Polyethylene plasma fluorination and permeability relationships to methanol‐gasoline mixtures

Abstract

SYNOPSISIn the case of cold plasma fluorination we analyzed effects of the main processing conditions (power, exposure time, nature of gas, and number of fluorinated faces) on gasoline permeability of polyethylenes. Optimization of processing conditions gave us a permeability reduction of 30% compared to untreated polyethylene. XPS analysis of fluorinated specimens before permeation experiments shows the PE to be highly fluorinated at the surface with a F/C ratio up to 2. Fluorination appeared to be homogeneous over the disk surface with a concentration depth profile showing a step decline below the extreme surface. However, significant fluorination is achieved only up to a few tens of nanometers (20 to 30). A more interesting effect is the evidence for chain breaking during the process suggests the creation of short chain segments at the surface. These segments would be highly fluorinated but easily leeched out by the diffusing molecules. Leeching seems more important with alcohol containing gasolines. These data show clearly that fluorination by cold plasmas in the conditions under studies has not a permanent effect.

Influence of the silane grafting of polyethylene on the morphology, barrier, thermal, and rheological properties of high‐density polyethylene/organoclay nanocomposites

“…These advantages include flexibility, light weight, low cost, and recyclability. However, the use of neat PE is restricted because of some of its inherent properties, such as a relatively high oxygen and aroma permeability, which weakens the long shelf‐ life properties required for these applications 1–21…”

“…In principle, a barrier function can be incorporated into a PE packaging material with alternative technologies, such as the surface treatment of the polymer by fluorination or sulfonation,2, 3, 22 multilayer coextrusion (the addition of a layer of barrier material),1, 23, 24 or mixing the barrier materials into the base polymer. In the case of PE, the barrier materials usually can be a barrier polymer, such as polyamide or ethylene vinyl alcohol copolymer,7–11, 17–19, 25 or a mineral filler, such as talc or mica powder 12.…”