Polymers at the Movies
PSLC - The Macroplex Cinema

Polymers at the Movies
SPECIAL FEATURE: Polymers on the Floor
The theater is full of polymers. I mean, if it weren't for polymers, our movie-going experience would not be the same at all. Here we will show you some of the ordinary polymers that make going to the theater special. There are some unexpected surprises just inside the theater doors.

Just look at that carpet. There's usually some neat pattern on it, like little confetti-looking designs or multicolored film reels. Either way it's part of the experience. Each theater has its own cool design and that carpet is made from
nylon, something tough that can stand up to wear and tear, popcorn and a LOT of cleaning.

And what about those seats you're sitting on? The covers are made of synthetic fibers, like the carpet - acrylic or polyester. And those plastic armrests and chair backs are probably some kind of polyethylene.

Theaters also often have different kinds of curtians or carpet on the walls to absorb sound from the speakers so there won't be noise bouncing all over the place from the loudspeakers or the crying baby in the back row. These kinds of sound insulation are probably a synthetic polymer, like nylon or polyester.

The first place we look in the movie theater is at the screen. Well, we're looking at polymers... usually
vinyl. This is a common material for those big screens. It is flexible and a good carrier for the reflective coating that makes the movie look nice and bright. It also can be made in large sheets which can be connected almost seamlessly. The reflective coating is made with minerals, including titanium dioxide and mica. Mica is a natural pearlescent mineral that is pretty reflective, so should it be called the mica screen instead of the silver screen? Or maybe the vinyl screen? The screen is usually one large piece stretched on a frame and held with a lot of hidden hooks and springs. Some of the frames are even electric so they can move to change the shape and size of a screen for different width films.

Another place polymers help to show the movie is in the projection booth. A stiff mylar leader is used at the head of the film so it's easy to string it onto the projector. The leader can even be encoded to tell an automatic projection system when to change lenses for different films. Since the mylar leader is crosslinked, it is not subject to melting or many other changes that extreme temperatures bring. The film itself is often made from polyester which is used for distribution prints because it is tougher and stands up better to repeated uses than cellulose acetate film, which is used to shoot and edit the movie... but it will melt! Has anyone else here ever seen the film get stuck in the projector at the theater? WOW! The hot light bulbs will melt the film in a couple of seconds if it sits still in the projector gate.

Now, a distribution print of a feature length motion picture is pretty long - thousands of feet, in fact. They ship these things on several, very large and heavy reels. The old tradition was to run two projectors and do a "change-over" between them as each reel ended using those little dots that flash in the corner of the screen as cues. Now, however, they've got monster projectors with huge platters that can hold an entire movie, so change-overs are no longer needed. Instead, the projectionist tapes the whole thing together with tough polyester splicing tape. When the show closes, he untapes all of it, puts it back in the box and sends it back to the distributor. This is also how the previews are attached to the head of the movie since they are all sent from different distributors.

AT THE CONCESSION STAND: Polymers in the food?
A really important way that polymers help at the theater is in the serving of food, especially drinks. How can a cold drink make it through a 2 hour movie without leaking? Well, the wax that they coat those cups with does most of that work, and it is made of the same molecular sructure as
polyethylene at a very low density. Best of all, plastic lids keep the drink from sloshing all over the person sitting next to you. And you can't drink the soda very easily wihtout a drinking straw (made of polymers). Strangely enough the lids and straws are made of the same stuff as the wax coating - polyethylene - or sometimes polystyrene.

Candy like "M&M's" and "Reese's Cups" come in a variety of plastic packaging materials which, unfortunately, often end up on the floor after the show, along with all the cups and popcorn tubs.
A teflon hot dog So what about all that overpriced food we buy at the movies? We're pretty sure that it has some kinds of polymers in it. The protein in those $3.00 hot dogs is a polymer (but don't eat the hot dog in our picture. It's made with a teflon molecule because all the protein molecules were way too big, and this one just happened to be bun length). Another polymer in food is gelatin, which is used in candy like "Twizzlers" or "Jujyfruits." There is also paraffin in chocolates like Hershey bars and Junior Mints; this is the same wax that is used to coat the paper cups. It is often used in chocolate to make it easier to form and less likely to melt in your hand or pocket.

popcorn made from starch molecules And some of us are under the suspicion that the butter stuff on the popcorn might be a polymer too, but this has yet to be proved. We do know for sure that the starch in the popcorn is a polymer. Either way, we're all eating polymers at the movies... Hey, what about that so-called "cheese" on the nachos?!

Polymers on the Floor We've all been stuck to the floor at the movies before. Now there are growing speculations about the make-up of and uses for the stuff on the floor. Scientists at Polydelphia Labs have found the composition of the sticky residue on the cinema floor to consist of soda, chocolate, oily butter stuff, Milk Duds and Skittles. The years of grinding and stomping, and friction of the shoes of theater patrons, plus the qualities of the oily butter stuff, have caused a crosslinking pheomenon which is yet to be understood, the result of which is an adhesive polymer which does not degrade but only grows stronger over time. They are considering this as an adhesive for the insulation tiles on the space shuttle as well as a replacement for the adhesive used on that incredibly useful polymer invention, duct tape. This stuff is also being considered as a new "super-glue," one that smells more like candy than chemicals.

Of course, all that isn't really true. In fact, we are still just as much "in the dark" as the rest of you theater-goers about that sticky goo on the floors. Maybe someday polymer scientists will figure out what to do with it. Until then, we can tell you this for sure: the floor itself is smade of polymers, most likely some kind of carpet made from nylon or linolium tiles which are made from PVC plastic.


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PSLC - Polymer Science Learning Center

Special thanks to Rich Burrows at Da-Lite Screen company for his information on movie screens, and Greg Brust for assistance with identifying many of the polymers mentioned here.