DN Staff

November 20, 2000

5 Min Read
Hot Products

BMC gets magnetic

Bulk molding compound (BMC) has gotten more attractive-literally-with the introduction of a new magnetic grade. Suitable for injection or compression molding, this fiberglass-reinforced thermoset gets its magnetic properties from proprietary metallic fillers, according to Jody Riddle, BMC Inc.'s manager of research and development.

The material, though too new to have seen any commercial use, targets magnet applications that can benefit from net shape manufacturing or from BMC's high-temperature stability. Riddle cites electric motor components as one likely candidate, but he adds that the material was developed for a confidential automotive application that does not involve motors at all.

Magnetic properties aside, the new material behaves much like standard BMC. "The moldability and mechanical properties are similar to a typical BMC," Riddle says.

Preliminary properties for magnetic BMC

Tensile strength

Flexural strength

Flexural modulus

Impact strength

Magnetic properties

B r

H ci

BH max

Low flamer

Where there's fire, there isn't always smoke. Consider, for example, a new highly brominated bisphenol-A epoxy-based vinyl ester (HBVE) and highly brominated general-purpose resin (HBGP) from AOC. Both resins meet ASTM E84 Class 1 standards for flame spread and smoke development UL94 requirements (HB, 5V, and V0), according to Bruce Curry, AOC's corrosion product leader. Both new resins combine flame-and-smoke resistance with corrosion resistance and "superior mechanical properties," Curry adds. Applications for the HBGP resin include structural reinforcement laminates for cooling towers, ducts, and shields, while HBVE has seen use in process equipment for chemical plants.

Mechanical properties of new brominated resins

Tensile strength, psi

Tensile modulus, psi

Elongation, %

Flexural strength, psi

Flexural modulus, psi

Heat distortion, degrees F

Barcol hardness

Big robot for FRP

For FRP applications, the new P-200T robot automates gelcoat and chopped fiberglass applications and can serve as a replacement for manual sprayers. Mounted overhead on rails, the six-axis P-200T has the reach needed for large parts. According to Fanuc's Rob Schwamberger, the P-200T's work envelope is big enough for the single robot to coat even large bathware and marine parts without the need for additional positioning devices. The new robot integrates Fanuc's AccuChop software, which provides open- or closed-loop control.

Composite rides along with Nissan

You'll have to climb on board the Nissan Xterra and look up to see the latest application for Azdel SuperLite GMT. The Xterra makes use of this glass-mat-reinforced polypropylene composite sheet to form a pre-assembled, modular headliner.

According to Tony Forden, Azdel Inc.'s commercial director, Azdel SuperLite grades offer glass contents from 40 to 60% and weights from 600 to 2,000 g/m 2 . Azdel's manufacturing process can vary the ratio of fibers to polymer and the web's basis weight. So the material can be supplied in thicknesses from 1 to 8 mm without changes in weight but with different degrees of stiffness.

Though first developed as an alternative to cardboard, polyesters, and polyurethane in headliner applications, Azdel SuperLite may fit into other automotive interior applications too-thanks to its light weight, thin profile, one-shot manufacturing process, stiffness-to-weight ratio, dimensional stability, and recyclability. Forden reports that these applications include rear electrical carriers, sunshades, door panels, load floors, and underbody panels.

SMC that does it all

Imagine an SMC with all the mechanical properties the material is known for but without the drawbacks that arise with the high temperatures of e-coat processing. Ashland Specialty Chemicals recently developed just such a resin system for exterior vehicle applications.

E-coat resin properties

Tensile strength, MPa

Tensile modulus, MPa

Flex strength, MPa

Flex modulus, MPa

Impact, j/m



Water absorption, %

24-hr immersion

10 days@100F and 95% H

Glass, %

Surface (LORIA)

Shrink, inch/inch

This e-coat resin exhibits a Class A surface finish, withstands e-coat temperatures, and absorbs little moisture, reports Troy Wade, product manager for Ashland's Composite Polymers Div. At the same time, it has at least the mechanical properties of a standard SMC. In fact, Wade notes the material is tougher than ordinary SMC thanks to the incorporation of recycled thermoplastic polyester-both as a blending partner for the thermoset SMC resin and as a low-profile additive. The PET "improves the physical properties and fatigue qualities of the SMC," says Wade. "And it contributes to the Class A surface."

Ashland plans to offer the new resin system as a "single pack" in which the base resin, monomers, and low-profile-additives arrive in a single package to ease manufacturing.

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