Aim of the Work

The present work was carried out to clarify the effect of various climatic conditions in urban areas e.g. Alexandria city and industrial areas e.g. Helwan city on some physical and mechanical properties (tensile strength, elongation, whiteness, yellowness and brightness as well as the variation of acidity of cotton fabric.) of Egyptian cotton fabric Giza 70.

Materials and Methods:

Materials:

Cotton fabric was made of extra long staple Egyptian cotton with the following specifications of the fabric:

• Warp and weft: (raw cotton ofGiza70)
• Fabric is plain weave 1/1.
• Weight of square meter: 103 gm.
• Number of threads per cm of: warp: 28, weft: 24
• Twist Factor: warp 4 , weft 3.5.

Methodology:

The samples under study were subjected to various weathering effects at urban and industrial sites in Egypt. The exposure started on May (2002) till April (2003). The exposed fabric samples were stretching on wooden frames (70x70) cm and racks at 45 degrees to the horizon facing south.

Thus, outdoor unprotected exposure for two sets of all the examined samples was performed at Alexandria and Helwan cities in Egypt. The first set, the samples were exposed at the start of the month and removed and examined at the end of the month with a total exposure of 30 days. The second set, was exposed at the start of the year and subsets were removed and examined after 4, 8 and 12 months successively. The previously exposed samples were removed simultaneously at Alexandria and Helwan from the exposure sites and conditioned in a room maintained at a temperature of (21-oC I) and 65% relative humidity for 24 hours before testing.

The examined samples were stripped to smaller samples of 25x5 cm. and a mean of 6 readings of tensile strength, elongation, pH value, brightness, yellowness and whiteness for each sample was recorded. The recorded values were compared to the values recorded from other samples of cotton fabric of the same kind of cotton, which were kept at room temperature of 21-oC I and 65% relative humidity, and they were not exposed to the previous environmental conditions.

Tensile Strength and Elongation:

Tensile strength and elongation for the exposed and unexposed strips were tested by using Shimadzu universal testing machine, type S-500, according to the standard method of testing .Tensile strength (TS in weft direction) was determined by the strip method according to ASTM procedure D 2256-66T ⁽¹⁸⁾.

Whiteness, Yellowness and Brightness Testing:

These tests were measured using spectrophotometer type LC.S. TEXICON Limited, England.

pH values:

The pH values of an aqueous extract of both exposed and unexposed samples were measured according to the standard method for pH testing. Thus a constant weight of each fabric was finely divided using an electric divider to which a constant volume of distilled water was added, stirred very well and allowed to stand for 24 hours, then filtered. The pH values were determined using a pH meter produced by (Italy). Mean value of six readings for each sample was evaluated.