novel alloy / blends barrier resins consisting of a composition of polyethylene terephthalate and polytrimethylene naphthalate or pet and polybutylene naphthalate exclusively for packaging beverages like beer in a monolayer bottle outperforming the existing other barrier multi - layer bottles is described . the alloy / blends of pet / ptn and pet / pbn are produced by using in situ polymerization or melt blending the two polymers or compounding the two polymers to get the ptn and pbn in a pet polymer matrix . the composition of pet alloy / blends with ptn and pbn additionally contains other barrier improving additives . incorporating a suitable oxygen scavenger in these new alloy / blends and converting to a stretch blow molded bottle , with or without heat setting , allows this monolayer bottle to be tunnel pasteurized for protecting beverages like beer filled at specific gas pressure to its maximum shelf life of & gt ; 180 days keeping under control both oxygen ingress and carbon dioxide egress . the recyclability of used bottles into bottles , fibres and strappings has been established .