BS 7344:1990 pdf free. Specification for Reeled low densitypolyethylene film forgeneral purpose application.
BS 7344 The gloss value of a specimen is the mean of the fourreadings obtained with the sample perpendicular tothe plane of the incident and reflected beams andwith the following orientations:
a) the front surface of the film towards theincident beam and the machine direction of thefilm parallel to the plane of the incident andreflected beams;
b) the front surface of the film towards the incident beam and the transverse direction of thefilm parallel to the plane of the incident andreflected beams;
c) the back surface of the film towards the incident beam and the machine direction of thefilm parallel to the plane of the incident andreflected beams;
d) the back surface of the film towards the incident beam and the transverse direction of thefilm parallel to the plane of the incident andreflected beams.
Cut three test specimens from the film under testwith the assistance of a template 120± 5 mm longand 50± 1 mm wide.
NOTE The width of the template is the same as that of theplatens described in C.2.
Carry out the test at a temperature of 20 5°℃.Place the test specimen symmetrically between twoflat platens 50 1 mm square and mmthick, which may be made of any rigid material thatwill not warp, e.g. polymethylmethacrylate or
aluminimum.Take care to prevent prematureseparation of the components of the specimen.Separate the layers of film outside the area of theplatens and secure the four lengths of film thusobtained by means of spring clamps or pressuresensitive adhesive tape to the platens, as indicatedin Figure 1 so that there is no slack length of film.Place the assembly of platens and test specimen ona flat surface and place a load on the assembly suchthat the total force on the test specimen
is 9.8 0.5 N.Connect the upper platen to a sensitive load measuring device (see note) and thelower platen to a driving mechanism which causesthe lower platen to move at a constant rate of 800 mm/min in a direction parallel with the longaxis of the test specimen.The general arrangementis shown in Figure 1.
NOTE A sensitive strain gauge used with a recording devicegiving full scale deflection in not more than 0.25 s is suitable.Record the force (N) required to separate the film.Report the resistance to opening of the tubing undertest as the mean of the values of N obtained on thethree test specimens divided by the area of theplatens (approximately 25 cm.BS 7344 pdf download.