Abstract: A sulfur-containing acryl oligomer composition represented by formula (I): ##STR1## wherein R.sub.1 represents a hydrogen atom or a methyl group; R.sub.2 and R.sub.3 each represents an alkylene group having from 1 to 12 carbon atoms; R.sub.4 represents an alkylene group having from 1 to 12 carbon atoms, an oxydialkylene group having from 2 to 12 carbon atoms, or an aralkylene group having from 6 to 20 carbon atoms; X represents a chlorine, bromine or iodine atom; m represents 0 or an integer of from 1 to 4; and n represents an average degree of oligomerization of 10 or smaller.The oligomer composition provides on polymerization a cured product having a refractive indices of 1.60 or higher, excellent transparency, and optical uniformity and is therefore useful as a material for plastic lenses.

Abstract: This invention relates to a method of manufacturing pyroelectricity and piezoelectricity elements consisting of a very thin film of polyvinylidene fluoride or a copolymer of polyvinylidene fluoride less than 7 micron thickness which is stretched while in close contact with a laminating resin which has a low adherence to said film so that said film can be stretched very thin as stated above.