Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.In developed economies, about a third of plastic is used in packaging and roughly the same in buildings in applications such as piping, plumbing or vinyl siding. Other uses include automobiles (up to 20% plastic ), furniture, and toys. In the developing world, the applications of plastic may differ; 42% of India's consumption is used in packaging. In the medical field, polymer implants and other medical devices are derived at least partially from plastic. Worldwide, about 50 kg of plastic is produced annually per person, with production doubling every ten years.
The world's first fully synthetic plastic was Bakelite, invented in New York in 1907, by Leo Baekeland, who coined the term "plastics". Dozens of different types of plastics are produced today, such as polyethylene, which is widely used in product packaging, and polyvinyl chloride, used in construction and pipes because of its strength and durability. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger, who has been called "the father of polymer chemistry" and Herman Mark, known as "the father of polymer physics".The success and dominance of plastics starting in the early 20th century has caused widespread environmental problems, due to their slow decomposition rate in natural ecosystems. Toward the end of the 20th century, the plastics industry promoted recycling in order to assuage environmental concerns while continuing to produce virgin plastic. The main companies producing plastics doubted the economic viability of recycling at the time, and this is reflected in contemporary plastic collection. Plastic collection and recycling is largely ineffective because of the complexity of cleaning and sorting post-consumer plastics. Most plastic produced has not been reused, either being captured in landfills or persisting in the environment as plastic pollution. Plastic pollution can be found in all the world's major water bodies, for example, creating garbage patches in all of the world's oceans and contaminating terrestrial ecosystems.
I'm new in design and I'm designing a plastic piece where I want to fit a ball bearing.
The outer diameter of the ball bearing is 10 mm. If I want to fit it in the plastic. What measure I've to use in the plastic hole? 11 mm?
Homework Statement
Consider the double-slit arrangement shown in the figure below, where the separation d is 0.280mm and the distance L is 1.16m. A sheet of transparent plastic (n = 1.50) 0.0513mm thick (about the thickness of a piece of paper) is placed over the upper slit. As a result, the...
Homework Statement
A light ray passes downward into a block of transparent plastic with an angle of incidence of θ1 = 77.7°.
If total internal reflection is to occur when the light strikes the left edge of the block at interface B, what is the index of refraction of the plastic?
Homework...
Hi! I have this experiment, that keeps getting me frustrated. The experiment is simple:
We have hot water and a long plastic tube with one end closed. We simply measure how much water is in the tube and from that we get the water volume (water is in cylinder shape).
But there is something I...
Homework Statement
One charged plastic ball is vertically above another in a test tube as shown. The balls are in equilibrium a distance "d" apart. If the mass of the upper ball is reduced by a factor of four, the distance between the balls in the test tube would become :
1) 4d
2) 8d
3)...
1. In tearing a paper towel or plastic bag from a roll, why is a sharp jerk more effective than a slow pull
2. I found this answer online
A quick, sharp jerk means a greater acceleration and a greater acceleration means a greater force. And it is force that tears the paper towel or...
http://postimage.org/image/urnvnzkhz/
I was watching a tv show (the astute watcher will recognize it as How I Met Your Mother), when I saw one of the characters holding this thing (the curved plastic measuring-thing).
My dad used to have one of those on his work bench, and I used to play...
I think this belongs in set theory? I may be wrong though. I always enjoy a good math problem, and my niece made me think of something that I couldn't figure out an easy way to get an answer.
She likes making those plastic bracelets with that plastic chord with the different colors and...
I'm working on building an enclosure for a machine that is to go on display in a foyer. The machine is about 2x1x1.5m and its primary purpose when switched on is to show how dynamic components work together. My considerations include:
Cost: Need something relatively cheap
Strength:High...
is there a simple way to determine the section modulus of a member made of a W and WT shape welded together, one on top of another about the x-axis. the steel manual has the properties for the individual sections; would the section modulus of each be able to be added together or will i have to...
Hi, I have to calculate the amount of times a 76g polypropylene lunchbox must be used in order to justify its purchase over disposable 2g polyethylene snaplock bags, in terms of the life cycle energy of the two products. However each time the polypropylene box is used it must be washed using...
Hi there,
My teacher gave me a homework, but this Theory of Plasticity is new and difficult to me.
He has calculated the strain according to path (1), now I have to do with the path (2) and (3).
This is what he did with path (1):
ε11=∫(1/E)dσ11 +...
Homework Statement
Determine the failure mechanism and plastic moment for the following structure, using either the upper bound or lower bound theorem for plastic analysis.
Picture
(There is a physical hinge in the middle of the structure)
Homework Equations
Internal Work = External Work...
Hi there,
There are many videos that show people converting plastic into oil, then refining the oil into diesel, kerosine, and gasoline. I have a few questions about this particular video,
1) When the plastics turn into gas, what is the process called? Is it pyrolysis or gasification...
Hi, sorry if this is in the wrong forum.
I have a physics problem I do not understand:
Jim is removing a piece of plastic wrap from a large roll. However, he is finding that this is difficult because the piece of plastic wrap keeps trying to stick to the roll. If the charge on the piece...
I need to Calculate the Skin Effect of water in a tube of X Diameter or Surface Area... The length of the Flow in the pipe would be 200 mm. I know that is short but it matters in this instance. The pressure of the water would be around 15 bar. I will post the flow rate through the pipe as soon...
Homework Statement
ABS plastic melts (and solidifies) at 105 °C. You want to inject it into a steel mold. When the part comes out at 20°C you want it to be 7.250cm long. Edit: If this isn't clear, it wants to know how big the steel mold should be.
α for ABS plastic α= 53.0x106/C°, for steel α=...
Is there a type of plastic that has a low melting point or better a low soft temperature?
What we need is to blow up a ball (3-7 cm in diameter), cover the ball except a 6mm hole, let it dry, and then removes the plastic ball through the 6mm hole.
So to remove the plastic it needs to be soft...
If gravity distorts space-time, does space-time return to equilibrium when the gravity mass is gone (let's say it vanished instantly)? If so, what happens to other satellite masses that are caught in the same gravity well?
Does space-time just instantly slip out from under them? Or do the...
A plastic ball is inflated enough to produce tangential stresses. Stress X = Stress Y = 2000Kpa
The radial thickness of the material is 1.2mm brfore inflation. Find the thickness after inflation if the tensile modulus of elasticity is 3.4Gpa and the shear modulus is 1.4Gpa.
I created a plastic bottle and aluminum can crusher. I researched and found out that my crusher should apply at least 175 lbf - 200lbf in order to crush the beverage container. My design idea is very similar to that of a cold rolling manufacturing process. Although I have research the cold...
The question to the lab is How can the spring constant and muzzle velocity for a toy ball launcher be determined through physical measurements and energy conservation considerations?
My lab group and I took our pastic ball launchers(pretty much toy guns) and shot them straight up and measured...
plastic extrusion material selection?
Hey all,
I work for a curtain wall manufacturing and design company out of Canada. I've recently been presented with the task of creating a new extrusion to improve the thermal performance of our curtain wall system.
My question to you all is, and...
I have a cylinder of plastic (polypropylene). It is 1 meter in diameter and 1.25 meters long. It starts out at an even temperature of 100 C throughout. I put it into a 135 deg heated room with lots of air moving around it, and I hold it in the air so that every surface is exposed to the hot...
Hello,
I am looking for something to keep plastic parts warm and pliable. We have plastic discs that need metal pins snapped into some grooves and they snap wayyy to tight. We checked with a vendor and the material is still within spec, but I cannot change the material
It takes one minute...
The link is to an article that describes the history of plastic combustion engines! The reason they are not in your automobile is that those who are experts don't like the idea. There are incentives in the U.S. to make cars more fuel efficient by some 5 years from now but the plastic combustal...
I'm having a significantly harder time finding information on this than I thought I would.
I'm trying to write a small report on the chemical processes that recycled plastics are put through, but I can't seem to find much information on the methods used to disinfect various plastic polymers...
Hello, I have somewhat of a difficult question. First of all I have to say I am not an engineer. I need help in identifying this type of plastic. I am well aware that visual identification alone is almost impossible but any help would do. If possible, could one provide a supplier of this kind...
Hi All
I am doing an experiment where I am analyzing how the volume of water in a plastic bottle affects the time taken for it to roll down an elevated ramp and particular distance along a horizontal plane. I need rigorous theory for this experiment which includes moment of inertia, fluid...
I have a plastic disk 0.5" in diameter whose radius of refraction is supposedly non-uniform. It will vary by 0.015 at most from the center to the outside.
I need to come up with some method of measuring the refractive index locally. I have access to:
helium neon laser
a photodetector and...
So my mother buried her cat 5 years ago this month. I remember I wasn't home back then and it was a hard time. Yesterday we were talking about this and she asked me if I think the body is completely gone, and I said of course until she mentioned she put the cat in a plastic bag before buring it...
Results show me that if I increase the volume of water inside a bottle the time taken for it to roll down a ramp and then a particular distance along a horizontal plane increases. How would we explain this relationship.
I took a cube polycarbonate sample and put a laser through it (perpendicular to a face). When light crosses both faces (front and back), some of the light will reflect while some goes through. My questions are:
1) For the light that reflects off the first face and goes straight back into the...
I have a project where I need a flat sheet of plastic that's about 1 foot by 1.5 feet and about a quarter inch thick, but probably less than that. It doesn't have to be exactly that size. It can't be brittle either, it needs to be able to bend some.
I don't know where to get something like...
A few weeks ago a 23 year old british reality tv star died getting breast implants the size of basketballs, she was barely 5 feet tall.
Heidi Montag is in the news about all of her plastic surgery. She was pretty before she changed her face, now, not so pretty, IMO.
Here are before and...
So I'm on my last try for this question, and I could really use some help, I'm completely clueless..
Two waves of light in air, of wavelength λ = 460.0 nm, are initially in phase. They then travel through plastic layers as shown in Figure 35-36, with L1 = 4.00 µm, L2 = 3.50 µm, n1 = 1.20, and...
Ok, I have an invention, it's a clip.. and I'd like it to be made out of plastic.
What I need out of the plastic is "spring back" quality. I need it to where one can pry it open, and it'll return back to it's original shape.
This is a small device, and the plastic only needs to be about...
Hey PF,
I normally frequent the EE portion of this board, but I had a question about plastics and plastic injection molding.
A buddy and I have an idea to create a rather small and specific plastic object in large quantities. We thought that to create small prototype quantities, we could...
I am looking for this part..
I was thinking that i could find it on http://www.smallparts.com"
but i have no idea how it might be called,
it's a 10mm plastic holder of plastic tubes,
here are some images I've designed:
http://img153.imageshack.us/i/holder1e.jpg/"...
Hi Guys,
I am new here, but I have a quick question.
I had a somewhat tepid liquid in a plastic soda plastic 2L bottle
When I tightened the cap to close it all was well and normal
After a day a portion of the top of the bottle deflated, as if oxygen was sucked out
Can someone...
Homework Statement
An open plastic soda bottle with an opening diameter of 2.7 cm is placed on a table. A uniform 1.95-{\rm T} magnetic field directed upward and oriented 21^\circ from vertical encompasses the bottle.
What is the total magnetic flux through the plastic of the soda bottle...
Hello,
I wanted to know which properties a foam plastic have in general and how it works in a Mattress.
I have a Foam mattress is there any difference between hot and cold foam?
My Mattress is a Foam mattress not a Spring mattress and it feels too hot after a while you lie on it...
I would like to know views on the force required to pull a cylindrical cover.
A plastic shade cover is almost 290 ft in length and 150 ft in breadth. It is wrapped around a cylindrical wooden rod which is at a height of 7 ft from the ground. The cover is pulled by plastic ropes to the right to...
Hi, I'm trying to understand the viability of making or having made - a hot -mould that can resize the neck of a standard cooldrink bottle. I want to reduce the neck of a 500ml bottle so that it fits loosely into another bottle's neck. So(ie) - to heat and compress the neck( threaded apperture)...