Alternating aliphatic polyketones are a new family of engineering thermoplastics. The molecular chains are linear, perfectly alternating carbon monoxide and alpha olefin structures that possess a unique combination of mechanical strength, barrier properties, wear resistance and chemical resistance. Specifically, these semicrystalline polymers maintain dimensional stability and mechanical strength in corrosive hydrocarbon environments at elevated temperatures. These qualities make PK well suited for horizontal pipe liners, inner barrier layers in coilable composite tubing and downhole tubing and casing liners.