PVC Vs. Polyurethane

A good start would be to compare the "formal" description of one versus the other.

Then, ask professionals, derived from those descriptions, about their pros and cons to given, common use, if any.

Then experiment some for yourself, on cases which make some significance to you, and then feel free to use this knowledge, for your benefit, or for sharing with people who may ask you.

For instance: Suppose someone comes to you and asks: "How do you describe the chemical, mechanical and practical differences, between PVC and Polyurethane?"

You could then reply: "A good start would be to compare the "formal" description of one versus the other.

Then, ask professionals, derived from those descriptions, about their pros and cons to given, common use, if any.

Then experiment some for yourself, on cases which make some significance to you, and then feel free to use this knowledge, for your benefit, or for sharing with people who may ask you."

This would be my suggestion, should someone asked me, anyway.

PVC or polyvinyl chloride is a thermoplastic polymer made by the polymerization of vinyl chloride. It is usually plasticized and has a wide variety of uses from coating electrical wires to siding. It is inexpensive and flame retardant although it gives of hazardous smoke.

Polyurethane is formed from reacting a diisocyanate with polyols typically polyether or polyester polyol, although there are many others such as polybutadiene and soy or castor based polyols. It is also used in a wide variety of applications from soft elastomers to viscoelastic foams and rigid foams to very hard elastomers. It is much more expensive than PVC, but can be tailored to almost any application. Most polyurethanes burn readily, but fire retardants can be added.

If you do a quick search on Google or look up either on Wikipedia you will find lots of info on both

In order to keep this reply less than book length we may need more information. So for the basics: Raw Material Cost - PVC is one of the least expensive plastics, PU is not cheap - 2 - 4 times more expensive - depending on grade. Both are used in medical applications - multilumen catheters, althought, PU is preferred in class 1 and 2 and 3 applications. Then again cost is an issue. PVC is used in construction, induistrial, and consumer and medical applications due to low cost and excellent chemical and material characteristics. Medical applications are mainly limited to external to the body and not inplantiable. PVC intermittent catheters are nearly all extruded from clear PVC. Clarity is the other difference of PVC over PU. PVC has some inherent image problems, mainly type of plastisol and issues with leaching. Govermental regulations have been circulating for years that attempt to ban PVC from use because it doesn't degrade in landfills. Even under this pressure, PVC is the main material for construction and electrical conduit boxes and tubing. It is considered self extinguishing in fire applications - in several grades with UL. There is no other replacement which has a low cost and sufficient material charteristics. Processing are similiar between the two materials - injection molding, extrusion, rolling, etc. Although some molding has some risks with PVC. If it degrades the chemical bonds will be broken and dangerious gasses will be released along with corrosive acids. This reason discourages some manufacturers from processing PVC.

If you would like to share more details I can share more information. Hope this helps.

PolyVinyl Chloride and PolyUrethanes (PU) are different class apart. There is no simple comparison of these two except both being polymeric materials. Unless you spell out what the end application is intended for, it will be difficult for anyone in the field to guide you. You will be wasting your time and effort in gathering information on these two class of very versatile polymers where forms of availability are from flexible to rigid. Be specific and you get the help!

R Baascaran

Hello all,

I am also curious about the difference in PU vs PVC and mainly for cost and carbon footprint reasons... I will be specific and say that i am a manufacturer of womens hand bags. PVC and PU can be manufactured to look identical to leather material. Now that you know the specifics of what i am inquiring can you explain to me how one is better than the other for the reasons stated above...??? Thanks for your help!

Andy

PVC -thermoplastic, Polyurethane (PUR)-thermosetting resin -these is very different families of synthetic polymers. Generaly speaking no extruded products (profiles) are produced from PUR. Take any text book for undergraduate students (Introduction to Polymers) to see the big difference between the two.

Dr. FS

Dr. FS,

Its amazing what advancements polymer science has made over the past 50 years. Extrusion of PU has been in practice since early late 80's/early 90's for catheter applications. You may want to read a book that wasn't written in the 60's. Then again, here's a link for you. (opps linkes aren't working) Anyway, google "PU extrusion or TP urethanes" for a list of suppliers and material options. You might be surprised and learn somehing yourself.

That is a broad comparison. Strenght in what applications of use - impact, low temp, high temp, fatigue, creep, etc. What grade of material? In what design and after what processing - extrusion, injection molding, (these factors give you different physical and mechanical properties for each material - then you have additives - any additives, or durometer (hardness)) We are all more than willing to share our knowledge, but, the question is too broad. Also, fire safety as in sparks, storage, combustion temperature, off gasing, resistance, insulation, or after combustion? Try MSDS sheets for both. You may be better to contact a material supplier for more general questions if you can't be specific.

Your advise is appreciated. I will follow this route and if OK with you contact you in the near future.

I would suggest considering a thermoplastic vulcanizate (TPV) as a third alternative. This product is priced mid-way between a PVC and a thermoplastic polyurethane (TPU). A TPV processes like a thermoplastic but has the performance of a thermoset rubber. One brand offering is Santoprene, (santoprene.com). This product is offered in many different durometers and can be extruded. Flame retardant grades are also available.

Dear hip888888, In China many business use 8888 in their phone numbers because it is considered good luck. Thank you for your input, I am not familiar with TPV. We are currently extruding PVC for use as a walking surface. What we are trying to accomplish is a harder more scratch resistant surface and one with minimum shrinkage and expansion. We do not want the product to be too brittle or too soft. That is why we are looking for alternatives. It may be that using PVC and just adding the right amount of Cac3 would solve the problem. We are not yet sure. So we are looking at alternatives. I will certainly contact Santoprene.com to see if their product makes sense. Of course price is another major factor.

PVC is dangerous when it's manufactured and when it burns, either accidentally or intentionally. Large amounts of chlorine (66 percent of the world's chlorine supply) are required to manufacture PVC, with dioxin produced as a bi-product. There is currently no successful method of recycling PVC, a known carcinogen since 1966. Other additives used in PVC production are lead, which damages brain development and impairs cognitive ability; cadmium, which is a potent neurotoxin and carcinogen, and organatins which suppress the immune system and disrupt the endocrine system. The most common plasticizer for PVC is phthalate, which can be as much as 60 to 80 percent by weight of a product. Phthalate plasticizers aren't used in any other building material. They are a known carcinogen linked to asthma and male and female reproductive problems including infertility, testicular damage, reduced sperm count, suppressed ovulation and abnormal development and function of testes. These plasticizers are released when PVCs are burned, and they leach out over time in landfills.

Dear Jamie, Well you certainly made your case against PVC. Now that you have done that what are your recommendatins for products to be used in the building industry. Is there a safe way to produce PVC, as a matter of fact PVC is reycycled and reused in the manufacturing of new PVC products. What can be done to reduce the deadly gases produced when PVC is burned? I am interested in your comments. Thanks.

I guess HDPE, which is currently used though more expensive, or the old stand by steel are the alternatives. Also, it takes some effort to burn PVC, so i do not think you'll see any accidental PVC fires. However, it can be a risk to the firemen who shouldn't breathe smoke anyways, since there are far more toxic things in a household. PVC is not a carcinogen vinyl chloride is, this means the degradation of polyvinylchloride to vinyl chloride is a health risk. Of note, promoting materials as if they posed a serious health risk degrades the position of science when it supports studies of seriously hazardous materials. Implying PVC is somehow hazardous because of a link to vinyl chloride poses the risk of people beginning to believe that vinyl chloride is not all that bad because it is the same as polyvinyl chloride.

Dear Guest, Some clarification please. Are you saying that on the surface PVC is relatively safe, while vinyl chloride is not? What does it take to convert PVC to vinyl chloride? What will cause the degradation of PVC to Vinyl Chloride? "PVC is not a carcinogenic while vinyl chloride is"' can you clarify that statement? Can HDPE be used in extrusion the same way PVC is used? Can you give me an example of where Vinyl Chloride might be used on its own? Thank you for your input.

Vinyl Chloride is a short, reactive molecule, with it's three protruding, bond-seeking hydrogen atoms, when compared relative to the bound, longer chain PVC molecule, with it's more restrained hydrogens, which in general is less chemically reactive.

Carcinogens are usually associated to some of the more chemically reactive compounds, able to mutate cell division phases of living tissue.

Naturally, it's complicated, and also case-dependent, but generally speaking, less reactive compounds are also less likely to be considered a carcinogen or a mutagen, in advance

Was that to far from fact, my dear professors?

PVC has been around for decades. It will probally be around for another lifetime. The reason is simple - its excellend chemical and mechanical properties. I don't recommend burning PVC as doing so will release chlorine gas and hydrocloric acid. HDPE is an excellent material for general purpose applications but lacks the strength and weatherability of PVC. For outdoor use where the polymer will be subjected to uv rays (sunlight) I would recommend concrete, steel, or other non-plastic. All plastics degrade readily in uv. Then again trash cans are made from HDPE and expect 10 years of service before degrading. Then again, the more uv stabilizer added the more waxy they feel. Probally not that good to walk on. Recycled tire would be a good option (vulcanized rubber). If interested then please respond as my company is responsible for this activity in the US and Asia.

PVC itself it tough to recycle and it is often difficult to find a substitute, but it is worth trying. One alternative is Fusiotherm, a special polypropylene tubing made without chlorine can be used for pipes. Also, The USGBC's Technical and Scientific Advisory Committee Issued a report on PVC, which addressed end-of-life issues like backyard burning and accidental landfill fires. Burning PVC releases dioxins – highly carcinogenic, persistent toxins that are among the worst materials for human health impacts. The report recommended against a LEED credit for PVC. For other PVC alternatives, see:
http://www.greenbuildingtalk.com/Forums/tabid/53/view/topic/forumid/3/postid/24594/Default.aspx

Does Polyurethane give off a hazardous smoke when burned? Does it degrade in landfills?

While Polyurethane is excellent for thermal isolation in the ambient temperature range, it is not fire-proof or fire-retardant and would give off toxic fumes when burnt.

Not only that, once the compound is dry, it should be encased and even sealed, because when rubbed against, it flakes off hazardous dust, dangerous to breathe or inhale in any form. This dust may also trigger skin and eye irritations.

Can Polyurethane be recycled?

Some weird ref (syllabus):

http://www.pfa.org/ce/lesson3.html

Chemically speaking, it cannot be recovered or re-moulded, being a thermosetting compound, once cured.

Yes, TPU (thermoplastic polyurethane) can be recycled. PUR can not.

Everything recycles. It's just a matter of timescale.

Ive got a product which is made from pvc and polyurethane. I am looking to have some designs put on them. Does anyone know what techniques are needed to print on a PVC and a polyurethane product? Ideally i would like to know if this is possible to do at home with an investment of £1000 like prinitng on t-shirts, but also would like to know companies who can offer prinitng on them as well

Thanks

PVC is a carcinog

Did you receive an answer to your question regarding engraving or branding your PU purses? I have a similar business and am wondering the same thing. Thank you.