What is Plastic: Definition and 288 Discussions

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.

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  1. Stephanus

    Can Plastic Be Made Without Oil?

    Can plastic be made NOT FROM oil? And not from remains of living organic matter. I mean, we extract carbon from atmosphere CO2 or from the rock... Oxygen from atmosphere or sea water... Hydrogen from sea water... Nitrogen from atmosphere or other sources... Combine them together and voila, we...
  2. J

    Strong, Low Friction material better than teflon?

    I'm working on an engineering problem where we are using Teflon as a low-friction material as a surface for plastic parts to move above. However, the material is wearing faster than expected due to the plastic rubbing away at the Teflon. Is there a non-metallic material that has equal or...
  3. C

    Can the Plastic Moment be smaller than Elastic Moment?

    Homework Statement Stress = 320 MPa Max Elastic Moment = Stress*Z Max Plastic Moment = Stress*S Solve the maximum moments and compare the % increase Beam is an I beam with dimensions: (b and d) Top Flange = 25*10 web = 10*180 Bottom Flange = 200*8 Homework Equations see above The Attempt at...
  4. Rotzooi

    Heat transfer of a hot plastic thread in a cold water bath

    Hi, I'll describe my problem more specific. I have a continuous flow of this polymer thread (polystyrene) at 465 °K (190°C sorry I'm metric) that needs cooling down. It passes trough a water bath which is kept at 310°K (35°C). Now i try to calculate the heat exchange into the water, to...
  5. xorisa

    Flow of Water in a plastic bottle

    Homework Statement You open the plastic bottle lid to take a drink,and notice fluid flowing from a small hole in the bottom of the bottle. You put the lid back on and the flow stops. Explain why the flow did not start until the lid was off. Explain why the flow stopped when the lid was put...
  6. E

    How can I prevent deformation of an ultrathin-walled tube during insertion?

    Designing mechanical system where two concentric tubes will pass through high density membrane. Outer tube will have tapered end .Outer tube will have ultra thin walls (about 0.3-0.5 mm) .Inner tube is more rigid and will fill all space inside outer tube,decreasing chance for deformation of...
  7. G

    Why does plastic container slides off at the same speed?

    Homework Statement Two small cylindrical plastic containers with flat bottoms are placed on a turntable that has a smooth flat surface. Canister A is empty; canister B contains lead shot. Each canister is the same distance r from the center. The coefficient of static friction between the...
  8. S

    Electrostatics Basics -- 2 plastic balls hanging on threads attract each other

    Homework Statement Two small plastic balls hang from threads of negligible mass. Each ball has a mass of 0.14 g and a charge of magnitude q. The balls are attracted to each other and the threads attached to the balls make an angle of 20.0 degree. with the vertical. The balls are 2.05 cm apart...
  9. Calpalned

    Exploring Plastic Surgery Transformations: From Celebrities to Neanderthals

    There have been cases of people going under the knife in order to look more like an idol, be it Superman Herbert Chavez)or Justin Bieber (Toby Sheldon). If someone wants to look like a neanderthal, can plastic surgery be used to change the shape of the skull? If it is possible to look like...
  10. R

    Microchannels in a plastic film

    Another grad student and I have figured out a way to create micron-sized channels INSIDE a piece of thermoplastic polymer using a laser. Basically it creates a porous channel inside the material (I attached a microscope image). This is a long channel but the inside of it is not empty - it has a...
  11. A

    Polarization of clear plastic - a puzzle

    I finished my online E&M class today, and the prof told us to experiment with polarizers. While doing that, I found this: I put a piece of plastic between two polarizers, and found that at a certain angle between the two polarizers, a portion - though not all - of the plastic darkened. So I...
  12. C

    Plastic vs metal gears / parts

    Hello, I wonder whether I can replace the Metal gears and other parts with Plastic material? If so, what kind of plastic material should I use? There is no heat and the force is also not that great but the speed is. This is not for toy but industrial machinery, with gear diameter of about 10...
  13. E

    Energy bands in plastic materials

    Plastic materials are said to have large gaps between the valence band and the conduction band. But what is its valence band properties? Why do plastic melt easily compared to the glass? What is the relationship between energy bands and melting? And what are the right words in goggling this...
  14. R

    Designing using Impact Energy of Plastics

    Hi, I am attempting to design a plastic scrap grinder. To begin my calculations I need to know the force needed to shear a certain area of plastic. After noticing that by using the shear stress equation would result in a huge, unrealistic force, it came to my mind that the plastic will be cut by...
  15. C

    Plastic or glass that can block one colour/ wavelength?

    Hi, new member here, I know very little about physics so have no idea if this is a very basic question or not, but I was wondering if anyone knows the answer to the following: Does there exist a type of plastic or glass that (whilst remaining completely see through) can allow the user to see...
  16. M

    Is an Acme Thread Suitable for Plastic Bottle Caps?

    Hi, My question regards a plastic bottle that I'm designing. For the threading that fits the two parts together, will and Acme thread work? This is how I've designed my part, but I can change the thread profile if need be. Also, is there anything that I need to know regarding the pitch? I have...
  17. P

    Help- Thin cheap board/plastic for waterproof poster

    Hi all- I am trying to make a semi-waterproof poster (only needs to be wet for a few hours and not necessary for the poster to last beyond the day) I need to back the poster on a hard surface - have tried correx but it won't accept any titebond glue as it is basically treated to be resistant...
  18. DaveC426913

    Bic pens - what type of plastic?

    When I was a young lad, schools provided Bic pens to write with. They are not the usual pens you are used to, these pens were solid dark-blue, round in cross-section (not polygonal), and both the pen and the cap tapered gently. When capped, the cap almost divided the pen in half (i.e the cap was...
  19. P

    Biodegradable Plastic: Cellulose Acetate & Checking Its Biodegradability

    Is cellulose acetate - in thin film form - biodegradable ? If yes,how do I check it's biodegradability ?
  20. C

    Pressure inside a plastic bottle filled with water and squeezed by X weight?

    Hi, I'd like to know how it'd be possible to calculate the pressure inside a plastic bottle filled with water and squeezed by say 20 kg sitting on the bottle, which is lying on its side (so that resistance to deformation does't come to play as much as it'd if it was sitting on a standing...
  21. K

    Can You Calculate Individual Energy Absorption in a Partially Plastic Collision?

    Homework Statement Is there a way to know how much kinetic energy has lost and transferred into internal energy for each of the members in a partially plastic collision? I can only know how much kinetic energy has lost in total, i don't know how much of it each member got. When a car...
  22. J

    Homework help:A small plastic sphere with a mass of 2.60 X 10-15 kg

    Homework Statement "A small plastic sphere (with a mass of 2.60 X 10-15 kg) is suspended between two plates, with a potential difference of 265.4 V across the plates. The separation of the plates is 0.500 cm. The upper plate is negative and the lower one is positive. a)What type of...
  23. L

    Hand Moldable Plastic: Find Material for Room Temp Shaping

    Hi, I am looking for a material that molds/gets shape with hand at room temperature and does not separate! Does such a material exist? (By the way I am do not have physics background!) Many thanks for you help :) Leila
  24. Evanish

    How can different types of plastic be cheaply and easily identified?

    From my reading various places online it seems that plastic recycling would benefit from a cheap and easy method for identifying different plastics. Resin codes can be used but they are definitely not easy. They require someone to search around on the product to find them. That takes a lot of...
  25. J

    Maximum Load on a Plastic Sheet

    I am going to attempt to use a sheet of HDPE betwen a concrete footing and the base of a column to allow the column to move with thermal expansion in the structure it is supporting. My question is how can I determine if the HDPE will be crushed by the weight of the column and no longer act as a...
  26. I

    Plastic shredder for shredding plastic?

    I am looking into the possibility of making this shredder to shred failed 3D prints, mostly ABS. https://grabcad.com/library/mini-shredder--1 Here is a printed version, which can't shred plastic- https://www.youtube.com/watch?v=A4rg--VEXVM These are expensive to make in steel, but I...
  27. T

    Large Plastic Deformation Theory

    Hello everyone, I'm studying the large plastic deformation theory based on the multiplicative decomposition of the deformation gradient, commonly noted as the matrix F, into an elastic and plastic part F=F_ e F_ p (theory introduced by Simo and Miehe) The constitutive law is : -\dfrac{1}{2}L...
  28. T

    Shear Thickening Fluid (in plastic)

    I have been looking into shear thickening fluids and how they are used with Kevlar for bullet proof vests. I am considering alternative uses but have limited knowledge on the subject. I would like to create a rigid solid that becomes harder and less flexible when a large force is suddenly...
  29. Greg Bernhardt

    Green plastic bottles and bags in the US

    I just got back from a trip to Japan and one thing I was super impressed with was that all the plastic bags and bottles were derived from plants and thus would safely breakdown over time. I know California has some tough laws, but what about the rest of the US. Why are we not using plant...
  30. C

    Bouyant Force in a U Shaped Plastic Tube

    Homework Statement A plastic tube has a cross-sectional area of 5.00 cm^2. The tube is shaped sort of like a "U". The left arm is filled with water until the right arm of length 0.800 m is full of water. The right arm is then sealed with a cap that won't pop off until a force of 9.8 N is...
  31. D

    Chemical for cleaning printed picture on plastic material?

    Hi all, I'm david from indonesia. Sory for my english. Can you help me to found a chemical that I can use to cleaning printed picture on plastic material? This is for recycling, means in big volume... Thanks before
  32. Vigardo

    Can plastic materials be modeled as Mooney-Rivlin materials?

    Dear experts, I wonder if semi-crystalline plastics can be considered as Mooney-Rivlin materials for an application in the analytic modeling of thin membranes. Any help will be very appreciated! The stored-energy function (W) of a Mooney material model is: W = C1(I1-3) + C2(I2-3)...
  33. Vigardo

    Inflation of a clamped isotropic and thin circular plastic membrane

    Appreciated experts, I want to model the inflation of a thin and isotropic circular plastic membrane clamped by a ring. I need to determine the maximum deflection at the pole, stresses, strain, etc..., as a function of the applied pressure difference. The large deflection range complicates it...
  34. gfd43tg

    Pumping a Bingham Plastic

    Homework Statement You have been employed by Sea World to help design rides for their new amusement park in Palo Alto. Your first task is to design a slime delivery system for a "Alien Adventure" ride. The slime is manufactured at Slimy Corp 225 miles away. The connecting pipeline has a 1.0...
  35. M

    Light refracting through a plastic sphere

    Homework Statement A small light bulb is placed 10.0 cm from the center of a plastic sphere of radius 1.0 cm and refractive index 1.40. Where is the image of the bulb? Homework Equations 1) Thin lens equation 2) Thick lens equation The Attempt at a Solution I realize that I'm...
  36. L

    What would the products of photolysis degredation of PET plastic be?

    Interested in this because plastic drinking bottles have a taint to them when left out in the sun. I gather its from UV degredation of the PET plastic. I'd like to find a catalyst that would allow the PET byproducts to be non water soluble/sequester or even evaporate.
  37. J

    What Material absorbs shock better? Rubber or plastic?

    For example a phone in a case is dropped, would it suffer more in a plastic case or a rubber case? Thanks
  38. E

    Steel Angle Plastic Section Modulus

    Hi all, I am after trying to find the plastic section modulus about both local axes (x & y) after having calculated them for the global axes (n & p). Is there a way I can transform global to local using Morh’s circle to evaluate plastic section properties? Attached is the key diagram I am...
  39. B

    How Thick Can Acrylic Latex Be Applied on a Vertical Surface Before It Runs?

    Homework Statement Acrylic latex can be described by a Bingham Plastic model where the yield stress is 11.2 N/m2, a limiting viscosity, m0, of 80 cp and a density of 0.95 g/cm3. What is the maximum thickness of this paint that can be applied to a vertical wall without running. Homework...
  40. Z

    Dissolving a plastic without dissolving freeze/thaw treated PVA

    Hi there We are two students that are looking for a specific plastic material for our project. We need to print the lumen of a blood vessel in a plastic material. We will put this inside a tub of PVA which we will freeze/thaw. We then need to dissolve the plastic material without...
  41. H

    Why do plastic warp when heated

    I have noticed that, in the plastic extruded from 3d printers, plastic fork that i put near the fire during bonfires, whenever plastic is heated they tend to warp(curve up) why is that the case?thank you
  42. T

    Design an Eco-Friendly Plastic Photodegrador

    i was thinking of a good thesis topic involving enviro-friendly touch and i came up with this: plastic photodegrador! the concept was from the idea that plastic degrades easily in the ocean, so i am planning to design an equipment that will make plastics degrade fast. the design is somehow like...
  43. R

    Credit card Magnetic strip and the plastic bag trick

    When my credit card magnetic strip is worn it won't scan at the grocery check out. The clerk then uses a plastic bag over the card and runs it through the scanner. I'm baffled why this should work, but it does every time. Any explanations ? Thanks
  44. W

    What's the best way to destroy pathogens on plastic?

    I've got a plastic bottle that I want to reuse for years, but the label said that you shouldn't reuse it for hygiene reasons. I'm assuming some bacteria builds up or something and this is dangerous? If so, what is the best way to kill these microorganisms without wearing down the plastic?
  45. T

    Help with plastic bridge design

    I am in a high school Precalculus class. We are about to have a project where we build bridges with PVC and twine. The goal is to hold as much weight as possible. For this project, I believe we will be given 28 feet of PVC, a roll of twine, and 5 or 6 days to design and construct our...
  46. S

    How to discharge a clear plastic film roll ? : (

    Hello ! Firstly, i'd like to say that I have nothing to do with physics - and everything I've learned in school - has been forgotten and I really hope you can help me with a small problem I have .. I bought a roll of clear plastic film (100 m) one like this...
  47. M

    Space in plastic to fit a ball bearing?

    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?
  48. E

    Double-Slit Arrangement With Plastic Sheet

    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...
  49. H

    Light ray passing thru plastic block

    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...
  50. G

    True Stress-Strain Curve on the Log Scale: Which portion is the plastic region?

    My math is a little weak, so I'm having a hard time finding the elastic and plastic regions on this curve. Any further help will also be appreciated!
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