Tackiness measurement

In contact adhesives, the so-called tack open time is important. This can be defined as the time available after the adhesive is applied during which the surface remains tacky enough for the application of the adherend. It can be easily measured by applying a thin layer of fresh adhesive on Kraft paper and making a bond at different times until no bond is obtained. 

The method is an analogue of measuring tackiness of a powder by squeezing it by hand and observing if the mass breaks apart readily or else remains as a lump. 

J.A. Monick, Measuring the tackiness of detergent powders, Proceedings of Chemical Manufacturers, (May 1966), 108-12. 

A. Dynamic mechanical measurements A resonantly driven instrument, the Dupont 981 DMA was used for wide temperature scans. It is used in conjunction with a Hewlett Packard 9825S desk top computer with 6940 interface. A Hewlett Packard 9872 multicolor plotter was the output device. Design principle and operation of the DMA were described elsewhere and will not be repeated (5,6,7). Samples of approximately 1.5mm thick by 12mm in length were used. Since the adhesive samples were tacky and difficult to handle at room temperature, all samples were first molded in a hot compression molder and cooled to dry ice temperature ( 78 C), cut and mounted on precooled DMA fixtures. 

The recorded force first increases, then decreases the maximum value, called the tack force is a measure of the adherence in this experimental condition the area under the curve, called the tack energy, is equal to the work GdA of the singular stress at the crack tip. Tackiness refers to the ability of an elastomer to adhere instantaneously to a solid surface, or to itself, after a brief time of contact under low pressure. Probe tack testing procedure can be analyzed by Eq. 14 and tack curves obtained by computer integration closely coincide with experimental ones (25). ... 

Tacciometer n. A device for measuring the surface stickiness or tackiness of a dried paint or varnish film. It operates on the principle that a suitably weighted piece of paper will or will not adhere to the coated surface. The instrument consists of three steel balls, which are placed on the paper,... 

Other important characteristics related to tack and commonly measured are dry tack and tack range. Dry tack is the property of certain adhesives to stick to one another even though they seem dry to the touch. Tack range is the time that an adhesive will remain in a tacky condition after apphcation to the adherend. 

Films of natural rubber latex were chlorinated with chlorine gas generated in situ from acidified hypochlorite solution at room temperature and characterised by FTIR/ ATR, SEM/EDX and contact angle measurements. The mechanism of the surface chlorination process of the films in aqueous solution is considered and the effect of chlorination on such properties as tackiness and hydrophilicity is discussed. (4th International Union of Materials Research Societies International Conference in Asia 97, Makuhari, Japan, 16-18 Sept.1997). 16 refs. 

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