Plastics and rubber for lightweight construction

The aim of using plastics and rubber for lightweight construction is to achieve a maximum weight saving in individual components or parts by means of either the design, the material selection or the method of production. Plastics and rubber offer considerable potential in the field of lightweight construction, not only because of their low density compared with their metal and ceramic counterparts (i.e. weight saving attributable to the material), they also offer considerable flexibility in processing and design (i.e. weight saving attributable to design and/or production).

Powerfull lightweight construction concepts are found mainly in the automotive and aerospace industries. By lightweight construction, material costs, and production costs can be reduced as well as subsequent operation costs. Because of reduced weight, less engine power is needed, resulting not only in the conservation of materials but also in lower fuel consumption and costs reductions.

Apart from applications in the transport sector, considerable potential for lightweight construction exists for plastics and rubber in sport and leisure articles and in the packaging and construction industries. While rigid, plastics and rubber are predominantly used for sport and leisure articles, cellular plastics and rubber are particularly suitable for packaging, building and transportation because of their good energy absorption and insulation properties, combined with the additional weight saving.

The simplest strategy for lightweight construction is material-based, and involves replacing the originally used materials with others having higher specific properties. Consequently, the weight can be lowered by reducing the wall thickness or by using a material with a lower density. This can be done, for example, in automotive construction and in the aerospace industry by the Substitution of metals with plastics. Beside engineering plastics such as polyamide (e.g. oil sump module), fibre-reinforced plastics also have considerable lightweight construction potential in the automotive and aerospace sectors. This class of materials will be dealt with separately in another article.

The second strategy for lightweight construction involves lightweight engineering. This means adapting the design of the component to the operation of efficient and economical structures. Thus areas subjected to high loads are reinforced, while the wall thicknesses can be kept as thin as possible in areas subjected to lower loads. In this respect, plastics offer major potential in all areas of application because of their outstanding flexibility in part design (complex, three-dimensional structures are possible). To achieve this kind of lightweight engineering, an accurate analysis of the individual components and the part as a whole are of major importance. If the safety margins are too high or if only insufficient information is available on the materials and the material behaviour under the expected loads, over-dimensioning the part and not fully exploiting the lightweight construction potential are high of risk.

While the two strategies for lightweight engineering dealt with so far look particularly at individual elements or subassemblies, the third strategy of lightweight design – production – looks at the system as a whole. By integrating several functions in one component, the overall weight of the system can be reduced without necessarily reducing the weight of the individual elements or subassemblies. Plastics and rubber, with their flexible application properties and design scope, have outstanding potential for putting this principle into practice. Plastics, for example, allow a material-to-material (cohesive) connection within a component by means of a single processing method (multi-component injection moulding, co-extrusion) without the need for any rivets or adhesive bonds. With the aid of these processes and the use of different types of plastic and rubber, a wide variety of functions can be integrated into a subassembly that has been tailor-made for the particular application (see torque roll restrictor for the Porsche Panamera).

The integration of several functions in one part can result not only in reducing the weight of the overall system because individual elements are no longer needed, it also saves costs. By shortening the process chain and/or saving production steps and cutting material consumption, the manufactoring and material costs of the entire system are reduced. Alongside the three strategies for lightweight construction already mentioned, there is a fourth, namely "economy lightweight construction". Plastics and rubber also offer considerable potential for innovation in this field through their capacity for flexible part design, their diverse processing possibilities, and their potential to minimise material consumption even further through foam production.

However, costs are incurred not only in product manufacture, but primarily also in the product's application or operation. In most cases, the overall cost of producing a lightweight part will be higher, because it requires expensive materials and increased manufacturing costs. These higher costs can, however, be justified through lower operating costs. In the aerospace industry, for example, although manufacturing and material costs are higher through lightweight construction, the overall costs of the product over the course of time are reduced drastically through lower fuel consumption or an increase in the payload.

Because of their property profile – low density, foamability, varied processability and flexible part design – plastics and rubber have the potential to be deployed in all the previously mentioned lightweight construction strategies and to offer innovative solutions for the future.


Innovations in the field of:

1) Machine construction

IMC and foaming with IMC
Compounding and processing in one single step

Fibre-reinforced plastics
Replacement of cast aluminium design with carbon fibre clip lever by RTM lightweight construction


2) Packaging, distribution

Flexible packaging material
E-Por® from BASF SE: innovative particle foam with high impact strength

Biodegradable plastic for special packaging
BASF offers a new biodegradable plastic called Ecovio FS to supplement its existing Ecovio range. BASF has optimised the new plastic for two special applications: paper coating and shrink film for simple wrapping applications. The two new plastic grades are thus called Ecovio FS Paper and Ecovio FS Shrink Film. Ecovio FS consists of an equally new, now bio-based Ecoflex FS (a biodegradable polyester from BASF) and PLA (polylactic acid), which is obtained from maize starch. Through the use of the new Ecoflex FS, the proportion of bio-based material in Ecovio FS Shrink Film is 66%, and in Ecovio FS Paper, 75%.


3) Automotive, aerospace

Structural foam based on epoxy resins
Terocore® structural foam from Henkel AG & Co. KGaA: epoxy resin foam for weight-savings in auto construction and for reinforcing the bodywork at critical points to increase accident safety by absorbing impact energy.

Plastic oil sump module
Zytel® polyamide from DuPont: for the first production-line oil sump module made of plastic.

Torque roll restrictor for the Porsche Panamera
Component from ContiTech made of BASF polyamide: high-performance composite part consisting of a high-strength polyamide from the Ultramid® CR family and a function-optimised rubber compound.

Sporty surface material for car seats
Sport-Esteem® from Benecke-Kaliko AG: The material feels like neoprene and looks like nappa leather. The necessary soil resistance is provided by a closed surface obtained by an innovative formulation, a unique production process and a new topcoat combination.

Artega GT sports car: Lightweight construction with a plastic body of Elastogran
The new Artega GT sports car is the first production-line vehicle to have a body made completely of polyurethane. The airy chassis was developed by German sports car manufacturer Artega in cooperation with the BASF subsidiary, Elastogran.

Interior lightweight construction for cockpits based on the "Light Attitude" study
Automotive supplier Faurecia has, with its "Light Attitude" study, united the present status of lightweight construction and projected it into the future. This project illustrates what weight savings are still possible in the cockpit and how this can be achieved.


4) Building and living

Thermal insulation with Neopolen P 9335 mg
A new patented variant of Neopolen P foam (EPP: expanded polypropylene) has been developed by BASF SE in Ludwigshafen, and is now available for appliances in the heating, ventilation and sanitary engineering segments.

Improvement of insulation properties
Development of nano foams.


5) Electronics, electrical engineering

Polyurethanes protect sensitive electronics
Polyurethanes system house BaySystems in Otterup, Denmark, and Isotherm AG in Uetendorf, Switzerland, have jointly developed an economical process for the production of housings and the protection of sensitive electronic components.
The process is based on Baydur E and Bayflex E polyurethane systems, processed by reaction injection moulding (RIM) in a single step.

Flexible plastic for alternating current power cable
With the flame-retardant flexible plastic Noryl, SABIC Innovative Plastics offers a non-halogenated material for use in alternating current power cables that conforms to the strict 62 TPE 90 ºC and 105 ºC safety standards from Underwriters Laboratories (UL). Available in three specialised grades for various configurations of alternating current power cables, the new plastic offers high flame-retardant properties that meet the relevant global regulations. In addition, says the manufacturer, the plastic has outstanding flexibility and high-quality surface characteristics. SABIC Innovative Plastics is currently working with customers to obtain EU certification to VDE HD 21.14.

Thermoplastic circuit board
Foamed circuit board of HT thermoplastics like PEI or PES are developing to an alternative to conventional FR4 curcuit boards and offer a high cost saving potential for high frequency applications.


6) Medical technology, precision engineering, optics

Functional compounds of high-performance plastics
Innovative compounds, primarily based on highly temperature-resistant amorphous and semi-crystalline plastics such as PEEK, PPS, PPSU and PEI, are being increasingly used in highly integrated components and systems – for example in OP containers. Through the incorporation of special additives, development engineers at Lehmann & Voss give such compounds improved friction and wear behaviour, and also increase the electrical and thermal conductivity. It is also possible to specifically adjust the colour, production tolerance, barrier properties, thermal expansion and anti-microbial properties. The main area of application for these Luvocom functional compounds is the substitution of metal parts – primarily for design, weight and cost reasons. Miniaturisation also plays a major role. Lehmann & Voss provides manufacturers of such components with service and support. Through the use of biocompatible raw materials and/or raw materials that conform to the FDA regulations, relevant certificates and results of material testing can be supplied for approval for applications in human medicine, e.g. to ISO 10993 (also batchwise).


7) Information and communications technology (ICT)

Energy-efficient technology innovations (micro electronics)
The CoolSensornet project is currently working on a minor revolution in aviation technology and safety. Sensor networks can be used to monitor and evaluate the service life of load-bearing construction elements, for example with aircraft in which the highly efficient organic light-emitting diodes with Novaled technology have to be examined regularly for material fatigue in the High Efficiency OLEDs test with Novaled technology in Testlab Microelectronics 87 Wing. CoolSensornet is therefore dedicated to the development of sensor nodes with integrated acoustic piezo sensors that can be permanently embedded in the lightweight carbon fibre composite wing or in other load-bearing structures during aircraft production.


8) Sport, leisure

High-performance kayak of polypropylene
Tegris™ from Milliken (USA): Tape yarn consisting of a heavily stretched PP core between two low-melting PP facings. Good impact strength in combination with high stiffness. Suitable for water and motor sports applications and for safety equipment.


9) Photovoltaics

Organic solar cells
Polymer-based organic solar cell printed on film.

Organic photovoltaics:
Solar power extremely thin plastic film.

Organic photovoltaics convert solar energy into electricity
The term organic photovoltaics is used to describe solar cells based on organic semi-conductor materials, which can in future replace the silicon used today.


10) Agriculture

Air collectors from plastic fabrics for agriculture
Use of solar energy e.g. for drying hay and corn.


11) Power engineering

Bonding of rotor blades
Macroplast® from Henkel AG & Co. KGaA: Polyurethane adhesive for the bonding of rotor blades. Polyurethane-based adhesives react very much faster than the previously used epoxy resins resulting in faster processes.

Polyurethane foam-covered steel frames
BBG GmbH & Co. KG: Foam covering and integration of all fixing elements for assembly as well as all cables and diodes. Increase in energy yield through edgeless polyurethane construction because dirt cannot stick to the module surface.

Plastics and rubber for lightweight construction - Vita Prof. Dr.-Ing. Volker Altstädt