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Corrosion of steel in concrete is a natural phenomenon causing severe distress to structures situated in areas with high humidity, sea coasts, high salinity, etc. This menace can destroy even the strongest buildings, bridges, ports, dams, plants, runways, etc. Various surface coatings are in practice for protecting the steel reinforcing bars from corrosion. However, the available coatings are solvent based and hence toxic and pollute the atmosphere. This paper deals with the formulation of suitable greener protective anticorrosive coating to steel rebars in order to enhance the corrosion resistance and protect the rebars. Fifteen polyurethane-based coatings with suitable functional pigments, fillers, corrosion inhibitor and hiding agent (titanium dioxide) were developed and their properties on resistance to corrosion were studied and the results are presented.

This study investigated the ability of natural dyes to impede the attack of black carpet beetles on wool. The dyes evaluated were naturally occurring quinines (cochineal, madder, and walnut) and flavonoids (chestnut, fustic, indigo, and logwood). All of the dyes, except indigo, were applied by using five mordanting agents (aluminum, chrome, copper, iron, and tin). Mordanting agents were used to bind natural dyes on wool. The insect resistance of the controls and dyed specimens was evaluated, following the fabric weight loss procedures in AATCC Test Method 24. All of the dyes, except indigo, increased the insect resistance of the wool fabric to attack by black carpet beetles. The wool specimens dyed with cochineal and madder, naturally occurring anthraquinone dyes, had the lowest fabric weight loss among eight natural dyes investigated. The flavonoid dyes were not effective in enhancing insect resistance. Alum, copper, and iron have no significant effect on enhancing or reducing insect resistance of any of the eight natural dyes used in this study. However, tin and chrome, when used as a mordant for cochineal, reduced the insect resistance dramatically. Surprisingly, tin improves the insect resistance of wool fabrics dyed with fustic dyes. The anthraquionones including cochineal, madder, and walnut were found to be quite effective in protecting wool fabric against black carpet beetles. Thus, the naturally occurring mordant dyes provide an alternative to insecticides in protecting wool textiles from insect attack. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 322–328, 2005

To evaluate the serviceability of a new textile product made of an unconventional fiber blend, it is important to determine if the fabric meets the specific standards required for the intended end-use. The value-added textile products of interest are fabrics made of 50/50 kenaf/cotton in the filling direction and 100% cotton in the warp direction, made in sateen, plain, twill, and oxford weaves. The control fabrics are of 100% cotton in only the plain and sateen weaves. The fabrics are characterized and compared based on ten of the most common fabric properties that affect their performance in everyday use: thread count, thickness, weight, breaking strength and elongation, dimensional stability, wrinkle recovery, abrasion resistance, tear strength, staining and stain release, and pilling resistance. Breaking strength of the experimental fabrics compares well with the control fabrics. Elongation at break is greater in the warp direction (19–35%) than in the filling direction (11–15%), but this difference is not significant. Wrinkle recovery for both fabrics is the same and improves over time. Shrinkage is identical in both fabrics. There is no significant difference in the stiffness of the two fabrics, possibly due to the carding step where kenaf fibers are carded to resemble cotton fibers. Abrasion and pilling resistance are good to excellent. Tear resistance is lower for the experimental fabrics compared with the controls, but it does pass the requirements for both upholstery and apparel fabrics. Kenaf/cotton blends perform the same or better than 100% cotton in their ability to release water-based stains, but the oil stain rates between 3 and 4, indicating a residual stain. Stain resistance can be improved by applying a soil-resistant finish. This study demonstrates that kenaf/cotton blend fabrics meet or exceed the performance requirements for both apparel (i.e., outer wear items such as barn jackets, hunting vests, overalls, and caps) and upholstery fabrics. Additional advantages of the blend fabrics may be luster, interesting texture, and lightness.

To incorporate kenaf fibers into textiles, it is important to establish uniformity of fibers extracted from the base to the tip of the plant. Bast fiber quality depends on both physical (crystallinity, crystallite size, and orientation) and chemical (lignin, gum, and hemicellulose) properties. Therefore, the first objective is to determine fiber uniformity, evaluating the effect of processing on tenacity, elongation, crystallinity, crystallite size, and chemical composition of fibers extracted from base to tip of the stalk. Second, to make fibers spinnable, the effect of various softeners is evaluated. Decorticated kenaf stems (variety E41) have been retted chemically and bacterially to extract fibers. Fiber bundle strength ranges from 22-30 g/tex. Gum content decreases from 20-10% with the initial chemical processing; later degumming does not reduce gum levels. Initial gum removal increases crystallinity by 3-5% and crystallite size by 20-25%. Physical and chemical properties of kenaf fibers are uniform along the whole length of the native stalks. Alkali treatment with 1% NaOH is not sufficient to impart noticeable stretch. Enzyme and degumming treatments weaken the fibers significantly (30-45%). The commercial softener makes fibers too sticky, and they stick to the carding equipment. Bending rigidity and hysteresis (recovery after repeated bending) do not significantly improve for the softened fibers. Degummed fibers are the strongest. most pliable, with least hysteresis and lowest residual gum content, and are spinnable.

Decorticated kenaf stalks were retted by bacterial and chemical processes. Bacterial retting was done in troughs at a temperature of 30 ± 2°C. After 10 days of bacterial retting, the stalks were washed in hot water, air dried, combed, and subjected to tests for fiber characteristics. Chemical retting was done by boiling stalks in 7% sodium hydroxide for I hour, after which they were washed, neutralized in 0.2% acetic acid. washed, air dried, and combed. Fiber characteristics such as bundle strength, elongation at break, color, luster, reed length, and gum content were compared for fibers extracted by both processes. Bundle strength, gum content, and reed length were lower for chemically retted fibers as compared with bacterially retted fibers. Gum content of bacterially retted fibers was uniform, and they were superior in luster. Residual gum content of bacterially retted fibers was 21-23% versus 7-12% for chemically retted fibers. Fiber quality from bacterial retting was superior, but a method that combines bacterial and chemical processing may have some merit. The feasibility of large-scale chemical retting and incorporation of fibers into nonwoven and woven textiles is being investigated.

The article offers information on use of 2,4-dinitro- 6-sec butylphenol (DNBP) in styrene production for protection against styrene polymerization. It mentions that symptoms in persons receiving exposure to DNBP include fatigue, thirst, sweating, insomnia, weight loss, headache, flushing of the face, nausea, abdominal pain and occasional diarrhea.

Durability of reinforced cement concrete structures is mainly affected by corrosion of steel reinforcements. In order to protect the reinforcing bars from corrosion and to enhance the lifetime of reinforced cement concrete structural members, anticorrosive treatment to steel is of prime importance. Conventional coatings are solvent based. In this study, water based Latex was used to formulate anticorrosive coating. Latex is applied to steel specimen substrates such as plates and rods and their mechanical properties such as flexibility, abrasion, bendability, adhesive strength, impact resistance, etc. were studied. It was inferred that coating containing latex, micro silica, zinc phosphate, ferric oxide, aluminum oxide, titanium oxide and silica fume was found to possess more corrosion resistance under marine exposure conditions.