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For batch or continuous weighing of solids or liquids For remote indication or continu­ous flow control With accuracy above 0.25% of range Highly sensitive, extremely rugged No springs, knife edges, or levers Unatfected by off-center loading on platform Unaffected by vibration

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TECHNOLOGY

Paper from Synthetic Fibers g l U H ν Laboratory work points to development of im­proved papers containing nylon, Orion, or other synthetics

iGKlN&COf 64-F Fulmor A v e .

N E W YORK.—Growing interest: is b e ­ing expressed in t he use of synthetic fibers in the manufacture of paper. T h e unusual properties of nylon polyamide fiber, Orion acrylic fiber, and Dacron polyester fiber, for example, indicate that these materials might be of con­siderable value in papermaking, accord­ing to James K. Hubbard , Franklin H . Koontz, and Robert A. A. Hentschel of Du Pont, reporting at the 40th annual meeting of the Technical Association of the Pulp and Paper Industry. Syn­thetic fibers have shown outstanding resistance to corrosive chemicals, molds, bacteria, sunlight, heat, and moisture. They also have high strength, ilex en­durance, and abrasion resistance.

Papers made from nylon, Dacron, and Orion are three to 10 times stronger than pulp or rag papers. Their high strength may make them especially use- > ful in heavy-duty b^.gs. Their stability in the presence of moisture may be of particular value in map and tracing papers, as well as for important records and documents where permanence is essential.

Exceptionally promising results have been achieved on a laboratory scale, they reported. Measured on pap-ers weighing about 60 pounds per TAPPI standard ream, papers made from syn­thetic fibers give tenacities ranging from 22 to 33 pounds per inch, elongation from 6 to 5 3 % , Elmendorf tear strength from 298 to 1228 grams, "bursting strength from f"7 to 207 pounds p e r square inch, and MIT fold endurance from 51,000 to 1 million cycles. Nylon papers have be sewn with, seam strengths equal to 40 to 1009^ of t h e base strength of the paper, depending on the way the seam is loaded.

Bonding of the fibers to one another is the critical step in the preparation of these papers. The fibers are usually bonded by such salts as calcium bro­mide, lithium bromide, calcium triio-cyanate, or specially formulated polya­mide or polyester adhesives.

Insect-Resistant Paper . Coopera­tive research between the U. S. Depart­ment of Agriculture and the Quarter­master Corps has led to a clear under­standing of the important factors in­volved in the production of insect-re­sistant packaging materials, reported Hamilton Laudani and Dean F \ Davis of the Department of Agriculture. Pro­tection against insects can be expected for 9 to 12 months with multiwalled

paper bags to which synergized pyreth­rum has been applied on the outside ply. Lindane and methoxychlor also have value as insecticidal coatings.

Better insecticidal treatments will have to be found if textile bags are to be made insectproof for periods of more than 6 months. Currently available treatments for paper shipping boxes are not sufficiently effective.

The greater part of the protection provided by pyrethrum synergized with piperonyl butoxide can be explained on the basis of repellency rather than toxicity. The effectiveness of this treat­ment may be enhanced by the develop­ment of compounds that increase or extend the activity of synergized py­rethrum.

Insecticidal Coatings. Because of - insect infestation, millions of dollars

worth of food products have been con­demned as unfit for human consump­tion by federal inspectors, declared Ken­neth A. Arnold of St. Regis Paper. In flour products, the main infestations are in the grain during the milling process and through the package during ship­ping and storage. Notable progress has been made in treating the grain with nontoxic insecticides to prevent infesta­tion at that point. Considerable ad­vance has also been made in the devel­opment of insect repellent coatings for multiwall paper bags. Tests show that coverage of 5 mg. of pyrethrum and 50 mg. of piperonyl butoxide per square foot of paper provides effective pro­tection against insect penetration.

W a t e r Acting on Cellulose. The effect of water on cellulose at 100° to 225° C. was outlined by B. B. Mithel, G. H. Webster, and W. H. Rapson of the University of Toronto. The mate­rial treated was highly purified wood cellulose containing 98.0% alpha-cellu­lose, which was exposed to heated dis­tilled water for 4 hours.

No cellulose dissolved below 170° C , but some did at higher temperature ( 2 3 % at 209° C ) . Below 150° C , the alpha-cellulose content of the residue dropped only slightly (to 9 5 . 3 % at 135° C ) , bu t at higher temperatures it fell sharply (to 7.2% at 209° C ) . This rapid decline was accompanied by a rise in beta-cellulose (to 90.7% at 209° C ) , bu t relatively little gamma-cellu­lose appeared in the residue (2 .1% at 209° C ) . As the temperature was raised, the viscosity of the cellulose de­creased, as did the p H of the liquor.

9 5 6 C H E M I C A L A N D E N G I N E E R I N G N E W S

W/C Weiqhinq Scale PNEUMATIC-PLATFORM TYPE

For process control