Overflow of innovation at AVK awards

Photo by Hobas A Hobas GRP CSO chamber

There were 66 applications made for the 2015 AVK plastic composites innovation awards. In this feature for Plastics News Europe David Vink looks at the 10 winners, a submission on a plastic engine and different pultrusion processes.

Klagenfurt, Austria-based Hobas Engineering received first prize in the products and applications category in the 2015 AVK Federation of Reinforced Plastics Innovation Awards for its large combined sewer overflow (CSO) chamber made of glass fibre reinforced plastic (GRP). The chamber was developed together with Prague Technical University. In line with the EU water framework directive 2000/60/EC, the CSO is a highly efficient system handling mixed rainwater and sewer water during periods of high rainfall, restricting rainwater flowing back into the sewer system.

Hobas claims the modular construction GRP chamber is the first to integrate cleaning (with self-cleaning vibrating grids), storage and overflow functions, and it also improves wastewater quality over conventional solutions.

Hobas sales manager Rudolf Haux told the AVK awards jury that concrete has been used for overflow systems for around 100 years. While a concrete chamber system requires 10 days to produce and assemble on site, the factory-ready CSO chamber can be installed in one day, and gives smoother water flow. Following completion of hydraulic performance data in 2015, the next task for Hobas is to convince wastewater communities of CSO benefits, aiming at official approval in European wastewater system standards.

Second prize went to Evonik for Rohacell Triple F in-mould foamed (IMF) polymethacrylimide (PMI), skin-free, ready-to-use, particle foam cores for sandwich composite parts. Dr Kay Bernhard of Evonik says they are an alternative to polyurethane (PU) foam cores, adding “if PU resin breaks through a PU core skin, it goes everywhere, while our material is the same throughout the core”.

PMI foam

He stressed the value of avoiding conventional CNC milling-to-shape from block polymer foam, such as with other Rohacell family PMI foams, as these had held back polymer foam cores in mass production. Metal inserts can be integrated in the foam during the IMF process.

Bernhard pointed out that although PMI is not a thermoplastic, it can be thermoformed. High load-bearing resistance at temperatures up to 180°C enables Triple F use in fast high-pressure resin transfer moulding (HP-RTM), while other particle foams are limited to 130-160°C, Bernhard stated. He said Triple F has been commercialised by Evonik’s joint venture LiteCon Advanced Composite Products in H?nigsberg, Austria, established in September 2015, and used already in serial production by renowned German vehicle producers.

Isola took third place for developing laminates using a benzoxazine epoxide resin polymer matrix in the €4.6m Help project for high temperature circuit boards. Partners in the 2011-2014 project included: epoxide resin producer Huntsman (with an Araldite LZ 8278 N90/Aradur HZ 8279 Z50 resin system), Bayreuth University, Fraunhofer IZM institute for reliability and micro-integration, and solder resist producer Lackwerke Peters. While circuit board producers Schweizer Electronic, Hofmann Leiterplatten, Linner Elektronik and Lüber Elektronik were also partners, circuit board user interests were represented by Bosch, Continental, Daimler, Siemens and the ECPE high performance electronics cluster.

Isola development manager Sascha Kreuer told the jury the Help project addressed increasing temperatures in high performance electronics with an epoxide resin based laminate, enabling direct bonded copper (DBC) ceramic circuit board substrate replacement at much lower cost.

Kreuer added that glass fibre fabric reinforced benzoxazine epoxide resin laminates are around 10% less expensive than conventional FR4-category epoxide laminates. With 60 minutes glass transition temperature (Tg) up from 175°C to 288°C with the new resin, the laminates achieve 175°C continuous use temperature and can withstand short-term exposure to 200°C.

It is interesting to note that, as a result of electronics miniaturisation and a shift of electronics production to Asia (accounting for 80% of circuit board sales value), Isola and Panasonic in Austria are believed to be the last two copper clad “laminators” left in Europe. This compares with 23 European laminators in 1990, who were serving around 1,000 European circuit board producers. Today there are around 400 European circuit board producers in Europe and 2,500 worldwide. However, Isola sees potential in Europe for its new high temperature FR4 copper clad laminates in newer areas of automotive electrical mobility, such as LED lighting circuits, and solar panels.

Crash beam

Help project partner Schweizer has developed p2 Pack circuitry with chips embedded in the laminate substrate for compact high performance inverter, power steering and direct wheel drive circuitry. It says p2 Pack is “merging the system border between circuit boards and semiconductors” and more efficiently conducts away heat developed by chips. Its Combi board combines logic and power functions with fine line and thick copper tracks on one board.

Working with Continental (Conti Temic Microelectronic) in the Hi-Level project, Schweizer has developed a 50kW demonstrator p2 Pack circuit for automotive hybrid drives, bearing in mind also future 48v systems replacing 12v ones. Its i2 Board circuits include sensor functions.

Automotive OEM Hyundai received first prize in the processing category for a front bumper crash beam in a new reactive thermoplastic curved (“radius”) pultrusion process. This involves in situ polymerisation to a polyamide 6 matrix of monomer components after impregnation of glass fibre fabric and unidirectional fibre rovings. The rovings consist of carbon (24%) and glass fibres (59%), or just glass fibres (83%), and the process is completed by thermoplastic injection overmoulding functionalisation.

This highly integrated solution was developed between September 2012 and May 2015 as a ?2m project with plastics producer Arkema as supplier of the monomer materials, French pultrusion processor CQFD and automotive plastic parts supplier Plastic Omnium.

Compared with a conventional steel crash beam weighing 8.7kg, the curved pultruded beam cuts weight by 3.3kg to 5.4kg with 24% CF content or by 3.1kg to 5.6kg in a glass fibre only version, according to Stephane Ringenbach, head of the composites group at Hyundai Motor technical centre in Rüsselsheim, Germany. He said the new part has been mounted on a Hyundai i30 demonstration car, replacing 27 steel parts and a 2.1m long steel welding length.

Second place went to Hilger & Kern for automatic recognition of leakage in vacuum film used in fibre reinforced composite production. Third place was shared by Evonik for its PulPress process for large scale production of complex fibre reinforced composites, and by Porsche and Munich Technical University for functionalisation by injection moulding of hollow reinforced thermoplastic composite profiles.

Evonik’s PulPress sandwich pultrusion process was developed together with Secar Technologies of Mürzzuschlag, Austria as a combination of pultrusion and compression moulding. Rohacell polymethacrylimide (PMI) foam sheets or profiles are combined as a supporting structure core with unidirectional fibres in a braiding unit prior to resin injection into the resulting braided fabric, and compression moulding in a movable press system fulfilling the pultrusion role.

Following project start-up in 2013, a research and pilot line was set up in Mürzzuschlag in 2014. Secar Technologies started continuous PulPress profile production there in 2015 at a rate of up to more than 30 profiles/hour and length up to 0.5m, with greater complexity than is possible with conventional pultrusion. Evonik says PulPress can save as much as 75% weight and cuts costs by 30-60% compared with conventional processes such as RTM. The company displayed an ultra lightweight bumper crossbeam in the product demonstration area at Composites Europe 2015 in September, made as a hybrid part in metal with a PulPress FRP sandwich profile.

PulForm process

The Fraunhofer ICT chemical technology institute’s FIL research group for innovative lightweight construction in Augsburg presented another new braided fabric variation on pultrusion at Composites Europe 2015 – a fully automatic PulForm process combining pultrusion with blow moulding. The part displayed involved a CFRP profile with a round section at one end and a square section at the other end.

A particular PulForm process feature is injected resin impregnation replacing a conventional pultrusion resin impregnation tank. Heating the pultrusion tool to 100°C results in partial resin cure, preventing fibre displacement. The flexible “rubber-like” preform obtained is then placed in a metal mould, where it is blown to final shape and fully cured at over 100°C.

In a process developed by Munich Technical University, a Porsche Boxer car composite battery tray demonstrator substitutes a multiple-part welded metal tray. The number of parts is reduced from six to three, 1kg (30%) weight is saved, while there is a moderate lightweighting cost premium below €10/kg. A metal bracket is no longer used in the plastic composite design.

The composite tray consists of a long glass fibre reinforced PA6/PA66 thermoplastic platform, a hollow profile in braided continuous hybrid glass/PA6 fibre yarn, and a short cast aluminium fixing console on both sides. The profile is formed under blown air pressure from a hose while the PA6 fibre melts and cools to form a rigid profile, which is then filled with a fluid or particle foam supportive medium to withstand injection overmoulding pressure of functional features.

Flow and mould filling simulation studies were based on placing knit line locations away from points of high mechanical load. The FRP composite tray retained the battery without itself showing external signs of damage when submitted to front, side and rear impact tests with acceleration peaks starting at 20g and reaching 36g for the most critical front impact.

The LCC carbon composites chair at Munich Technical University achieved first place in the research and science category for a hybrid resin matrix shape-adapting side crash absorber. This involves a rigid conventional epoxide resin based FRP composite combined with a flexible low viscosity polyurethane elastomer matrix one. The latter changes its shape by pyrotechnic activation pressure under crash conditions.

The LCC work and Evonik’s development of the PulPress process were both part of the EU’s Matisse project for development of FRP adaptive crash structures and high-pressure storage tanks in alternatively powered vehicles (APVs).

Bio developments

Second place went to the plastics technology and macro-molecular chemistry laboratory at Münster University for work on intrinsically anti-microbial thermosetting plastics and composites. This involved synthesis from vinylbenzylchloride and tertiary butyl amine into a new tertiary butyl amino methyl styrene (TBAMS) monomer and polymerisation of TBAMS into a new intrinsically anti-microbial amorphous poly-TBAMS thermoplastic polymer. As of June 2015, the laboratory’s TBAMS monomer pilot line production capacity was 5l per week.

Tertiary butyl-amino groups on the poly-TBAMS surface cause electrostatic interactions with micro-organisms, while higher organisms are unaffected. The university’s researcher Bj?rn Fischer told the jury there are poly-TBAMS downsides in thermosetting resins: plasticising action leading to lower glass transition temperature, reduced organic solvent resistance and partial solubility in water. But he has also used TBAMS monomer as a “reactivity thinner” in thermosetting polyester resins, resulting in higher heat resistance, less creep, better chemical resistance, lower moisture and water absorption than with the poly-TBAMS polymer – along with anti-microbial behaviour.

The ECEMP European centre for emerging materials and processes at Dresden Technical University received third prize for development of Biohybrid bio-based lightweight hybrid structures. These use natural fibre reinforced biobased thermoplastic cellulose ester for unidirectional and fabric reinforced Biosheet organic sheet preforms for compression moulding structural composite parts, and also for Biocomp compound for injection overmoulding functionalisation.

Among additive solutions adopted was biobased citric acid ester as a plasticizer and flow enhancement additive for the polymer matrix. The use of chemical adhesion promoter on the fibres was avoided by adjustment of cellulose ester polarity. ECEMP has produced a bicycle baggage carrier demonstrator weighing 300g, compared with 780-800g in conventional metal design.

Although the submission made by Fraunhofer ICT’s NAS new drive systems institute for development work on a plastic car engine did not get into the 2015 AVK award finalists’ list, it is nevertheless interesting. ICT is working with materials supplier Sumitomo High Performance Polymers (SBHPP) on a phenolic resin based version of the Polimotor car engine, based on a BMW Rotax 650 motorcycle engine.

A plastic engine has been the dream of Matti Holtzberg in the US since 1969, leading to his forming Polimotor Research in 1970 and developing a 2.3-litre Ford Pinto demonstration engine in polyamidamide (PAI), from Amoco at that time. The engine weighed 69.4kg compared with 188.2kg for the original metal one, despite metal cylinder linings, combustion chambers, piston tips, valves and valve seats.

Having founded Composite Castings in 1990, Holtzberg’s patents included glass fibre reinforced phenolic and epoxide resin composite engines. This led to partnership with carbon fibre producer Toho Tenax Americas and IDI Composites International in 2010 to develop a Polimotor 2 engine in epoxide resin based CFRP. But Fraunhofer ICT and SBHPP are working with both phenolic and epoxide based 50% reinforced GFRP for their Polimotor 2 version. SBHPP refers to 20% weight saving and 10% lower production cost for 30,000 engines/year.

Meanwhile, Solvay announced in May 2015 that it is working on PAI (therefore carrying on with PAI where Amoco left off), as well as its other high performance thermoplastics, in development work on Polimotor 2 (see Plastics News Europe, October 2015). So, as in the past with Polimotor 1, both thermoplastics and thermosetting plastics are now again under investigation for Polimotor 2.