Engineering Polymers
PC- Polycarbonate Polycarbonate is an excellent engineering polymer. PC has a good balance of properties, with good temperature resistance, excellent impact resistance and also superb optical properties. Physical Properties Polycarbonate is tough, durable, strong, hard, rigid, has good cold-temperature impact strength (up to – 100°C) is clear as glass, non-toxic, takes colour pigmentation well, has low moisture absorption […]
Read more >Designing with Plastics
Designing with plastics is similar to designing with other materials but more attention has to be paid to the time-dependant properties of plastics and how plastics behave with changes in temperature and environmental conditions.
Read more >Polymer manufacturing processes
The conversion of raw polymers into finished products involves a series of polymer manufacturing processes. The first step consists of mixing additives into the polymer to achieve the required modification to the properties of the raw polymer.
Read more >Introduction to Polymers
The family of plastics materials is closely related to two other important families of manufacturing materials, textile fibres and elastomers (rubber), in that they are all based on carbon (organic materials) and they consist of extremely large molecules (polymers).
Read more >Coping with weld lines
In injection moulding, weld lines (knit lines) form when two melt fronts meet. If the melt fronts do not coalesce completely, at best there will be a cosmetic flaw. At worst there will be a mechanical weak-spot, with strengths of the order of 10 - 90 % of the material potential.
Read more >Will Styrenic thermoplastics evolve further to meet design demands ?
Styrenic thermoplastics?
Read more >Polypropylene: the Workhorse of the Plastics Industry
Polypropylene. Little did Karl Zeigler or Giulio Natta realise, 60 years ago, when they were developing a catalyst system to produce a useful thermoplastic from the inexpensive monomer, propylene, that their work would have such far reaching consequences.
Read more >Where is Wear….. and Why.
Material loss (wear, abrasion loss) when two surfaces rub together, follows a similar pattern to friction. One mechanism, ‘adhesion loss’, consists of transfer of material from one surface to another. Adhesion loss is related to the chemical attraction between the two surfaces. In the second mechanism, ‘abrasion loss’, material is removed by a rupture process when nanoscale ‘peaks’ interact at the interface.
Read more >What determines friction between thermoplastic components?
Friction is an important property for thermoplastics in bearings and gears but also has a part to play in assembly of plastic parts (snap-fit and interference-fit) and ejection during moulding.
Read more >Polyacetal (POM): When to Select Homopolymer or Copolymer?
The production of stable thermoplastics from formaldehyde was discovered around 60 years ago, using two independent approaches. To prevent unzipping of the polymer chains at high temperature, DuPont used an end cap mechanism. Celanese opted for incorporation of a comonomer which also stopped the unzipping. Today you still have a choice between the homopolymer grades […]
Read more >Creepy things can happen with long term loading of thermoplastics.
Deformation is defined as the change in the shape of a body caused by the application of a force (stress). It is proportional to the stress applied within the elastic limits of the material.
Read more >What makes medical grade plastics so special?
Toughness and transparency are important properties for the constituents of intravenous lines.
Read more >The Long and the Short of Fibre Reinforcement of Thermoplastics
Fibre Reinforcement. The advantages of adding glass fibre to thermoplastics to increase stiffness (modulus), strength, heat distortion resistance and dimensional stability are well known.
Read more >What causes mouldings (and moulders) to be off-colour?
When mouldings are not the intended colour, the first thing to check is the raw material, particularly the dosing rate, if you are using masterbatch, and the quality of regrind.
Read more >Do your mouldings suffer from jet lag?
When explaining the moulding fault commonly known as ‘jetting’ to part-time students from the plastics moulding sector, I usually prefaced my remarks by saying that ‘jetting’ was not a fault that you should see these days. Then one of the students appeared the next week with a classic example of ‘jetting’.
Read more >Transparent ABS can be a clear winner
Transparent ABS. Mentioning transparency in the context of ABS moulding materials can raise a few eyebrows. This is because ABS is normally taken to be opaque and indeed the vast majority of grades of ABS are opaque.
Read more >How useful is Tensile Strength data ?
When scanning a thermoplastics data sheet for a new project or finding a replacement for an existing grade, the eye tends to get drawn to the values quoted for tensile strength (or more correctly ‘tensile stress at break’) as an indication of the material’s mechanical properties.
Read more >Where are Engineering Thermoplastics Blends going ?
The timeline of appearance of materials for the plastics industry can be viewed as several overlapping phases.
Read more >Understanding the difference between SBS & SEBS thermoplastic elastomers?
The difference between SBS and SEBS thermoplastic elastomers explained.
Read more >How do electrostatic dissipative (esd) thermoplastics work?
When two polymeric surfaces are rubbed together static electrical charges are generated on the surfaces. Party tricks involving picking up pieces of paper with a comb are amusing. However, static electricity can be a nuisance in the plastics industry with dust attraction during storage or in service.
Read more >Is MFR really much help to moulders these days ?
Often a moulder has to change material grades. One of the first properties to be consulted on the new data sheet is usually the MFR. This is to establish if the new grade has the same melt viscosity performance.
Read more >What gives Moulders a Warped View on Life?
Warping is one of the most frustrating injection moulding faults. This is because it does not always appear immediately, the causes are complex and prevention is difficult.
Read more >How to A-Void that Sinking Feeling
A previous knowledge base article addressed mould shrinkage. We recognised mould shrinkage (the difference between the mould cavity dimensions and the final dimensions of the moulding) depends on the material (amorphous v semi-crystalline; filled v unfilled) and also on the specific process conditions (melt temperature, injection pressure, hold pressure, hold time etc). Avoid a void! […]
Read more >Why is Mould Shrinkage the Source of so many Disputes?
Consider when thermoplastic melt in a mould cavity cools from processing temperature to room temperature.
Read more >Colour your thinking on the Optical Properties of Thermoplastics
Very few commercial polymers have chemical groups (chromophores) which absorb light in the visible region of the spectrum. Consequently the base polymers are colourless.
Read more >How Easy is it to See Through the Optical Properties of Thermoplastics?
Transparency in thermoplastics is a property that differentiates them from many other manufacturing materials. This includes metals, ceramics and wood, and, in some cases surpasses glass.
Read more >How can a thermoplastic elastomer be both thermoplastic and elastomer ?
Thermoplastic elastomer? The class of polymers known as thermoplastic rubbers (TPR), or thermoplastic elastomers (TPE), describes pretty well what it says. As thermoplastics these materials soften with heat. They can be melt processed, by extrusion or injection moulding, but regain their soft solid properties when cooled. As elastomers they conform to the ASTM definition of […]
Read more >Understanding the causes of silvering in injection mouldings .
Silvering. Water is essential for human and plant life but can prove inconvenient for thermoplastics.
Read more >Has PVC weathered the negative attitudes of Environmentalists ?
A common observation is “If PVC appeared on the market now, it would be rejected”
Read more >Does FR imply fire resistance?
When we see ‘FR’ in a plastics grade coding we can sometimes be lulled into believing we have a material that is ‘fire resistant’.
Read more >Looking for colour stability in plastics for outdoor exposure ?
When it comes to outdoor exposure, ABS (acrylonitrile-butadiene-styrene) struggles a bit because the butadiene in the rubbery phase is prone to oxidation and yellowing on exposure to uv light, particularly after heat ageing.
Read more >What do Liquid Crystalline Polymers have to offer?
When liquid crystalline polymers (LCP) first appeared in the 1980s it looked like the dawn of a major new class of thermoplastics.
Read more >What does a moulder understand by the term ‘diesel burning’
In the early days plastics moulders tended to apply descriptive terms to moulding faults, such ‘gate splay’, ‘mica marks’, ‘orange peel’, ‘flash’ and ‘record grooves’.
Read more >What can imide links do that amide cannot?
Polymers with amide links have been around for some time but the close cousins, the imide links, are less well known.
Read more >Hardie Polymers in BPF Strategic Discussion with MP
Dunbartonshire -based BPF member Hardie Polymers met with local MP, Jo Swinson, Nick Clegg’s Parliamentary Private Secretary, on Friday 29th June, to discuss the strategic future of the UK plastics industry. Joining Fergus Hardie, the Company’s Managing Director, was Philip Law, BPF’s Public and Industrial Affairs Director. The meeting was based on the BPF’s recently […]
Read more >Who needs formal polymer education?
Polymer technologists today can access on the internet a massive amount of technical information on plastics and their related processes.
Read more >How to reduce your plastic raw material costs…
Interested in how to reduce your plastic raw material costs? This short Hardie Polymers video will help you learn how to do just that...
Read more >Making the most of impact testing
Falling weight impact tests, either from dropping a product onto a hard surface or dropping a weight onto a product, can yield much more relevant information
Read more >Do Izod and Charpy make the appropriate impact?
Cracking of plastics components under impact was a major blow to the plastics industry in the early days.
Read more >Low cost Identification of plastics
Low cost identification of plastics is certainly desirable. Identifying an unknown plastics material can be an expensive exercise if you submit it for a full chemical analysis.
Read more >Thermoplastics and UV: Friend or Foe?
Thermoplastics and UV: Radiation in the ultraviolet region of the spectrum is a bit of a mixed blessing for polymers.
Read more >Is Solvent Resistance Predictable ?
To assess solvent resistance, first consider solvents spread out on a polarity scale.
Read more >How to crystallise your thoughts on selecting a thermoplastic.
When faced with selecting a thermoplastic for a new component, I find it helpful to view potential materials in two groups .
Read more >Sulphur: From the Underworld to Thermoplastics
In 1839, by inserting sulphur atoms as bridges between polymer chains, Charles Goodyear transformed Natural Rubber from an interesting curiosity into a superb engineering material that has had a huge impact on society.
Read more >Can you modify a polymer grade safely ?
One of the exciting attributes of polymers is that the properties of any polymer can be modified by tinkering with the basic molecular structure or incorporating a range of additives.
Read more >What do we mean by the Heat Resistance of thermoplastics?
In some applications heat resistance can mean the material’s ability to carry out its intended function at elevated temperatures for short periods.
Read more >Is PTFE a thermoset or a thermoplastic?
Many assume that polytetrafluoroethylene is a thermoset because it seems unaffected by heat.
Read more >A Polymer Data Sheet – Just how useful are they?
Every polymer supplier will provide you with a basic data sheet describing the properties of a particular grade.
Read more >Is Thermoplastic Polyester your PET Subject?
The most important member of the Thermoplastic Polyester family is polyethylene terephthalate (PET). It was invented in the early 1940s in Manchester by Whitfield and Dickson.
Read more >See-through Kettles may not be a transparent material selection.
See-through Kettles may not be a transparent material selection.
Read more >Does POM stand for ‘Plastics Outperforming Metals’ ?
POM is the abbreviation for ‘polyoxymethylene’ (also known as ‘polyacetal’ ... or just plain old ‘acetal’) synthesised from formaldehyde. It's a readily available starting material, but, despite humble beginnings, is an engineering thermoplastic suitable for metal replacement.
Read more >Why does PPO have to be ‘Modified’ ?
Polymer scientists worked out that the molecular stiffness of the backbone of a polymer chain was the key to increasing the glass transition temperature (Tg) and hence rigidity at elevated temperatures.
Read more >Let it snow, let it snow…
Around this time of year we see a lot of artificial snow. A favourite trick of the special effects experts is to exploit an unusual acrylic polymer. Sodium polyacrylate, a powder which swells with water to produce convincing looking ‘snow’.
Read more >Does the coding for Polyamides mean anything to designers and processors?
Polyamides are macromolecules with repeating units linked by amide bonds. Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk.
Read more >The hidden attributes of polycarbonate
When polycarbonate (PC) first appeared in the market over 50 years ago, the immediate appeal was its amazing impact resistance compared to other transparent rigid thermoplastics at that time. It also provided a huge jump in heat distortion temperature, 50 degrees Celsius higher than other thermoplastics.
Read more >Can environmental stress cracking be avoided?
Environmental stress cracking (esc) is the development of cracks and eventual catastrophic failure due to a combination of mechanical stress (from external loading or from moulding strain) and exposure to an ‘aggressive’ chemical (a ‘near solvent’ for the thermoplastic material).
Read more >What is Environmental Stress Cracking?
Environmental stress cracking (esc) is not the result of the continual battle that the plastics industry has in convincing environmentalists and politicians that plastics can be the solution to environmental problems and not the cause.
Read more >Just why would you choose ABS….
ABS is one of the original engineering thermoplastics. A classic all-rounder with a good blend of performance and also aesthetic properties.
Read more >What are Engineering Thermoplastics?
Have you ever wondered about the term Engineering Thermoplastics? Today it is conveniently applied to certain families of thermoplastics which have a higher performance than the group of thermoplastics labelled ‘Commodity Thermoplastics’.
Read more >