PEL PLASTICS UPDATE highlights recent progress in key areas of polymer/plastics technology including: catalysis, biopolymers, smart/functional polymers, alloys & blends and polymer modification. A recent issue of PEL Plastics Update follows.

Complimentary Copy
Vol. 6, No. 2
PEL PLASTICS UPDATE
March-April, 1998
By Mort Wallach
ISSN 1094-656X
 

Nanotechnology & Dendrimers-New hyperbranched nanofoams with very low dielectric constant and robust thermal and mechanical features were reported at the recent ACS Meeting in Dallas. These materials have potential in the new electronic devices with greater on-chip device densities and smaller electronic circuit dimensions. Also, novel polyphenylene dendrimers and hyperbranched materials have high thermal stability, shape persistence, and surface functional groups, allowing for the preparation of nanoparticles of differing size, shape, and functionality. These materials have possible use in medical, electrical and aerospace applications.

• J. Remenar and coworkers at IBM Almaden are developing hyperbranched nanofoam alternatives to vapor deposited silicon dioxide with very low dielectric constant (<2) and with robust thermal (>400C) and mechanical features. Initial results involve a variety of hyperbranched structures based on polycaprolactone, which vary in the size, shape, and number of branch points, and end group functionality. Examples include hyperbranched polymers based on AB₂ and AB₄ macromonomers, dendrimers, and star and graft polymers. Incorporation of these materials in SSQs (e.g., phenyl and methyl/phenyl silsesquioxanes) followed by curing, yields thin film nanofoams with dielectric constants below 2.0. This development could reduce signal delays and crosstalk which result from the trend towards greater on-chip device densities and smaller circuit dimensions. (Polymer Preprints, 39(1), 631, 1998).

   

• K. Mullen and coworkers at the Max-Planck-Institut fur Polymerforschung in Mainz have established a route to new polyphenylenes with an unprecedented density of benzene rings. The polyphenylenes are prepared by the cycloaddition reaction of an ethynyl group sterically accessible for a Diels-Alder reaction, and the diene function of a tetraphenylcyclo- pentadienone, followed by the elimination of carbon monoxide. Thermal stability, process- ibility, and surface functionalization render these polymers very promising in applications such as intermediates for drug carriers, high heat, and electrical uses. Functional cores such as chromophores, and removable cores after crosslinking of dendrimer branches creating a cavity inside the dendrimer are other important areas. These dendrimers and hyperbranched materials are also suitable precursors to large, two dimensional graphite subunits which could have important aerospace applications. (Polymer Preprints, 39(1), 721, 1998).

Catalysis-New iron and cobalt based catalysts have been uncovered rivaling metallocenes in polyolefin polymerizations. Complexes with aryl-imine ligands activated by cocatalyst methyl-alumoxane (MAO) produce polyethylene in high yield at a high rate. The new iron based catalysts are also active in polypropylene polymerizations and for oligomerizing ethylene to a-olefins, e.g., to produce LLDPE.

• V. Gibson and coworkers at Imperial College, London teaming with BP Chemicals, and independently M. Brookhart and coworkers at U. of North Carolina teaming with DuPont have discovered a new family of low cost iron and cobalt based catalysts with high activity in olefin polymerizations. Both teams prepared five-coordinate precursor complexes of tridentate iron(II) and cobalt(II) with 2,6-bis(imino)pyridyl ligands. Ethylene pol- ymerization tests by both groups showed that the catalytic activities of the MAO-activated complexes are very high and comparable with or even higher than those of metallocene catalysts under analogous conditions. The new catalyst family is said to share many of the advantages of metallocene catalysts in terms of activity and control of polymer properties, and in addition offers the potential for producing a much broader range of polymeric materials at low cost. The new iron based catalysts are also active for propylene polymerization and with certain modifications are very active for oligomerizing ethylene to a-olefins. They are said to exceed the activities of other catalysts currently used for a-olefin production. Hexene and octene are used for copolymerization with ethylene to produce linear low density polyethylene. Work in the US includes investigations of the structure and active catalyst in these systems, details of chain growth and termination, and polymerization behavior of other monomers. DuPont reportedly plans to develop both the a-olefin and polyethylene technologies, while BP Chemicals has a broad ongoing program to explore the considerable commercial implications of this catalyst discovery. (M. Freemantle, C&EN, April 13, 1998, p. 11; M. Brookhart et. al., Polymer Preprints, 39(1), 213, 1998; V. Gibson, et. al., Chem. Communications, 849, 1998).

Self Assembly-Rod-coil block copolymer structures of poly(phenylquinoline) and polystyrene were found to self-organize into various geometric shapes. In particular, encapsulation of fullerenes led to spheres via guest/ host recognition. Potential applications include extraction, purification and processing of fullerenes as well as possible drug delivery, adhesives, composite materials, and microelectronics.

• Prof. S. Jenekhe and coworkers at U. of Rochester have found that rod-coil block copolymers of poly(phenylquinoline) and polystyrene form very large self assembled structures not often found outside living systems. These rod-coil polymers self organize into various geometric shapes (e.g., stable hollow cylinders, and spheres, flat disks, and doughnut shaped vesicles) with diameters as large as 30 (m. These structures solubilize fullerenes encapsulating the buckyballs in hollow polymer spheres. The asymmetry of the stiff poly(phenyl- quinoline) block linked to flexible polystyrene blocks is thought to lead to these novel properties including the formation of hollow spheres with diameters of 0.5-10 (m. The size is thought to result from the rigidity of the rod blocks which link together in parallel. The dominant shape of the copolymer aggregates is determined by solvent composition and the drying rate. However, the presence of fullerenes inhibits formation of all of the aggregates except the spheres which suggests the possibility of guest-host recognition. The solubilized fullerenes are contained within the core of a hollow sphere with the stiff rod blocks assembled perpendicular to and around the circumference. Potential applications include extracting, purifying, and processing fullerenes, possible uses in drug delivery, adhesives, composite materials, and microelectronics. (Science, 279, 1903, 1998).

Alloys & Blends-With a model melt blended system and a spinning drop apparatus, it was shown that on addition of a block copolymer compatibilizer, the interfacial tension is reduced considerably and enhanced dispersed phase droplet breakup is dominant relative to reduced probability of coalescence.

• G. Schoolentber and coworkers at Shell R & T Centre in Amsterdam have studied the mechanism of the considerable morphological size reduction by adding a suitable interfacial compatibilizer, e.g., a block copolymer, to a melt blended, heterogeneous polymer system, and whether the effect is due to enhanced dispersed phase droplet breakup or the reduced probability of coalescence. The key parameters that govern these processes are the interfacial tension and interfacial mobility. They can be assessed by a spinning drop apparatus using a two droplet technique introduced by the authors. Investigations were carried out on the effect of block copolymer compatibilizers on these properties and thereby on break-up and coalescence behavior. Furthermore, the results were compared to the effect on the blend morphology of the same systems. It was found that for a model system of PE, PS, and SEBS block copolymer the interfacial tension reduces considerably. Most results point in the direction of mobilization of the interface, particularly in the case of low molecular mass compatibilizers which give a low interfacial tension. (Proc. Eur. Conf., Adv. Mater. Processes Appl., 5th, 2, 231, 1997).

Alloy & Blend Patents-Among 1000 patents reviewed during this period, there are several noteworthy inventions involving: chlorinated polyolefin/ABS-graft blends for automotive interiors; films, fibers, and containers from polyesters containing terephthalate, and isophthalate moieties; and biodegradable films, moldings and fibers, from polylactic acid compositions.

• "Thermoplastic Elastomer Composition Containing Chlorinated Polyolefins And Graft Copolymers". R. Wypart et. al. (General Electric Co.) US 5,717,028, Feb. 10, 1998. The title composition comprises (a) 25-85% of a chlorinated polyolefin, and (b) a graft copolymer having a rubber substrate present at a level of 65-90% based on the total weight of the graft copolymer; where the composition has a Shore A hardness <90, and elongation of > 200% at a crosshead speed of 20 in./min., and a tensile strength > 200 psi. Preferably the graft copolymer is an acrylonitrile-butadiene-styrene graft copolymer and preferably the chlorinated polyolefin is a chlorinated polyethylene having a high molecular weight and a relatively low chlorine level. The composition is useful for making molded articles such as interior automotive components requiring high elongation and tear resis- tance, reduced hardness and often high strain recovery. (Chem. Abs. 128: 168565y).

   

• "Polyesters Containing Isophthalate And Terephthalate Moieties, Manufacture Thereof, And Films, Fibers And Containers Therefrom". E. Paschke et. al. (Amoco Corp.) PCT Int. Appl. WO 98 02,479, Jan. 22, 1998. Semicrystalline polyesters comprising terephthalate, 2,6-naphthalate and/or isophthalate moieties, have density > 1.362 g/cm³ achieved by strain-induced and/or thermal crystallization and excellent gas barrier properties. Thus, a poly(ethylene terephthalate isophthalate) (10 mol % isophthalate) preform was used to blow mold a 2 liter bottle at a temperature profile 260, 270, 270, and 255C in the nozzle, front zone, middle zone, and rear zone respectively, in 33.9 seconds, giving sidewall density of 1.3640 g/cm³ and crystallinity 23.8% before heat setting and 1.3715 and 29.9% respectively after heat setting 2.5 seconds at 160C, and established shelf life of bottle 14.5 weeks (vs. 11.7 weeks for PET). (Chem. Abs. 128: 115755d).

   

• "Biodegradable Polylactic Acid Compositions". M. Matsui et. al. (Shimadzu Corp.) JP 10 36,652, Feb. 10, 1998. The compositions useful for manufacture of films, moldings, and fibers contain (A) 60-99% lactic acid-based aliphatic polyesters, (B) 0.5-35% C_2-4 alkylene group containing polyethers and/or surfactants bearing the above polyether segments and C_>6 alkyl group, and (C) 0.5-25% aliphatic carboxylic acid metal salts. Thus, a composition containing L-lactide polymer, polyethylene glycol, and Na stearate was made into filaments showing tenacity 4.7 g/d, elongation 28%, and good degradability. (Chem. Abs. 128: 168672f).

New Ventures & Alliances
Akzo Nobel has agreed to acquire Courtaulds for about $3.1 billion to create the largest coatings company and the second largest fibers company worldwide. The new coatings company will be made up of 70% of the old Akzo and 15% of Courtaulds' businesses such as marine and heavy duty coatings where Akzo has little or no presence, and 15% of integration businesses such as aerospace and coil coatings where both firms participate. Akzo intends to combine Courtaulds' fiber and chemical business with its own fiber group to create an independent fiber company ranked number two worldwide after DuPont. Akzo will then study the best way to spin off the combined fiber business. It will be admittedly difficult for the largely European fibers company to compete in a stagnant market against rising asian players. The fibers company will have three subsectors: businesses with growth potential such as Akzo's aramids and Courtaulds' Tencel and Lyocell; established businesses including Akzo's industrial fibers and Courtaulds' acrylics and acetates which are expected to provide cash flow for the growth areas; and poor performers such as rayon in which both companies are involved. The deal needs to be cleared by the European Commission. Meanwhile Akzo needs to rethink it's announced plans to form a joint venture involving their industrial fibers business and Sabanci of Turkey, as well as the effects of its joint aerospace venture with Dexter and its large combined European market share of this segment. (M. McCoy, C&EN, April 27, 1998, p. 7).

Hoechst's worldwide polyester business is being sold to a consortium of privately held Koch Industries of Wichita, KS and Grupo Xtra of Mexico City. The consortium will buy 11 production sites including Hoechst's US, European, and Mexican polyester fibers and resin interests as well as Hoechst share of polyester JVs in China and Turkey. The annual polymer capacity is 4.4 billion lbs with sales of $2.7 billion, and a workforce of 11,000. The consortium is also discussing purchase of Hoechst's 56% stake in Celanese Canada's polyester business. Koch, the second largest private US company with sales of more than $30 billion employs 16,000 people worldwide in businesses including oil and gas recovery, refining, petrochemicals, sulfur, asphalt, and real estate, but this new venture marks Koch's entry into the polyester fiber and resins business. Grupo Xtra owners (Saba family) via 32% holdings in Grupo Celanese is the largest Mexican shareholder in Hoechst's Mexican-based bottle resins, fibers, and chemical operations. In addition they are a significant factor in textile yarns, and fabrics, agriculture, food processing, real estate, and tourism. The new company will retain regional headquarters in Charlotte NC, Toluca, Mexico, and Frankfurt, Germany. (P. Layman & M. Reisch, C&EN, April 27, 1998, p. 8).

IBM plans to purchase the chemical consulting firm Chem Systems, of Tarrytown, NY with the goal of capturing more business in the chemical industry. Chem Systems is well known in the chemical and petroleum industries for its expertise in process technology, economic evaluations, market research and forecasting, and competitor analysis. Proprietary consulting is the companies primary business, but the group also prepares multiclient reports and conducts industry seminars. The company was established in 1965 and has 160 employees with offices in Tarrytown, London, and Bangkok. IBM feels that the combination of Chem Systems' industry knowledge with IBM's information technology implementation skills will create an important resource for chemical companies. It is felt that information technology is a powerful tool for dealing with competitive issues faced by the chemical and petroleum industries. For Chem Systems this combination will allow it to become involved with the implementation of the various strategies that they help companies develop. Wall Street sources feel that IBM and Chem Systems can leverage each others contacts to get more of the 15 to 20% of the billion dollar capital budgets used for information technology by large chemical companies. We expect to see more of such alliances involving large IT firms with specialized consulting companies serving chemical, petroleum, and other major industries. (P. Morse, C&EN, Mar. 23, 1998, p.7).