Two microscopic methods for characterizing the maturity of a cotton sample have been developed, using either cross-sectional or longitudinal scanning of fibers by image analysis. This study compares the two methods for consistency with the aim of opti mizing their efficiency and accuracy as reference methods. Longitudinal scans of cotton fibers at immature (3.5 weeks post-anthesis) and mature (7 weeks, field opened) growth stages are compared with cross-sectional measurements of the same fiber samples. Maximum projections along the length of cotton fibers agree with cross-sectional mea surements, but minimum projections do not. Variations in fiber twisting and folding render minimum width projections inaccurate. The only true measure of wall thickness is from cross-sectional data, and fiber alignment is critical. Sample preparation for developing a reference method dictates that bundles of combed, parallel fibers be sectioned in the center. This procedure will decrease errors in sampling due to the natural taper of the fiber along its length.

A quick embedding method employing UV polymerization reactions has been devised for embedding fibers in acrylic and methacrylate media. The resultant thin, flat embeddings are suitable for both light and electron microscopy.

A durable-flame retardant based on tetrakis (hydroxymethyl ) phosphonium hydroxide (THPOH), urea, and trimethylolmelamine has been developed and applied to cotton fabric. The process is accomplished by padding fabric through a water solution of the three components to a wet pickup of about 75%, drying at moderate temperature, and curing at an elevated temperature. Solutions of 25-34% total solids containing the three components in a molar ratio of 2 : 4 : 1 (THPOH: urea : methylolmelamine), when applied to cotton fabrics of 8-9-oz weight, imparted flame resistance, and only minimal losses in breaking and tearing strength. The treated fabrics retained 91-95% break strength and 73-80% tear strength. Wrinkle recovery angles (W + F) of treated fabrics ranged from 280° to 306°. Wash- wear and durable-press properties are discussed. Little or no yellowing of treated fab rics was observed when bleached with sodium hypochlorite solution and scorched between heated plates. Resin add-ons of fabrics treated in this manner ranged from 15 to 19%. Flame resistance of fabrics treated by this process is retained after boiling the treated fabrics in a soap-sodium carbonate solution for 3 hr or after 15 laundering cycles.

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Neps appearing in all stages of textile processing up to the dyed fabric were extracted from cotton samples. These neps were disassembled and the individual fibers making up each nep, along with any foreign material appearing in the nep, were studied using microscopic techniques. Three distinct types of neps could be recognized. The data obtained from each tend to support the theory that for the most part, problematic neps are a result of immature fibers present in the cotton.