25/0-KE, PU-65/35/0-KE, PU-55/45/0-KE, PU-45/55/0-KE and PU-35/65/0-KE. The detailed formulations are shown in Table 2.

TABLE-US-00002 TABLE 2 Formulation of PIR foams expressed in number of parts PU- PU- PU- PU- PU- REF 90/10/0-KE 75/25/0-KE 65/35/0-KE 55/45/0-KE 35/65/0-KE Molar ratio NCO/OH 3.2 3.2 3.2 3.2 3.2 3.2 Polyol (pbw) Petrosourced 100 90 75 65 55 35 polyol BASAB 0 10 25 35 45 65 Catalyst KE 0.12 0.12 0.12 0.12 0.12 0.12 (% wt) Triazine 0.08 0.08 0.08 0.08 0.08 0.08 BDMAEE 0.03 0.03 0.03 0.03 0.03 0.03 Surfactant PDMS 2.5 2.5 2.5 2.5 2.5 2.5 (pbw) Flame TCPP 15 15 15 15 15 15 retardant (pbw) Expansion Water 1 1 1 1 1 1 agent (pbw) Isopentane 22 23 25 27 29 32

[0264] d. Characterisations

[0265] The thermogravimetric analyses (TGA) were carried out using an instrument from TA: TGA Q5000 at high resolution under reconstituted air (flow rate of 25 mL/min). Samples of 1-3 mg were heated from room temperature to 700° C. (10° C./min). The main characteristic degradation temperatures are those of the maximum of the weight loss curve (DTG) (Tdeg, max) and the characteristic temperatures to which 50% (T.sub.deg50%) and 100% (T.sub.deg100%) were added.

[0266] The infrared spectroscopy was carried out with a Nicolet 380 Fourier transform infrared spectrometer used in reflection mode provided with a diamond module ATR (FTIR-ATR). An atmospheric blank was collected before each sample analysis (64 scans, resolution 4 cm.sup.−1). All the spectra were standardised on the elongation peak C—H at 2,950 cm−1.

[0267] The temperature of the foams, the expansion heights, the flow rates, the bulk density and the pressure were recorded with a Foamat FPM 150 (Messtechnik GmbH) provided with cylindrical recipients 180 mm high and 150 mm in diameter, an ultrasound probe LR 2-40 PFT/a thermocouple of the K type, and a pressure sensor FPM 150. The data was recorded and analysed with specific software.

[0268] The closed cell content was determined using a Ultrapyc 1200e from Quantachrome Instruments based on the gas expansion technique (Boyle's Law). Cubic foam samples (of about 2.5×2.5×2.5 cm3) were cut for the first measurement then the samples was again sectioned into eight pieces and the measurements was again taken. The second measurement corrects the closed cell content based on closed cells that were damaged due to the cutting of the sample. The measurements were taken according to standards EN ISO4590 (October 2016) and ASTM 6226 (January 2015).

[0269] The fire resistance of the foams was evaluated according to the standardised method EN ISO 11925-2 (February 2013). This flammability test consists of a small exposure to the flame (20 mm high) of a planar sample of foam for 15 s in a combustion chamber with controlled air flow rate. This flammability test is evaluated by measuring the maximum propagation of the flame over the planar surface of the foam. The result of the test is positive if the propagation of the flame stops before reaching 15 cm high on the foam sample.

[0270] The morphology of the cells made of foam was observed with an emission scanning electron microscope from Jeol JSM-IT100 (SEM). Cubic foam samples were cut with a microtome blade and analysed according to two characteristic orientations: parallel and perpendicular to the direction of the rising of the foam. By using the ImageJ software (Open Source processing program), the average size of the cells was measured as the aspect ratio of the cells defined by eq. 1.

[00003]$R=\frac{1}{n}\underset{i=1}{\overset{n}{.Math.}}\frac{D_F^{\max }}{D_F^{\min }}$

[0271] Where D.sub.Fmax and D.sub.Fmin are maximum and minimum Feret diameters, n is the number of cells measured for a given sample.

[0272] The hardness of the foam was measured with a Shore 00 hardness tester from Hilderbrand according to the standard ASTM D 2240 (January 2005). Each sample was tested ten times, the average value of the measurements and the standard deviations were determined.

[0273] The quasi-static compression tests were conducted with a Instron compression test machine (E1000, USA), provided with a 1 kN load sensor, at room temperature and at a constant deformation speed of 2.5 mm/min. The cubic samples used for the compression tests have dimensions of 25×25×25 mm.sup.3. The samples were tested in the longitudinal direction (corresponding to expansion) and in the transverse direction. The Young's modulus was defined as the slope of the stress-strain curves in the elastic region and the yield strength as the first maximum of the stress curve.

[0274] The resistance to compression at 10% deformation (CS(10/Y)) was determined according to the standard EN 826 (May 2013).

[0275] The thermal conductivity was measured using the conduction of the heat flow according to the standard EN 12667 (July 2001). Typically, the installation consists of a heating element with two thermocouples in order to determine the temperatures on the front and rear faces. The device is also provided with sensors dedicated to measuring the heating time and the cycle time. The heating and cycle time are used to correct the maximum conduction heat flow, required to determine the thermal conductivity coefficient, using Fourier's Law, used in thermal conduction in the steady state. Plates of different materials, sizes 300×400×3 mm.sup.3, were used to determine the thermal conductivity coefficient.

[0276] Hansen's solubility parameter is characterised in the following way. A small quantity of polyol was poured into a 5 ml bottle which was then filled with the desired solvent. The bottles were placed in an ultrasonic bath for 1 hour, then the solubility of the polyols was evaluated visually 3 hours later and confirmed after 24 h. The corresponding results (soluble or insoluble) were collected. Hansen's solubility parameters and the predicted compatibility of the two polyols were determined by modelling their solubility sphere with the HSPiP software.

II. Results and Discussion

[0277] Hansen's solubility parameters for the petrosourced polyol and BASAB were determined according to a protocol described hereinabove, by qualitatively measuring their dissolutions in fourteen known solvents. Table 3 shows the list of solvents used and their three Hansen parameters (i) the dispersion parameter (δd), (ii) the polar parameter (δp) and (iii) the hydrogen bond parameter (δh). These parameters are used to determine a solubility sphere with the HSPiP software. The solubility score expresses the total solubility of the polyol in the solvent with a score of 1. When the polyol is insoluble or partially soluble, the result obtained is 0.

TABLE-US-00003 TABLE 3 Set of solvents used to model the solubility spheres as well as their Hansen parameters and the solubility scores of the BASAB and of the petrosourced polyol Solubility score Petrosourced Solvent δ.sub.d δ.sub.p δ.sub.h polyol BASAB Dimethyl Sulfoxide 18.4 16.4 10.2 1 1 (DMSO) Tetrahydrofuran (THF) 16.8 5.7 8 1 0 Dimethyl Formamide 17.4 13.7 11.3 1 1 (DMF) p-Xylene 17.8 1 3.1 0 1 Toluene 18 1.4 2 0 0 Pyridine 19 8.8 5.9 1 1 Chloroform 17.8 3.1 5.7 1 0 Methylene Dichloride 17 7.3 7.1 1 0 (Dichloromethane) Ethyl Acetate 15.8 5.3 7.2 1 0 Acetone 15.5 10.4 7 1 0 Ethanol 15.8 8.8 19.4 1 1 2-Propanol 15.8 6.1 16.4 0 0 Acetic Acid 14.5 8 13.5 1 1 Acetonitrile 15.3 18 6.1 1 0 1,4-Dioxane 17.5 1.8 9 1 0

[0278] Before any formulation of substituted foam, the compatibility between the two polyols was studied. The results obtained make it possible to predict the solubility spheres (not shown) of the two polyols according to the three parameters determined by Hansen. It clearly appears that the two spheres largely overlap and that the centres of the spheres are separated by a distance less than their respective radius. Using these observations, it is possible to suppose that the two polyols are compatible and can give rise to the preparation of a stable emulsion before the foaming process.

[0279] a. Characteristic Reaction Times and Kinematic Profile of PIR Foams

[0280] The petrosourced PIR foam reference (REF) has short reaction times, as shown in Table 4. The characteristic times recorded for the REF were respectively 10, 60 and 148 s for the cream, thread and tack-free drying times. The PIR foam has a typical collar due to the second step of expansion induced by the trimerisation of the isocyanates. This second step is also visible on the Foamat measurements, shown in FIG. 1, b. The expansion speed of the foam starts to decrease after 30 s of reaction and increases again after 60 s of reaction. The temperature curve of the foam (FIG. 1-a) also shows a local plateau at 50 s with an increase up to 150° C., which is linked to the trimerisation of the isocyanates. The same phenomenon is visible in FIG. 1-c.

[0281] After 50 s, a change in the slope is observed and the standardised height quickly increased from 80 to 100% with the trimerisation of the isocyanates.

TABLE-US-00004 TABLE 4 Characteristic foaming times of the foams REF REF Characteristics times Cream time (s) 10 Thread time (s) 60 Tack-free drying time (s) 148

[0282] FIG. 2 shows the change in the characteristic cream, thread and tack-free drying times of the foams REF, PU-90/10/0-KE, PU-75/25/0-KE, PU65/35/0-KE, PU-55/45/0-KE, PU-45/55/0-KE and PU-35/65/0-KE plotted as a function of the respective biosourced polyol content of 0%, 10%, 25%, 35%, 45%, 55%, 65%. It can be observed in FIG. 2 that the cream times increase slightly with the increase in the BASAB content. This seems to be linked to the lower reactivity of the secondary hydroxyls of the BASAB. Thread times similar to the REF are observed however for the foams PU-90/10/0-KE to PU-65/35/0-KE. However, the tack-free drying time is subject to variations. It is therefore noted that when the BASAB content increases, the tack-free drying time decreases, and approaches the thread time. This reduction in the interval of time between the thread time and the tack-free drying time indicates that the polymerisation of the polyurethane network of the biosourced foams is improved by the superior functionality of the BASAB. This decrease in the tack-free drying time is a substantial advantage during the method for obtaining a panel with a rigid foam base.

[0283] FIG. 1-a shows the temperature of the foam as a function of time. The exothermicity of the reaction between the polyol and the isocyanate is higher for the REF as well as for the foam PU-90/10/0-KE. A progressive decrease in the exothermic nature of the reaction is then observed for higher substitution rates due to the lower reactivity of the secondary hydroxyls of the polyol BASAB. The temperature curves show an inflection point around 70° C. followed by an increase in the temperature for all of the foams observed. This is linked to the exothermicity of the catalysed reaction of trimerisation of the isocyanates and to the formation of the PIR network.

[0284] FIG. 1-b shows the expansion profile of the foam. The foaming speed is influenced by the expansion of the gas, it is therefore expected that the change thereof has similarities with the change in the temperature of the foam. The increase in the biosourced polyol content delayed the increase in the temperature and a decelerated the expansion of the foam. Thus, the peak of the foaming speed becomes wider and the maximum thereof decreases from 3.5 (REF) to 1.5 mm/s (PU-35/65/0-KE). The second increase in the foaming speed linked to the trimerisation of the isocyanates is consequently delayed. The change in the standardised height of the foams (H/Hmax) as a function of time is shown in FIG. 1-c. The second increase in the standardised height is linked to the foaming speed and to the trimerisation of the isocyanurate. Up to 35% by weight (PU-65/35/0-KE) of the substitution of biosourced polyol, the standardised height increases linearly. Then, when the trimerisation of the isocyanates occurs, a net change in the trend is observed. For the other samples, the standardised height has a sort of plateau before the inflection, due to the trimerisation delay observed hereinabove on the foaming speed.

[0285] b. Closed Cell Content and Morphology of the Foams

[0286] FIG. 3 shows the SEM images of the foam REF in the transverse and longitudinal directions in relation to the rising of the foam. A typical honeycomb structure in the transverse direction is clearly observed. The stretching of the cells in the longitudinal direction is characteristic of a partially free expansion foaming process carried out in an open cylindrical recipient (Hawkins, M. C., 2005. J. Cell. Plast. 41, 267-285). This is actually visible thanks to the anisotropic coefficient R of all the PIR foams shown in Table 5. The coefficients R are close to 2.0 in the longitudinal direction (oval shape), while in the transverse direction, R is close to 1.2 (close to the spherical shape). Surprisingly, the introduction of the polyol BASAB into the formulation has a substantial influence on the size of the cells as observed with electron microscopy (not shown). The observation of the SEM snapshots of all the PIR foams formulated in the direction transverse and longitudinal to the rising of the foam clearly illustrates the decrease in the size of the cells, compared to the reference for foams that have a substitution rate of the petrosourced polyol from 10% to 45%. An inverted trend is observed for the foams PU-45/55/0-KE, PU-35/65/0-KE. The distribution of the maximum and minimum diameters of the cells such as observed in SEM in the transverse and longitudinal directions for the formulated PIR forms is shown in FIG. 4. The distribution of the diameters of the cells follows a normal distribution centred on the average value of the diameter of the cells of the PIR foam concerned. These curves were obtained by measuring a minimum number of one hundred cells per foam in the longitudinal and transverse directions, respectively. The size of the diameter of the cells decreases with respect to the reference for foams PU-90/10/0-KE to PU-55/45/0-KE and has a narrower distribution. Other formulations of foams have higher cell diameters and wider distributions. The minimum size of the diameter of the calls falls from 275 to 155 μm in the transverse direction for PU-75/25/0-KE in relation to REF. The same phenomenon is observed in the longitudinal direction (Table 5). With a substitution of 35 to 45% by weight, the cell size increases in relation to the PIR foam with 25% by weight of substitution. However, foams with 25 to 45% by weight still have cell sizes smaller than REF (Table 5). Above 45% by weight of substitution, the PIR foams (PU-45/55/0-KE, PU-35/65/0-KE) have larger cells compared to REF and this in all directions (Table 5). The lowest temperatures are reached for the foaming of PU-45/55/0-KE, PU-35/65/0-KE (FIG. 1-a). These drops in temperature delay the trimerisation of the isocyanates, and induce lower reaction speeds (for example a longer thread time). The longer reaction times, linked to an slower foam expansion, are at the origin of a strong coalescence before the stabilisation/“setting” of the morphology by complete polymerisation of the network, inducing larger cells. FIG. 4-a,b shows the distribution of the cell size of the PIR foams in the transverse direction for substitution rates of the petrosourced polyester polyol ranging up to PU-55/45/0-KE. The cell size distributions are narrow and the average diameters of the cells decrease progressively with the increase in the BASAB content in the foam up to PU-65/35/0-KE. The PIR foam having a substitution rate of 45% by weight (PU-55/45/0-KE), marks the change in the trend as its diameters of cells increase in relation to PU-65/35/0-KE. FIG. 5 shows the distribution of the cell size of the PIR foams in the transverse directions determined in electron microscopy having smaller average cell sizes than the REF. With respect to the REF, the foams PU-90/10/0-KE to PU-55/45/0-KE also have a narrower cell distribution. Foams with a BASAB content greater than 45% by weight have cells that are larger than REF, in accordance with the change in the trend observed on PU-45/55/0-KE.

TABLE-US-00005 TABLE 5 Feret diameters and anisotropy coefficient R in the directions longitudinal and transverse to the expansion of foams PU- PU- PU- PU- PU- PU- REF 90/10/0-KE 75/25/0-KE 65/35/0-KE 55/45/0-KE 45/55/0-KE 35/65/0-KE Longitudinal Max Feret,  408 ± 117 269 ± 70 254 ± 66 251 ± 59 301 ± 93 728 ± 218 938 ± 60  direction D.sub.F.sup.max (μm) Min Feret, 223 ± 44 145 ± 34 118 ± 22 126 ± 27 147 ± 37 320 ± 77  421 ± 87  D.sub.F.sup.min (μm) R = D.sub.F.sup.max/ 1.83 1.86 2.15 2.00 2.05 2.28 2.23 D.sub.F.sup.min Transverse Max Feret, 275 ± 72 208 ± 47 155 ± 39 158 ± 39 183 ± 45 495 ± 126 643 ± 189 direction D.sub.F.sup.max (μm) Min Feret, 242 ± 72 176 ± 48 128 ± 36 134 ± 33 147 ± 40 392 ± 110 518 ± 147 D.sub.F.sup.min (μm) R = D.sub.F.sup.max/ 1.14 1.18 1.21 1.18 1.24 1.26 1.24 D.sub.F.sup.min

[0287] The inventors of the present invention consider, without desiring to be limited by a theory, that the surface tension of the BASAB (Table 1) is greater than that of the second petrosourced polyol. This increase slows down the growth of the bubbles according to Laplace's equation (2) because the pressure inside the bubble must exceed the surface tension in order to increase (Minogue, E., 2000. An in-situ study of the nucleation process of polyurethane rigid foam formation. Dublin City University).

[00004]$\begin{array}{cc}\Delta P=\frac{2\gamma }{r}& \left(2\right)\end{array}$

[0288] Where ΔP is the excess pressure of the bubble gas, γ the surface tension and r the radius of the bubble. Then, the largest functionality of BASAB leads to a faster structural organisation of the cell wall by decreasing the thread time, thus preventing the coalescence of cells which would lead to higher cell sizes.

[0289] The closed cell content of the foams is shown in Table 7. The REF and PU-90/10/0-KE to PU-65/35/0-KE have closed cell contents greater than 90%. The closed cell content of foam samples PU-55/45/0-KE, PU-45/55/0-KE and PU-35/65/0-KE falls to 87, 47 and 28%, respectively. These foams have lower foaming temperatures and longer reaction times according to the results mentioned hereinabove. This means that the cell walls cannot withstand the expansion of the gas and collapse during the expansion of the foam (Septevani, A. A., Evans, D. A. C., Chaleat, C., Martin, D. J., Annamalai, P. K., 2015. Ind. Crops Prod. 66, 16-26). Table 6 displays the Shore 00 hardness data. The Shore 00 hardness results can be divided into two main populations. PU-90/10/0-KE to PU-65/35/0-KE, having values similar to the REF. The Shore 00 hardness results are similar to those of REF for the foams PU-90/10/0-KE to PU-55/45/0-KE manifesting rigidity similar to that of REF. The other foams have a slightly lower Shore 00 hardness indicating a decrease in the rigidity.

TABLE-US-00006 TABLE 6 Shore 00 hardness results of PIR foams PU- PU- PU- PU- PU- PU- REF 90/10/0-KE 75/25/0-KE 65/35/0-KE 55/45/0-KE 45/55/0-KE 35/65/0-KE Shore 00 72 ± 3 71 ± 3 71 ± 4 73 ± 2 65 ± 3 56 ± 2 43 ± 9 hardness

[0290] c. Properties of Foams: Bulk Density, Resistance to Compression, Thermal Conductivity, Chemical Structure (FT-IR), Thermal Stability and Fire Resistance

[0291] The bulk density values shown in Table 7 are similar for all the PIR formulations, except for samples PU-45/55/0-KE and PU-35/65/0-KE. Since the content in blowing agent is maintained constant in each formulation, the densifications of PU-45/55/0-KE and of PU-35/65/0-KE are linked to their lower foaming reactivity, resulting in lower temperatures which decrease the expansion rate of the blowing agent. The FT-IR spectra of the foams are shown in Figure SI. 6-a, b. All the foams have characteristic peaks, such as the stretching vibration of the N—H groups at 3,400-3,200 cm.sup.−1 and the stretching vibration C═O at 1,705 cm.sup.−1 coming from the urethane functions. The signals located at 2,955 cm.sup.−1 and 2,276 cm.sup.−1 are respectively attributed to the stretching of the C—H bond of the polyurethane skeleton and of the residual NCO groups that did not react. The signal at 1,596 cm.sup.−1 corresponds to the Ph-H stretching of the phenyl groups of the pMDI. The flexion signal of the N—H groups is located at 1,509 cm.sup.−1. The stretching of the C—O bonds is located at 1,220 cm.sup.−1. The strong signal at 1,408 cm.sup.−1 is attributed to the isocyanurate rings, typical of PIR foams.

TABLE-US-00007 TABLE 7 Properties of PIR foams PU- PU- PU- PU- PU- PU- REF 90/10/0-KE 75/25/0-KE 65/35/0-KE 55/45/0-KE 45/55/0-KE 35/65/0-KE Bulk density (kg/m.sup.3) 31.1 30.2 32.3 32.9 32.1 36.1 39.8 Closed cell content 95 94 92 92 87 47 28 (%)

[0292] The thermal stability of the PIR foam samples was studied by thermogravimetric analysis. FIGS. 7-8 show the TGA and DTG curves of all the PIR foams. All the PIR foams have a conventional weight loss in two steps (Sheridan, J. E., Haines, C. A., 1971. J. Cell. Plast. 7, 135-139). The PIR foams with a higher BASAB content (PU-45/55/0-KE, PU-35/65/0-KE) have better thermal stability than the REF. The Table 8 shows the temperatures at the maximum of the curve derived from the weight loss: T.sub.deg max1 and T.sub.deg max2. T.sub.deg max1 are in the range from 200 to 300° C. T.sub.deg max2 is observed around 500° C. for all the substituted PIR foams. T.sub.deg max1 corresponds to the decomposition of the urethane linkage. The decomposition mechanism of the urethane linkage is generally described as three simultaneous processes such that (i) the dissociation of the isocyanate and of the alcohol, (ii) the formation of primary and secondary amines and (iii) the formation of olefins (Javni, I., Petrovi, Z. S., Guo, A., Fuller, R., 2000. J. Appl. Polym. Sci. 77, 1723-1734). T.sub.deg max2 is more pronounced than the first T.sub.deg max1 and it is assigned to the double degradation of the isocyanurate and of the cleavage of the carbon bond (Sheridan, J. E., Haines, C. A., 1971. J. Cell. Plast. 7, 135-139). The first weight loss is less substantial due to the isocyanurate groups. The isocyanurate groups are more stable thermally than the urethane due to the absence of labile hydrogen and the corresponding degradation is then mainly due to the cleavage of the carbon bond (Sheridan, J. E., Haines, C. A., 1971. J. Cell. Plast. 7, 135-139). The Table 8 has two temperatures corresponding respectively to 50% (T.sub.deg 50%) and 100% (T.sub.deg 100%) of the weight loss PIR foams. T.sub.deg 50% and T.sub.deg 100% are similar for all the formulations of PIR foam, except for the sample PIR PU-35/65/0-KE which have T.sub.deg greater than 50% and T.sub.deg 100%. These two foams have the highest biosourced content. This is in accordance with the TGA and DTG observations hereinabove. All of the PIR foams were subjected to an ignitability test according to standard EN ISO 11925-2 (February 2013) such as described hereinabove. No foam has a sustaining combustion after exposure to a 2 cm flame for 15 s. The maximum heights of the flames never exceeded 15 cm in height before going out. Thus all the PIR foams of the study successfully passed the ignitability test described by standard EN ISO 11925-2 (February 2013). The aromatic petrosourced polyol has an aromatic structure and it is well known that the aromaticity provides a higher resistance to fire, favouring surface carbonisation, which reduces flammability (Celzard, A., Fierro, V., Amaral-Labat, G., Pizzi, A., Torero, J., 2011. Polym. Degrad. Stab. 96, 477-482).

TABLE-US-00008 TABLE 8 Degradation temperature of PIR foams at 50% and 100% of weight loss ATG T.sub.deg50% T.sub.deg100% DTG Sample (° C.) (° C.) T.sub.deg max1 T.sub.deg max2 REF 448 645 301 523 PU-90/10/0-KE 425 628 290 519 PU-75/25/0-KE 432 604 294 512 PU-65/35/0-KE 440 605 295 511 PU-55/45/0-KE 437 614 292 507 PU-45/55/0-KE 466 646 302 509 PU-35/65/0-KE 473 702 303 505

[0293] FIGS. 9 and 10 show the stress-strain curves of all the PIR foams, obtained in the longitudinal and transversal directions. As described above, in the longitudinal direction (FIG. 9), the stress increases linearly with the deformation (due to the elastic behaviour of foams), before reaching the elastic threshold. After the elastic limit, the strain remains practically constant due to the collapse of the cells of the foam.

[0294] In the transverse direction (FIG. 10), the foam behaves differently. After an elastic portion, up to the elastic limit, the strain continues to increase, corresponding to the densification of the foam. The difference between the behaviours of the foam in the longitudinal and transverse directions is due to the anisotropic nature of the foam. This behaviour was explained well in a preceding work PCT/IB2017/055116. It is confirmed by the ratio of the longitudinal and transversal Young's modulus which decreases from 5.75 to 3.08 for foam samples REF to PU-65/35/0-KE, respectively.

[0295] The lowest ratio of Young's modulus of PU-65/35/0-KE reflects the least anisotropic behaviour. This observation is in accordance with the prior results concerning the anisotropic coefficient R of the foam cells (shown in Table 5) because PU-65/35/0-KE has the smallest value of R. In the longitudinal direction, it clearly appears that the mechanical properties, including Young's modulus and the yield strength, presented in Table 9, successively describe two main trends.

[0296] The Young's modulus and the yield strength increase first when the concentration in biosourced polyol increased from 0 to 25% by weight (foam samples REF to PU-75/25/0-KE), where a load threshold is reached. Then, a decrease in the mechanical properties is observed for a concentration in biosourced polyol ranging from 35 to 65% by weight.

[0297] During the ascending phase of the mechanical properties, the longitudinal Young's modulus increases from 6.9 to 13.5 MPa for the foam samples REF and PU-75/25/0-KE, respectively. This corresponds to an increase in the longitudinal Young's modulus of about 96%.

[0298] According to the preceding observations, the mechanical properties follow a similar trend. When the average size of the cells decreases, the distribution of the load is more homogeneous in the foam sample, which gives higher Young's moduli. Then, after the loading of the threshold, with a direct liaison to the architectures of foams, the samples become more fragile due to the polyfunctionality of BASAB. This results in a decreased Young's modulus of about 45%, between PU-65/35/0-KE and PU-35/65/0-KE.

[0299] In the transverse direction, a similar and less pronounced change can be observed with an increase in the Young's modulus from 1.2 to 2.9 MPa (Table 9), from foam REF to PU-75/25/0-KE. Then, as in the longitudinal direction, a decrease in Young's modulus is observed from 2.4 to 1.0 MPa from foam PU-65/35/0-KE to foam PU-35/65/0-KE. As mentioned hereinabove, from REF to PU-65/35/0-KE, the foam cell size decreased when the quantity of BASAB increased. This leads to a good distribution of the load, combined with the content of the closed cells, resulting in an increase in performance. The gas enclosed in the cells generates a pressure that resists the compression load, improving the mechanical properties of the foam.

[0300] On the other hand, when the content in biosourced polyols increases from 45 to 65% by weight, the content in closed cells decreases significantly. At the same time, the cell size increased and certain defects appear in the morphology of the foam, visible on the SEM snapshots (not shown). All of these factors contribute to losses of mechanical properties.

[0301] By adjusting Young's modulus in the longitudinal and transverse directions according to the content of BASAB, it was observed that the change in the Young's modulus can be described by a 3D polynomial adjustment. (FIG. 11). FIG. 11 shows the change in the Young's modulus in the transverse direction (ET) and longitudinal (E.sub.L). This change is in accordance with the lower scale established by Gibson and Ashby (L. J. Gibson, M. F. Ashby, Cellular Solids: Structure and Properties, Cambridge University Press, 1997; L. J. Gibson et al., Failure surfaces for cellular materials under multiaxial loads—I. Modelling, Int. J. Mech. Sci. 31 (1989) 635-663) to describe the relative density as a function of the ratio between the average cell walls and the cell diameters. E.sub.L and ET are the longitudinal and transverse modules respectively, and C.sub.polyol the concentration in polyol, these changes can be given by the following equations 1 and 2:

E.sub.Longi×0.72C.sup.3.sub.polyol−0.026C.sup.2.sub.polyol+2.34E−4C.sub.polyol+7.01  (1)

E.sub.Transv=0.19C.sup.3.sub.polyol−0.006C.sup.2.sub.polyol+5.40E−5C.sub.polyol+0.23  (2)

Contrary to what was observed in the longitudinal direction, the yield strength in the transverse direction decreases continuously when the content in BASAB increases.

[0302] Mechanical properties in the transverse direction (FIG. 10), two groups of biosourced foams can be distinguished. The first is comprised of the systems REF, PU-90/10/0-KE, PU-75/25/0-KE and PU-65/35/0-KE, which behaves like the REF, with good recovery. The second comprises PU-55/45/0-KE, PU-45/55/0-KE and PU-35/65/0-KE, which have poor recovery. The latter behaviour could be explained by the fragile nature of these foams because of the high cross-linking structures due to the high-functionality of BASAB.

[0303] The results for resistance in compression obtained according to the standard EN 826 (May 2013) has a behaviour similar to the results of quasi-static compression. At 10% strain, foams PU-90/10/0-KE and PU-75/25/0-KE have higher CS(10/Y) than REF. They are therefore more resistant to compression. The other foams have a resistance to compression that decreases with the increase in the BASAB content.

TABLE-US-00009 TABLE 9 Mechanical and thermal conductivity parameters of different PIR foams, E.sub.L: Young's modulus in the longitudinal direction, E.sub.T: Young's modulus in the transverse direction, C.sub.L Strain value in the longitudinal direction, C.sub.T Strain value in the transverse direction, λ.sub.L Coefficient of thermal conductivity in the longitudinal direction, CS(10/Y) Resistance to compression. CS(10/Y) (kPa) E.sub.L C.sub.L E.sub.T C.sub.T E.sub.L/ according to λ.sub.L Samples (MPa) (MPa) (MPa) (MPa) E.sub.T EN 826 (mw/mK) REF 6.9 0.29 1.2 0.14 5.75 298.8 24 PU-90/10/0-KE 11.7 ± 0.1  0.28 2.3 0.12 5.09 303.5 23 PU-75/25/0-KE 13.5 ± 0.5  0.35 2.9 0.10 4.66 320.3 22 PU-65/35/0-KE 7.4 ± 0.3 0.31 2.4 0.10 3.08 281.4 23 PU-55/45/0-KE  6.2 ± 0.10 0.17 1.3 0.08 4.77 166.2 22.5 PU-45/55/0-KE 5.9 ± 0.4 0.11 1.2 0.05 4.91 118.1 25 PU-35/65/0-KE 4.1 ± 0.3 0.08 1.0 ± 0.1 0.05 4.1 n.d n.d

[0304] The thermal conductivity coefficient in the direction longitudinal to the expansion of foams (see Table 9) decreased slightly when the quantity of biosourced polyol increased. The corresponding values are comprised between 22 and 24 mW/(m.Math.K) for REF, PU-90/10/0-KE, PU-75/25/0-KE and PU-65/35/0-KE. The conductivity value of 22 mW/(mK) for foam PU-75/25/0-KE is remarkable. Recently work on rigid PU foams with a sorbitol base has been published, the average conductivity value was 36 mW/(mK) (Ugarte, L., Gómez-Fernández, S., Peña-Rodriuez, C., Prociak, A., Corcuera, M. A., Eceiza, A., 2015. ACS Sustain. Chem. Eng. 3, 3382-3387). The thermal conductivity (λ.sub.t) of these foams depends on four conductivity coefficients (λ), namely λ.sub.gas, λ.sub.PIR, λ.sub.radiation and λ.sub.convection, as described in equation (3). In the PU foams, the conduction in the gas phase represents 65-80% of the heat transfer, while the solid and radiative component represents 20-35%. As these PIR foams are obtained with isopentane and have similar bulk densities as well as a closed cell content that are close, the thermal conductivity is mainly influenced by the decrease in the size of the cells. The smallest cell size influences the extinction coefficient (K) of λ.sub.radiation expressed by equations (4) and (5) (Hejna, A., Kosmela, P., Kirpluks, M., Cabulis, U., Klein, M., Haponiuk, J., Piszczyk, L., 2017b. J. Polym. Environ, Septevani, A. A., Evans, D. A. C., Chaleat, C., Martin, D. J., Annamalai, P. K., 2015. Ind. Crops Prod. 66, 16-26).

[00005]$\begin{array}{cc}{\lambda }_t={\lambda }_{gas}+{\lambda }_{\mathrm{PUIR}}+{\lambda }_{\mathrm{radiation}}+{\lambda }_{convection}& \left(3\right)\\ {\lambda }_{radiation}=\frac{16\sigma T^3}{3K}& \left(4\right)\\ K=4.1\frac{\sqrt{\frac{{\rho }_f}{{\rho }_p}{f}_s}}{d}& \left(5\right)\end{array}$

[0305] σ is the Stephan-Boltzmann constant (5.67*10−8 W/m.sup.2K.sup.4), T is the temperature, d is the diameter of the cell, f.sub.s is the fraction of polymer contained in the foams, ρ.sub.f and ρ.sub.p are the foams and the density of the polymer, respectively. Thus, the lower thermal conductivity of the foam sample PU-75/25/0-KE is a consequence of the combined effect of the closed cell content and of the reduction in the cell size in relation to REF. For a content in biosourced polyol comprised between 35 and 45% by weight, the thermal conductivity remains constant around 23 mW/(m×K). Then increases slightly to 25 mW/(m×K) when the content in biosourced polyols reaches 55% by weight. In this particular case, the increase in the thermal conductivity is mainly due to the decrease in the closed cell content and to the increase in the size of the cells. The decrease in the closed cell content substantially affects the value of λ.sub.gas because the open cells are mainly filled with air which is a less insulating gas than isopentane (Fleurent, H., Thijs, S., 1995. J. Cell. Plast. 31, 580-599).

[0306] It has successfully been shown the possibility of adapting the formulation of PIR foam by a method of partial substitution of a petrosourced polyol with a biosourced polyester polyol obtained from sorbitol. The PIR foams have a high content in closed cells (greater than 90%) and a decrease in the average size of the cells of 44% in relation to the petrosourced reference. The characteristics of the cells observed and in particular the presence of fine cells is a key parameter of a foam because they improve the thermal conductivity as well as the mechanical properties of the foam. The partial substitution of a petrosourced polyol with a biosourced polyol allows for the observation of a foam that has increased resistance to compression of 95% as well as reduced thermal conductivity of 2 mW/(mK). Furthermore, for such a foam, a Young's modulus increased respectively by 96 and 142% in the longitudinal and transverse direction is observed when the content in biosourced polyols is optimal. The biosourced PIR foams developed respond to the main required linked to the targeted fields of application (thermal insulation) such as: [0307] i. good fire resistance, [0308] ii. mechanical performance, [0309] iii. low bulk density, [0310] iv. high content in closed cells, [0311] v. low thermal conductivity