Technology & solutions
FRP pushing boundaries in lightweight applications
2018.11.01   |   조회 : 601
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The requirements of modern lightweight applications can no longer be met by conventional materials, but can only be achieved by optimum solutions with innovative materials. Fiber reinforced plastic (FRP) is becoming the material of choice for lightweighting thanks to its extremely strong and lightweight properties.

Weight reduction is one of the most important development trends in numerous sectors such as automotive, aerospace, construction, sports and leisure, etc.

As technologies advances, in order to facilitate lightweight design and structural parts construction without sacrificing performance, more efforts are focusing on composite materials engineering, such as the development of FRP in high volume production.

FRP is a composite material made of a polymer matrix reinforced with fibers. The fibers generally used now are carbon fibers and glass fibers.

Carbon fiber reinforced plastic (CFRP) is an advanced non-metallic composite material composed of carbon fibers embedded in a polymer resin, in which the carbon fibers function as the reinforcement material and the polymer resin functions as the matrix to hold the fibers.

CFRP has the advantages of many superior performances, such as high strength, lightweight, no corrosion and excellent fatigue resistance.

CFRP is a key growth driver within the overall fiber reinforced lightweight materials market, according to a report published by Carbon Composites e.V. and AVK (Federation of Reinforced Plastics) based in Germany.

The global demand for CFRP reached 101,000 metric tons in 2016, representing an increase of 11% when compared to previous year. Meanwhile, the total turnover for CFRP worldwide increased 14% to US$13.23 billion in 2016 from previous year.

For the coming years, steady and continued, double-digit growth rates between 10% and 13% are expected.

Automotive sector drives strong demand of lightweight composites

One of the innovation drivers for the development of FRP is the automotive sector. It is very clear when considering a 100 kilogram lighter car consumes around 0.5 litres less fuel per 100 km.

Many chemical suppliers have been introducing FRP for the automotive sector. For example, Solvay has expanded its portfolio of solutions for the automotive thermal management modules and multi coolant valves.

The company’s new Amodel A-89XX series of glass fiber reinforced PPA grades ranges from 30-50% glass-filled loading, offering improved dimensional stability, lower moisture uptake and enhanced chemical resistance. Targeted applications include thermostat housings, multi-coolant valves, water inlets/outlets and cross overs, and other under-the-hood components.

Asahi Kasei North America has also launched the Thermylene P11, a next-generation family of glass-reinforced PP compounds with unprecedented strength. As introduced, it provides a 40% improvement in measured tensile strength at 80°C and 120°C compared to conventional glass-filled PP.

The new Thermylene P11 family expands the performance envelope for conventional glass-reinforced PP design and opening opportunities for thinwall molding of interior and exterior automotive parts.

With special design of layers and high level of function integration, FRP provides more solutions for lightweighting and safety in the automotive sector.

Lanxess’ Tepex dynalite continuous fiber reinforced, semi-finished thermoplastic composites have found new applications in vehicle interiors such as the backseat system.

The center backseat is equipped with a load-through that enables the backrest of each seat to be folded down individually. This load-through component is produced by shaping and back-injecting Tepex dynalite.

The new component is said to be more than 40% lighter than its steel counterpart. At the same time, this safety-relevant component withstands all load scenarios, because the orientation of the continuous fiber layers in the only two millimeter-thick semi-finished product was designed to bear the mechanical stress.

Reinforced composites evolve to stay ahead in aerospace sector

The aerospace sector was one of the earliest and most significant adopters of CFRP. Apart from lightweighting, the ability to add functionality to a composite part is also the added value for the performance.

Driven by their superior strength and stiffness-to-weight ratio, composites can account for more than 50% of the structural parts in the latest models of civil aircrafts.

The Airbus A350 XWB is one of the aircrafts with the highest weight ratio for CFRP. It is built of 52% CFRP, including wing spars and fuselage components.

It was also one of the first commercial aircrafts to have the wing spars made from composites. Its central wing-box, trailing edge, along with the rear bulkhead, empennage and un-pressurized fuselage are made of CFRP.

Composites have not exhausted their innovation avenue, according to the report “Additive Manufacturing and Lightweight Materials for Aerospace and Defense 2018–2028” by IDTechEx.

Many new processes are re-inventing this class of material and advancing more than just mechanical properties, says IDTechEx. There are many progressions to improving the lightweight performance of a composite part. This includes next-generation prepreg materials and the rise of high-performance thermoplastics, the report notes.

One recent development gaining increasing attention is thin-ply composites from spread-tow fibers. This involves spreading the fibers for a reduced density (typically below 75 gsm) and a stronger homogeneous fiber-matrix interaction.

This material is already being used by aircraft overhaul and maintenance firm Hong Kong Aircraft Engineering for interior seating in the Airbus A350 aircraft.

Meanwhile, application of pure boron fibers for polymer reinforcement is at a much earlier stage. This fiber can potentially replace carbon fiber in much the same way that carbon fiber has displaced aluminum over the very long term. The fibers are synthesized via a laser chemical vapor deposition route. However, there are still many technical and economic obstacles to overcome.

New hybrid prepreg used for sports and leisure applications

Toho Tenax Co., Ltd., the core company of the Teijin Group’s carbon fibers and composites business, has developed a new high-tensile, highly shock-resistant prepreg that incorporates carbon fiber developed by Toho Tenax for aerospace applications and specialized carbon nanotubes.

The new hybrid prepreg has been adopted by Mizuno Corporation in a new golf club shaft that weighs nearly 30% less than conventional shafts of the same thickness.

A prepreg is a carbon fiber sheet pre-impregnated with matrix resin and used as an intermediate material for CFRP.

The high-tensile prepreg enables the shaft to bend suitably as the ball is impacted and then cuts the shock of impact by more than 10% to reduce club movement on the follow-through swing.

The hybrid combination of carbon fiber and carbon nanotubes realizes superior CFRP that offers improved tensile strength and shock resistance, according to the company. The CFRP also is extra durable because the carbon fiber and matrix resin do not peel away from each other thanks to the carbon nanotube’s balanced dispersion.

Since CFRP is used in different fields, its prescribed properties must differ widely depending on the application. Teijin is developing technology for various combinations of carbon fiber and matrix resin and for specific processing needs.

Competitiveness increased thanks to natural fiber reinforced plastics

In their published study “Inventory of Lightweight Construction in Germany”, the experts from the VDI Centre for Resource Efficiency also described the role of fiber and natural fiber reinforced plastics in the scope of lightweight materials.

There is great potential for further weight reduction through the use of FRP, according to the study. As mentioned, FRP such as CFRP and glass fiber reinforced plastic (GFRP) have been posting very high growth rates and would very likely to gain in importance in the long term (after 2020).

The experts said the use of natural fibers would increase the competitiveness of FRP as using renewable resources has been an emerging trend.

Flexible plastic and corrugated paperboard packaging supplier Rengo Co., Ltd. has leveraged its cellulose production technology to develop a cellulose nanofiber via an intermediate material. The target applications include composite materials for automotive.

Typically made by “microfiberizing” the cellulose contained in wood cellulose fiber to the nanometer level using chemical or mechanical processes, the cellulose nanofiber is said to have one fifth the weight of steel but five times its strength.

As the production costs remain high, Rengo hopes to work with companies and universities on product development in order to achieve commercialized production.

On the other hand, Mitsubishi Paper Mills believes that the adoption of lower cost cellulose microfibers will be a good alternative. It says that cellulose microfibers are adequate enough for reinforced thermoplastics for many applications, and they can be incorporated into the polymer matrix much more easily.

The Japanese company already offers cellulose fiber reinforced PP compounds on a commercial basis. Its high purity cellulose fiber PCV30-F PP compound offers reinforcement levels of 10%, 20% and 30% with better tensile strengths when compared to neat PP resin. In addition, heat distortion temperatures are substantially improved.

Looking forward, the research and developments of FRP will definitely continue to be a trend in the plastics industry. While innovative and improved formulation plays a crucial role in the process, enhancing automation of composite fabrication and extending into 3D printing of composites could also be the key facilitators to give the materials greater design freedom and cost efficiency.

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