**5.5. Rheological and kinetic properties**

The PU system is polymerized kinetically using tetramethylhexadiamine, TMHDA as a gel/blow catalyst and pentamethyldiethylenetetramine, PMDETA as a blow catalyst. The addition of both catalysts is very minimum (0.05-0.10 pbw) in achieving an optimum kinetic reaction time (Tamano et al. 1996) especially when reactive RBD PKO-based polyol (Scheme 2) is used in the formulation. The cream time, gelling/fiber time, tack-free time and rise time (Appendix B) were 23, 71, 105 and 156 seconds respectively at 20ºC. The PUF is demolded after 10 minutes of mixing with skin thickness of about 1.5 mm. It has a flow index of 1.050 cm/g, a moderate flowability PU system (Colvin 1995). This is assumed to be helpful in reducing the consumption of raw materials, especially the RBD PKO-based polyol.

#### **5.6. Resistance to environmental stress**

The chemical resistance of the PU with normal closed-cell structures of rigid urethane foam prepared from the crude MDI and RBD PKO-based polyol is carried out to investigate the limitation of the interactions with surroundings to the surface layer in order to produce a chemically and physically stable material. Effects produced by chemical agents depend both on the chemicals and on the permeability of cell membranes. Solubility of the chemical in the foam affects both permeability and swelling. Results obtained are not representative of other temperatures, concentrations or exposure times.

Biobased Polyurethane from Palm Kernel Oil-Based Polyol 465

in a major increment in the strength at 10% deflection. Readings of above 0.20MPa (compared to the control foam) with maximum compressive strength are observed in benzene at about 0.34MPa, followed by PUF at ambient temperature (0.30MPa), freeze-thaw condition (0.26MPa), 10% NaOH (0.25MPa), saltwater (0.20MPa) and finally 10% HNO3 (0.19MPa). The same trend is observed in compressive strength at 5% strain where the maximum value is encountered at freeze-thaw condition followed by at ambient temperature, 10% NaOH and finally benzene. The compression modulus reaches as high as

**Figure 11.** Effect of various environmental stresses on the compressive strength and compression

Practically, the absorption of chemicals into the foam results in swelling of the cell faces, which apparently increases the compressive strength. Weathering conditions (ambient and freeze-thaw) however are very much dependence on the diffusion rate of carbon dioxide being replaced by the air which causes expansion of the foam and increases the compressive strength (Wood 1990). The foams are found to be unaffected by the test medium basically due to the mixture of organic components (RBD PKO-based polyol and MDI). Rigid PU foam is stable in the present of most solvents such as found in binders and

Physically, the foam becomes spongy with the formation of waxy material on the surface of the foam, as a result of prolonged exposure to benzene as an aromatic hydrocarbon. It is important to note that ester-based polyurethanes are easily attacked by hot aqueous alkali or moderately concentrated mineral acids, swollen by aromatic hydrocarbons and decomposed by prolonged contact with water, diluted acids and moist heat (causes swelling and slow

The compression modulus of the PUF ranges from 7.8 to 10.8MPa. the compression modulus for the control PUF is at 8.5MPa which is lower compared to the modulus in 10%HNO3,

11.0MPa and others are in the range of 8.0 to 9.0MPa.

modulus of the RBD PKO-based PU foam

sealers (Oertel 1993).

hydrolysis) (Roff et al 1971).


Note: \* Physical property requirements following BS6586: Part 1: 1993 industrial standard.

**Table 5.** The mechanical properties of the PU foam synthesized from the RBD PKO-based polyol.

Fig. 11 illustrates the compressive strength at 10% deflection and 5% strain as well as its compression modulus upon exposure to stress. All resistivity test medium being used result in a major increment in the strength at 10% deflection. Readings of above 0.20MPa (compared to the control foam) with maximum compressive strength are observed in benzene at about 0.34MPa, followed by PUF at ambient temperature (0.30MPa), freeze-thaw condition (0.26MPa), 10% NaOH (0.25MPa), saltwater (0.20MPa) and finally 10% HNO3 (0.19MPa). The same trend is observed in compressive strength at 5% strain where the maximum value is encountered at freeze-thaw condition followed by at ambient temperature, 10% NaOH and finally benzene. The compression modulus reaches as high as 11.0MPa and others are in the range of 8.0 to 9.0MPa.

464 Polyurethane

\*Apparent molded density, kg/m3

foam rise at 10% deflection, kPa

5% strain, kPa

\*Apparent water absorption,%

kg/m3

N/m2

\*Apparent density (core),

\*Compressive strength to

\*Compressive stress at

Compressive modulus,

**5.6. Resistance to environmental stress** 

other temperatures, concentrations or exposure times.

The chemical resistance of the PU with normal closed-cell structures of rigid urethane foam prepared from the crude MDI and RBD PKO-based polyol is carried out to investigate the limitation of the interactions with surroundings to the surface layer in order to produce a chemically and physically stable material. Effects produced by chemical agents depend both on the chemicals and on the permeability of cell membranes. Solubility of the chemical in the foam affects both permeability and swelling. Results obtained are not representative of

Min 38 43.6 ±0.85

Min 35 38.9 ±0.53

Min 180 185.7 ±8.22

Min 140 105.4 ±2.41

Not available 8.52 ±0.46

Width: -0.433 ±0.03 Thickness: 1.373

Width: 0.017 ±0.04 Thickness: 1.654

±0.06

±0.09

Maximum 3.0 Length: 0.359 ±0.25

Maximum 6.5 2.25 ±0.89

At -15 ±2oC for 24h Maximum 1.0 Length: -0.151 ±0.03

**Parameter Method Standard Results** 

BS 4370:Part 1:1988

BS 4370:Part 1:1988

BS 4370:Part 1:1988

BS 4370:Part 2: 1993

BS 4370: Part 1: 1988 (Appendix A)

At 70 ±2oC, 95 ±5% r.h.

BS 6586: Part 1: 1993

Note: \* Physical property requirements following BS6586: Part 1: 1993 industrial standard.

Shore A Hardness ASTM D 2240 Not Available 29.0 ±1.4

**Table 5.** The mechanical properties of the PU foam synthesized from the RBD PKO-based polyol.

Fig. 11 illustrates the compressive strength at 10% deflection and 5% strain as well as its compression modulus upon exposure to stress. All resistivity test medium being used result

(Method 2)

(Method 2)

(Method 3)

(Method 6)

(Method 5B)

for 24h

(Annex D)

\*Dimensional stability,% BS 4370: Part 1: 1988

**Figure 11.** Effect of various environmental stresses on the compressive strength and compression modulus of the RBD PKO-based PU foam

Practically, the absorption of chemicals into the foam results in swelling of the cell faces, which apparently increases the compressive strength. Weathering conditions (ambient and freeze-thaw) however are very much dependence on the diffusion rate of carbon dioxide being replaced by the air which causes expansion of the foam and increases the compressive strength (Wood 1990). The foams are found to be unaffected by the test medium basically due to the mixture of organic components (RBD PKO-based polyol and MDI). Rigid PU foam is stable in the present of most solvents such as found in binders and sealers (Oertel 1993).

Physically, the foam becomes spongy with the formation of waxy material on the surface of the foam, as a result of prolonged exposure to benzene as an aromatic hydrocarbon. It is important to note that ester-based polyurethanes are easily attacked by hot aqueous alkali or moderately concentrated mineral acids, swollen by aromatic hydrocarbons and decomposed by prolonged contact with water, diluted acids and moist heat (causes swelling and slow hydrolysis) (Roff et al 1971).

The compression modulus of the PUF ranges from 7.8 to 10.8MPa. the compression modulus for the control PUF is at 8.5MPa which is lower compared to the modulus in 10%HNO3, 10%NaOH, under freeze-thaw condition, and in saltwater but higher if compared to the modulus of the rest of the resistivity test.

Biobased Polyurethane from Palm Kernel Oil-Based Polyol 467

action of most organic solvents and are seriously degraded only by strong acids, oxidizing agents and corrosive chemicals. Only polar solvents, which significantly swell the polymer, lead to shrinkage of the foam structure. Evaporation of the solvent normally returns the

In terms of application, these composites are most suitable in structures where stiffness and dimensional stability are of prime importance but is only a secondary choice to areas where

These works on the production of the RBD PKO-based polyol and other ranges of polyurethane polyols have been at present being produced at larger scale and ready to depart January 2012. This is being brought into realization with the support of Universiti Kebangsaan Malaysia under its entities School of Chemical Sciences and Food Technology, Polymer Research Center and Faculty of Science and Technology (UKM-OUP-FST-2012) for all the facilities provided. Thank you to Ministry of Higher Education, Ministry of Science, Technology and Innovation (previously known as Ministry of Science, Technology and Environment) and Yayasan Felda for the financial supports. Major contributions definitely came from graduates and colleagues of Universiti Kebangsaan Malaysia. For special individuals who initiated this project, Zulkefly Othman and in memory Haji Badri Haji

Ahmad, S., Siwayanan,P. & Wiese, D. 1995. Porim and INTERMED Sdn.Bhd. Malaysian

Alfani, R., Iannace, S.&Nicolois, L. 1998. Synthesis and Characterization of Starch Based

Apukhtina, N.P. 1973. Methods for Increasing the Thermal Stability of Polyurethanes: Soviet Urethane Technology, Ed. Schiller, A.M. pp. 198-210. Connecticut: Technomic

Athawale, V.D., Rathi, S.C. & Bhabe, M.D. 2000. Novel Method For Separating Fatty Ester From Partial Glycerides in Biocatalytic Transesterification Of Oils, *Separation and* 

Austin, P.E., Derderian, E.J.& Kayser, R.A. 2000. Hydrosilation in High Boiling Natural

Patent Application Number. PI9502302. Filling Date: 7 August, 1995.

Arnold, J.M. 1983. *Vegetable Oil Extended Polyurethane System.* US 4375521

Polyurethane Foams. *J. Appl. Polym*. Sci. 68 (5) : 739-745

structural strength is more vital than the component rigidity.

*Polymer Research Center, Faculty of Science and Technology,* 

*Universiti Kebangsaan Malaysia, Selangor, Malaysia* 

Zakaria, my greatest thanks to both of you.

*Purification Technology*, 18:3:209-215.

Vegetable Oils. US 6071977.

polymer to its original state.

**Author details** 

Khairiah Haji Badri

**Acknowledgement** 

**7. References** 

Publishing Co., Inc.

Rigid PU prepared has high resistivity to the action of most organic solvents and are seriously degraded only by strong acid, oxidizing agent and corrosive chemicals. Only stronger polar solvents, which significantly swelled the polymer, led to shrinkage of the foam structure. Evaporation of the solvent normally returns the polymer to its original state (Oertel 1993).
