Monday, 20 September 2021

Design Properties for Engineers: UL RTI vs HDT of Commodity, Engineering and High Performance Polymers

In this blog post, we compare the long-term thermal properties (based on UL RTI 746B) to the short-term properties (based on the Heat Deflection Temperature, HDT @ 1.8 MPa).

The figure below shows the comparison of the long-term and short-term thermal data. This allows designers to immediately assess the suitability of a selected polymer in terms of continuous heat exposure as well as short-term heat impact. Furthermore, alternative polymers can be selected too.

UL RTI vs. HDT (1.8 MPa):Long-Term vs. Short-Term Thermal Properties of Thermoplastics


I made a YT video which shades light into this topic in more detail:



Thank you for reading and #findoutaboutplastics

Greetings

Herwig Juster

#materialselection #polymerengineering #plasticsdesign

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] UL Prospector – 746B

Monday, 13 September 2021

Rule of Thumb for Plastics Injection Moulding: Weld Line vs Meld Line

 In this rule of thumb post, we discuss the difference between a weld line and a meld line in polymer injection moulding as well as how we can apply effective troubleshooting.

In short: the angle at which the converging polymer flow front meets in the tool again determines the difference between weld line and meld line.

A weld line is formed if the angle is less than 135°.  A meld line is formed if the angle is greater than 135° and the polymer molecules are more uniform compared to the orientation formed after a weld line. This is demonstrated in the picture below.

It is important to understand the flow fronts and the flow angle for achieving proper weld lines. Such an understanding allows the use of multiple submarine gates rather than fan gates to be used. Prediction of weld lines prior to the tool being cut allows the optimization of the part design and gate location which in turn reduces tool development time. Consideration of material, filler and pigmentation is important and this is why discussion with the technical team at your material supplier at the early stages are useful.

Rule of Thumb: Weld Line vs Meld Line


Troubleshooting of weld and meld lines

Weld and meld lines can cause a decrease in mechanical properties and are often clearly visible on the surface. An effective way of troubleshooting them is to move them in a non-functional / non-visible area. This can be achieved by changing the gate position or part thickness. Furthermore the allover quality can be improved by increasing the melt and mould temperature. This facilitates a better interfusion of the flow fronts. Also injection speed can help as well as an optimization of the runner system design.



Thank you for reading and #findoutaoutplastics

Greetings,

Herwig Juster

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] https://knowledge.autodesk.com/support/moldflow-insight/learn-explore/caas/CloudHelp/cloudhelp/2017/ENU/MoldflowInsight/files/GUID-099634AE-DB7A-41BA-B70C-5A23FB013B06-htm.html

Tuesday, 7 September 2021

Design Properties for Engineers – Comparison Property Data of Polyphthalamides (PPAs)

 Hello and welcome to a new post. In this post I provide you engineering comparison data of the 5 most used PPA base polymers and their glass-fiber reinforced compounds. Semi-aromatic polyamides are used when the aliphatic counterparts reach their limits due to high temperature and/or mechanical loads.

The five base polymers of PPA are:

-PA 6T/6.6

-PA 6T/6I/6.6

-PA 6T/6I

-PA 6T/DT

-PA 10T/X

The data are shown in property vs. density plots and we are comparing the semi-aromatic polyamides to aliphatic polymers.  

Background

Semi-aromatic polyamides have an amide linkage together with an aromatic ring. The aromatic content is most of times derived from 2-methylpentanediamine (DT), terephthalic acid (TPA) and/or isophthalic acid (IPA). In general, the aromatic structure helps to increase the glass transition temperature, which in turn increases the thermal and chemical resistance. Furthermore, reduction in water uptake is achieved. More details can be found in this post.

The following properties are presented in the below infographic (PPA reinforced with 50% glass fibers):

-Glass transition temperature

-Melt temperature

-Tensile strength (dry as moulded; conditioned)

-Tensile modulus (dry as moulded; conditioned)

-Heat Deflection Temperature (HDT; 1.8 MPa)

-Izod notched impact strength




Design Properties for Engineers – Comparison Property Data of Polyphthalamides (PPAs)

Thanks for reading and #findoutaboutplastics

Greetings,

Herwig

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] D. Kemmish: Practical Guide to High Performance Engineering Plastics, Smithers

[2] D. Glasscock: High Performance Polyamides Fulfill Demanding Requirements for Automotive Thermal Management Components, DuPont Engineering Polymers

[3] Eurotec: Tecomid High Performance Compounds

[4] Saechtling Kunststoff Taschenbuch, Hanser



Wednesday, 25 August 2021

Polymer Material Selection: Pre-Selection of Thermoplastics

Hello and welcome to this post. Today I will discuss with you a practical approach on how to pre-select thermoplastics for your application.

In a past post I touched on some rules of thumb for making an educated guess on plastics material selection and in this post we will add another approach into our plastic selection toolbox.

Thermoplastics can be divided into amorphous and semi-crystalline morphology. Amorphous polymers are transparent or translucent, whereas semi-crystalline polymers are opaque. If you need a transparent part, then selecting an amorphous polymer is the path forward. Flexible polymers with a Young’s Modulus of < 1500 MPa are always semi-crystalline. Amorphous polymers can only be used below their glass transition temperature (Tg) and therefore have always a stiff behavior up to their Tg. If you need flexible and transparent polymers, amorphous Polyamide can be an option when working with additives (clarifiers) helping to make a semi-crystalline transparent. 

Maximum use temperature and Young’s modulus

In the table below are amorphous and semi-crystalline resins shown, together with the Young’s modulus and maximum use temperature as selection criteria. All the values are for orientation and further investigation for proper material selection needs to be done (for example, mechanical properties over different temperatures). Detailed data can be found in the Technical Data Sheets (TDS) of material suppliers or in material databases. Also on my blog, I have several engineering data in particular for high performance polymers listed.


Polymer material selection: pre-selection of thermoplastics by using maximum use temperature and Young's modulus


Thanks for reading and #findoutaboutplastics,

Herwig

#polymerMaterialSelection #herwigjuster

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] M. Bonnet: Kunststofftechnik: Grundlagen, Verarbeitung, Werkstoffauswahl und Fallbeispiele


Wednesday, 18 August 2021

Why Plastic Parts Fail & How to Prevent Failure [Infographic]

 

Why Plastic Parts Fail & How to Prevent Failure [Infographic] by Herwig Juster

Thank you for reading and #findoutaboutplastics

Greetings,

Herwig

 #polymerMaterialSelection #herwigjuster

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Monday, 16 August 2021

Polymer Processing – Resin Moisture After Drying (Support Table)

 Hello and welcome to this blog post on resin drying before processing them. In this post I provide you with a drying table of the most used polymers which can support you in your processing operations.

A word on resin drying

If material is not properly prepared for processing operations such as injection moulding, the moisture will break down the polymer in the barrel at the processing temperatures. In general, this is referred to as hydrolysis.

This can occur for many different polymers, including:

-Polyamides (all types)

-Polyesters (PET, PBT)

-Polycarbonate

-Polysulfones

-Polyurethanes

 

There are five keys to remember which ensure good drying of resins [1]:

1. Pellet / regrind incoming moisture level

2. Air temperature

3. Dewpoint/ Desiccant

4. Residence time

5. Air flow

In this video below here, I discuss the topic of material drying and troubleshooting of moisture streaks in detail:

 


The table below shows the different maximum moisture levels after resin drying to ensure proper processing.

 

Table: maximum moisture content after resin drying of most used polymers

Thank you for reading and #findoutaboutplastics

Greetings,

Herwig

 #polymerprocessing #herwigjuster

Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] GE Plastics – Moulding Guide

[2] Saechtling Kunststoff Taschenbuch, Hanser-Fachbuch

Sunday, 8 August 2021

Composting Biodegradable Polymers – Helpful Standards

Hello and welcome to this blog post on biodegradable plastics and their related standards. In one of my last blog posts we discussed the difference between the standards EN16785-1 (bio-based content) and ASTM D6866/EN 16640 (bio-based carbon content). Today we have a closer look at ASTM D6868, ASTM D 6400, EN 13 432, ISO 17 088 and what it means for composting biodegradable polymers.

In general, biopolymers can be biodegradable or non-biodegradable as well as made from renewable sources or from fossil-based resources. This is shown in Figure 1 below.

Figure 1: Overview classification of biopolymers [1].

Standards for composting of biodegradable polymers

Apart from the estimation of the bio content, clarification of compostability after usage of the product is the next key topic for biodegradable plastics.

In Table 1, the most important ASTM / EN standards are shown to help you guide through the jungle of standards.

For example, ASTM D6868 standard is used for labeling of products that consist out of biodegradable plastics and polymers together with paper and other carriers intended for aerobically composition in municipal or industrial facilities. The products also include packaging applications. Performance of the materials in terms of compostability or biodegradability is not covered by this standard, only labelling.

Table 1: standards for composting of biodegradable polymers.

Update: ISO 17088 has been revised in 2012 and more recently in 2021.

Thanks for reading and #findoutaboutplastics

Greetings,

Herwig

#biopolymers #herwigjuster

 Interested to talk with me about your plastic selection and part design needs - here you can contact me 

Interested in my monthly blog posts – then subscribe here and receive my high performance polymers knowledge matrix.
New to my Find Out About Plastics Blog – check out the start here section
Polymer Material Selection (PoMS) for Electric Vehicles (xEVs) - check out my new online course


Literature:

[1] https://bpiworld.org/page-190424

[2] https://www.astm.org/Standards/D6868.htm

[3] https://bpiworld.org/page-190422

[4] https://docs.european-bioplastics.org/publications/bp/EUBP_BP_En_13432.pdf

[5] https://www.iso.org/standard/43373.html