Drain marks and drain drops

Terminology in plastics engineering – presented in a humorous and easy-to-understand way. Did you know that, in many cases, comparisons with nature and the human body can be used to explain concepts in plastics engineering? Today’s term: flow marks and flow droplets „Gravity makes no distinction between honey and PVC.“ Have you ever noticed a […] in a jar of honey […]

Creeper behaviour

Terminology in plastics engineering – presented in a humorous and easy-to-understand way. Did you know that, in many cases, comparisons with nature and human behaviour can be used to explain concepts in plastics engineering? Today’s term: Creep behaviour „If you know plastics, you use cement.“ This is a phrase that a professor of plastics engineering at what was then Darmstadt University of Applied Sciences […]

Frozen tensions

Imagine putting on the suit you last wore to a wedding after a long time. You notice that the trousers have been looser in the past, but buying a new suit is out of the question for you. You pull your stomach in a little, zip the trousers and think: "For a [...]

Stress cracking

Some people are familiar with this: a lot to do, a lot to do, constant stress, constantly new topics and new deadlines - you do and do and basically don't get anywhere. You maintain the same image to your colleagues. „Everything is fine, everything is ok.“ But then comes the moment when you buckle under the weight. [...]

Silverfish (stress cracks)

The nimble little silverfish in the bathroom are not a sign of a lack of hygiene. Rather, they are an indicator of a warm and humid microclimate. A single animal is therefore usually harmless, but a mass occurrence serves as an alarm signal for moisture damage, mould or structural defects. Especially with transparent plastics such as PMMA (known as acrylic glass or Plexiglas®), stress cracking is a particularly [...]

Plastic soul

Did you know that in many cases, comparisons with nature and humans can be used to explain facts in plastics technology? Today's term: The plastic soul - the liquid core under the skin Cherry tomatoes on a pizza should be enjoyed with caution. Even if the pizza has already cooled down a little [...]

Back pressure, holding pressure, holding pressure

Did you know that in many cases, comparisons with nature and humans can be used to explain facts in plastics technology? Today's term: dynamic pressure, holding pressure, holding pressure - nothing happens without pressure! We all know it. Homework, tax returns, ironing laundry... As long as there is no pressure, nothing happens for a long time! In [...]

Rheology

Morning grouch vs. party volcano At low temperatures, plastics are stiff and sluggish - like a person shortly after waking up and without coffee. As the temperature rises, movement comes into play - the party can soon begin. The plastic pellets melt inside the heated injection moulding cylinder and become increasingly mobile due to the rotary movement of the screw and [...]

Thixotropy

Movement makes wallpaper paste and ketchup thin - two typically thixotropic liquids. If you leave them alone, they are immobile and sluggish. Only movement, such as stirring the paste in the bucket or shaking the ketchup bottle, changes their almost human characteristics. The wallpaper paste can be effortlessly applied to the wallpaper by moving the brush [...]

Hose core

„True beauty comes from within“. In the 1970s and 1980s, this wisdom was used in a slightly modified form as an advertising slogan for a food supplement and cosmetics manufacturer, which promoted the natural beauty that comes from within. The term "inner tube", which describes the material that forms the inner surface of a plastic or rubber tube, is used in a figurative sense [...].

Frictional heat

Why do you rub your hands together vigorously in winter when your fingers are cold? Because rapid rubbing converts kinetic energy into heat. And it is precisely this physical phenomenon that is used in several ways in plastics processing, the injection moulding process. When explaining the concept of rheology, we remember that the plastic granules in a [...]