BYD

Design to RealityEvolution of the Plastic BottleIn the dark nights of my soul, I fret about how inconsistently engineered my life is. The coffee table I made a year or two ago was intended to look like the dining room table I built a few years earlier, but in reality the two bear only a vague resemblance to each other. Open a drawer of my tool chest at random, and perhaps you’ll find a thematically-aligned collection of well-loved hand tools, meticulously cut into a nest of Kaizen foam, or maybe you’ll find a random assortment of half-forgotten specialty wrenches. My bookshelf is nicely sorted and stacked, but my magazines are dumped into a basket this way and that. We manage to invest embarrassing amounts of engineering and infrastructure into physical objects that are barely worth mentioning. So when I look out at the world outside of my own home, I am reassured to find that even our most disposable objects are the result of staggering quantities of serious and earnest engineering work. You’ve got to give it to humanity: We don’t just put all of our design cycles on the big, impressive projects—pyramids, bridges, and semiconductor fabs. No: We manage to invest embarrassing amounts of engineering and infrastructure into physical objects that are barely worth mentioning. Stuffed animals, given away as carnival prizes, are the beneficiaries of untold logistical and supply-chain management efforts. A pair of pantyhose might contain materials that required eight or nine figures’ worth of R&D work to develop. A plastic water bottle, whose entire usable lifespan is measured in seconds, is the result of decades upon decades of engineering across a range of functions. From glass to plastic I stand up, put on my shoes, and walk over to the grocery store. The walk to the grocery store takes maybe 120 seconds, and I walk it about once a day. I recognize that this is absurdly frequent and revel in treating the grocery store as an extension of my pantry. Today, I get ketchup and crackers then scoot around to the dairy aisle for unsalted butter. Walking past the bottled water I pause—the selection there is honestly incredible, a little Darwinian competition playing out on the shelves. I stand there, registering the different phenotypes and thinking about how each species and sub-species of water bottle evolved.

A guy in his thirties reaches in front of me to grab a gallon-sized jug of Poland Spring from the shelf. I make room for him, consider my options, and for some reason end up with a liter each of Pellegrino, Evian, and Smartwater. As weird as it sounds, water from the Evian source was bottled in earthenware jugs from 1826 all the way until 1908. Glass and glassblowing were not all that reliable in the belly of the nineteenth century, but around the turn of the twentieth, glass technology had trickled down from lenses and lightbulbs to proliferate within beverage packaging. If you were starting a bottling company in 1900, you probably started in glass. Coca-Cola was first bottled (in glass) in 1899, the same year that Pellegrino, with their distinctive green glass bottle, was founded. Evian switched to glass in 1908. Coke’s acrylonitrile misadventure While synthetic plastics were first developed in the 1880s, and Dustin Hoffman was getting lectured about the material’s business potential in 1967, it wasn’t until the mid-‘70s that food-safe (or at least vaguely food-compatible) formulations began to roll out. One of the most notable of these was acrylonitrile copolymer, which was brought to market in the form of Coca-Cola’s “Easy-Goer” bottle in 1975. Coke’s acrylonitrile bottles lasted less than two years on the market. From an engineering perspective, acrylonitrile copolymer was a great fit for soda bottles. It was transparent, tough, and impervious to gas. Coca-Cola executives touted its “environmental advantages” (namely its lower shipped weight) and its resistance to biodegradation, claiming that the bottles, which were manufactured by Monsanto, would cost “essentially the same as glass.” Pepsi, who had also been working on plastic bottles, fumed on the sidelines. While Coke was camped out at a hotel launching the Easy-Goer, Pepsi held a competing PR event, down the hall at the same hotel, to unveil “a champagne from the Soviet Union.”

The short career (1975-1977) of Coke’s Monsanto-designed Easy-Goer acrylonitrile bottle. This author was unable to definitively identify imagery of Pepsi’s Soviet champagne, but this state-owned Russian site seems to indicate it was Nazdorovya. The Easy-Goer bottles were, to my taste, a bit on the chunky side. Coke’s acrylonitrile bottles lasted less than two years on the market. It turns out acrylonitrile bottles will leach acrylonitrile into whatever liquids they contain; furthermore, test animals who were fed “large amounts of acrylonitrile in their drinking water” developed “significantly lower body weight and other adverse effects, including lesions in the central nervous system and growths in the ear ducts.” The FDA banned acrylonitrile beverage containers in March of 1977; Monsanto sued and lost; Coke looked to other materials. Injection Stretch Blow Molding (ISBM) Here’s how most plastic beverage bottles are made today: A bottle preform, also known as a parison, is typically injection-molded out of PET. The preform looks kind of like a test tube, with threads at its mouth and a disc-like collar just below. Its walls are thick. Maybe it’s stored for a while, still devoid of cap, but eventually it’s installed onto a stretch blow molding machine where it’s heated, stretched lengthwise internally with a metal rod, and injected with compressed air, blowing up rapidly like a balloon before being cooled and spat out. The same preform might be blown into a variety of different bottle designs, each with different volumes and wall thicknesses and design details, but their thread profiles and necks will remain identical to the preform from which they were made. Coke’s Easy-Goers had metal caps, but today virtually all plastic bottles are also capped in plastic. Plastic caps are injection or compression molded, with their tamper-evident rings attached. The injection molds are honestly beautiful—polished, multi-part assemblies, with twelve or twenty-four or forty-eight caps all being molded at the same time. Watching caps being compression molded, meanwhile, is mesmerizing: semi-soft blobs of plastic goop being extruded, cut, and squished into a rotating tool that then dumps a finished cap assembly off of its backside.

Either way, when caps meet their bottles the bottles will have been filled with some fluid, and in some cases pressurized with carbon dioxide gas (for that bubbly sizzle) or liquid nitrogen (for structural and preservative reasons). This all happens at staggeringly high speed, dozens of bottles per second, tens of thousands of bottles per hour, frankly unfathomable numbers of bottles per day. Injection stretch blow molding forms bottles in two stages: a heated PET preform is stretched and blown inside a mold, aligning the polymer chains to create a lightweight container with high strength and clarity. The rise of PET Again, I’m struck by the stupidly obvious fact that human beings invented all of this stuff. Real people, with dreams and fears and families to support, spent big chunks of their lives inventing not only the beverage packaging itself but the machinery required to make, fill, cap, and package these unfathomable numbers of bottles. Disposable water bottle engineering is a career path that you could choose, and if you did choose it then you would not be alone in having done so. While Monsanto had been toiling away on their yet-unproven acrylonitrile copolymer bottles, there was an entirely different group, at DuPont, working on polyethylene terephthalate. Even more incredible is the fact that some of Dustin Hoffman’s contemporaries—indeed lots of them—chose careers in plastic bottle engineering, even before plastic bottles had been proven viable. While Monsanto had been toiling away on their yet-unproven acrylonitrile copolymer bottles, there was an entirely different group, at DuPont, working on polyethylene terephthalate. Polyethylene Terephthalate, “PET.” So many ethylenes! Take a bunch of gaseous ethylene molecules, and catalyze them with metal salts such that they form long, caterpillar-like solid molecules, with each segment containing one carbon atom and two hydrogen atoms. In this form, bulk polyethylene can be incredibly strong and durable, especially when the caterpillar-like molecules get really long. (Ultra-high-molecular-weight polyethylene, whose chained-together ethylenes can be hundreds of thousands of units long, has yield strengths comparable to steel—at dramatically lower densities. Lots of high-end sailing rigging is made from this stuff, and also ultralight camping gear.)

Polyethylene is also environmentally stable, optically clear, and doesn’t, like acrylonitrile, leach into food or beverages that it’s put into contact with. People have been catalyzing polyethylene this way for about 75 years now, and because of its remarkable physical properties, we now make more of the stuff than any other polymer; today, global annual polyethylene production is something on the order of a hundred million metric tons—equivalent in mass to almost eight years’ worth of New York City’s solid trash production. Within two years of the Easy-Goer’s downfall, DuPont was in full production, making two-liter PET bottles for the Coca-Cola company’s caramel-colored sugar water. I can just imagine the excitement at DuPont’s polyethylene team when the FDA put an end to Coke’s acrylonitrile adventures. DuPont had been working on soda bottles since at least 1967, when Nathaniel Wyeth (a DuPont “engineering fellow” who was also the other brother of painter Andrew Wyeth) began tinkering with polypropylene. By this time the younger Wyeth had a painting in the permanent collection at MoMA; I imagine Nathaniel, the less famous Wyeth, crawling around in the chemical weeds, grasping for some way to make his own name. Finally he found his path through the undergrowth: A “hollow thermoplastic article,” which he patented in 1973. Within two years of the Easy-Goer’s downfall, DuPont was in full production, making two-liter PET bottles for the Coca-Cola company’s caramel-colored sugar water. Wyeth’s 1990 obituary showcases his invention of the now-ubiquitous PET plastic soda bottle. Source: New York Times. I actually remember these bottles from the birthday parties of my youth. Produced from the late ‘70s until the early ‘90s, the first generation of enormous PET beverage containers, with their opaque, glued-on bases, arose in tandem with the soda industry’s shift to high fructose corn syrup. Both “New” Coke and “Crystal” Pepsi were packaged in these thick-walled, two-liter bottles, our parents using two hands to pour them into our trembling plastic cups. These bottles were totems to American excess, their contents slowly going flat in the fridge if they weren’t spilled all over the dining room table first.