Wednesday 22 February 2023

Polymer Selection Funnel Example - Plumbing Water Pipes (Building and Construction example)

Polymer Material Selection - Example water pipes for plumbing (Herwig Juster)

Hello and welcome to this new blog post with the topic of polymer material selection. In this post we cover the material selection of water plumbing pipes as an example of the building and construction market. For the selection we will apply my developed Polymer Funnel Method (in detail explained here and in this video).

Figure 1 presents the four different stages of the material selection funnel and this overview serves us as a guideline.

Figure 1: Polymer Selection Funnel with its four stages.

What are the top 5+ plastics used in building and construction?

Most used plastics in building and construction are polyvinyl chloride (PVC), high density polyethylene (HDPE), expanded polystyrene (EPS), polyurethane (PU), polycarbonate (PC) and polymethyl methacrylate (PMMA). PVC is used for window frames and floorings, HDPE for tubing and piping, EPS and PU for outside and inside insulation. PC and PMMA is used for transparent sheeting applications applied for example at carports. 

Benefits of using plastics in construction are that they are lightweight, energy efficient, quick and safe installation compared to other materials, cost effective and high resistance to UV and fire. 

Polymer material selection for water plumbing pipes

Let us get started with the funnel.

Funnel stage 1: Material selection factors

In Funnel stage 1 we assess the water supply piping  requirements. We have to consider the three legs of the Environmental Stress Cracking (ESC)-triangle

  • Environment including temperature rating: inhouse mounting; no exposure to UV-light and no special weatherability conditions are needed; temperature of water is up to 80 °C.
  • Stress: mainly the fluid pressure and the pipe is fixed (no permanent bending movement); 
  • Chemicals and chemical compatibility: water and chlorinated water
  • Agency ratings: EU 10/2011; NSF/ANSI 51
  • Space layout: limited; flexibility of piping is needed, 
  • Function: transport drinking water (hot and cold) from heating station inside the house to different sanitary locations within the house; 
  • Lasting: 50 years life span
  • Costs: medium cost range since volume is on high end; 
  • Recyclability: must be given at end of life

Table 1 summarizes the important requirement information (requirement worksheet).

Table 1: requirement worksheet of Funnel stage 1. 

Funnel stage 2: Decision on thermoplastic or thermoset

Since flexibility is needed for mourning the pipes in confined space thermoplastic solutions are preferred. Apart from the already discussed thermoplastics used in plumbing, there are two major types of thermosetting pipes: 1) reinforced plastic mortar (RPM) pipe and (2) reinforced thermosetting resin (RTR) pipe. Together with glass fiber reinforcement such pipes show high strength, however they cannot be melted and reformed again. 

In our example, thermoplastics are preferred due to easier forming and mounting, as well as high regulatory fulfillment for drinking water. 

We pre-selected:

  • BorPex HE2590 (PEX)
  • BorSafe™ HE3490-LS (HDPE)
  • Vestolen™ P 9421 (PP-R)
  • Vinnolit® S 3268 (PVC-U)

Table 2 summarizes the pre-selected thermoplastics and its details which will be used for the detailed selection discussion in Funnel stage 3.  

Table 2: overview pre-selected thermoplastics.

Funnel stage 3: Selection discussion with worksheet (qualitative matrix analysis)

Funnel stage 3 represents with the qualitative matrix analysis the major element for the selection discussion. Table 3 summarizes the outcome of this process. In the first step we rank how good each material can fulfill the requirements (0 to 5=best) and then we assign priorities to each of the requirements (0 to 5 = highest priority). In the last step we multiply the requirement fulfillment with the priority and add the values up. 

In our case PP-R (score: 99 points) and PEX (score: 97 points) have the highest rank and both materials should be evaluated in Funnel stage 4. 

Table 3: result of the qualitative matrix analysis. 

Funnel stage 4: Testing, selection of material and vendor

We reached the final phase of the Polymer Selection Funnel where we test and further evaluate our findings from Funnel stage 3. 

Both PEX and HDPE are suitable for usage in our application case, however PEX is due to its cross-linking not as easy for recycling as HDPE. However, this is changing too, since chemical recycling of PEX waste makes promising steps. Therefore, recycling challenges will be no limitation. 

Check out here another polymer material selection example (baby bottles).

Thanks for reading and #findoutaboutplastics

Greetings Herwig 

Interested to talk with me about your polymer material selection, sustainability, and part design needs - here you can contact me 

*NEW* my Polymer Material Selection book is available for purchase here *NEW*

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.


Tuesday 14 February 2023

Plastic Multipoint Design Data: Tensile Stress and Strain of Thermoplastics as a Function of Temperature

Hello and welcome to this blog post. Today we discuss the tensile stress and strain data of selected thermoplastics as a function of temperature. 

Why  are multi-point data important in polymer material selection and part design?

Multipoint data of different polymer and polymer compound properties prevail information which would otherwise may be overlooked during material selection and product design. Most property data shown on technical data sheets are single-point values at failure level. Most of the time only a single temperature is covered (room temperature). This is useful for comparing different material data sheets however for part design it has its limitations. Multipoint data help to think in time-dependency and temperature-dependency behaviors. Graphically such behaviors can be better accessed. Single point data can lead to misjudgment.

Stress-strain curves of thermoplastics as function of temperature

In Figure 1 the results of stress experiments and in Figure 2 the strain results of different amorphous and semi-crystalline plastics are shown. Following grades were analyzed: 

PBT: Ultradur® B 2550 FC

PA 6-GF30: Ultramid® B3EG6

PC: Makrolon® 2205

PA 6: Ultramid® B3K


PPS-GF40: TEDUR L 9107-1

POM: Ultraform® H4320 Q600 

PA 12-GF23: VESTAMID® L1833

Figure 1: Stress vs. temperature of thermoplastics

Figure 2: Strain vs. temperature of thermoplastics

Through the increase in temperature, mobility of the polymer chains is increasing and some brittle polymers turn into more tougher polymers allowing them to withstand certain loads. 


DMA and stress-strain curves used combined are an efficient way to explore part application properties at use temperature. 

Check out here more multipoint data 

Thank you and #findoutaboutplastics

Best regards, 

Interested to talk with me about your polymer material selection, sustainability, and part design needs - here you can contact me 

*NEW* my Polymer Material Selection book is available for purchase here *NEW*

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.


Tuesday 7 February 2023

Rule of Thumb for Thermoplastic Material Design: 3 Effective Ways to Achieve ESD properties

Hello and welcome to this new Rule of Thumb post. Today we discuss three effective ways to achieve Electrostatic discharge (ESD) properties with thermoplastics. 

Overview and introduction to ESD 

In Europe the ATEX Directive (from the French "ATmosphère EXplosive") 94/9/EC contains regulations for the use of components and systems in potentially explosive atmospheres.

If an electrical discharge in a potentially explosive area (so-called EX area) produces the necessary ignition energy, a spark may be generated which ignites the explosive substance. 

Thermoplastics with specific conductive properties can discharge static charges in a controlled and permanent manner. They are used in many industrial sectors such as electric & electronics, semiconductor industry, medical technology, chemical and pharmaceutical industry, and other industries handling dusty bulk materials, combustible substances. It is important during polymer material selection to ensure the maximum safety for these applications by modifying the selected plastic.

Plastics are insulating and their electrical conductivity ranges between 10^-18 to 10^-12 Siemens per meter (S/m). In general plastics have an eclectic surface resistance of >10^15 Ohm and can be electrostatic loaded. Anti Static conductive behavior is achieved from 10^-9 to 10^-3 S/m with a corresponding resistance of 10^6 to 10^10 Ohm. For electromagnetic shielding (EMI), electrical conductivity of 10^3 to 10^9 S/m is needed. 

3 ways to have ESD properties in thermoplastics

3 effective ways to achieve ESD properties in thermoplastics

Stainless steel filler

Stainless steel fillers are an effective way to provide thermoplastic compounds with conductive properties. They can be directly added during injection moulding by a master batch or in a continuous way during compounding. 

Achieving ESD properties, 0.25-0.5 vol.% of steel fiber (4 w%) needs to be added. This is enough to have a volume resistivity of <10^2.

Inner anti static additives

Fatty acid esters and  Fatty acid amides are added either directly or over a masterbatch to the polymer compound. They migrate onto the surface of the finished plastic part and create a hydrophilic layer which in turn takes water up. The result is an electrically conductive outer layer. Anti static masterbatch concentration is between 3 to 50 w%.  Also, hydrophilic polymers such as Polyamidcopolymer can be added which results in a surface and volume conductivity. 

Conductive carbon black

Conductive carbon black in a concentration up to 15 w% is often used in polyolefin compounds. Specific volume resistance between 10^2 to 10^5 Ohm cm can be achieved. Apart of conductive carbon black, carbon fibers can be used too. 

More Rule of Thumb posts can be found in my "start here section".

Thank you and #findoutaboutplastics

Best regards, 

Interested to talk with me about your polymer material selection, sustainability, and part design needs - here you can contact me 

*NEW* my Polymer Material Selection book is available for purchase here *NEW*

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.




[3] Sachtling Kunststoff Taschenbuch, Hanser