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. theycallmevirgo

    Fumes from heating a plastic Sterilite container?

    Howdy folks. I have a couple spares of these https://www.amazon.com/gp/product/B01NAL6MND/?tag=pfamazon01-20 and I was thinking about repurposing one as a food dehydrator. Do I need to worry about fumes? IIRC the max temp is 150F. Will one of these help...
  2. K

    Correcting the retrobrite "marble" effect

    Hi all, For those of you are unfamiliar with the concept of "retrobriting" plastic, it involves exposing yellowed plastic to UV light whilst being submerged in some variant of peroxide. This has proven to be effective in reversing the yellowing effect on old plastics. However, certain plastics...
  3. C

    Looking for ways of joining metal and plastic

    i have a plastic handle and want to join it with a metal body. i can join it with heat stacking method i have find a product who done done that. is there any other way to join permenently?
  4. EddieP

    Thermal expansion of air bubbles in plastic

    I am interested in the potential for air bubbles in a plastic structure to expand with heat, and put pressure on the plastic surrounding the air bubble. In this case the plastic structure is formed by melting a thermoplastic powder. In between the grains of powder are voids with air in them. As...
  5. W

    Tilting a 55 Gal Plastic Drum: Calculating Force Needed

    I have been tasked with tilting a plastic 55 gallon drum that contains lube to an angle of about 20 degrees. I would like to use pneumatic cylinders as air is readily available here. The plastic barrel has a 23.5 inch diameter and is 35 inches tall. The barrel and contents weighs 450 pounds...
  6. X

    I Why do droplets of condensation run at an angle on a plastic sheet?

    I think the picture says it all! As the droplets of condensation reached a certain size they begin to run down the plastic sheet, but rather than just running straight down, they veer off to the left or right. Most of the tracks are at fairly much parallel, with some exceptions, and the pattern...
  7. jaumzaum

    Working out after plastic surgery

    Hello guys! 7 days ago I did a Blepharoplasty (eyelid surgery). It's one of the simplest plastic surgeries on the face. However, for my surprise, I was told by the doctor after the surgery that I would have to stay 4-6 weeks without heavy lifting for the scars to heal properly. I think that...
  8. OlPhyz

    12 ton frame lowered on plastic --> What Happens?

    Summary:: 12 ton rectangular frame is lowered by a 4 point crane attached to each corner of the frame. Frame will be lowered onto plastic supports, these supports have guiding ramps of 60 degrees to help the operator lower the frame in the correct spot. The frame has 4 feet, one on each corner...
  9. K

    Safety of plastic spoons, etc. below their advised maximum temperature?

    I like using polypropylene dishware e.g. spoon, and storage box. I can see that from its label sometimes the maximum temperature recommended is 110 degree C or 120 degree C but it usually doesn't go away from this range. By common sense, I will never heat the polypropylene dishware directly but...
  10. Philip Koeck

    What is growing inside plastic?

    I've found something growing apparently inside plastic (microwave-proof Tupperware). Two photos are appended, a bit fuzzy, I'm afraid. The whole structure is about 2 cm long and the close-up (lowest part of the overview) shows a part that's about 5 mm in diameter. I wasn't able to scratch it off...
  11. L

    Can ABS Plastic Be Safely Broken Down for Recycling?

    Is there a process to break ABS plastic down into safe non carcinogenic chemicals? Maybe even down to its basic elements? Maybe an enzyme exists? I want to recycle my 3D printed objects that didn't turn out well.
  12. xWaldorf

    I Friction Coefficient of Marble & Iron on Plastic

    hey, i was looking for information on friction coefficient of marble on plastic and iron on plastic. if you know these values i'll be very glad! thanks in advance
  13. M

    What kind of plastic is best for this loudspeaker enclosure?

    I want to build a spherical speaker with a diameter of about 50 cm. The frequency response should be relatively deep. Now my question is, which type of plastic is best for it and how thick does the housing have to be?
  14. K

    Could microplastics be leached when a plastic bottle is hit?

    For example, I have some fingernails, I touch the mouth of a plastic bottle but the fingernail hits on the edge, I could feel it is a big hit, of course no observable damage is seen because it is just a fingernail, could this already create some microplastics that we don't see?
  15. G

    Question about humidity and plastic and rubber

    Is it possible to maintain an environment with low humidity to preserve electronic devices from oxidation without this low humidity drying out plastic and rubber from electronic devices and DVD discs that are plastic and in that environment? in my room I have two digital hygrometers and an air...
  16. G

    Question UV plastic and rubber

    I have a PS2 Slim 90000 and its case is ABS plastic and it has rubber parts, this device is located on a wooden table, the lights with UV in my house and the sunlight coming into the house will dry out, crack and damage the ABS plastic and the rubber of this device? my house uses LED bulb
  17. T

    I Two stage amplifier for a plastic scintillator

    When detecting a muon, we can use a plastic scintillator which consists of the components in the diagram attached. I am trying to understand what exactly the "two-stage amplifier" does which is located in the top left corner in the image attached? I am unable to find any information on it online...
  18. Narzog

    Welded plastic safe for mouth contact?

    Hey guys. So I make pennywhistles. And its popular to make the heads out of acetal / delrin. So my question is, if I were to weld two parts together using a soldering iron or plastic welding tool, would it still be safe for mouth contact? My knowledge of this stuff is very limited. But from...
  19. G

    Question about plastic bags and humidity

    What material is the plastic market bag made of? does this material retain (hold) moisture in the bag and everything in the bag or around the bag becomes damp? i put some bags inside a cardboard box and inside the cardboard box i also put dvd cases and i am worried if the bags will hold...
  20. shk

    Material properties -- Elastic and Plastic deformation in automobile crashes

    a)plastic deformation because of permanent deformation b) the other parts that have been destroyed have stored the energy and this saved the passenger compartment. C) the alloy crash barrier is stronger than the car body and and saves more of the energy by deforming shape. I'm not sure about my...
  21. B

    Does silicone as hard as plastic exist?

    I saw rubber-like silicones. Are there types of silicone that can be used in injection molding and once the process is finished - become as hard as, let's say, PVC? At the same time they should have all(/majority) of silicone's properties (citing Wikipedia): - Low thermal conductivity - Low...
  22. FEAnalyst

    Plastic bending - analytical calculations

    Hi, I have a question regarding plastic bending of beams (assuming bilinear elastoplastic material - with or without hardening) . In literature one can find calculations of load capacity for those beams. But what else can be calculated in such case ? Stresses ? Deflection ? Where can I find...
  23. person123

    Does Sample Strain Decrease At Failure?

    My guess is that the deformation immediately before would be the sum of elastic and plastic deformation, and the deformation after would be just the plastic deformation, and it therefore would decrease. Is this correct?
  24. S

    Is polycaprolactone (moldable plastic) toxic?

    Polycaprolactone is used as moldable plastic and you can mold in into thousands of shapes. Is it toxic like Acrylic? Does Polycaprolactone have polymerization chain as described below for acrylic? "Acrylics are not completely safe materials because their polymerization chain...
  25. terminator 87

    Questions about UV light and dry plastic and rubber

    UV causes dryness of plastic and rubber and lights have UV so keeping it in the dark away from light inside boxes prevents this but notice this photo where the box where the arrows are marked the clarity q enters this region of the closed box is enough for the long term the UV of this clarity...
  26. A

    MHB Find the volume of the hexagonal-shaped plastic box

    A chocolate company produces triangular chocolate bars. The length of the chocolate bar is x cm, and its cross section is an isosceles triangle. The length of the base side of the cross section is 3 cm, the height is h cm, and the two base angles are 50 degrees. Moreover, the company uses a...
  27. N

    Shrinkage & Expansion of plastic parts

    Hi, I'm currently doing a shrinkage study upon this plastic part. I hv been observing how much can the part able to shrink over the time after molding, and now hv been on the 5th month observation. However, on the 5th month, the part starting to expand, compared with the data from the 4th...
  28. EsinDerin

    Electric Field's Force on a Suspended Plastic Ball

    Hi,I couldn't do this problem.I hope someone could help meths is my first time in this forum
  29. K

    Can I use plastic tape to fix the rips on batteries

    I bought a new battery of D size today but I noticed that there is some rips (not much), I am not experienced and I certainly won't rewrap the whole battery. I'd like to know if it's okay to use fix it by taping the part with a small plastic tape??
  30. M

    Engineering Plastic Analysis: Upper Bound Theorem

    Hi, I have a quick question about part 1 of this upper bound theorem question (in the attached image). Answer says that \lambda_c = 2.25 . First, we know that there is 1 redundancy and therefore there will be a maximum of 2 plastic hinges for failure. I have found that there needs to be...
  31. K

    Plastic containers made in different countries?

    I have been shopping around and looking at the label on different home products carefully. I am especially concerned about plastics. There are tons of different plastic products but most of them only state what it is made and where it is made without other chemical details. For example...
  32. adil_mohammad

    Polymers that have spring properties similar to spring steel

    Hello everyone, First of all a very happy new year to everyone! And a big thank you to all the people who contribute to this forum, I have learned so much from here. I am prototyping a design for a part that will be used in a consumer product. I am in the early stages of researching...
  33. Lidor

    A force exerted on a plastic ball in a rubber tube

    Hello, How can I calculate the force that must be exerted on a ball inside a rubber tube? Thanks
  34. danielp3

    How Can a Junior Mechanical Engineer Excel in a New Plastic Molding Industry?

    So recently I got my first job as an mechanical engineer. YAY! The factory produces plastic products such as bottles/jar/etc with 2 main methods. blow molding for PP and HDPE & ISBM for PET. The whole area of plastic is completely new to me, my boss know that. I'm the only mechanical engineer...
  35. K

    Heating up plastic before its melting point -- could it be bad?

    I am interested in a water heater found in consumer market, however, it's made of kind of plastic, I often "feel" that there must be some problem heating up something like plastic. I understand that it should be tested and safe before putting into the market, however, I still wish to know -...
  36. T

    Tensile Test Results: Adhesion of Tape to Plastic Surface

    Hello, I am currently writing my thesis, where I have to investigate if a surface treatment increases the adhesion (between tape and a plastic surface). For this purpose, I have among other tests, performed a tensile test between the tape and plastic surface. The tensile test can be separated...
  37. S

    Is there plastic film on this phone or not?

    I got this phone and it came with this film mask thing that i think your supposed to apply to the screen, then peel it off, which is supposed to removed some film (?) But the phone already has a little tab on top of the covering that's already attached (it says A5L so you know what I am...
  38. S

    Hermetic seals of metal housings with over-molded plastic?

    Does anyone have any experience with creating a hermetic seal on metal housings that are sandwiching a thin metal membrane? Specifically with the fluid leak path between the metal and the plastic.
  39. D

    Photosensor-Brake System for a Small Plastic Car

    Hello, I am attempting to expand my physical understanding of some engineering principles I’ve learned during my first semester of ChemE. I am making a small plastic car that will be propelled with a weak fan. I am attempting something similar to a ChemE project car. Is there a way I can use a...
  40. A

    What are the materials and methods for testing plastic levels in water?

    On wikipedia (https://en.wikipedia.org/wiki/Iron(III)_chloride) it says: The ferric chloride test is a traditional colorimetric test for phenols, which uses a 1% iron(III) chloride solution that has been neutralised with sodium hydroxide until a slight precipitate of FeO(OH) is formed.[26] The...
  41. Tone L

    Searching for a strong inflexible plastic that is transparent

    Hi all, I think this is the right place to post this?! Material sciences.. Nonetheless, I am searching for a strong inflexible plastic, that is transparent. The principle job of the plastic is to be a long piece with a sensor attaching at the end. The sensor will weigh about 2kg, putting a...
  42. TechTree

    Suitable plastic type for animal enclosure?

    Hello, So I've got a pet hamster which I'm trying to build an enclosure for. And so I was wondering what would be the most suitable type of plastic to use for the walls and floor. Obviously it's going to have the appropriate ventilation as the top and the front will be made entirely out of metal...
  43. D

    Tensile yield strength of fiber reinforced plastic

    Hello! I am in a student-run engineering team that heavily utilizes fiber reinforced plastics, and I am just trying to get a better understanding of FRPs. I am wondering how exactly the fiber reinforces the plastic. Let's say the yield strength of the fiber in the 0 degree tensile direction is...
  44. K

    What is the smell from the new plastic storage box

    It's a tool storage box, probably made of PP (According to the label) When its lid opened, quite an obvious (but not very strong) smell coming out ,what it could be? vaporized form of plastic?
  45. T

    Plastic formation in cast-iron pan

    Yesterday morning, before work, I cooked eggs in canola oil in a cast-iron pan. Afterward, I rinsed out the pan and heated it to dry it. By mistake, I left the stove on. When I returned home, in addition to my house being smokey and smelling like IHOP, my cast-iron pan was lined with a...
  46. N

    Optical Smoothest yet not specular metal or plastic sheets?

    I'll get into the details why I need this for below but first I'll explain what I'm looking for. I basically need a flat sheet of aluminum or any plastic in grey or black color that doesn't provide specular reflections, yet is smooth enough to not have any noticeable texture when looking with...
  47. N

    Optical Where to get some VIS block, NIR pass plastic sheets?

    I'm talking about nealy black plstic in front of some remote controls to add to my similar DIY device. https://i.imgur.com/lmL4XN5.png I found some plexiglass that does this (blocks visible light, let's NIR pass) but the thinnest is 2mm so I don't think it is usable for this because is...
  48. J

    I What is the physics behind piercing a plastic piece?

    I want to know an object's (in this case, the plastic) "tolerance" to being pierced until it gets pierced.
  49. Evanish

    Misc. DIY - Replacing my bicycle tire with recycled plastic

    So the rubber on one of my bicycle tires has worn out to the point it needs to be replaced, and I was thinking I'd prefer a solid tire this time. Rather then buying one like a normal person I was thinking if I could make my own out of recycled plastic. Here is the plan as it currently...
  50. H

    Need help with shredder calculations -- Plastic bottle shredder forces....

    this is my design i want to calculate its various stress and forces. since the bottle is being cut, i think there is perpendicular force upwards, how do i calculate this cutting shear force? 1) force and stress applied by cutting blade on the plastic bottle 2) force moment and stress...