New fibers and spheres introduced at SPI conference in Dallas.

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New Fibers and Spheres Introduced At SPI Conference in Dallas

A number of new fiber reinforcements for thermoplastics and thermosets, as well as some new organic and inorganic microsphere fillers were among the numerous product introductions announced at the recent 44th annual SPI Composites Institute conference held in Dallas in February. Here's a quick rundown of the news.

NOVEL GLASS FIBERS IN R&D

Charles H. Dana, president of the newly formed Industrial Materials Group of Owens-Corning Fiberglas Corp., Toledo, provided a glimpse ahead at some novel glass-fiber reinforcements in R&D at the company's Granville, Ohio, Technical Center:

* Lobed glass fiber - A proprietary fiber-forming process created by OCF produces non-round fibers with two or three lobes, which may offer substantial improvements in stiffness and tensile strength.

* Hollow glass fiber - This other unusual fiber form is expected to have mechanical properties comparable to ordinary glass, but at about one-third less weight.

* Ultra-high-strength glass - It's expected to fill a niche between OCF's S-2 glass and quartz fiber. Strength and dielectric properties are said to be comparable to quartz, but at lower cost. Structural applications in aerospace and defense are the targets.

* Low-dielectric textile reinforcements - Printed circuit boards may eventually benefit from new glass compositions giving substantially lower dielectric properties and lower thermal expansion.

NEW FOR THERMOPLASTICS

Meanwhile, OCF plans to make commercially available in this quarter three new E-glass reinforcements for thermoplastics. One is 193A roving, an E-glass product that employs a high-temperature sizing similar to that used on OCF's S-2 glass, making it compatible with high-temperature thermoplastics such as PEEK, PEK, PPS and polyetherimide (PEI). The sizing withstands processing at up to 780 F, compared with a standard glass fiber processing range of about 350 F. OCF 193A is aimed at military and aerospace uses, in filament winding and pultrusion, or chopped for long-fiber composites. (CIRCLE 107)

OCF's second new reinforcement is 145A roving for high-strength, long-fiber thermoplastic molding compounds. It has a sizing compatible with nylon, polycarbonate and TP polyesters. A company official says one aerospace firm is field testing the 145A reinforcement for composite armor, while other firms have tested it in power-tool housings, fuse holders and safety shoes. (CIRCLE 108)

Cratec chopped-strand reinforcement is the third product introduced in Dallas by Owens-Corning. Proprietary technology is said to give it enhanced flow and durability in nylon, polyethylene, PP, PVC and PBT (CIRCLE 109).

Manville Corp., Toledo, is also introducing new glass reinforcements for thermoplastics, including two new chopped-strand products in its Star Stran 700 series. Star Stran 730 has applications in both thermosets and thermoplastics, while Star Stran 761W is for nylon copolymers and PET. Manville also will unveil and test market an experimental chopped-strand product known as Star Stran R26-1, a reinforcement for PBT resin with applications in the electrical and automotive industries. (CIRCLE 110)

Manville also recently signed a technology licensing agreement with Nippon Electric Glass (NEG) of Japan for production of chopped-strand glass reinforcements for thermoplastics, with a focus on automotive applications. Gary N. Bolen, reinforcements segment manager for Manville's Mats, Fiber & Reinforcements Div., said Manville will use NEG's technology both to expand capacity this year at its Waterville, Ohio, facility and at a planned $80-million plant at an as yet unspecified location.

It's expected that new products from the agreement will begin to emerge next year. Bolen said that an important thrust in the agreement will be to supply Japanese "transplant" auto makers in North America.

FIBERS FOR THERMOSETS

Manville has introduced a new 615A roving for pigmented and structural sheet molding compound (SMC). It's being used by several molders of laundry tubs and shower basins. (CIRCLE 111)

Manville also is introducing Star Rov 502 and 503 single-end rovings, and Star Rov 502U multi-end roving. These three reinforcements will have applications in filament winding, pultrusion, knitting and weaving. (CIRCLE 112)

And new from OCF is 357 gun roving for spray-up of marine components and shower tubs. (CIRCLE 113)

Three new glass rovings for epoxy filament winding and pultrusion have been introduced by PPG Industries Inc., Pittsburgh. Hybon 2001 and 2006 roving utilizes a new binder designed for improved wet-out capabilities with epoxy resins, while Hybon 2002 was developed to improve dry-handling properties. (CIRCLE 114)

Late last year, Certain Teed Corp., Valley Forge, Pa., introduced its 23R roving to selected automotive SMC customers for field testing. It's now in full commercial production and replaces Certain Teed's 235 roving. Faster wet-out is said to be a main feature. (CIRCLE 115)

Certain Teed is also developing a new pre-formable mat specifically for pultrusion and electrical applications. (The company already offers Unifilo preformable mat for RTM and SRIM uses.) Technical details on the product were unavailable, as was a target date for its commercial availability. (CIRCLE 116)

Other news in fabric reinforcements includes a product called Texweave from Fiber Glass Industries, Inc., Amsterdam, N.Y. It consists of woven roving with FGI's Texstrand air-texturized bulked roving in the fill direction. The free fiber loops on the surface of the material enhance its ability to bond to adjacent layers in a laminate, reportedly producing increased interlaminar shear strength and exceptional impact resistance. (CIRCLE 117)

A new line of nonwoven, unidirectional fabrics and tapes of glass, carbon and aramid fibers has entered production at Anchor Reinforcements, Inc., Santa Fe Springs, Calif. Trade-named Ancaref, these fabrics are aimed at tooling and high-performance composites such as racing yacht hulls, sports equipment, and structural components for aircraft and automobiles. A thermoplastic binder allows them to be preformed and bonded under heat and pressure for use in RTM. The binder reportedly also allows the fabrics to be trimmed or slit without fraying.

Anchor Reinforcements is a subsidiary of Anchor Chemical, which was acquired by Air Products & Chemicals early last year. It is producing reinforcements for sale throughout North America under license from Heinsco, a U.K. manufacturer of nonwoven reinforcements and prepreg materials. Ancaref-type materials have already achieved some acceptance in Europe. (CIRCLE 118)

CERAMIC FIBERS PROGRESS

Latest word from the Fibers Div. of Carborundum Co., Niagara Falls, N.Y. (previously known as Standard Oil Engineered Materials Co.), is that its Fiberfrax ceramic fiber will probably achieve its first thermoplastic and epoxy reinforcing applications in the next year or so. (Certain grades are already being used as reinforcements in phenolic molding compounds and as a "reinforcing thixotrope" in epoxies.) When properly compounded with high-shear mixing equipment, Fiberfrax reportedly has been demonstrated to give approximately equivalent properties as an equal loading of chopped glass in epoxies. Furthermore, Fiberfrax reportedly yields far superior strength and modulus retention than glass after boiling epoxy samples in water for 48 hr, owing to the ceramic fiber's better corrosion resistance.

Performance of Fiberfrax composites reportedly is also better than with glass at elevated temperatures (e.g., 250-300 F).

Product engineer Margery J. Wirtner expects to see Fiberfrax HSAR grade (1 micron diam.) used in high-performance thermoplastics, where the ceramic fiber reportedly is competitive with chopped fibeglass, Kevlar aramid fiber, and other discontinuous- and short-fiber reinforcements in wear resistance, but at a lower price of $3-4/lb. New, larger diameter fiber grades with reduced levels of particulate content are being developed and are said to look promising in epoxies. Designated EF113 (6-10 micron diam.) and EF121 (2 micron diam.), they're expected to sell for $1.00-1.50/lb. Larger fibers are intended to reduce entanglement during mixing and thereby increase dispersion. (CIRCLE 119)

`NEW' CELLULOSE FIBERS

As if to prove the saying that "what's old is new again," a line of cellulose fibers is being introduced as partial replacements for chopped fiberglass in unsaturated polyester molding compounds by Custom Fibers International, Valencia, Calif. Paul W. Tillisch, managing director, said the CF Fiber product line is capable of reducing chopped glass in bulk- or sheet-molding compound components by as much as 50%, while retaining all of the necessary physical reinforcement properties of the glass and reducing cost.

Because of its ability to fill in voids between the resin and glass, overall reinforcement dispersion is said to be improved. Furthermore, impact strength may be improved and density reduced. Levels of thickener reportedly may also be reduced.

The accompanying table shows data from a report by MFG Research Co., Ashtabula, Ohio. They show partial replacement of glass fiber in polyester BMC with no loss, and sometimes improvement, of physical properties. MFG polymer engineer Greg Quirk concluded that the maximum substitution was 50% by volume. "In a 1000-lb BMC mix, this would mean that you could replace 60 lb of glass with approximately 40 lb of cellulose, a savings of approximately $35-40 per batch," he said. [Tabular data omitted]

CF Fibers are offered in five grades from 0.27 mm to 1.26 mm or more. Gray grades cost 20-30[cents]/lb and white ones 30-40[cents]/lb. Tillisch said the first commercial SMC application for CF Fibers involves an unnamed domestic shower-stall manufacturer. (CIRCLE 120)

HOLLOW MICROSPHERES

A hollow glass microsphere designed to withstand thermoplastic injection and compression molding pressures has been introduced by Potters Industries Inc., Parsippany, N.J., an affiliate of PQ Corp.

Sphericel 110P8 is an 8-micron glass sphere product. Harold A. Arbit, market development manager for polymer additives, said Sphericel was designed to provide improved melt flow and dimensional stability for thermoplastic parts in aerospace, automotive and marine applications. Arbit said that besides significant weight savings, Sphericel can offer savings in amount of pigments needed, because of the whitening effect it has in most resins. (CIRCLE 121)

"Ultralight" microspheres were introduced by PQ Corp., Valley Forge, Pa. They have an effective density of 0.10 g/cc, believed to be the lightest commercially available glass spheres. Particle-size range is 10 to 150 microns, with an average of 82 [mu] crush-strength tests showed a 9% volume loss at 100 psi. The spheres have a hydrophobic surface treatment and are aimed at pourable casting and other low-viscosity thermoset applications, including polyesters, epoxies and urethanes. (CIRCLE 122)

Even lighter hollow polymeric microspheres are now being marketed in this country by Nobel Industries Sweden, Marietta, Ga. (They were previously offered in the U.S. by Pierce & Stevens Chemical Corp., Buffalo, N.Y.) These Expancell PVDC/acrylonitrile copolymer spheres come in several grades. Unexpanded versions have a mean particle size of 11-17 microns. The spheres contain isobutane, which causes them to expand 35-fold when softened at 200-225 F. For most thermoset applications, pre-expanded versions are recommended, with average particle sizes of 25-50 [mu] (ranges are 6-60 and 10-100 [mu] and true densities of 0.036-0.060 g/cc, depending on grade.

According to North American marketing manager Peter Bergoo, 1% by weight of Expancell in polyester resin takes up about 25% by volume. He says these spheres permit one to add a greater volume percent of filler with less increase in viscosity, compared with other low-density spheres. Putting it another way, he notes that expanded spheres cost around $10/lb, which is $3/gal, compared with $8/lb for unfilled polyurethane.

Substituting spheres for resin can reduce styrene fume emissions in fabricating by up to two-thirds, he claims. Part of that effect is also due to the tendency of the spheres to lie on the surface of the laminate and suppress fume evaporation.

Unexpanded spheres have been used in urethanes, where they expand as the material exotherms. They can thus be used as a sort of syntactic foaming agent and a means of tailoring the resiliency of an elastomer. They can also be used as shrinkage-compensation or anti-sink additives in RIM urethanes. (CIRCLE 123)

PHOTO : Cratec, a chopped-strand fiber introduced by Owens-Corning, makes use of a proprietary sizing chemistry that has been formulated for thermoplastics such as nylon, polyethylene and polypropylene.

PHOTO : Designed as a filler for thermoset and thermoplastic resin systems, Sphericel 110P8, introduced by Potters Industries, consists of hollow glass microspheres designed to withstand extrusion pressures.