Processability meets performance.

Processability Meets Performance

Novel copolymerization and alloying technologies will be the critical factors shaping thermoplastic development in the 1990s, helping to achieve high-performance resins with enhanced processibility. Given the possibilities of such reactive polymer modification methods, this decade promises to be fruitful with new thermoplastics, though not at the blistering pace of recent years, according to most major suppliers.

Alloying technology, the compatibilization of two or more discrete resin systems, will continue to play a major role in the development of new thermoplastics. However, as the decade progresses, the major thrust for developing new materials will be in-reactor copolymerization technologies, which enable a resin's molecular backbone to be restructured.

Entirely new resin types or completely different classes of polymers will be sparse in the 1990s, according to most materials suppliers. That's not to say new-polymer research will be abandoned this decade. However, the stakes for creating a totally new thermoplastic material will continue to rise during the next 10 years. A tightening economy, increasing market demands, rising global competition and mounting regulatory pressures make the commercial rewards of such research more of a gamble in the 1990s, say resin producers.

The priorities of the marketplace, rather than the research lab, increasingly will dictate the thrust of materials R&D during the next 10 years, according to nearly all thermoplastics producers interviewed. Resin companies say new materials will be designed explicitly to meet the needs of specific applications. In this vein, impact-modified copolymers, thermoplastic composites and elastomers will receive particular attention. Suppliers say copolymerization and alloying will be the means for achieving the specific properties required for such "niche" resins.

Also in this decade, high-volume (so-called "commodity") thermoplastics producers will be seeking to attain "engineering" status for new grades of their materials. Producers of commodity materials, especially polypropylene, feel the '90s will offer major opportunities for them to penetrate applications of higher-priced thermoplastics in "over-engineered" applications. "Today we have many over-engineered applications, but no one will be able to afford over-engineering in the 1990s," one resin producer conceded to PLASTICS TECHNOLOGY.

This overview, as well as the following two feature articles on engineering and commodity thermoplastics, respectively, will highlight the advances in new materials development expected to take shape during the next 10 years, according to recent interviews with materials suppliers. (A feature on Thermosets in the '90s follows the thermoplastics sections.)

'COPOLYMERIZATION DECADE'

"The 1980s will be seen as the decade in which alloys were th dominant theme," observes Joseph G. Wirth, v.p. and general manager of the technology div. of GE Plastics, Pittsfield, Mass. "But in the 1990s, copolymer technology, with which we can alter the polymer's molecular backbone, will be the dominant trend."

New copolymer technology is expected to diminish significantly the role of additives in thermoplastic systems. Properties such as flame retardance, thermal stability and toughness will be engineered directly into a polymer's molecular structure, rather than compounded in with additives, which often disrupt material propertie or processing efficiency. Materials producers also expect copolymerization technology to provide significant benefits in the overall processability of materials.

Block and random copolymerization technology will offer the means to combine material properties that formerly could be achieved only at a compromise of one or the other--e.g., impact strength with high modulus, or flame retardance with improved processability.

New catalysts and initiators, as well as a wider selection of monomers, now give engineers the ability to predictively order the "block segments" of a polymer's molecular chain (patching repeating elastomer segments into a high-modulus plastic, for example) or create the environment for a "random" dispersion of one material phase into another.

PROCESSABILITY IS

JOB ONE

It's expected resin producers will focus increasingly on processing issues in efforts to make their products more competitive during the next 10 years. This will go beyond considerations of melt-flow rate or incorporating mold-release agents in certain polymer grades, toward a more comprehensive approach to the overall manufacturing issues for processors.

"we're trying to better understand the processability requirements of our customers," says Victoria M. Franchetti, director of technology for Monsanto Chemical Co., Springfield, Mass. "But processability is more than just how fast a material fills a mold." Franchetti says the new emphasis will be on issues such as the long-term heat stability of a material in processing; resin surface quality and level of gloss; alloy morphology and interactions with processing; efficient tooling designs that complement resin properties; and controlling molded-in part stresses caused by material orientation.

This intensified focus on overall processability amounts to a change in corporate R&D culture, observable throughout the resin producing industry, here and abroad. It's evident, for example, at BASF AG in Ludwigshafen, West Germany, according to Willy B. Hoven-Nievelstein, director of plastics applications development and technical services for BASF Corp. in Wyandotte, Mich. He says aspects of processability have become part of the early conceptual engineering of thermoplastics.

"Eventually, we materials producers always seem to come back to processing problems," Hoven-Nievelstein says. "Process technology will be a key for material development in the 1990s. Everyone is striving for better thermal and mechanical end-use properties in thermplastics, but many of these higher-property materials cannot find applications. Higher molecular weights and higher thermal properties mean more processing problems and more complex tooling and systems."

Hoven-Nievelstein adds that "many people seem to forget the total cost of using a material includes both its price and the cost to process it, and that this overall cost is an important material property." Defining the processing requirements along with the material properties will be a challenge this decade, he says.

The shakeout now under way in liquid-crystal polymers is a clear example of how processing will affect materials R&D in the '90s (see PT, April '90, p. 92). While the impressive physical and thermal properties of that material were trumpeted when the materials first appeared in the mid-1980s, several resin producers recently have begun to pull back and re-evaluate their plans to fully commercialize LCPs. A major cause of this apprehension is that development of processing technology for LCPs during the past five years has not kept pace with advances in the materials' performance properties, Hoven-Nievelstein says. Greater awareness of the material's high cost and inherently complex molding characteriestics has thrown uncerntainty into the cost/performance equation, he concludes.

THE 'NEW' RECYCLED MATERIALS

Already being exploited by independent compounders, recycled materials are expected to become a viable "new" feedstock stream for major thermoplastic producers in this decade. The consensus is PET and HDPE will be the two most widely accessible recycled materials generated by municipal waste streams during the next 10 years.

The major role of recycled materials for resin suppliers will be as what they're calling "value-added regrind" in virgin resin systems. Reclaimed resin will be blended in with virgin resin of the same type, or alloyed with another type, rather than sold on its own. Virtually all suppliers interviewed balked at the suggestion that recycled materials might themselves become "wide-spec" product lines in the 1990s, with an independent market thrust and property data sheet. Apparently no firm is anxious to market a "lower-quality" resin line.

TEST STANDARDS: LOW PRIORITY

Rationalizing the confusing and unsatsifying state of standard test methods for either plastics processability or end-use performance properties is not high on resin suppliers's agenda for this decade (see PT, Jan. '90, p. 7; Dec. '89, p. 7). Interviews with most major suppliers elicited little interest in pushing for such standards. Several suppliers state flatly such standards will not be a priority area, either forthe industry as a whole or within their respective companies, given what they consider to be more urgent issues to address in this decade.

Others say standardizing the characterization of resin processing properties is too difficult an issue to address, as any given test procedure (such as spiral flow) would not necessarily predict accurately the processability or flow of a material in every fabrication method and every application. Development of a new, universally accepted processability test procedure in the 1990s is unlikely, they say, because processability is intimately dependent on the particular equipment on the factory floor, as well as on the particular resin. Qualifying the many variables between materials and machinery would virtually negate any substantive benefit to processors, suppliers say.

There seems to be little motivation on the part of domestic producers interviewed for this article to enlist in the European movement known as CAMPUS (Computer-Aided Material Preselection by Uniform Standards), a system for uniformly testing and specifying material properties on data sheets. However, at least one multinational supplier has made data on its U.S. materials available in the CAMPUS ISO-type format, although this would be primarily of benefit to overseas customers for the time being (see page 62). Kishor S. Mehta, manager of design engineering services for Mobay Corp., Pittsburgh, says that ASTM Committee D/20 is working on a document for harmonizing ASTM with ISO and IEC test protocols and specimen geometries, as are used in CAMPUS.

The one standardization trend that did generate attention during recent interviews was the ISO 9000 quality verification movement in Europe. Resin producers feel attaining a world-recognized quality approval of material uniformity and performance would be of great interest to domestic processors and end users.