Collapsible bag

FIGURE 16.2 Schematic diagram of typical outdoor 40-m collapsible bag environmental chamber (adapted from Fitz el al., 1981). 

To increase the barrier to oxygen, polymer packaging is coated with impermeable layers of metal or silicate glass. Aluminium, if vacuum deposited, is less than a micron thick. Table 11.4 shows that it reduces the permeability of a PET/ PE composite film by a factor of 10. Such collapsible bags are used inside wine boxes, as a method of increasing the shelf life of the partly consumed wine. 

The composite foil bag can easily be changed and since nearly 100% of the material is pressed out, only the collapsed bag must be thrown away. Filling the warm adhesive into 200 litre drums is not possible due to thermal degradation of the adhesive (poor heart transfer) and thus, long-term storage stability is not guaranteed in such cases. 

Sepro Conta.iner, The Sepro container consists of a collapsible plastic bag fitted into a standard three-piece, tin-plated container such as a 202 X 214, 202 x 406, or 202 x 509 can. The product is placed within the bag, and the propellant is added through the bottom of the container, which is fitted with a one-way valve. There is no limitation on the viscosity of the product but compatibiUty with the plastic bag must be considered. A free-dowing hquid can be dispensed either as a stream or a fine spray, depending on the type of valve employed. A viscous material is often dispensed as a stream. This system has been used for caulking compounds, postfoaming gels, and depilatories. 

The film tube is collapsed within a V-shaped frame of rollers and is nipped at the end of the frame to trap the air within the bubble. The nip roUs also draw the film away from the die. The draw rate is controlled to balance the physical properties with the transverse properties achieved by the blow draw ratio. The tube may be wound as such or may be sHt and wound as a single-film layer onto one or more roUs. The tube may also be direcdy processed into bags. The blown film method is used principally to produce polyethylene film. It has occasionally been used for polypropylene, poly(ethylene terephthalate), vinyls, nylon, and other polymers. 

On 5 January 1943, my father was already so weakened that when we had to drag a 50-kilogram bag at doubled pace he collapsed before my very eyes. He was carried to the camp by his comrades. He had been beaten constantly by the guards, and this most severely on the last day. Inasmuch as the physician in the sick barracks to which he had been taken was a Czech professor, I could see my father once more and he died in my presence on 7 January 1943... 

Cardiovascular Effects. In a recent report on the clinical treatment of phenol poisoning, Langford et al. (1998) provide a summary of a case report in which a woman accidentally consumed an ounce of 89% phenol which had been mistakenly been given to her in preparation for an in-office procedure. Her immediate reaction upon consuming the phenol was to clutch her throat and collapse, and within 30 minutes she was comatose and had gone into respiratory arrest. Treatment was initiated with an endotracheal intubation. Ventilation with a bag and mask led to the detection of a lamp oil odor. Within an hour she developed ventricular tachycardia which responded to cardioversion however, she subsequently developed (in the first 24 hours) supraventricular and ventricular dysrhythmias, metabolic acidosis, and experienced a grand mal seizure. After a 15-day hospital stay, she was completely recovered with no evidence of impaired motility or compromised gastrointestinal or cardiovascular systems. 

Calibration of FAGE1 from a static reactor (a Teflon film bag that collapses as sample is withdrawn) has been reported (78). In static decay, HO reacts with a tracer T that has a loss that can be measured by an independent technique T necessarily has no sinks other than HO reaction (see Table I) and no sources within the reactor. From equation 17, the instantaneous HO concentration is calculated from the instantaneous slope of a plot of ln[T] versus time. The presence of other reagents may be necessary to ensure sufficient HO however, the mechanisms by which HO is generated and lost are of no concern, because the loss of the tracer by reaction with whatever HO is present is what is observed. Turbulent transport must keep the reactor s contents well mixed so that the analytically measured HO concentration is representative of the volume-averaged HO concentration reflected by the tracer consumption. If the HO concentration is constant, the random error in [HO] calculated from the tracer decay slope can be obtained from the slope uncertainty of a least squares fit. Systematic error would arise from uncertainties in the rate constant for the T + HO reaction, but several tracers may be employed concurrently. In general, HO may be nonconstant in the reactor, so its concentration variation must be separated from noise associated with the [T] measurement, which must therefore be determined separately. 

The most inexpensive and simplest system is the glove bag, which is basically a plastic bag open at one end with glove inserts. The materials to be used are placed in the bag in the collapsed condition. Holes are cut in the plastic for making electrical connections and so on, and then sealed with tape or other suitable material. The bag is then purged with inert gas for several minutes and the open end is sealed with the gas continuing to flow. 

A. Transfer Into a Glove Bag. It is cumbersome to transfer large items into a glove bag once work is underway. Therefore all of the items to be used should be placed into the bag, which is then fully deflated and sealed by rolling and clamping the inlet flap. Inert gas may then be introduced and the bag may be flushed through an exit tube and bubbler, or opened slightly, collapsed, and inflated several times to expel air. 

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