2.4.2. Evaluation of film characteristics:
2.4.2.1. Film resistance
Water, alkali (10% NaOH) resistance acid (10% HCl, 20% H2SO4) resistance and solvents (acetone, ethanol,
methanol, ethyl methyl ketone, and toluene) resistance were carried out according to standard methods.
2.4.2.2. Mechanical tests:
After tack-free drying, the film properties such as: bending test, adhesion (tape test), impact, gloss and scratch
hardness by pencil test, were determined by standard methods.
3.1. Physicochemical properties of jojoba seed oil
The properties of the JSO are shown in table 2. The iodine value (95) indicates a level of unsaturation that may
consider the oil as semi-drying. It is noteworthy that the degree of unsaturation of the oil is directly related to the
drying property of the alkyds.
3.2. Preparation of jojoba seed oil-modified alkyd resins:
The alcoholysis was carried out by heating jojoba seed oil with glycerol to 240˚C for about 4 hours in the presence
of calcium carbonate as catalyst until a clear solution was obtained. The time needed for the alcoholysis step was
dependent and is nearly proportional to the percentage of oil contents. Thus the relationship between the percentage
of oil used in the alkyd formula and the time taken for alcoholysis may be used to estimate the time taken for the
alcoholysis reaction of JSO for different percentage of oil (Fig 1).
Polyesterfication was conducted by heating a mixture of phthallic anhydride and benzoic acid to the product
obtained from the alcoholysis step until the acid value was dropped about 10. The change of the acid value during
the polyesterfication process is illustrated in Fig 2 which shows that acid value decreases gradually with time of
polyesterfication until it reaches a minimum after about 4 hours.
2.4.2. Evaluation of film characteristics:
2.4.2.1. Film resistance
Water, alkali (10% NaOH) resistance acid (10% HCl, 20% H2SO4) resistance and solvents (acetone, ethanol,
methanol, ethyl methyl ketone, and toluene) resistance were carried out according to standard methods.
2.4.2.2. Mechanical tests:
After tack-free drying, the film properties such as: bending test, adhesion (tape test), impact, gloss and scratch
hardness by pencil test, were determined by standard methods.
3.1. Physicochemical properties of jojoba seed oil
The properties of the JSO are shown in table 2. The iodine value (95) indicates a level of unsaturation that may
consider the oil as semi-drying. It is noteworthy that the degree of unsaturation of the oil is directly related to the
drying property of the alkyds.
3.2. Preparation of jojoba seed oil-modified alkyd resins:
The alcoholysis was carried out by heating jojoba seed oil with glycerol to 240˚C for about 4 hours in the presence
of calcium carbonate as catalyst until a clear solution was obtained. The time needed for the alcoholysis step was
dependent and is nearly proportional to the percentage of oil contents. Thus the relationship between the percentage
of oil used in the alkyd formula and the time taken for alcoholysis may be used to estimate the time taken for the
alcoholysis reaction of JSO for different percentage of oil (Fig 1).
Polyesterfication was conducted by heating a mixture of phthallic anhydride and benzoic acid to the product
obtained from the alcoholysis step until the acid value was dropped about 10. The change of the acid value during
the polyesterfication process is illustrated in Fig 2 which shows that acid value decreases gradually with time of
polyesterfication until it reaches a minimum after about 4 hours.
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