SURFACE STRUCTURAL STUDIES OF POLYETHYLENE, POLYPROPYLENE AND THEIR COPOLYMERS WITH TOF SIMS

Static secondary ion mass spectrometry (SIMS) was applied for probing structural differences such as unsaturation and branching in the case of simple aliphatic hydrocarbon polymers (polyethylene, polypropylene and their copolymers). The parameter introduced for quoting surface am ounts of branching is the percentage of C6 to CS cluster emission rela tive to the sum of all C2 to C8 clusters. The ratio of the total emiss ion of hydrogen-deficient fragments to the sum of all C2 to CS cluster s is found to be a good pointer for unsaturation, especially for probi ng vinyl bonds. While applied successfully to polymers of the same fam ily, these pointers cannot provide structural information on polyethyl ene/polypropylene copolymer surfaces in a straightforward way. The che mical surface composition of these copolymers is correlated to the per centage of the m/z 69 fragment.