Plastic additives which are useful as nucleating agents and which are especially useful for improving the optical properties of polymeric materials are provided. More particularly, this invention relates to certain alkyl (or alkoxy) substituted halo-benzylidene sorbitol acetals and polymer compositions thereof which may be utilized within, as merely examples, food or cosmetic containers and packaging. These inventive halogenated (that is, chlorinated, brominated, or iodinated) and alkylated benzylidene sorbitol acetals are also useful as gelling agents for water and organic solvents, particularly those used in the preparation of antiperspirant gel sticks.