BS 14022:2010 pdf download – Structural adhesives — Determination of the pot life (working life) of multicomponent adhesives
6.2Method 1: Determination by means of a change in apparent viscosity (rotatingviscometer or oscillating rheometer)
6.2.1 Principle
A multi-component adhesive is mixed and its pot life established by measuring the time taken for its viscosityto change by a specified amount.
This method is not suitable for the determination of pot lives that are shorter than 5 min in duration.
6.2.2Apparatus
6.2.2.1alance, capable of weighing up to (500± 0.2)g.
6.2.2.2 Beaker, squat form,capacity 400 ml, made of an unreactive material with adhesive,whose wallthickness does not exceed 1 mm.
6.2.2.3 Spatula made of a non-reactive material with adhesive and with an angular , not circular end.
6.2.2.4 Viscometer,any suitable means of measuring the viscosity of the adhesive (rotating viscometer oroscillating rheometer) may be selected.See EN 120922001，Method 1, for the viscosity measurement withrotating viscometer.
6.2.2.5Stopwatch,accurate to 土 1 s.
6.2.2.6 Test enclosure, capable of being maintained at the test temperature and if necessary at a relativehumidity of (50 ± 5)%.
6.2.3 Procedure
Both components of the product shall be maintained separately at (23 ± 2)*℃. The single components shallbe weighed into the beaker (see 6.2.2.2) according to the mixing ratio specific for the product,with thepreferred mass of the batch of the products being (200 主 20) g.
Start the stopwatch (see 6.2.2.5) and mix the batch with an angular , not circular end of a spatula (see 6.2.2.3)for (60 ±10) s. Take care that also the areas within the angle between side and bottom of the beaker are wellmixed.
lt is also allowed to determine a pot life of a batch which was produced with the help of a static or dynamicmixer, which has to be defined specifically.
lmmediately after mixing measure the viscosity with a viscometer (see 6.2.2.4) of the freshly preparedadhesive.
Record the first data after having finished mixing as the starting viscosity point. Continue the measurement inintervals dependent on the pot life expected.
NOTE The number of measurements as will as the extent of shear at mixing of the components and themeasurement itself can have an infuence on viscosity and pot life.Therefore,it is recommended to fix the intervals ofmeasurements as well as mixing, shear speed and rotational speed specific to the adhesive,
The pot life of the adhesive is the difference between time at the end of mixing and the time when a fixedagreed viscosity is reached. Usually the fixed agreed viscosity is double the starting viscosity.
6.3 Method 2: Determination by means of a change in extrusion rate 6.3.1 Principle A multi-component adhesive is mixed and its pot life established by measuring the time taken for there to be a specified decrease in the quantity of adhesive extruded through a calibrated orifice, in unit time, under standard conditions. This method is not suitable for the measurement of pot lives that are shorter than 5 min in duration.
6.3.2 Apparatus
6.3.2.1 Cartridge, plastic disposable cartridge of 47 mm internal diameter and 210 mm length, fitted with an appropriate piston; both components being made from a non-reactive material. 6.3.2.2 Balance, capable of weighing up to (500 ± 0,2) g.
6.3.2.3 Stirrer, rigid, helicoidal steering spindle made from non-reactive material suitable for use in conjunction with the adhesive being assessed.
6.3.2.4 Motor, an electrically or pneumatically powered stirrer motor whose speed can be regulated between 0 r/min and 1 000 r/min.
6.3.2.5 Nozzle, calibrated made from non-reactive material, capable of being screwed onto the end fitting of the cartridge (see 6.3.2.1). The diameter of the nozzle’s extrusion orifice shall be suitable for dispensing the mixed adhesive. An orifice diameter of 2 mm to 4 mm is recommended for evaluation.
6.3.2.6 Extrusion gun, air pressurised extrusion gun suitable for use with the cartridge described in 6.3.2.1.
6.3.2.7 Pressure gauge, air pressure gauge capable of measuring air pressure up to 500 kPa with a precision of ± 10 kPa.
6.3.2.8 Stopwatch, accurate to ± 1 s.
6.3.2.9 Dishes, of suitable capacity, pre-weighed, aluminium foil dishes.
6.3.2.10 Bath, capable of being maintained within ± 0,1 °C throughout a temperature range between 15 °C and 30 °C.
6.3.2.11 Test enclosure, capable of being maintained at the test temperature and if necessary at a relative humidity of (50 ± 5) %.