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How to process LCP's.



How to Process LCP's

Getting the best out of liquid-crystal polymers may require innovative processing techniques; new grades and alloys may help, too.

One of the interesting wagers on the future of plastics in the 1990's concerns the odds that liquid-crystal polymers (LCP's) will advance from their present status as a small-volume, high-priced, "exotic" niche material into the ranks of more widely used engineering resins.

While many industry observers have speculated that LCP's are poised for sharp growth in the 1990's, what makes the bet interesting is that its outcome will depend on new technologies that are only just beginning to emerge--technologies for LCP (Link Control Protocol) See PPP.

LCP - Link Control Protocol
 polymerization polymerization

Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same.
 and compounding, and new techniques for molding and extruding LCP's so as to take best advantage of their unique properties.

First commercialized in late 1984, all currently available LCP's are random copolymers of aromatic polyesters, produced from a select group of monomers. Unlike most resins, LCP's have the ability to form highly oriented, fibrous crystalline chains under shear in the melt phase (see PT, Dec. '84, p. 82; April '85, p. 85).

Despite LCP materials' impressive thermal and physical properties, commercial utilization reportedly amounts to only 2-5 million lb/yr., primarily in small electrical surface-mount connectors and encapsulated devices, along with some chemical-processing applications and microwave cookware. LCP producers hope to move them into larger, more diverse structural parts in the '90s.

Wider utilization would help to bring down the cost of LCP's--typically $7-10/lb. But since high prices have been identified as one barrier to wider utilization, LCP suppliers are taking the initiative on seeking ways to reduce LCP costs and increase their value in use (cost/performance). One supplier anticipates bringing prices down below $5/lb by 1992.

Injection molding injection molding
n.
A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold.
 of glass-filled compounds have been identified by resin producers as the main thrust for processing of LCP's during the next 10 years. (Some work, as noted below, also is occurring in extrusion of unfilled LCP's.) Though often referred to as a "self-reinforcing" polymer, most material development efforts so far have concentrated on filled grades to minimize their anisotropic Refers to properties that differ based on the direction that is measured. For example, an anisotropic antenna is a directional antenna; the power level is not the same in all directions. Contrast with isotropic.  nature and improve transverse strength, reinforce weak weld lines, and also bring down the cost. Besides glass, other reinforcements used in LCP's include various minerals and carbon fibers.

Much of the materials and processing development work to address the LCP challenge already is beginning to unfold, with the promise of yielding major results during the next three years. On the material development side, LCP resin producers have offered PLASTICS TECHNOLOGY some glimpses into their proprietary research efforts toward making LCP's more useful engineering materials. Their goals for the 1990s are to reduce LCP prices, expand the range of product offerings, counter the drawbacks of the materials' greatest strength--their tendency toward high orientation, and balance the resins' outstanding thermal and mechanical properties with improved processability. Alloying and blending LCP's with other resins is being actively investigated as one means of achieving these goals.

As for processing development, the handful of experienced LCP molders (five of which were interviewed for this article) have compiled an extensive database on the unique behavior of these materials in the five years since they were introduced. They regard this as an "information platform," upon which they can proceed to more advanced fabrication fabrication (fab´rikā´shn),
n the construction or making of a restoration.
 methods. Tooling and part design, proper gating and venting, and gaining better understanding of melt-flow characteristics are vital areas demanding further work.

Along with optimizing their adaptations of existing processing methods to LCP behavior, processors believe that new types of processing technology are needed to more fully exploit the benefits (and minimize the drawbacks) of LCP's. One such production breakthrough may be the new "push-pull" injection molding technique from Klockner Ferromatik Desma GmbH in West Germany West Germany: see Germany. , unveiled at last year's K'89 exhibition in Dusseldorf (see PT, Jan. '90, p. 72). Some processors and resin suppliers also are conducting research on new extrusion techniques for LCP film and sheet. Complementing such developing fabrication advances is computer software that has proven successful for finite-element mold-filling and cooling analysis of LCP parts.

EASY TO PROCESS?

One of the most widely trumpeted attributes of these high-performance polymers is that they are "easy to process" (see PT, April '85, p. 85 for a 5-page LCP processing guide). Molders and resin producers have agreed on the ability of LCP's to easily fill thin-walled parts (down to 10 mills), their wide processing window for melt and mold temperatures, high dimensional stability dimensional stability,
n See stability, dimensional.
 and low shrinkage, and sharp shear-rate/viscosity curve and rapid transition in the mold from melt to solid, which results in quick cycle times.

However, there also has been a downside to processing LCP's: limited flexibility in mold gating configurations; restricted part size and geometry; and inability to fully exploit the material's superior physical properties or effectively orient the polymer melt to control weld-line weakness or undesirable anisotropic characteristics. It's also true that the higher the temperature capability of the LCP resin, the "stiffer" its processing characteristics. Molders and resin producers concur in an optimistic view that these limitations are all manageable factors, and that improvements will be forthcoming.

At least one LCP manufacturer asserts that concern over their anisotropic nature has been greatly overblown o·ver·blown  
v.
Past participle of overblow.

adj.
1.
a. Done to excess; overdone: overblown decorations.

b.
. John R. Dole, marketing manager and development specialist for Hoechst Celanese Corp., says anisotropy anisotropy /an·isot·ro·py/ (an?i-sot´rah-pe) the quality of being anisotropic.
anisotropy (an´āsôt´r
 is a manageable condition that also occurs with other polymers: "Any crystalline engineering thermoplastic A polymer material that turns to liquid when heated and becomes solid when cooled. There are more than 40 types of thermoplastics, including acrylic, polypropylene, polycarbonate and polyethylene.  tends to be anisotropic. The anisotropy in LCP's can be diminished with increased levels of fillers, and also is dependent on the particular material grade and mold gating." He characterizes claims of LCP weld-line weakness as a similar case of overstatement o·ver·state  
tr.v. o·ver·stat·ed, o·ver·stat·ing, o·ver·states
To state in exaggerated terms. See Synonyms at exaggerate.



o
, since other crystalline resins also cause problems with the knitting of melt fronts in a mold. However, not all sources interviewed shared Dole's conviction on these issues.

MOLDER FEEDBACK

Moderate improvements in LCP resin quality have been noted recently by experienced processors. They told PLASTICS TECHNOLOGY that mold plate-out, material consistency, pellet size variation, and flow characteristics all had been typically mild problems when processing LCP's. However, even these slight difficulties apparently have been rectified during the last 12 months, as resin producers have introduced new grades and generations of material. Processors say current LCP grades afford them a wide molding-temperature window, with consistent, predictable cycle times and little tool wear or plate-out. "We've known Xydar since it was a puppy, and it's come a long way," says a spokesman for Cincinnati-based Performance Plastics Inc. "Weld lines are no longer a problem, and the material has much better flow properties for molding." Several molders also indicated that they worked closely with resin suppliers in fine-tuning the material to meet processing and end-use requirements.

Along with resin improvements, computer software for mold-filling analysis has been found to aid processors using LCP's. One such package is the TMconcept software system from Plastics & Computer Inc., Montclair, N.J. Ernest Bernhardt, president, says this expert system for injection mold-filling and analysis, shrinkage evaluation, and manufacturing cost optimization has been proven successful with LCP's and is now being used by two leading LCP materials producers--Amoco and Hoechst Celanese--to aid customers in mold and process design. Other suppliers of mold-analysis software--Moldflow, Inc., Advanced CAE (1) (Computer-Aided Engineering) Software that analyzes designs which have been created in the computer or that have been created elsewhere and entered into the computer.  Technology, and Unisys CAD/CAM CAD/CAM
 in full computer-aided design/computer-aided manufacturing.

Integration of design and manufacturing into a system under direct control of digital computers.
, Inc.--all say they have achieved accurate results in analyzing flow of LCP's with their standard software.

Both Hoechst Celanese and Amoco plan to publish LCP processing and design guides this year. The guides will provide technical support to molders in the areas of material selection, processing methods, mold-filling analysis, and tooling and part design.

MOLD DESIGN CRUCIAL

Mold design is the most critical aspect of working successfully with LCP's, according to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3.
 molders. This seems to be especially true because the majority of LCP applications are in tight-tolerance, very-thin-walled parts, as well as insert molding of pins and electrical connectors, which also demand exacting tolerances.

Gate placement with regard to a part's weld line is considered to be a crucial, though manageable, aspect of mold design. Processors say designing and positioning gates to move the knit line to a noncritical area of a part is a relatively easy task--and they recommend single gating whenever possible to minimize the problem. One also recommends edge gating over subgating whenever possible. "Mold and part design is the key to working with LCP's," according to Edward R. Christie, marketing manager for Pixley-Richards Inc., Plymouth, Mass., a molder of LCPs. "It's knowing where to put gates on a part," he adds, especially on long, thin components.

"Like any other highly crystalline material, LCP melt fronts have a hard time joining," according to Christie. "But relative to other crystalline resins, LCP's do show weakness at the weld lines." Most LCP molders feel this condition can be compensated for by tailoring mold design for non-critical placement of weld lines.

David P. Berkowitz, Pixley-Richards' regional accounts manager, says the anisotropic nature of the material is well understood and can be harnessed through mold design. He says that in designing molds for parts with complex geometries, LCP's can be made to approach a more isotropic Refers to properties that do not differ no matter which direction is measured. For example, an isotropic antenna radiates almost the same power in all directions. In practice, antennas cannot be 100% isotropic.  nature, via structural support by arched shapes and ribs. "We can build in strength," he says. "The complex structure of parts can help to alleviate the material's anisotropic nature. To further compensate for the transverse weakness, we can mix up the flow patterns when molding. Glass fillers also add strength in the transverse direction of a part."

Brian Daly Brian Daly is an Irish news journalist currently working as Ireland Correspondent for Sky News in Dublin. He was one of the Sky News Ireland's two anchors for its twice-weeknightly programmes alongside colleague Ray Kennedy, following the departure of previous Sky News Ireland , plastics manufacturing engineer The profession of manufacturing engineer is defined as a person having the education and experience to understand and control manufacturing systems such as processes and/or automation, including industrial processes and equipment used to produce goods.  at Superior Electric Co., Bristol, Conn., says the high inherent dimensional stability of LCP's makes mold-design accuracy an essential consideration. The firm does its own mold design on precision stators and rotors encapsulated by LCP via insert molding. "The material has excellent dimensional stability," he says. "Shrinkage isn't a consideration with LCP. You get what you expect, so you need a high degree of accuracy in your mold design."

Daly says his most successful way of dealing with a high-tech material like LCP's has been to take a deliberately low-tech approach to processing. "We try to keep the process as simple as possible. We've stayed away from a high-tech, computer-control approach with LCP's."

Molders like Daly add that mold temperature is not a critical factor in the process, he adds, as the material doesn't require a hot mold to develop crystallinity. One molder that uses primarily Hoechst Celanese's Vectra LCP says a typical processing window includes mold temperatures between 60 and 200 F, and melt temperatures between 520 and 580 F.

Predictive engineering The use of computer-generated models and software simulations that are continually verified against hard empirical data. The benefits are better product designs and a smoother, faster product development process. Finite element analysis (FEA) has a closely integrated role in predictive engineering.  and specially designed tools are keys to working with LCP's at Molex Inc., Lisle, Ill., a custom molder of electrical components. Robert Petrie, mold engineering manager, says Molex has established a working database on mold flow and tool design for LCP's. Because of the material's predictably low shrinkage rate, Petrie says his firm is able to rework and convert older tooling used for other resins to process LCP's. Molex overcomes weld-line problems through using single, end gates rather than multiple gating. As for dealing with LCP's anisotropic nature, he says Molex has devised ways to "play with the material's glass-fiber orientation," as well as include specially designed interrupters and deflectors in the tool to adjust flow patterns. "Successful processing of LCP's is very dependent on controlling mold flow, more than any other factor." To accomplish this, Molex relies on team meetings among leaders of the production, tooling and design departments, to collaborate on what Petrie calls predictive engineering.

Careful analysis of flow, with venting at the end of fill patterns, is one tip offered by Richard D. Caufman, manager of project engineering for Loranger Manufacturing Corp., Warren, Pa. In molding a 12-pin electrical connector for automotive ignition systems, Caufman said he prefers to keep vents away from the gates to prevent flash problems. "LCP's flow very well, and the material we use has a very low viscosity," he explains. "We found that we had a flashing problem when the material reached the vent, so we designed the vents at the end of the fill pattern." Nonetheless, Caufman points out that, in general, LCP's exhibit far less flash than most other engineering thermoplastics. He also says that compared with other high-temperature materials High-temperature materials

A metal or alloy which serves above about 1000°F (540°C). More specifically, the materials which operate at such temperatures consist principally of some stainless steels, superalloys, refractory metals, and certain ceramic
, such as PPS (Packets Per Second) The measurement of activity in a local area network (LAN). In LANs such as Ethernet, Token Ring and FDDI, as well as the Internet, data is broken up and transmitted in packets (frames), each with a source and destination address. , LCP's create less wear on tools.

FAST CYCLES PRAISED

Processors agree that LCP's demonstrate superior capabilities in accurately filling molds for thin-walled parts, down to 10 mils. But they rate the materials' ability to provide fast cycle times as their greatest processing advantage. Molders explain that LCP's, because they don't need to be crystallized crys·tal·lize also crys·tal·ize  
v. crys·tal·lized also crys·tal·ized, crys·tal·liz·ing also crys·tal·iz·ing, crys·tal·liz·es also crys·tal·iz·es

v.tr.
1.
 in the mold, require less cooling time (Law) such a lapse of time as ought, taking all the circumstances of the case in view, to produce a subsiding of passion previously provoked.
- Wharton.

See also: Cooling
. They noted that LCP's have a relatively low heat of fusion--the amount of heat energy needed to melt a resin, as well as the heat that must be drawn out to have the resin set up in a mold. LCP's maintain much of their ordered crystallinity in the liquid state, unlike other thermoplastics. As a result, less heat needs to be dissipated from LCP's before they set up in a mold.

A NOVEL INJECTION APPROACH

The one really new processing technique developed specifically for LCP's is Klockner's "push-pull" or "counterflow" process, noted above. This approach utilizes a twin-injector molding machine (Woodworking) A planing machine for making moldings
(Founding) A machine to assist in making molds for castings.

See also: Molding Molding
 (such as is used for two-color work) with some control software modifications. As shown in the accompanying diagram (adapted from an article on the subject published in the November 1989 issue of Kunstoffe German Plastics), the part is gated at either end and may be filled by one injector alone or both together, producing a weld line in the middle. By either method, once the mold is initially filled, one injector screw advances while the other retracts, and vice versa VICE VERSA. On the contrary; on opposite sides.  in alternation alternation /al·ter·na·tion/ (awl?ter-na´shun) the regular succession of two opposing or different events in turn.

alternation of generations  metagenesis.
. Thus, the melt is oscillated back and forth within the cavity, with some of it being temporarily sucked back into the injector barrel before being re-injected.

This reportedly has two beneficial effects: One is that the innermost core of the part is replenished with fresh, hot melt, achieving a higher degree of orientation in what is normally the least oriented region of the part, owing to owing to
prep.
Because of; on account of: I couldn't attend, owing to illness.

owing to prepdebido a, por causa de 
 relatively low shear and cooling of the melt. This results in higher flow-direction tensile strength tensile strength

Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its
 than in a part injected normally from a single end gate. Second, reheating Reheating

The addition of heat to steam of reduced pressure after the steam has given up some of its energy by expansion through the high-pressure stages of a turbine.
 of the material during the push-pull phase is said to permit greater knitting of the flow fronts, effectively "erasing" the weld line, as shown by the higher strength attained. A patent application has been filed on this process. (See "Production of Technical Parts by Means of Counterflow Injection Molding," by L.M. Gutjahr and H. Becker in Kunstoffe German Plastics, Nov. '89, p. 8; published by Carl Hanser Verlag, Darmstadt, W. Germany.)

EXTRUSION AND ALLOYING R&D

Besides injection molding, research is also under way on new extrusion techniques for neat LCP films--for example, by Foster Miller Inc., an R&D contractor in Waltham, Mass. Although the work is proprietary, Richard W. Lusignea, manager of the Polymer & Composite Materials Div., says the program involves developing new extrusion die designs that create biaxial biaxial /bi·ax·i·al/ (-ak´se-al) having, pertaining to, or occurring in two axes.  and multiaxial Mul`ti`ax´i`al

a. 1. (Biol.) Having more than one axis; developing in more than a single line or plain; - opposed to monoaxial nt>.
 orientation in unfilled LCP sheet and film.

Extrusion of LCP sheet and thin films is at the semi-works scale of development at Hoechst Celanese Corp. One R&D project involves extruding LCP sheets for cross-ply lamination lamination

a laminar structure or arrangement.
 into structural composites. Other extrusion development work at Hoechst Celanese is aimed at taking advantage of LCP gas-barrier properties in coextruded thin packaging films. Du Pont Du Pont (dpŏnt), family notable in U.S. industrial history. The Du Pont family's importance began when Eleuthère Irénée Du Pont established a gunpowder mill on the  is also working on extrusion techniques for its "amorphous" LCP, but details could not be obtained from the company. (See PT, Feb. '86, p. 23 for more on LCP extrusion.)

Alloying and blending with other resins has been proposed as a means of realizing LCP properties at lower cost. LCP's apparently can serve as a "molecular reinforcement" in other polymer matrixes; some observers have suggested that the low viscosity of LCP's may enable them to serve as processing aids for other polymers.

However, LCP's may present some difficulties as an alloy partner because of their high crystallinity, which causes problems of compatibility, or adhering to other resins on a molecular level, according to Prof. Robert A. Weiss, of the Dept. of Chemical Engineering and Polymer Science Polymer science or macromolecular science is the subfield of materials science concerned with polymers, primarily synthetic polymers such as plastics. The field of polymer science includes researchers in multiple disciplines including chemistry, physics, and engineering.  at the University of Connecticut The University of Connecticut is the State of Connecticut's land-grant university. It was founded in 1881 and serves more than 27,000 students on its six campuses, including more than 9,000 graduate students in multiple programs.

UConn's main campus is in Storrs, Connecticut.
 in Storrs. Weiss is the director of a federally funded, $3.8-million LCP research program at the university. He notes that LCP's have high interfacial tension Noun 1. interfacial tension - surface tension at the surface separating two non-miscible liquids
interfacial surface tension

surface tension - a phenomenon at the surface of a liquid caused by intermolecular forces
, thus requiring wetting agents in order to blend with other polymers, much like sizing chemicals used for glass fibers in a composite matrix. Finding suitable compatibilizing and wetting agents for LCP's is one goal of resin suppliers' research.

One processor that's working independently on LCP alloying is Foster Miller. Lusignea says the firm has a $50,000 phase-one Small Business Innovation Research contract, which it won in February from The National Aeronautics and Space Administration National Aeronautics and Space Administration (NASA), civilian agency of the U.S. federal government with the mission of conducting research and developing operational programs in the areas of space exploration, artificial satellites (see satellite, artificial),  (NASA NASA: see National Aeronautics and Space Administration.
NASA
 in full National Aeronautics and Space Administration

Independent U.S.
). The project involves alloying LCP with a thermoplastic polyimide Pronounced "poly-ih-mid." A type of plastic (a synthetic polymeric resin) originally developed by DuPont that is very durable, easy to machine and can handle very high temperatures. Polyimide is also highly insulative and does not contaminate its surroundings (does not outgas).  called LARC-TPI, developed by NASA's Langley Research Center Langley Research Center (LaRC) Oldest of NASA's field centers, LaRC is located in Hampton, Virginia and directly borders Poquoson, Virginia and Langley Air Force Base. LaRC focuses primarily on aeronautical research, though the Lunar Lander was flight-tested at this facility and a  in Norfolk, Va. The goals are to develop chemical and rheological compatibilization for LCP to function as a molecular reinforcement in the LARC LARC Langley Research Center
LARC London Action Resource Centre
LARC Lighter, Amphibious Resupply, Cargo
LARC Long Acting Reversible Contraception
LARC Learning and Academic Resource Center (University of California, Irvine) 
 polyimide, creating a "microcomposite."

"LCP's are generally unfriendly when it comes to alloys," says Lusignea.

"It's difficult to form a miscible miscible /mis·ci·ble/ (mis´i-b'l) able to be mixed.

mis·ci·ble
adj.
Capable of being and remaining mixed in all proportions. Used of liquids.
 blend with LCP's. Our work involves developing special compatibilization chemistry between the two resins. Aerospace applications for an LCP/polyimide alloy extruded sheet would be cryogenic fuel-tank liners and satellite solar collectors and reflector reflector: see telescope.  panels."

Target for completing phase one is August, when a phase-two contract for up to $500,000 may be offered. Foster Miller is seeking joint-development partners to assist in commercializing this technology.

MATERIALS DEVELOPMENT

Hoechst Celanese Corp. and Amoco Performance Products are the two best known suppliers of LCP's today. Du Pont entered the field in mid-1988, while several other contenders promise to unveil their materials soon, or have placed their development programs on hold. The following summary outlines their LCP R&D plans for the next few years.

* Hoechst Celanese: A boost in higher-temperature grades, with HDT's about 75 [degrees] F above existing levels, is one current research thrust for Hoechst Celanese's Vectra LCP line in the 1990s, according to John R. Dole, marketing manager and development specialist. The Vectra line currently has HDT's in the mid-to-high 400-500 F range. Attaining higher temperatures would involve using new monomers and polymerization techniques, says Dole.

Lower-molecular-weight LCP's is a second area of development under way at Hoechst Celanese. Dole says low-MW, highly filled (50-75%) LCP's will be needed for application such as insert molding and encapsulation (1) In object technology, the creation of self-contained modules that contain both the data and the processing. See object-oriented programming.

(2) The transmission of one network protocol within another.
 of electrical/electronic components and wiring.

A third focus of R&D will be to expand the product range and tailor new LCP grades to satisfy specific application needs, through development of new polymers and blends, according to David W. Trott, Vectra senior product manager. The search for compatibilizing agents is a key element of that program.

* Amoco Performance Products: Since it already has the most heat-resistant LCP's on the market (with HDT's up to 675 F), Amoco Performance Products will focus its research efforts on improving the processing characteristics of its Xydar LCP line, according to marketing manager Daniel Love Daniel Love! is a British Lucid Dreaming/Dreaming maven. He is credited with the introduction of various new Lucid Dreaming methods the most famous of which is the "CAT" method (Cycle Adjustment Technique). . Filler technology, including particle size Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials.  and orientation, and wetting agents for carbon and glass fibers and mineral reinforcements, will be another research thrust for Amoco, he says.

Amoco plans to introduce a Xydar grade for under $5/lb by 1992. This third-generation material currently is in the second phase of test-market evaluations, Love says. He expects the company to make a final decision on this new material by the fourth quarter of this year. Love says this lower-cost grade would be glass-filled, with HDT HDT Heat Deflection Temperature (plastics)
HDT High Dose Therapy
HDT Heatpipe Direct Touch (Xigmatek)
HDT Heat Distortion Temperature (plastics)
HDT Henry David Thoreau
 around 500 F and a processing window similar to Amoco's current Xydar 300 series.

* Du Pont Co.: Du Pont, which fully commercialized its crystalline HX-4000 and "amorphous" HX-2000 LCP lines late last year, will introduce a new generation this year, says LCP business manager James Godfrey. The new type will be a crystalline, glass-reinforced material with a melt temperature of 608 F and glass-transition temperature of 345 F. It will have a HDT of 482 F @ 264 psi--midway between Du Pont's two existing product lines, while offering faster cycle times and a wider processing window. The new grade also will provide higher tensile strength (26,000 psi) and elongation (2.6%) than either of the two current grades, but with a lower flexural flexural

pertaining to the flexure of a joint.


flexural deformity
fixation of joints in flexion. In the newborn called contracted calves or foals.
 modulus (2 million psi).

Du Pont is the only supplier to have introduced what it calls an "amorphous" LCP (see PT, Aug. '88, p. 99; Sept. '88, p. 89). Godfrey explains this apparent contradiction in terms Noun 1. contradiction in terms - (logic) a statement that is necessarily false; "the statement `he is brave and he is not brave' is a contradiction"
contradiction

logic - the branch of philosophy that analyzes inference
 thusly thus·ly  
adv. Usage Problem
Thus.

Usage Note: Thusly was introduced in the 19th century as an alternative to thus in sentences such as Hold it thus or He put it thus.
: Amorphous LCP has a glass-transition temperature of 375 F, but no crystalline melting point melting point, temperature at which a substance changes its state from solid to liquid. Under standard atmospheric pressure different pure crystalline solids will each melt at a different specific temperature; thus melting point is a characteristic of a substance and . The material softens gradually over a temperature range, rather than having a sharp melting point, giving it suitable processing characteristics for film and sheet extrusion.

Godfrey says Du Pont is also working on applications in larger, structural engineered components that will use LCP's as a processing aid or reinforcement in other resin systems. "There is an upside to the fact LCP's don't wet out very well with other resins, and we feel we can take advantage of this aspect," he said, declining to explain further.

* Rhone Poulenc, Inc.: This French-based firm plans to introduce four grades of LCP to the U.S. next year, according to a company executive interviewed at the K'89 show (see PT Jan. '90, p. 92). Known as Rhodester C.L., the line includes one unfilled and three mineral-filled grades, with HDT's in the 446-518 F range. Rhodester material will be priced slightly higher than comparable Vectra grades, according to this spokesman.

* Eastman Performance Plastics: The company will begin market sampling of a new LCP in the third quarter. The unfilled resin has a melting point between 662 and 680 F, HDT above 572 F (at 66 psi), flexural strength Flexural strength is also known as modulus of rupture, bend strength, or fracture strength. Flexural strength is measured in terms of stress, and thus is expressed in pascals (Pa) in the SI system.  above 20,000 psi, tensile strength over 30,000 psi, and a notched Izod impact strength above 6 ft-lb/in. The material, which has not yet been given a trade name, will be available in both filled and unfilled versions, and priced at or below existing LCP lines.

OTHER SUPPLIERS `ON HOLD'

Resin producers with LCP development programs "on hold" include ICI (language) ICI - An extensible, interpretated language by Tim Long with syntax similar to C. ICI adds high-level garbage-collected associative data structures, exception handling, sets, regular expressions, and dynamic arrays.  Advanced Materials Advanced Materials is a leading peer-reviewed materials science journal published every two weeks. Advanced Materials includes Communications, Reviews, and Feature Articles from the cutting edge of materials science, including topics in chemistry, physics,  (which previously introduced Victrex SRP SRP - A data link layer protocol.  resins); BASF BASF Bar Association of San Francisco (since 1872; San Francisco, California)
BASF Badische Anilin und Soda Fabrik (German chemical products company)
BASF Builders Association of South Florida
 Corp., Plastic Materials (Ultrax); Granmont Inc. (Granlar); and GE Plastics (no commercial introduction as yet). Most of these firms concede that the relative small market size, high material price and limited applications, as well as strength of the established commercial producers, has caused them to stay on the sidelines On the sidelines

An investor who decides not to invest due to market uncertainty.


on the sidelines

Of or relating to investors who, having assessed the market, have decided to avoid committing their funds.
 for now and reconsider their LCP development efforts.

Bayer AG in W. Germany, parent of Mobay Corp. in the U.S., cancelled its plans to introduce four new grades of LCP's, citing tepid market conditions and the existence of well-established producers (see PT Jan. '90, p. 93). This decision reversed plans the company had announced earlier in the year (see PT Oct. '89, p. 33). A Bayer executive interviewed at the K'89 show in Dusseldorf was candid about the reasons for his company's change in plans, saying LCP is a limited market already saturated by current producers. He did say Bayer would continue development on semifinished sem·i·fin·ished  
adj.
1. Made, treated, or sold to be used in a finished product: semifinished steel.

2. Partially finished: a semifinished basement. 
 LCP products such as its Polystal line of tapes and reinforcements.

Patrick Collins, manager of high-performance products for GE Plastics, says his firm "basically has shelved" its plans for near-term commercial development of LCP's. GE has decided instead to start over and develop a new LCP thrust. "We decided we didn't want to come out with a `me-too' LCP product," says Collins. "We're looking for Looking for

In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with.
 a unique technology and product line. We certainly think LCP's will be a market in the 1990s, and we think we could stimulate interest with a new LCP. But it's not something for the near future for us."

Granmont's efforts to develop and commercialize an LCP line have been stalled by ongoing reorganization moves at Montedison and uncertain market conditions, according to a spokesman. While he would not reveal details of the company's LCP development program, he said the resin, known as Granlar A, would be a low-cost LCP with an HDT above 600 F (see PT, June '88, p. 125).

The Blends & Advanced Materials unit of Dow Chemical Co. has initiated a research program into LCP's. A spokesman described the project as a "modest effort" still in the early stage of development. [Figure 1 to 2 Omitted]

PHOTO : The majority of parts made from liquid crystal polymers to date have been injection

PHOTO : molded, surface-mount electrical components, like these from Pixley-Richards. Processors

PHOTO : and resin producers seek to expand LCP applications in the 1990s.

PHOTO : High heat resistance and dimensional stability are among the most impressive properties of

PHOTO : LCP's. In this demonstration, Amoco's Xydar withstands a 2000 F burn-through test used to

PHOTO : qualify aircraft materials.

PHOTO : Mold design was identified by processors as the most crucial aspect to be considered when

PHOTO : working with LCP's. Part gating in order to locate weld lines in non-critical areas of the

PHOTO : component is one of the essential points in mold design.

PHOTO : Injection molding of glass-filled LCP's is expected to predominate in the 1990s. However,

PHOTO : several firms also are developing various extrusion applications for the material.
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Title Annotation:liquid-crystal polymers
Author:Gabriele, Michael C.
Publication:Plastics Technology
Date:Apr 1, 1990
Words:4185
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