Multiple film barrier material

The selected clothing depends on the severity of exposure (duration and concentration). Dupont s SafeSPEC interactive software-based tool provides the data required for selection of protective clothing. If selected parameters are for low concentration and short duration of exposure, then the program suggests use of a general protection fabric with serged seam in coverall style. If a person is exposed to severe conditions (high concentration for several hours), then a multiple film barrier material with a broad level of chemical protection and a taped or double taped seam is selected. The chemical resistance of various materials is discussed in the next section of this chapter. Selection should be made by a professionally trained person. 

In 2004, Office Media (Tokyo) developed a new PLA film exhibiting vastly improved functionality as a packaging material. Through combination with other biodegradable plastics, the film s transparency, flexibility, heat resistance and impact resistance, have been balanced in multiple dimensions, and through adopting two-layer and three-layer structures, gas barrier properties have also been improved. Technology to eliminate the characteristic odour of PLA developed independently by Office Media, have also been applied. 

A combination of the chaotic mixing mechanism and the selection of an optimum mixing regime enables structures to be obtained at selected parts of the striation-to-droplet structures achieved by Scott and Makosco described in Section 14.5. The chaotic mixing mechanism supports the development of a unidirectional striated ( tape ) structure which provides the multiple layers required for the unidirectional properties required in films for oxygen barrier and impact properties and in some circumstances for electrical properties. The incorporated material can be a masterbatched additive or a second polymer. 

The fact that polyethylene does not provide an adequate barrier to a number of key molecules (or whole families of substances) means that it is often used in conjunction with other polymers or materials that make up for this deficiency. In the packaging industry it is common to use multilayer films that combine the merits of two or more polymers. Multiple layers are not restricted to films they are also found in bottles, tubs, and other containers. Polymer properties of interest to the packaging industry are not limited to barrier properties polymer components also serve to physically protect their contents, act as a window to view the product, and provide a surface that can be decorated by the packager to make the contents more appealing to the consumer. 

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