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

Vol. 7, No. 4
PEL PLASTICS UPDATE
May-June, 2000
By Mort Wallach
ISSN 1094-656X
 

Engineering Resins-General Electric has developed several new PPO technologies which extend its market reach in auto fenders, wheel covers, TV housings, business equipment, plumbing and other applications. Suppliers of competitive resins (e.g., ABS, PC/ABS, nylon and PP) will likely be driven to respond. These areas include FR grades, vibration-dampening products, chrome-plating advances, and progress in conductivity.

• Advances in flame retardancy include a halogen-free system for the electrical market, FR systems for PPO alloys, and FR versions of new vibration-dampening and plateable products.

   

• Vibration-dampening is achieved via technology which changes the mechanical response of PPO to vibration, reducing sound generation and extending part durability. This patented GE technology overcomes the disadvantage of amorphous materials like PPO relative to crystalline materials like PP. Target markets for quiet operation include printers, business machines, underhood automotive, (intake manifolds and battery holders), as well as pump and medical equipment, TV housings, and cabinets for sound and recording systems.

   

• Chrome-plating advances for auto wheel covers and plumbing fixtures provide an HDT in excess of 275F which allows for new wheel cover design freedom required in emerging high heat braking systems and other higher heat applications. Potable and hot water plumbing systems such as faucets and brass fixtures as well as the newer highly convoluted parts can be addressed by higher temperature chrome plating.

   

• Conductive properties in Noryl GTX alloy allows automotive exterior fenders, mirror housings, and other parts to be painted alongside steel parts in demanding paint oven conditions without need of a primer. Carbon nanotube technology is one of several advances employed to achieve this. (R. Leaversuch, Modern Plastics, Jan. 2000, p. 35).

Catalysis-Application of Atom Transfer Radical Polymerization (ATRP) has proven effective in several areas including: 1) amplifying monolayers of initiators patterned by microcontact printing into polymer brushes for micro transfer 2) synthesis of hybrid homopolymer and block copolymers from polyhedral oligomeric silsesquioxane monomers and 3) the controlled growth of polymers at interfaces i.e., from silicon surfaces in the absence of untethered sacrificial initiator.

• C. Hawker and co-workers at IBM Almaden and U. of Wisconson demonstrated the usefulness of ATRP to amplify initiators patterned on surfaces by microcontact printing into polymeric brushes that can serve as robust barriers to a range of wet chemical etchants. The use of ATRP permits a high level of control over the thickness and functionality of polymer brushes and makes possible the tailoring of brush properties such as their wettability and resistance to wet chemical etchants. (Macromolecules, 33, 597, 2000).

   

• K. Matyjaszewski and coworkers at Carnegie Mellon U. in Pittsburgh synthesized novel hybrid polymers from a POSS-based methacrylate monomer using ATRP. From this approach, homopolymers, triblock copolymers, and star-block copolymers of (MA-POSS) were prepared. While polymers containing POSS were made by other methods, using ATRP, hybrid-POSS polymers with previously unattainable compositions and much lower polydispersities were synthesized. (Macromolecules, 33, 217, 2000).

   

• K. Matyjaszewski and co-workers at Carnegie Mellon U. in Pittsburgh & GE Corp. R&D Center in Schenectady & Technische U. Wien, & Max-Planck Institute, Mainz demonstrated the versatility of ATRP in the preparation of high concentrations of surface bound layers. Analogous to the control of polymer molecular weight for chains grown in solution, control over film thickness was maintained through a sufficient concentration of deactivator in the absence of untethered initiator. Verification of control over terminal chain functionality was obtained by block copolymerization. Finally, by choice of monomer or through post-polymerization functionalization reactions, the wettability of the surfaces was varied over a broad range. (Macromolecules, 32, 8716, 1999).

Nanomedicine-At the U. of Michigan Medical School Center for Biologic Nanotechnology in Ann Arbor, dendrimers are being investigated for safer gene therapy to replace vector viruses which are thought to trigger potentially dangerous immune response. In one application so-called smart bombs are being developed to treat cancer. These dendrimers infiltrate cells to detect pre-malignant and cancerous cells and then release a substance to kill the cell.

• J. Baker and D. Tomalia are investigating whether dendrimers which can be engineered on a nanometer scale can be used to insert DNA through immune defenses into target cells. Dendrimer research has expanded significantly since Tomalia's early work into applications including drug delivery and medical imaging. Unlike other polymers dendrimers have a precise nanostructure. They are formed nanometer by nanometer wherein the number of synthetic steps dictate their exact size. The dendrimer surface can be tailored to form a dense field of molecular groups that serve as hooks for attaching other useful molecules. They can also carry internal guest molecules. It is these features which make dendrimers good transporters of DNA into cells. In this process the dendrimer molecule is decorated with DNA on to the polymer surface and the dendrimer/DNA package is injected into the tissue. The dendrimers tailored to just the preferred size trigger endocytosis a process where the cell deforms to let the package in. The DNA is then set free and migrates to the cell nucleus where it becomes part of the cell genome. Initial results indicate that these synthetic nanostructures might be a safer alternative to viral transporters for gene therapy. In lab experiments to date they efficiently transfer DNA into the cell's genes. Animal trials are being conducted to demonstrate that there are no toxic side effects and to demonstrate their efficiency. The next step will be to assess the promise of dendrimers for fixing genes in humans. In a recent project dendrimer devices are being developed to infiltrate living cells to detect pre-malignant and cancerous changes. If the dendrimer 'bomb' senses such threats it will release a substance to kill the cell. In one version of this dendrimer based device laser light is used to trigger the release of chemical agents from the polymer. The device will also be able to verify that the cancerous cell is dead. Engineering on a scale of biomolecules could prove to be very powerful-opening up a new field of nanomedicine. (D. Voss, Technology Review, (MIT) Jan.-Feb., 2000, p. 60)

Alloys & Blends-Polypropylene/PET blends with substantial property improvements were prepared by reactive processing with PP-g-GMA compatibilizer.

• M. Champagne and coworkers at Industrial Materials Institute in Quebec have investigated the reactive compatibilization of polypropylene/poly(ethylene terephthalate) (PP/PET) blends by addition of glycidyl methacrylate grafted PP (PP-g-GMA). Two PP-g-GMA copolymers containing either 0.2 or 1.2 wt% of GMA, were used as interface modifiers. These were incorporated into PP blends (with either 70 or 90 wt% PET). The use of these modifiers changed the blends' tensile mechanical behavior from fragile to ductile. Blend tensile strength was improved by 10% and elongation at break showed 10 to 20-fold increases while stiffness remained constant. Scanning electron micrographs showed the PP average domain size in injection-molded specimens decrease to the micron/sub-micron size upon addition of the GMA-modified resins, while the unmodified blends exhibited heterogeneous morphology comprising large lamellae 10-20 µm wide. The low GMA-graft content PP seemed slightly more efficient than the high GMA-content PP in emulsifying PP/PET blends. The GMA grafting level on PP had very limited effects on the blends' mechanical behavior in the range of GMA graft density provided by the two modified resins investigated. (Polym. Eng. Sci., 39, 976, 1999).

Alloy & Blend Patents-Among 1000 patents reviewed during this period, there are several noteworthy inventions involving: coated glass fibers in composites, polyketone-ABS graft rubber blends, and poly(phenylene ether) compositions.

• "Coated Glass Fibers, Composites And Use In Polymer Composites". P. Schell et. al. (PPG Industries) PCT Int. Appl. WO 99 52,834, Oct. 21, 1999. Fiber strands and products are coated with a blend of a hydrophobic fluoroalkylacrylate polymer and an amine-reactive material or a polymerization reaction product of a hydrophobic fluoroalkyl acrylate and an amine reactive monomeric material. The coated fibers are useful as reinforcements for nylon composites to inhibit hydrolysis. The amine reactive material is selected from (1) unsaturated carboxylic acids or anhydrides, (2) epoxides, (3) cyanoacrylates, (4) acrylamides, (5) acrylonitriles, (6) aldehydes, (7) diketones, and mixtures. (Chem. Abs. 131: 300340q)

   

• "Thermoplastic Polyketone-ABS Graft Rubber Blends For Fabrication Of Molding Compositions And Shaped Articles". H-J. Dietrich et. al. (Bayer AG) PCT Int. Appl. WO 99 54,406, Oct. 28, 1999. Thermoplastic polymeric materials are prepared containing: (1) at least one alternating polyketone from carbon monoxide and at least one C_<20 olefin, and (2) at least one graft ABS - type rubber fabricated by radical emulsion polymerization of at least one monomer or related monomer combination selected from styrene, (-methylstyrene, Me methacrylate, acrylonitrile, methacrylonitrile, in a rubber latex, with a glass transition temperature <0°C, an average particle diameter (d₅₀) of 80-600 nm, and a gel content of 30-95 wt.%. Suitable graft rubbers present in the polymerization emulsion include butadiene-styrene, acrylic, EPDM, and styrene-propylene rubber. The emulsion polymerization latex has an average particle size of preferably 150-450 nm and a gel content of 45-85 wt.%. The thermoplastic compositions, containing 40-99 (preferably 40-99) wt. parts polyketone and 1-60 (preferably 7.5-40) wt. parts graft rubber, are used to fabricate molded and shaped articles. (Chem. Abs. 131: 311267x)

   

• "Poly(phenylene ether) Compositions Containing High-Crystalline Syndiotactic Alkenyl Aromatic Polymers With Excellent Impact, Heat, And Solvent Resistance And Their Manufacture". S. Moritomi et. al., (Sumitomo Chemical Co.) JP 11 236,474, Aug. 31, 1999. The compositions comprise poly(phenylene ethers) 10-98, syndiotactic alkenyl aromatic polymers (B) 1-89, and alkenyl aromatic polymers (C) which have no syndiotactic structure 1-89% and are manufactured by melt-kneading of 2 of the above components, mixing with the rest of the components, and further melt-kneading. The compositions are made into flyback transformers, deflecting yokes, pumps, tanks, ducts, automotive lamp reflectors, connectors, etc. Styrene was polymerized at 20°C for 1 hour in the presence of Me aluminoxane and pentamethyl-cyclopentadienyltitanium chloride to > 95% -syndiotactic polystyrene (I), 40 parts of which was kneaded with 60 parts of a melt-kneaded composition comprising 66.7% poly(2,6-dimethyl-1,4-phenylene ether) and 33.3% Sumibrite E 163K (atactic styrene polymer) to give a composition showing crystalline fraction of I 145% and good heat and solvent resistance. (Chem. Abs. 131: 200795y)

New Polymer Ventures-Important alliances formed during this period include: the Phillips Petroleum/Chevron combination of chemical businesses with assets of $6.1 billion and interests in polyethylene, polystyrene, and polypropylene, as well as ethylene, styrene, p-xylene and other specialty petrochemicals, and DuPont/Fluor Daniel's polyester packaging resin manufacturing alliance using new technology with lower operating costs, reduced emissions and larger than current worldscale units.

Phillips Petroleum and Chevron Corp. have agreed to combine their chemical businesses in a 50/50 joint venture with assets valued at $6.1 billion. J. L. (Jim) Gallogly Phillip's senior vice president of chemicals and plastics has been named president and CEO of the Houston-based partnership. The aim in uniting their chemical businesses is to achieve financial strength and a complimentary fit. 1999 revenues of the combined businesses are $5.7 billion with pretax earnings of $700 million. The partnership's board will be governed equally by Phillips and Chevron managers. The joint venture will rank fifth globally in ethylene, fourth in polyethylene, and third in p-xylene capacity. The deal couples the largest domestic ethylene buyer Chevron with the biggest ethylene seller. Chevron will contribute one of the worlds largest styrene and polystyrene businesses. Phillips will add its 50% interest in a polypropylene plant in Pasadenea, Texas and strong positions in numerous specialty petrochemical products. The companies do not foresee any problems in securing regulatory approval and the deal is expected to be completed by mid-2000. (A. Tullo, C&EN, Feb. 14, 2000, p. 18)

DuPont and Fluor Daniels have formed an alliance to market the first polyester packaging resin manufacturing units based on DuPont's NG-3 technology. According to Robert G. Hirsch managing director of DuPont Polyester Technologies, this is the first polymerization technology specifically developed for packaging resin. DuPont brings licensing and technical knowledge and service to the alliance while Fluor contributes engineering, construction, and operational services. DuPont says the NG-3 technology has exceeded its expectations in regard to lower capital and operating costs, reduced environmental emissions, and improved resin quality. Plants based on NG-3 are expected to have capacities reaching 200,000 metric tons per year, which is much higher than current world-scale polyester units. (C&EN, Jan. 31, 2000, p. 9)