Properties of PVC are partly related to the polymer itself and partly to the formulation. Among these properties we will emphasize the following ones:
• Chemical resistance.
• Electrical resistance.
• Mechanical properties and methods.
• Thermal properties and methods.
• Durability-Weatherability.
• PVC in case of fire.
• Appearance properties.
The a.m. properties are a main criterion when it is intended to use PVC for a particular application. In addition, exists also a wide range of standards that connect applications with some properties, establishing specific values and trial methods.
a. Chemical resistance
1. I have a PVC linear for my swimming pool. Does it resist to chlorine and ozone produced by the treatment station?
2. Which kind of product can I use to clean PVC furniture?
3. Why is the PVC chemical resistance good and better than other plastics?
4. What's the resistance of PVC goods against different chemicals?
5. What’s the resistance of rigid PVC pipes against fluids like sludge?
b. Electrical resistance
6. What is the maximum voltage for which PVC could be used as cable sheathing?
c. Mechanical properties and methods
7. What could be the maximum modulus of rigidity of PVC?
8. How can PVC become very good in impact?
d. Thermal properties and methods
9. What is the melting point of rigid PVC?
10. How can I evaluate the softening point of my products?
11. What is the lowest temperature of use of PVC?
12. What is the highest temperature of use of PVC?
e. Durability - Weatherability
13. How to get a very good outdoor durability?
14. Can PVC be used in tropical countries?
15. Can the colour of the PVC windows getting yellow or pink?
16. May we place the drinking water pipes outside of the building, or do we have to cover them?
17.What shall I do for the maintenance of the PVC window frames?
18. What is the lifetime of PVC windows?
19. What is the lifetime expectancy of PVC pipes?
20. Does the impact strength of PVC products decrease with time?
f. PVC in case of fire
21. What is the meaning of B1 and M1 as a technical requirement for building equipment?
22. Why is the reaction to fire of PVC much better compared to other plastics?
g. Appearance properties
23. Is it possible to get special surface aspect with PVC?
24. Can PVC be transparent?
25. Can PVC have metal appearance?
26. Can PVC have wood appearance?
a. Chemical resistance
1. I have a PVC linear for my swimming pool. Does it resist to chlorine and ozone produced by the treatment station?
PVC items have intrinsically a good resistance to water solutions of oxidizing substances such is Cl2 , NaClO or Ozone. For more details please consult ISO/TR 10358.
2. Which kind of product can I use to clean PVC furniture?
The best way to clean PVC is to use water with a household detergent. Some special products containing solvents (cleaning liquids for glasses) could be used only when the water/detergent solution is not efficient and when it is recommended for PVC. Avoid liquids containing ketones (acetone,…).
3. Why is the PVC chemical resistance good and better than other plastics?
PVC is not soluble in aqueous solvents and in alkane solvents. The Carbon-chlorine chemical bond gives a high resistance to acids, alkalis or oxidising agents. Some engineering polymers present a higher resistance to chemicals than PVC but they are much more expensive and/or more difficult to process.
4. What's the resistance of PVC goods against different chemicals?
The resistance of PVC against chemicals is generally good to very good especially against acids and oxidising agents. To check the resistance of PVC against a specific chemical it is useful to refer to ISO/TR 10358. This document gives a qualitative assessment of the resistance of the main polymers against chemicals. If you need special information, please, contact us.
5. What’s the resistance of rigid PVC pipes against fluids like sludge?
Sludge is a particular case of a water solution. PVC is not soluble in water and can withstand a large range of acidities or alkalinities (namely from pH = 0 up to pH = 14). Concrete pipes are damaged by the H2S acid emitted by the sludge, PVC pipes are not affected by this chemical.
b. Electrical resistance
6. What is the maximum voltage for which PVC could be used as cable sheathing?
Plasticized PVC is widely use for the insulation of domestic cables with home-type voltage (110 V, 220 V, 380 V). Plasticised PVC with special formulation can also be used for much higher voltages ( > 1kV). The sheathing of cables is technically less requiring in terms of electrical resistance than insulation for cables.
c. Mechanical properties and methods
7. What could be the maximum modulus of rigidity of PVC ?
The properties of PVC are linked to the formulation of the composition. So the modulus of rigidity as well as all other mechanical properties is linked to this composition. For a wide range of U-PVC (unplasticized PVC) the modulus is very close to 3000 MPa. With significant amounts of specific fillers (such as glass or wood fibres) the modulus can reach up to 10 GPa.
8. How can PVC become very good in impact?
By adding impact modifier in the composition, such as acrylic polymer or MBS modifier. It should be noted also that even without Impact Modifier but with a limited amount of good quality filler and the right gelation level, the breakage energy will be maintained high and the behaviour will be more ductile than brittle.
d. Thermal properties and methods
9. What is the melting point of rigid PVC?
PVC is an amorphous polymer, so it does not have a precise melting point. We speak about a softening point above which the rigidity decreases sharply. For rigid PVC it is called the glass transition temperature (Tg) and it is situated around 80°C, depending on the formulation.
10. How can I evaluate the softening point of my products?
A method commonly used to evaluate the softening of PVC is the measure of the Vicat Softening Temperature (following EN ISO 306). The Heat Deflection Temperature (HDT following EN ISO 75) can also be used. It is the recommended method for wood/PVC composites.
11. What is the lowest temperature of use of PVC?
PVC articles can be used at very low temperatures : the modulus will increase as temperature is getting lower. Special care should be taken if the PVC article is exposed to blows or impact at low temperatures. For each composition one could establish the curve for ductile-brittle transition.
The point where the material behaviour starts to be brittle is linked to the nature and amount of impact modifier. For a standard PVC (no impact modifier) it becomes brittle below 0°C, for an impact modified PVC it can be -20°C (depending on the impact modification).
In static conditions, it can be used at much lower temperature (i.e. window frames in Nordic countries). Usually the highest resistance of a plastic item is requested at the beginning of its life during transportation and installation. Once installed the pipe or window frame is not so much exposed to impacts anymore.
12. What is the highest temperature of use of PVC?
For standard unmodified PVC the glass transition temperature is approximately 80°C. Above this temperature the behaviour is not rigid anymore but rubber like.
In pipes it is generally recommended not to trespass 60°C but for some composition containing heat resistant additives, it is possible to allow periodic temperatures changes up to 90°C for a few minutes.
For applications above 90 °C it is not recommended to use PVC but it is better to use PVC alloys or C-PVC (Chlorinated PVC).
e. Durability - Weatherability
13. How to get a very good outdoor durability?
Use opaque pigments such as TiO2 or carbon black for example, at an adequate level (see chapter 5) and additives which are resistant to UV-light. For coloured items, use special pigments recommended for outdoor applications. It is also recommended to avoid impact modifiers based on butadiene such as ABS.
14. Can PVC be used in tropical countries?
For a given region it is advisable to check the map of incident sun radiation (see also maps of incident sun radiation). According to this incident energy, the level of UV-absorbing pigment has to be determined in order to get the optimal UV-resistance (for example²: North of Europe: 4 phr of TiO2, for mild Mediterranean countries : 6 to 7 phr of TiO2).
² Solvay Benvic conference
15. Can the colour of the PVC windows getting yellow or pink?
PVC window frames have a long term guarantee (generally 10 years) which includes also the colour of the frame. A few reports of abnormal colour changes have been reported²², these are generally related to the presence of an incorrect quality of pigment in the formulation. The majority of window profile extruders have a sufficient knowledge of the right types of pigment they have to use.
²² Solvay Benvic article
16. May we place the drinking water pipes outside of the building, or do we have to cover them?
PVC is a plastic material and, as such, is sensitive to UV-light. So it should be covered and not exposed during long periods to direct sunlight. Nevertheless a pipe exposed to sunlight will mainly bleach out (it will turn white) without significant influence on the mechanical properties or on the service ability of this pipe.
The suppliers of drinking water consider that a good quality drinking water should always be kept below 25°C. So, to comply with this request, it is necessary to keep the pipe a few dozens of centimetres under the ground to keep a constant temperature (whatever the material of the pipe).
17. What shall I do for the maintenance of the PVC window frames?
PVC windows require less maintenance than any other material. No painting or any other treatment is necessary. Only cleaning with water and soap is recommended to keep a nice look of the window, but a lack of cleaning will have no adverse effect on the properties of the window even after many years.
18. What is the lifetime of PVC windows?
The PVC windows exist approximately since the 1960's and so far it is not necessary to replace these windows for reasons linked to the window frame itself. There is generally a guarantee from the window supplier of 10 years but the real lifetime is not known and will probably be larger than 50 years.
19. What is the lifetime expectancy of PVC pipes?
The durability of rigid PVC pipes is related, as it is for all other thermoplastics materials, to the chemical degradation of the polymer of the pipes. However unlike other thermoplastic pipes, rigid PVC pipes do not oxidise.
Stabilisers are used in rigid PVC pipes to prevent degradation of the polymer during the extrusion process, and eventual storage of the pipes before they are placed in the ground. However, when the pipes are buried in the ground, no chemical degradation is expected to take place. For this reason the durability of the rigid PVC material in buried pipes is expected to be very long (May even be more than 1000 years¹).
In standardised pipes for potable water (EN 1452) the expected lifetime of rigid PVC pipes under pressure is extrapolated based on hoop stress testing of pipes for up to 20 000 hours. This then allows an estimation of the durability by extrapolation to a life expectancy under pressure of 50 to100 years ² .
Real experience in Germany³ has shown that buried rigid PVC pressure pipes dug up after 60 years of active use were proven to be fit for purpose when analysed and likely to have a further life expectancy of 50 years.
"Studies in the Netherlands have examined several potential degradation processes for rigid PVC pipes and carried out tests on pipes up to 45 years old. These studies also concluded that the life of rigid PVC drinking water systems could exceed 100 years."4
1. Janson, Lars Eric 1996 "Plastics Pipes - How long can they last? KP Council Nov. 1996.
2. EN-ISO 9080.
3. 60 Jahre Erfahrungen mit Rohrleitungen aus Weichmachfreiem PVC, 1995, KRV.
4. 'Long Term Performance of Existing PVC Water Distribution Systems' by A. Boersma and J Breen, 9th International PVC Conference, Brighton, 26-28th April 2005, pp 307-315.
20. Does the impact strength of PVC products decrease with time?
The order of magnitude of impact resistance is not changed after months or years. PVC, just like other plastics will show some ageing after years which will give some increase in the E-modulus but also a slight reduction in the value of impact resistance. Usually the highest resistance of a plastic item is requested at the beginning of its life during transportation and installation. Once installed the pipe or window frame is not so much exposed to impacts anymore.
f. PVC in case of fire
21. What is the meaning of B1 and M1 as a technical requirement for building equipment?
In the past many countries had defined categories for fire classification of the materials used in buildings. The French system was one of the best known systems, the categories were the following :
M0 : No contribution or minimal contribution to fire.
M1, M2 : Low contribution to fire.
M3 : Medium contribution to fire.
M4 : High contribution to fire.
Due to its content in Chlorine, PVC is generally M2 and special formulations give a M1 classification for the PVC item.
Most plastics are mainly based on oil, so they are classified as M3 or M4.
Similar classes are used in Germany (B0 –B1 – B2). The new European classification (EN 13501) is based on a higher scale test (SBI EN 13823) and corresponds to the following:
A1 : Incombustible.
A2 : Minimal contribution to fire.
B : Very low contribution to fire.
C : Low contribution to fire.
D : Medium contribution to fire.
E : High contribution to fire.
F : No requirement.
Rigid PVC is generally classified as B.
22. Why is the reaction to fire of PVC much better compared to other plastics?
The chlorine present in the molecule is a very efficient fire extinguisher. PVC is a self-extinguishing material, doesn’t generate flaming droplets and gives low heat release (4 – 27 MJ/kg for PVC) compared to standard polyolefins (above 40 MJ/kg).
g. Appearance properties
23. Is it possible to get special surface aspect with PVC?
Depending on the additives (pigments, fillers, modifiers, etc.) and on processing conditions (temperature, type of tools, embossing, etc.) it is possible to get a wide range of different appearances, as well for extruded material as for calendered material. It is also possible to apply a film to cover the articles with the desired texture and colour.
24. Can PVC be transparent?
PVC is intrinsically transparent. Some additives can make it opaque : fillers, pigments, and all additives having a limited compatibility with PVC.
So, in order to keep the transparency of PVC it is necessary to choose the right additives with excellent compatibility. Most additives producers can supply such one-packs. In rigid applications some sheets or profiles for green-houses show an excellent transparency and keep most of the good properties of rigid PVC. In plasticised PVC the flexible transparent doors for storage halls are one of the best known applications.
25. Can PVC have metal appearance?
Yes. By adding special pigments, it is possible to give to PVC a metal appearance, like aluminium, copper or even gold. It is also possible to apply a film to cover the articles with the desired texture and colour.
26. Can PVC have wood appearance?
Yes. The wood appearance can be obtained by covering the surface with a decorative film giving the wood appearance. More recently, wood and other natural fibres/PVC composites have been developed. They give not only the wood appearance but also, after specific brushing, the wood touch and in special cases, a natural smell.
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