**4. Properties of the PKO-based polyol**

454 Polyurethane

50 mm × 50 mm.

was followed.

(Scheme 2)

The PU foams were characterized for their apparent molded and core densities, compression strength, dimensional stability and water absorption following standard method BS4370: Part 1:1988 (1996) Methods 1 to 5: Methods of test for rigid cellular materials. Foam samples were cut using into cubes of 100 mm × 100 mm × 100 mm in dimensions. A replicate of five specimens were used and carefully weighed using an analytical balance. The dimensions were measured following BS4370: Part 1:1988 (1996): Method 2. The apparent molded density was determined by using a simple mathematical equation, mass (kg)/volume (m3). The core density is determined by the same method but using skinless foam. The compressive strength test was carried out on a Universal Testing Machine Model Testrometric Micro 350 following BS4370: Part 1:1988 (1996): Method 3 at 23 ±2°C. The specimens were cut into cubes of 50 mm × 50 mm × 50 mm in dimensions. The foam rise direction was marked and a crosshead speed of 50 mm/min was applied. The compression stress at 10% deflection, compression stress at 5% strain and compression modulus was noted. For the dimensional stability test, the specimens were cut into dimensions of 100 mm × 100 mm × 25 mm. The specimens were then put into a controlled temperature-humidity chamber each at –15 ± 2°C and 70 ± 2°C, 95 ± 5% relative humidity for 24 hours. Method 5A of BS4370: Part 1:1988 (1996) standard was followed. The specimens were remeasured and percentage of change in dimensions was calculated. These are then converted to percentage in volume change. The water sorption was carried out using method in Annex D BS6586: Part 1:1993. The specimens were cut into dimension of 50 mm ×

The thermal decomposition of the polyurethane foam was measured using a thermogravimetric analyzer model Shimadzu TGA-50 with temperature ranging from room temperature to 600°C at heating rate of 10°C/min under nitrogen gas atmosphere. Samples were placed in alumina pan holders at a mass ranging from 5 to 15mg. The thermal property of the foam was determined using a Perkin Elmer Model DSC-7 differential scanning calorimeter interfaced to the Model 1020 Controller. The samples were analyzed from room temperature to 200°C at a heating rate of 10°C/min. Standard aluminum pans were used to analyze 10 mg samples under nitrogen gas atmosphere. The insulation value (k-factor or λvalue) of the polyurethane foam was determined using the Thermal Conductivity Analyzer model Anacon at testing temperature for cold plate at 25°C and hot plate at 35°C. The thickness of the specimens was 20-30 mm and method 7 of BS4370: Part 2: 1993 standard

The RBD PKO consists of triglycerides that when undergoes esterification form by products such as glycerol and other possible polyester network (Loudon 1988) as shown in Scheme 1 and Scheme 2. During the reaction, the acetate ion forms an intermediate, the carboxylic acids. These acids attack the lone pair in nitrogen atom in diethanolamine, DEA and formed the probable structure of the esteramide with hydroxyl terminal

R1, R2 and R3 generally are represented by R and it is very common to have lauric-lauric-

oleic composition of fatty acid in the carbon chains (Scheme 2).

The derivatised RBD PKO-based polyol is a golden yellow liquid with a cloud point of 13°C. It has very low moisture content of 0.09% and low viscosity of 374 cps and specific gravity of 0.992 g/cm3 at room temperature. Low water content and liquidy nature of the polyol are advantageous in formulating the polyurethane system especially when processing of end product is concerned. Less viscous polyol offers less viscous polyol resin which leads to system with good flowability. The viscosity increases as the degree of polycondensation and branching increases (Wood 1990). The physical properties of the PKO-based polyol are summarized in details in Table 4. It is important to note that raw RBD PKO solidified at room temperature with cloud point of about 23-24°C whilst the derivatized polyol solidified only at 13°C (cloud point). Polyol heating system is not required here as what is being used by other studies (Parthiban et al. 1999 and Ahmad et al. 1995).


Biobased Polyurethane from Palm Kernel Oil-Based Polyol 457

identify the progress of the derivatization process (Chian and Gan 1998). Fig. 4 also showed that the hydroxyl value (OHV) reached to a constant at 350-370 mg KOH/g sample at intervals of 175-180°C for 15-30 minutes of reaction time. The FTIR spectrum and hydroxyl value (OHV) curves both demonstrated that 175-180°C at 15-30 minutes as optimum temperature and reaction time respectively. Both methods are advantageous in the identification of optimum processing parameters assuming that Beer's Law is applicable here. However, OHV determination method is slow and time-consuming. Therefore, FTIR method is more preferable in determining the completion of reaction for the RBD PKO-

**Figure 3.** FTIR spectra of (a) the raw RBD PKO and (b) the palm-based esteramide

based polyol (Chian and Gan 1998).

**Table 4.** Physical properties of the derivatised RBD PKO-based polyol.

#### **4.1. Chemical analysis**

#### a. Fourier Transform Infrared Spectroscopy (FTIR)

The RBD PKO, a chain of fatty acid with carboxylic acid group displays intense C=O stretching bands of acids absorb at 1711 cm-1 as shown in Fig. 3 (a). The C-H stretches at 2932 and 2855 cm-1. Two bands arising from C-O stretching and O-H bending appear in the spectra of RBD PKO near 1320-1210 and 1440-1395 cm-1 respectively. Both of these bands involve some interactions between C-O stretching and in-plane C-O-H bending. The C-O-H bending band near 1440-1395 cm-1 is of moderate intensity and occurs in the same region as the CH2 scissoring vibration of the CH2 group adjacent to the carbonyl (Silverstein et al. 1991).

The FTIR spectrum of the derivatized RBD PKO was obtained from samples taken at 175- 180°C (Fig. 3(b)) during the esterification process. The spectrum was evaluated at peak 3351 cm-1 (designated as peak A) and 1622 cm-1 (designated as peak B). Peak A and B, which are the hydroxyl (-OH) and carbamate (O=C=N-) peaks respectively (assigned by IR Mentor Pro Classes, Sadtler Division Bio-Rad Laboratories 1990 and Silverstein et al. 1991). These peaks do not appear in the spectra of the raw RBD PKO (Fig. 3(a)). A vague trace of the hydroxyl peak was observed when PKO is mixed with the hydroxyl compound. Further increase in the reaction temperature and reaction time changed the percentage of transmittance for both peaks A and B significantly. It also indicated a formation of ester cleavage at 1710 cm-1. The sharp absorption bands in the region of 1750-1700 cm-1 are characteristic of carbonyl group of ester (C=O) stretching vibrations (Silverstein et al. 1991).

Transmittance ratio of both peaks, the OH and the carbamate peaks (% transmittance of peak A divided by the % transmittance of peak B) was plotted as in Fig. 4. It was used to identify the progress of the derivatization process (Chian and Gan 1998). Fig. 4 also showed that the hydroxyl value (OHV) reached to a constant at 350-370 mg KOH/g sample at intervals of 175-180°C for 15-30 minutes of reaction time. The FTIR spectrum and hydroxyl value (OHV) curves both demonstrated that 175-180°C at 15-30 minutes as optimum temperature and reaction time respectively. Both methods are advantageous in the identification of optimum processing parameters assuming that Beer's Law is applicable here. However, OHV determination method is slow and time-consuming. Therefore, FTIR method is more preferable in determining the completion of reaction for the RBD PKObased polyol (Chian and Gan 1998).

456 Polyurethane

**Parameters Result**

State at 25°C Liquid

Odor Odorless

Density at 25°C, g/cm3 0.992

Cloud Point, °C 13

Viscosity at 25°C, cps 374

pH 9-10 Moisture content at 25°C, % 0.09

a. Fourier Transform Infrared Spectroscopy (FTIR)

of ester (C=O) stretching vibrations (Silverstein et al. 1991).

**4.1. Chemical analysis** 

et al. 1991).

**Table 4.** Physical properties of the derivatised RBD PKO-based polyol.

Color Golden yellow

Solubility Alcohol, Ketone, Ether, Alkane, Water

The RBD PKO, a chain of fatty acid with carboxylic acid group displays intense C=O stretching bands of acids absorb at 1711 cm-1 as shown in Fig. 3 (a). The C-H stretches at 2932 and 2855 cm-1. Two bands arising from C-O stretching and O-H bending appear in the spectra of RBD PKO near 1320-1210 and 1440-1395 cm-1 respectively. Both of these bands involve some interactions between C-O stretching and in-plane C-O-H bending. The C-O-H bending band near 1440-1395 cm-1 is of moderate intensity and occurs in the same region as the CH2 scissoring vibration of the CH2 group adjacent to the carbonyl (Silverstein

The FTIR spectrum of the derivatized RBD PKO was obtained from samples taken at 175- 180°C (Fig. 3(b)) during the esterification process. The spectrum was evaluated at peak 3351 cm-1 (designated as peak A) and 1622 cm-1 (designated as peak B). Peak A and B, which are the hydroxyl (-OH) and carbamate (O=C=N-) peaks respectively (assigned by IR Mentor Pro Classes, Sadtler Division Bio-Rad Laboratories 1990 and Silverstein et al. 1991). These peaks do not appear in the spectra of the raw RBD PKO (Fig. 3(a)). A vague trace of the hydroxyl peak was observed when PKO is mixed with the hydroxyl compound. Further increase in the reaction temperature and reaction time changed the percentage of transmittance for both peaks A and B significantly. It also indicated a formation of ester cleavage at 1710 cm-1. The sharp absorption bands in the region of 1750-1700 cm-1 are characteristic of carbonyl group

Transmittance ratio of both peaks, the OH and the carbamate peaks (% transmittance of peak A divided by the % transmittance of peak B) was plotted as in Fig. 4. It was used to

**Figure 3.** FTIR spectra of (a) the raw RBD PKO and (b) the palm-based esteramide

Biobased Polyurethane from Palm Kernel Oil-Based Polyol 459

<sup>w</sup> Functionality M OHV / 56100 (3)

product of esterification) and DEA (C:\ DATABASE\WILEY275.L). Others (0.49%) are traces of oligomeric polyester components from C14 and C18 chains. The GC-MS scan of the RBD PKO-based polyol showed an estimated molecular weight of 477. Molecular weight obtained at 165-170 and 170-175oC of reaction temperature was 296 and 355 respectively. Thus, molecular weight obtained at 175-180oC is considered to be the most desirable molecular weight for this study. The functionality of the RBD PKO-based polyol derived from this molecular weight and the determined hydroxyl value (OHV of 350 to 370 mg KOH/g) is 2.98 to 3.15 calculated using the mathematical equation in

Note: Mw is the estimated molecular weight of the RBD PKO-based polyol obtained from GC-MS which is 477 OHV is the hydroxyl value of the RBD PKO-based polyol obtained

using ASTM D4274-88 method, which is about 350-370 mg KOH/g sample

equation 3.

**Note**:

PEA RBD PKO-based polyol DEA diethanolamine MEG monoethylene glycol STD standard lauric acid

180/0 derivatised RBD PKO at starting of 180°C 180/15 derivatised RBD PKO at 180°C for 15 minutes 180/30 derivatised RBD PKO at of 180°C for 30 minutes

**Figure 5.** The thin layer chromatography of the ingredients

containing compounds would react with crude MDI.

This range of functionality is suitable for rigid foam application (Wood 1990).

Both FTIR (IR Mentor Pro 1990) and GC-MS approaches (Wiley MS-database) could be used to estimate the most probable molecular structure of the RBD PKO-based polyol at 175- 180oC/30 minutes (optimum temperature and reaction time) as 2-hydroxy-undecanoamide as in Scheme 2 (library search on Wiley MS-database giving 98% quality match). There is no intention of purification of the synthesized RBD PKO-based polyol as all these hydroxyl-

#### **Note:**

25 refers to derivatized RBD PKO at ambient temperature, 25oC 140 refers to derivatized RBD PKO at 140oC 160 refers to derivatized RBD PKO at 160oC 180/0 refers to derivatized RBD PKO at starting of 180oC 180/15 refers to derivatized RBD PKO at 180oC for 15 minutes 180/30 refers to derivatized RBD PKO at 180oC for 30 minutes 185/0 refers to derivatized RBD PKO at starting of 180oC 185/15 refers to derivatized RBD PKO at 185oC for 15minutes 185/30 refers to derivatized RBD PKO at 185oC for 30 minutes

**Figure 4.** Curve of ratio of OH peak to the C-N peak and the OHV curve of the blend at intervals

#### b. Thin Layer Chromatography

The thin layer chromatography (TLC) test on the desired products obtained at intervals of reaction time at 175-180oC (0, 15 and 30 minutes) indicated a clear qualitative separation. These separations were compared to TLC carried out on individual ingredients: The RBD PKO, diethanolamine (DEA), the catalyst-potassium acetate in monoethylene glycol and standard lauric acid (Athawale et al. 2000). There were three separation peaks, identify as the PKO, DEA and small trace of the catalyst up to 175-180oC at 0 minute. At 175-180oC for 15 minutes, only two separation peaks were observed and finally at 175- 180oC for 30 minutes, only one separation peak was observed (Fig. 5). The result is parallel to the gas chromatography (GC) peaks of the final product, the RBD PKO-based polyol (Fig. 6)).

c. Gas Chromatography-Mass Spectrometry (GC-MS)

The samples collected at intervals ranging from 165-170oC, 170-175oC, 175-180oC and 180-185oC were also evaluated for its purity using gas chromatography, GC coupled with mass spectrometry, GC-MS. Fig. 6 is the GC of the RBD PKO-based polyol reacted at 175- 180oC for 15-30 minutes. The signal at retention time of 31.92 min is the desired product, the RBD PKO-based polyol (98.24%) while signals at retention time of 13.37 (0.08%), 16.36 (0.92%) and 27.91 (0.27%) representing small percentage traces of MEG, glycerol (byproduct of esterification) and DEA (C:\ DATABASE\WILEY275.L). Others (0.49%) are traces of oligomeric polyester components from C14 and C18 chains. The GC-MS scan of the RBD PKO-based polyol showed an estimated molecular weight of 477. Molecular weight obtained at 165-170 and 170-175oC of reaction temperature was 296 and 355 respectively. Thus, molecular weight obtained at 175-180oC is considered to be the most desirable molecular weight for this study. The functionality of the RBD PKO-based polyol derived from this molecular weight and the determined hydroxyl value (OHV of 350 to 370 mg KOH/g) is 2.98 to 3.15 calculated using the mathematical equation in equation 3.

$$\text{Functionalality} = \text{M}\_{\text{w}} \times \text{OHV} \text{ / } 56100 \tag{3}$$

Note: Mw is the estimated molecular weight of the RBD PKO-based polyol obtained from GC-MS which is 477 OHV is the hydroxyl value of the RBD PKO-based polyol obtained using ASTM D4274-88 method, which is about 350-370 mg KOH/g sample

**Note**:

458 Polyurethane

**Note:** 

(Fig. 6)).

25 refers to derivatized RBD PKO at ambient temperature, 25oC

c. Gas Chromatography-Mass Spectrometry (GC-MS)

**Figure 4.** Curve of ratio of OH peak to the C-N peak and the OHV curve of the blend at intervals

The thin layer chromatography (TLC) test on the desired products obtained at intervals of reaction time at 175-180oC (0, 15 and 30 minutes) indicated a clear qualitative separation. These separations were compared to TLC carried out on individual ingredients: The RBD PKO, diethanolamine (DEA), the catalyst-potassium acetate in monoethylene glycol and standard lauric acid (Athawale et al. 2000). There were three separation peaks, identify as the PKO, DEA and small trace of the catalyst up to 175-180oC at 0 minute. At 175-180oC for 15 minutes, only two separation peaks were observed and finally at 175- 180oC for 30 minutes, only one separation peak was observed (Fig. 5). The result is parallel to the gas chromatography (GC) peaks of the final product, the RBD PKO-based polyol

The samples collected at intervals ranging from 165-170oC, 170-175oC, 175-180oC and 180-185oC were also evaluated for its purity using gas chromatography, GC coupled with mass spectrometry, GC-MS. Fig. 6 is the GC of the RBD PKO-based polyol reacted at 175- 180oC for 15-30 minutes. The signal at retention time of 31.92 min is the desired product, the RBD PKO-based polyol (98.24%) while signals at retention time of 13.37 (0.08%), 16.36 (0.92%) and 27.91 (0.27%) representing small percentage traces of MEG, glycerol (by-

180/0 refers to derivatized RBD PKO at starting of 180oC 180/15 refers to derivatized RBD PKO at 180oC for 15 minutes 180/30 refers to derivatized RBD PKO at 180oC for 30 minutes 185/0 refers to derivatized RBD PKO at starting of 180oC 185/15 refers to derivatized RBD PKO at 185oC for 15minutes 185/30 refers to derivatized RBD PKO at 185oC for 30 minutes

140 refers to derivatized RBD PKO at 140oC 160 refers to derivatized RBD PKO at 160oC

b. Thin Layer Chromatography


**Figure 5.** The thin layer chromatography of the ingredients

This range of functionality is suitable for rigid foam application (Wood 1990).

Both FTIR (IR Mentor Pro 1990) and GC-MS approaches (Wiley MS-database) could be used to estimate the most probable molecular structure of the RBD PKO-based polyol at 175- 180oC/30 minutes (optimum temperature and reaction time) as 2-hydroxy-undecanoamide as in Scheme 2 (library search on Wiley MS-database giving 98% quality match). There is no intention of purification of the synthesized RBD PKO-based polyol as all these hydroxylcontaining compounds would react with crude MDI.

Biobased Polyurethane from Palm Kernel Oil-Based Polyol 461

**5. Properties of the PKO-based polyurethane foam** 

**Figure 8.** Scanning electron micrograph of the PUF at 250 magnification

**Figure 9.** FTIR spectrum of the RBD PKO polyurethane foam

The PKO-based polyurethane foam (PUF) produced is a light yellow solid with skin thickness of about 1.5 mm. It is a stiff/rigid but brittle solid at 43-44kg/m3 molded density

The PUF is analysed by FTIR spectroscopy which showed the absence of the free OH groups and indicates a complete conversion of both –OH groups of the PEA to the urethane moiety (NH-C(O)-O). Typical FTIR spectrum of the PU is as shown in Fig. 9. The characteristic –NH stretching vibration of the –NH2- (amide) is located at 3405 cm-1, overlapping with the OH peak as a broad band. Bands at 2932 and 2894 cm-1 are the synchronous reflection of asymmetric and symmetric of CH2 bridges, from the linkage of the urethane with the PEA. Bands at 1650 cm-1 is the overlapping of –N=C=O (urethane) and ester linkage of the PEA. Obviously, bands 1550, 1650 and 3350 cm-1 indicate complete conversion to urethane moiety

and core density of 38-39 kg/m3 with average void size of 0.10-0.15 mm (Fig. 8).

**5.1. Physical properties** 

**5.2. FTIR analysis** 

(Silverstein et al. 1991).

**Figure 6.** GC chromatogram of the RBD PKO-based polyol obtained at 175-180ºC for 30 minutes.

#### **4.2. Thermal testing**

The thermogram of the resulted RBD PKO-based polyol is as shown in Figure 7. Thermally, it is stable up to 167.6ºC and undergoes two stages decomposition at 167.6 to 406.3ºC with total weight loss of 99.41%. The initial 3.34% weight loss is contributed to the moisture content and other volatile impurities in the RBD PKO-based polyol (Oertel 1993). The initial decomposition is contributed by the degradation of RBD PKO-based polyol and traces of glycerol supported by the DTA curve which representing the softening temperature at 385ºC. Charred residue was obtained after testing.

**Figure 7.** TGA thermogram of the RBD PKO-based polyol obtained at 175-180ºC for 30 minutes
