Terephthalamide esters used as plasticizers are of the general formula <FORM:0808366/IV (a)/1> where n is 1 or 2 and R and R1 are selected from hydrogen, halogen and alkyl groups of 1-6 carbon atoms. They may be used as plasticizers preferably in a proportion of 5 to 45 per cent by weight of the total solids for cellulosic films and sheets, natural rubber, chlorinated rubber, rubber hydrochloride, cyclized rubber and coumarone indene with rubber, or for thermoplastic resins, e.g. polyvinyl chloride, polyvinylidene chloride, polystyrene, copolymers of vinyl chloride and vinyl acetate, copolymers of methyl methacrylate and vinyl chloride, polyvinyl butyral, polyvinyl acetal, polymethyl methacrylate, polymethyl acrylate, polyethylene, polyamides, synthetic rubbers, polysulphides, polyisobutylenes, oil modified and unmodified alkyd resins and phenol formaldehyde resins. They may also be used to plasticize, e.g. cellulose acetate, cellulose acetate-butyrate, cellulose acetate-propionate, cellulose propionate, benzyl cellulose, ethyl cellulose, butyl cellulose, hydroxyethyl cellulose, cellulose nitrate, mixed esters or ether-esters, e.g. cellulose acetate-nitrate, ethyl cellulose nitrate, urea-formaldehyde, melamine-formaldehyde, phenol-furfural, polyallyl alcohol and protein-formaldehyde resins, and also mixtures such as polyvinyl chloride and urea formaldehyde ether, polyvinyl chloride and phenol formaldehyde, polymethacrylate and urea formaldehyde, polystyrene and alkyd resins, coumarone-indene and alkyd resins, polyvinyl acetal and melamine-formaldehyde. In such compositions the terephthalamide ester of the invention may be present in 5-45 per cent by weight of the total solids. Other plasticizers, e.g. dibutyl phthalate, dilauryl phthalate, cyclohexyl butyl phthalate, di (methylcyclohexyl) phthalate, di (dimethylcyclohexyl) adipate, dicyclohexyl adipate, tricresylphosphate, esters of o-benzoyl benzoic acid such as butyl benzoyl benzoate and derivatives of toluene sulphonamide may be present. The terephthalamide esters may be incorporated in moisture-proofing coating compositions comprising a cellulose derivative and a wax, such as japan wax, palm wax, beeswax, Chinese insect wax, paraffin, petrolatum or certain chlorinated hydrocarbons. Such compositions may include a blending agent such as ester gum, rosinates, hydrogenated rosins, hydrogenated rosin esters, dammar, copal, kauri, alkyd resins, vinyl derivatives, chlorinated diphenyl resins, phenol formaldehyde resins, hydrogenated castor oil, castor oil phthalate, lanolin, ethyl abietate, methyl abietate, diethylene glycol rosinate or diethylene glycol hydrorosinate. Examples are given of a composition containing nitrocellulose, paraffin, dammar gum, dibutyl phthalate and the dibenzoate of N,N1-bis-(beta hydroxyethyl) terephthalamide and a composition containing nitrocellulose, paraffin, ester gum and the tetra(m-chlorobenzoate) of N,N1-tetra (beta hydroxyethyl) terephthalamide. Specification 671,141 is referred to.ALSO:Terephthalamide esters used as plasticizers are of general formula <FORM:0808366/IV (b)/1> where n is 1 or 2, R and R1 are selected from hydrogen, halogen, and alkyl groups 1-6 carbon atoms. They are prepared by heating mono or di ethanolamine with a terephthalic acid or ester thereof, in ethyl alcohol until a clear solution is obtained. The N,N1 bis-(beta hydroxyethyl) terephthalamide or N,N1-tetra (beta hydroxyethyl) terephthalamide so formed is then removed from the solution and reacted with aromatic acyl halides to produce the corresponding ester thereof. Suitable acyl halides are benzoyl chloride, and halogen and/or alkyl substituted derivatives up to 7 carbon atoms, e.g. p-ethylbenzoyl chloride, p-bromo benzoyl chloride, m-chlorobenzoyl chloride, 2-bromo-4-methyl benzoyl chloride, 3-chloro-4-hexyl benzoyl chloride, 4-iodo-2-butyl benzoyl iodide, 2,5-dichloro benzoyl chloride, 3-ethyl-5-amyl benzoyl fluoride. Examples are given of the preparation of the dibenzoate of N,N1-bis-(beta hydroxy) ethyl) terephthalamide, di (m-chlorobenzoate) of N,N1-bis-(beta hydroxy ethyl) terephthalamide, tetrabenzoate of N,N1-tetra-(beta hydroxyethyl) terephthalamide, tetra - (m - chlorobenzoate) of N,N1-tetra-(beta hydroxy ethyl) terephthalamide, and di-(p-ethylbenzoate) of N,N1-bis - (beta hydroxyethyl) terephthalamide. Specification 671,141 is referred to.