The food that the country pledges check total bureau was announced 2004 is packed (film) selective examination to make clear as a result, special provision packs fraction defective of bag sampling observation to be as high as 15% , main problem is product physics machinery function and wholesome index do not accord with national level. In the plastic respect that pack, a few enterprises use industrial level plastic replace food form plastic, excessive joins stuff stuff or add the toxic substance such as useless old stuff, stone dried meat; With industrial level compound film, add artificial brightening gent, presswork food of printing ink infiltration; In the compound respect that pack, harmful material cuts off requirement of function short of, remain is in a few dissolvent between compound film the elapse as time, from inside food of velar surface infiltration, made metamorphism, change flavour. Expert analysis, by food the material that pack causes the incident of metamorphism of food expiration period of about 30% , the food of about 60% packs material to have safe hidden trouble. Cut off one of a function is function of the material that pack main index. The material that pack is had cut off very well function, can prevent gas invade, lest mildew of commodity be affected with damp be affected with damp changes; And the permeability with have some of material to need to have again better and fully wet sex, exchange at packing the gas of inside and outside with benefit. Accordingly, wet to breathe freely or be being appeared the test that waits for function, it is to pack material to cut off one of function test very serious content. Plastic film of article key introduction cuts off the main test method of function, pass through what quantity and vapor pass through a quantity to detect to country's at present common oxygen the method undertook analytic comparative, the should note a few problems in the actor defect that pointed out them and actual unit process of cargo bandling.

Try what proved recipe law packs to cut off function is commonly measure what pass through a quantity with vapor to detect through be being passed through to gas will reflect.

Vapor passes through a quantity to detect

One, standard of basis of cup type law: GB/T1037-1988 " plastic film and sheet appear method of vapor sex experiment---Cup type law " experiment principle: Below condition of formulary temperature, relative humidity, two side carry sample certain vapor presses difference, measure the vapor volume that passes through sample, computational vapor passes through coefficient through quantity and vapor. Unit G/ (M2·24h) . Detect equipment: Sweatbox of blast of electric heat of balance of analysis of electron of wet box of constant temperature constant experiments this kind the method is the most traditional the test method that measures vapor to pass through a quantity again through the balance. Seal cup it is its main job. Before having a cup, need first the desiccative of will full amount (the anhydrous chloridize that granuality is 0.60mm~2.36mm is calcic) in be being put in sweatbox of blast of 200 ℃ electric heat the refrigeration in putting desiccator is taken out half hours after dry 2h, the desiccative that metage measures certainly is put into fully wet cup, the film that is detected is put to be used on fully wet cup dried meat sealed, make a space that close is formed inside fully wet cup, fully will wet cup is put into wet box of constant temperature constant, after vapor passes through test data, be absorbed by desiccative, after the environment of lukewarm, humidity that provides through the standard handles proper time, take out fully wet cup fixed balance is heavy, the increment that passes fully wet cup calculates those who give vapor to pass through a quantity. In appearing wet cup to transfer desiccator quickly from climate box, metage environment arrives again after placing half hours, undertake metage.
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