Thursday 30 November 2017

High performance polymers used in children buggies

Weight reduction to save energy and costs has been and will continue to be a constant topic of interest in the aircraft and automotive industries. In this regard, much has been done toward replacement of metals especially the heaviest ones by lighter materials still able to fulfill application demands. Nevertheless, there are other industries where metal replacement and consequent weight reduction can also make life easier especially when you have children. I am talking about children buggies. Most buggies have between 8.5 kg and 10 kg. Heaviest ones may range from 12 kg to 17 kg in total weight (frame plus seat). The weight is a result of using aluminum, which is already among the lightest metal materials (2700 kg/m3). Furthermore, it is naturally resistant to corrosion. Is it still possible to make buggies lighter while keeping their current application suitability? Yes, by using high performance polymers.
Following, I will present you a commercial example of the company Quinny that won the 2014 Red Dot ‘Best of the Best’ Award for their 5 kg Yezz buggy [1,2].
5 kg Yezz buggy using PARA frames [1,2]

Why is it only 5 kg heavy and still a high-end performer?
The frame of the buggy is made of several frame parts using the high performance polymer, polyarylamide, commonly known as PARA (or MXD6), reinforced with glass fibers (50 wt%) [3]. The weight reduction is achieved by the reduced density of PARA, 1600 kg/m3. The high-end performance comparable to metal is achieved by the aromatic amide macromolecular structure of PARA, which provides this polymer with inherent high stiffness and strength. For instances, the tensile modulus of PARA can reach values up to 23 GPa at 20°C.

In terms of processing, a major added value of PARA is that it can be loaded up to 60%wt with glass fibers for reinforcement purposes [4] without this to be noticed in the moulded part. The latter will still exhibit a smooth surface with no evidence of contained glass fibers. Such surface allows excellent painting and/or metallization. Additionally, PARA has good flow properties at melting temperatures, which allow the moulding of parts as thin as 0.5 mm. For these reasons, PARA can be a suitable material when complex parts requiring high stiffness in combination with superior surface quality are needed. Accordingly, premium automotive interiors could be of interest.
Next time when you’re are looking for a buggy keep in mind that there are lightweight solutions to make travelling activities with your children easier.

Thanks for reading!
Herwig Juster

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