Composites '97.

There's some really big news in glass reinforcements, a cheaper way to get rid of styrene fumes, and signs of life in FRP recycling.

It's not every day that composites fabricators get to try out a brand-new fiberglass composition that could become the workhorse standard of the next decade. It's also not often that SMC formulators hear of an entirely new way to reinforce their product and save trouble and money without sacrificing performance. Nevertheless, these are two of the most unusual developments that marked this year's annual SPI Composites Institute conference and expo in Nashville, Tenn. Although packed with news of all sorts, the meeting focused particularly on three themes:

1 New glass reinforcements - Added to the two most dramatic introductions were several other new rovings and fabrics and some particularly intriguing new capabilities in braiding. Swelling interest in braided and knitted engineered fabrics, stimulated partly by composites' penetration in more demanding structural applications, was evident in many of this year's parts exhibits.

2 Infrastructure - Vast new market potential in roads, bridges, and other infrastructure applications accounted for more conference papers than any other topic and for several of the most eye-catching parts exhibits. One of them, a novel honeycomb bridge structure, captured SPI's Grand Design Award (see sidebar).

3 Environmental issues - New state and federal regulations on VOC emissions could prove costly and cumbersome to FRP fabricators. This year's expo was the first to host four exhibitors of styrene-abatement equipment, one of them showing a new approach that offers welcome advances in simplicity and economy. Another environmental theme in Nashville was composites recycling. The meeting showed rumors of its death to be clearly premature.

This report contains other news from the show in resins, additives, adhesives, in-mold coatings, and more. For reasons of space, equipment developments will be covered in a separate report next month. News already covered in our conference preview (PT, Jan. '97, p. 19) won't be repeated here.

NO GLASS LIKE NEW GLASS

Both Owens Corning and PPG Industries announced dramatically new developments in glass reinforcements. Owens Corning has invented a new glass formulation that company officials think could eventually replace E-glass as the industry standard. Called Advantex, it has mechanical and electrical properties virtually identical to those of E-glass, combined with acid corrosion resistance comparable to E-CR glass (see left). Not only does Advantex cost the same as E-glass, it can replace premium-priced E-CR glass at lower cost.

Owens Corning has already converted 10% of its global capacity to Advantex, including its entire plant at Guelph, Ont., and is phasing it in elsewhere. The company currently offers Advantex gun rovings and chopped-strand mat. The new fiber reportedly has been approved by customers for use in pipe, tanks, hand lay-up, boats, trucks, and vans.

The other big announcement in reinforcements was PPG's introduction of MatVantage SMC, a needled glass mat intended to replace chopped roving in SMC. It eliminates the need for large roving creel areas, tubing to transport roving strands to the long-blade chopper, and the chopping operation itself. Also gone are fuzz and fly problems, strand entanglement, and chopper cost and maintenance, PPG says. The mat also reportedly eliminates machine-direction SMC weight variation and reduces transverse variation. There won't be any cost penalty for these advantages because PPG intends to the mat competitively with roving.

Instead, MatVantage SMC reportedly saves money because its square edge greatly reduces edge-trim scrap. Also, the z-direction needled reinforcement reportedly reduces scrap and rework because of fewer blisters. At the same time mold flow is not reduced, PPG claims. The product will be available soon for customer sampling in both rolls and festooned boxes.

BOLD NEW BRAIDS

Striking advances in braided fabrics were announced by A&P Technology (formerly part of Atkins & Pearce, Inc.). Now the firm can braid up to 800 yarns at a time - up from 600 a year ago - in order to produce large tubular fabrics that can be slit into continuous broad goods up to 48 in. wide. Braid is thus no longer restricted to narrow fabrics, say company spokesmen.

Something else quite new is the ability to concentrate different fibers on opposite sides of a braided fabric, A&P claims. An example is its Crimpex product, a crimpless, tubular preform that was developed to make self-lubricating tubular bearings that have glass on the outside and PTFE fibers on the inside.

Connex, another new type of tubular braid from A&P, has a raised helical rib around the outside. It can be tailored to provide net-shape composite bolts that have stronger threads than those produced by machining a smooth tube.

Also new from A&P is Unimax, a "unidirectional" braid that has a triaxial structure with elastic bias yarns as a small percentage of the total braid weight. The result is an axial reinforcing sleeve that can fit snugly around tapered, curved, or irregular shapes while distributing the axial reinforcements uniformly around the part.

Another novel capability is production of prepregged braids. These are produced by Thiokol Corp. from A&P braids using Thiokol's special ambient-storable epoxy that does not require refrigeration.

MORE NEW FIBERS & FABRICS

There was plenty of other news in rovings and fabrics at the show:

* PPG's Type 7810 roving is designed for continuous laminating of opaque panels. It reportedly has minimal catenary, fuzz, and static build-up during chopping. The glass bundles break up completely, giving a flat, smooth panel, PPG says.

* Also new from PPG is Hybon 6100 roving for general-purpose polyester spray-up. The new chrome-free silane finish reportedly reduces fuzz while providing faster wet-through, which reduces time and effort in roll-out.

* PPG has begun production of Hybon direct-draw pultrusion rovings in yields of 52, 56, and 62 yd/lb. Direct-draw or single-end rovings in heavy yields have previously been unavailable, PPG says, but they are easier to process than multi-end types because the ends are less likely to break or separate. Heavier-yield rovings also allow processors to make larger pultruded parts without adding creel space.

* Gaftex 105 single-end roving for pultrusion from GAF has a yield of 113 yd/lb and exceptionally fast wet-out with most resins, the company says.

* Owens Corning introduced Cratec 163D and 152A chopped strands for BMC, epoxy, and phenolic molding compounds. The 152A products reportedly show enhanced solubility, while 163D versions are said to give lower solubility and higher impact strength in injection molded parts.

* New 150-in.-wide glass fabric from CollinsCraft Composites allows production of panels, bridge decking, and other larger parts with fewer seams and less fabrication time.

* Double-bias stitch-bonded fabric from Fiber Glass Industries consists of [+ or -]45 [degrees] cloth plus mat.

* Heavyweight (250 oz/sq yd) quadraxial knitted glass fabric has been developed by Brunswick Technologies for infrastructure applications.

* Two polyester surfacing veils from Freudenburg Nonwovens include T1794C for filament winding and press molding, which weighs 70 g/[m.sup.2], and T1731 for pultrusion, which weighs 30 g/[m.sup.2]. New T1702P C-glass veil (30 g/[m.sup.2]) is used for pultrusion and press molding with printed designs.

* Nylon and polyester spunbonded fabrics are said to be useful to help tack together layers of reinforcements in preforms. Spunlab adhesive fabrics from Dry Adhesive Technologies were designed for textile bonding but have been introduced to composites fabricators in the past year. They melt at 200-260 F.

UV LIGHT ZAPS STYRENE FUMES

An important topic at this year's SPI meeting was new state and federal environmental initiatives that will impose greater burdens on composites fabricators to control volatile organic compound (voc) emissions such as styrene vapors. The growing importance of this issue was evident at the SPI Composites Expo, where exhibitors of VOC-abatement equipment were a more noticeable presence than ever in the past.

Although a variety of incineration and bio-digester systems are available to consume styrene fumes, they can cost well into six figures to install and may have significant operating costs as well. The good news at Nashville was that there may be a much simpler and less expensive solution.

The new Wega photo-oxidation system from VVK Weege of North America uses a combination of uv lamps and ozone generators to break down a wide variety of organic vapors into carbon dioxide, water, and oxygen. A catalytic converter turns any leftover ozone back into oxygen before it leaves the system. The device is very simple: It is basically a sheet-metal box through which air passes to be cleaned. Its size is comparable to a small car. It has no moving parts except a blower, and requires only electric power. Air is said to leave the system 99% clean. The smallest system handles 3000 [m.sup.3]/hr of air with a pollutant concentration of 200 mg/[m.sup.3]. It costs under $100,000.

Developed in Germany, the Wega system has been used for a little over a year. There are 23 installations in Europe - two in composites fabrication-but none yet in the U.S. VVK Weege has a mobile demonstration system on a trailer that can be driven up to your plant and connected to an air-vent outlet.

At present, the major proven approach to eliminating VOCs from plant air is incineration. Its drawbacks are the need to move large amounts of air and consume substantial amounts of natural gas. One supplier of incineration systems is United McGill Corp. Its ThermaGrid regenerative thermal oxidizer can be tested at your plant by means of a trailer-mounted system. The company has no installations yet in composites.

What's said to be a more efficient incineration option concentrates the pollutants into a smaller volume of air and then oxidizes them. One type uses a catalytic oxidizer that reportedly can generate enough energy to power the system without additional fuel.

Weatherly Inc. offers the Polyad system, which has been used at two European composites plants for more than three years. The first U.S. installation is at FRP bathtub producer American Standard Inc. in Salem, Ohio. About a year ago, the firm installed a Polyad system to clean the air from a four-station spray-up booth, a second smaller spray booth, and a mixing station.

A total of 35,000 cfm of air laden with 25-50 ppm styrene is directed to a fluidized bed where a polymer adsorbent removes styrene and clean air is exhausted to the atmosphere. The adsorbent is conveyed to a desorbing section, where hot air liberates the styrene. The clean adsorbent is then returned to the adsorber, while a stream of air in which styrene has been concentrated 20-fold flows from the desorber to a catalytic oxidizer. Energy released in the oxidizer is said to be sufficient to maintain the catalyst at its operating temperature and to provide hot air for the desorption section. Heating with natural gas is needed primarily at start-up.

Weatherly cites a typical installed cost of $20-30/cfm. The roof-mounted system at American Standard includes two adsorbers, one desorber, and one oxidizer. It took a month to install and occupies 59 x 35 x 20 ft. Although Weatherly aimed for 95% styrene removal, the presence of silicon, phosphorus, sulfur, and chlorine compounds in the plant air poisoned the catalyst, adding to maintenance costs and reducing system effectiveness. Weatherly hopes to overcome this hurdle - possibly by switching from catalytic to thermal incineration, though this would add 10-15% to operating costs.

Another adsorption/desorption system concentrates styrene-laden air ten-fold before feeding it to a thermal oxidizer (incinerator). The HTO system from Durr Environmental comes in pre-engineered packages designed to handle from 4000 to 30,000 cfm. Typical cost is said to be $10-25/cfm. These systems are commonly used in auto plants to incinerate paint fumes. One U.S. customer has bought a system for styrene removal but it is not yet installed.

SMC RECYCLING SURVIVES

Efforts to encourage composites recycling continue despite last year's demise of the first North American SMC recycler, Phoenix Fibreglass Inc., Oakville, Ont. Filler supplier R.J. Marshall Co. acquired grinding equipment from the defunct Phoenix operation and is now offering its own reground SMC filler.

Marshall's FBG 200 filler is said to be a close equivalent to Phoenix's PHX 200, although Marshall's product contains glass as well as filler and resin. (Phoenix separated out the glass.) Nonetheless, the density of FBG 200 is the same as or even less than PHX 200. The resin demand is also lower, which could be advantageous in compounding. Tests comparing the new and old filler indicate equivalent thickening performance and similar mechanical properties.

Marshall sells FBG 200 for slightly more per pound than calcium carbonate, which it partly replaces in the SMC compound. But the price is the same per cubic inch, since the density of FBG 200 is 25% lower.

Marshall has one new success story in composites recycling, though it involves BMC, not SMC. In the last few months, V-6 engines on 17 General Motors car lines have begun using polyester BMC valve covers that contain 5-6% reground manufacturing scrap from compression molding of the same parts. This "closed-loop" recycling application was developed by Cytec Industries, which supplies the regrind-containing Cyglas 685 BMC to the molder, Skrl Die Casting, Inc., Eastlake, Ohio. This application could use at least 100,000 lb of regrind this year.

Marshall has also teamed up with Seawolf Industries in a joint venture called Sea-Mar. This venture is licensing patented technology and selling equipment developed by Seawolf for using FRP regrind as a sprayable core material in boats and other products. Sea-Mar offers proprietary grinders that can consume even FRP/acrylic tub and spa scrap. Also available is a cart-mounted spray-up system with a 110-gal low-shear mixer. Sea-Mar says its technology maintains sufficient glass-fiber length to provide reinforcement, not just a filler.

At the show, Marshall displayed a test boat made in Sweden by OMC Rydes using Seawolf technology. The usual deck and hull core materials were replaced by a sprayed core containing 33-40% ground SMC and FRP spray-up scrap, for a total regrind content of 25-30%.

Ongoing tests show that equal bending strength is achieved when the scrap-containing core replaces 50% by weight of the standard laminate. The scrap-containing laminate will then be 15% thicker because of its lower density. Replacing marine plywood cores with an equal thickness of the scrap mix doubles the bending strength of the laminate and increases the screw-holding strength.

RELATED ARTICLE: Honeycomb Holds Up Traffic

This year's winner of SPI's Grand Design Award is a 23-ft-long, 24,000-lb highway bridge over No-Name Creek in Russell County, Kans. The bridge showcases an unusual corrugated or "honeycomb" composite core and an equally unusual manufacturing process. John B. Kunz, v.p. of production for Kansas Structural Composites Inc. in Russell, Kans., calls the proprietary method "continuous-flow contact molding." It uses low heat to continuously laminate a 36-in.-wide web of polyester and chopped-strand glass mat. The webs are 45-50% resin and 0.1 in. thick, though the process is capable of 0.025 to 0.250 in., Kunz says.

Kunz will not describe the method in detail, though he says his firm would consider licensing it to others. He says the core web for this bridge is actually two webs - one flat and the other corrugated in a sine-wave shape - that come out of the machine bonded together and fully cured. The web is slit in two longitudinally with a saw, and the two halves are bonded together to make the core sandwich.

The core is sealed with flat skins made from unidirectional and bidirectional nonwoven fabrics. The bridge deck consists of 0.75 in. of polyester concrete.

RELATED ARTICLE: Automated Preforming Gets Test Run For SRIM Pickup-Truck Box

After at least five years of development, Owens Corning has sold its first P-4 automated preforming system to the Automotive Composites Consortium, Troy, Mich. This joint venture of Detroit's Big Three auto makers will use the Programmable Powdered Preform Process in a semi-commercial project to mold a prototype SRIM pickup-truck box. The project is partly funded by government R&D grants. The system will be set up this summer in a hangar at Wright-Patterson Air Force Base in Kettering, Ohio. First production parts are expected by September.

The only P-4 system ever yet built is a lab version at Owens Corning's Technical Support Center in Battice, Belgium (PT, Dec. '95, p. 23). Owens Corning is working with machine builder Aplicator AB of Sweden, which is supplying the glass-delivery system and is acting as the systems integrator. Overall cost is estimated at $1-2 million.

The system consists of glass-delivery robots, a heating/cooling system, and a mold carrier. The robots deposit a surface veil of roving, then chop and orient the fiber lengths, and combine them with powdered binder, as well as placing continuous fibers. The mold carrier moves into the press, where hot air is used to melt the binder, followed by cold air that cools the preform. The system is designed to produce a net-shape preform every 4 min with only about 3% waste.

RELATED ARTICLE: New Resins, Additives, Adhesives, Coatings

An experimental epoxy system from Shell Chemical Co. reportedly combines low viscosity and low curing temperature with high tensile strength and elongation. Research Resin RSL-2704 (a bis-A epoxy) and Research Curing Agent RSC-2705 (non-MDA polyamine) are designed for RTM or vacuum-bag molding of large parts. The resin has a viscosity of 350 cp at room temperature, cures at 160 F, and has a tensile elongation of 7-8%.

A flame-retardant polyester from Alpha/Owens Coming is a corrosion-resistant bisphenol-A grade. K299FR is for filament winding and hand lay-up. With addition of 3-5% antimony oxide, it reportedly can achieve a Class I flame-spread rating of 10-15. Even without antimony, the resin can achieve a Class II flame spread of 45, says AOC. Elongation of a cast sample is 3.6% and HDT is 230 F at 264 psi. AOC is also developing a general-purpose FR polyester and an FR epoxy vinyl ester.

E-8000 resins for structural SMC are polyester/vinyl ester hybrids from AOC that reportedly have the strength and heat resistance of vinyl esters but thicken easily and consistently just like polyesters. They contain a TP polyester low-profile additive. Castings have elongation of 2.87% and HDT of 251 F at 264 psi.

New vinyl esters are the first from McWhorter Technologies. The Verimac family includes grades of high, medium, and low molecular weight, as well as promoted, unpromoted, thixotropic, and non-thixotropic versions. A developmental brominated grade reportedly achieves Class I flame spread of less than 25 with 3% antimony oxide. Another grade has low styrene emission, and still another is for use as a barrier or bonding coat in sprayed-up spas, pools, and boat hulls. Developmental Verimac 157-0584 is a highly crosslinked resin for pultrusion and hot-press molding. It reportedly resists acids, bases, and many aggressive organic solvents and retains its mechanical properties at 280 F.

Phthalate-free MEKP initiators reportedly emit less VOCs than standard products. Akzo Nobel Chemicals has converted its Cadox L-50 and Cadox M-50 to a less-volatile ester carrier. A newer non-phthalate product is Cadox D-5O, a low-hydrogen-peroxide, high-monomer product that reportedly reduces gel coat porosity and provides improved curing of vinyl esters. (It's reportedly equivalent to Lupersol DDM-9 from Elf Atochem.)

Peroxides for elevated-temperature cures include Trigonox 117 from Akzo Nobel, a medium-reactivity per-oxycarbonate for SMC, BMC, and pultrusion. It's said to be very stable to pigments and additives, and activates at 220-285 F. It's equivalent to Lupersol TBEC from Elf Atochem. New to the U.S. market is Trigonox D-C50, a peroxyketal that cures like t-butyl perbenzoate while providing longer shelf life in SMC. Meanwhile, Akzo Nobel is re-introducing to the U.S. its Trigonox 127 t-amyl perbenzoate.

Internal lubricants from Axel Plastics include Mold-Wiz #INT-XL51 for gel coats. Used at only 0.5%, it's said to reduce porosity and improve mold release without affecting bonding. This liquid also reduces gelcoat viscosity, improving surface wet-out and air release. Also new is Mold Wiz #INT-PS125GL, a gel version of INT-PS125 liquid internal lubricant for pultrusion. Whenever you have to halt the line, you can brush the gel onto the dry fibers in order to prevent die lock-up.

Inorganic hollow microspheres from The PQ Corp. include new QCel 7019, 7023, and 5043, whose low alkali and moisture content reportedly provide better stability in polyester resins for putty and spray-up. Also new is Extendosphere SL-90, a 90-micron, white ceramic sphere with a crush strength of 4000 psi. Two developmental hollow acrylonitrile microspheres have densities of 0.022 g/cc.

Water-based, semi-permanent mold releases from Franklynn Industries are non-wax systems said to reduce build-up on tools and to be non-transferring. The new system consists of Diamondkote W-3429 sealer and Diamondkote W-224 basecoat.

A methacrylate adhesive from ITW Plexus reportedly bonds nearly all types of FRP resins and gelcoats with no surface preparation. Plexus AO425 provides a bond strength of about 1800 psi and elongation at break exceeding 100%.

Weatherable in-mold coatings that act as one-shot primers and topcoats were introduced by GenCorp Specialty Polymers. They include a one-component clear coat and color coats designed to be mixed with GenCorp's pigment dispersions. Both systems are said to exhibit outstanding uv resistance when compared to gelcoats and to be very comparable to paints.

Non-hazardous, non-regulated resin cleaners for thermosets are offered by Cook Composites and Polymers. Mc/Cleaner 095-0047 is a glycol-ether-based cleaner that provides quick waste separation, is reducible with up to two parts water, and can be used at room temperature or heated for maximum cleaning. Aquawash FS 095-0046 is a water-based emulsifier that can be diluted with up to 120 parts water.