Hello and welcome to a new blog post. Today’s topic is the important role of polymer additives and since it is a broad topic I will split it into several parts.
In the first part we discuss the types of additives and things to consider when you use additives in material- and application development. Having a basic understanding of fillers and what they can enable in a plastic compound is important for polymer material selection too.
What can additives do for your polymer?
The limited usage range of certain polymers can be improved by incorporating additives into the polymers. Thinking of polyolefins, without adding antioxidants, not even processing would be possible in a proper way. Another example is rigid PVC which can be made flexible by adding plasticizes. Adding glass fibers to Polyamide 6 increases the heat distortion temperature (HDT), as well as strength and stiffness. Using color pigments allows the PC to be moulded in several colors and PP can be made radiation stable by adding free radical scavengers. Conductive fillers turn polymers from an isolator to a material which can be used as a heat sink. Another example is the chemical compound Piperine which is responsible for the spicy appearance of black pepper. It is added during fuel line extrusion for cars to prevent biting of cables due to animals. If they bite, it will start hurting and they will immediately stop.
Additives can turn brittle polymers such as Polystyrene into a toughened polymer by using impact modifiers. Also can additives improve processing, dimensional stability, and strength. Furthermore, they can improve thermal, radiation, and light stability. They are able to improve the flame retardant level and turn for example Polyesters flame retardant and improve long-term aging, scratch resistance, aesthetics, and biocompatibility. Another example is that additives can improve electrical properties such as the Comparative Tracking Index (CTI).
Polymer material performance: the effects of additives in an overview
Table 1 shows the different additive classes and their effect in the final plastic compound. Flame retardant additives we discussed previously already here.
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| Table 1: Overiew of different additive classes and their effect in the final plastic compound. |
What do we need to consider when we use additives?
The different effects of various additives on the final compound need to be considered by the formulators. Physical and chemical properties, toxicity, sterilization as well as biocompatibility (in case of health care applications) must be evaluated. Also checking the shelf life of the new material compound needs to be considered since the used additive may cause some side reactions which lead to a decrease in properties.
In the next part we discuss how to modify the properties of compounds by using different shaped fillers.
Thanks and #findoutaboutplastics
Greetings,
Herwig
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Literature:
[1] Gächter and Müller: Plastics Additives
[2] Sastri - Plastics in Medical Devices: Properties, Requirements, and Applications
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