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.

Vol. 5, No. 4
PEL PLASTICS UPDATE
July-August 1997
By Mort Wallach
ISSN 1094-656X
 

Nanotechnology-Promising new nanotechnologies were introduced at the Fall Meeting of the American Chemical Society in Las Vegas. These include new nanoscale organic-inorganic Si-O hybrid intermediates, and polyurethanes which have thermoplastic, elastomeric properties with increased T_g , decomposition temperature, and char yields. Also, novel nanostructures of polymer dispersed liquid crystals obtained via holographic photopolymerization have potential applications in a variety of electro-optic devices based on switchable holograms.

• J.J. Schwab and coworkers at Edwards AFB and Wright-Patterson AFB have developed hybrid nanoscale reagents based on polyhedral oligomeric silsesquioxane (POSS) precursors. These are well defined Si-O compounds which can easily be functionalized with a variety of groups commonly employed in polymerizations or grafting reactions. Hybrid polymers prepared from POSS reagents have the unique feature that the inorganic portion of the hybrid is covalently linked to the organic polymer chain. In addition, POSS based hybrids have desirable features including: thermoplasticity, increased T_g and T_dec , increased oxidation resistance, reduced flammability, reduced heat evolution, increased char yields, and enhanced miscibility. A series of these aromatic and aliphatic POSS diols were used as chain extenders in the synthesis of polyurethanes. Properties were enhanced significantly relative to non-POSS polyurethanes. These POSS polyurethane copolymers appear to be the first hybrid polymers to exhibit thermoplastic, elastomeric properties. (PMSE, 77, 549, 1997).

   

• L. Natarajan and coworkers at Wright Patterson AFB and Science Applications International Corp. in Beavercreek, OH have fabricated polymer dispersed liquid crystal (PDLC) films by a novel technique involving the holographic irradiation of prepolymer syrup containing nematic liquid crystals (LC). The resulting PDLC pattern exhibits coherent scattering of light in the Bragg diffraction regime. Volume holograms recorded in the PDLC film had LC domains much smaller than the optical wave length resulting in clear samples. The size of the LC droplets are of the order of 50-200 nm as compared to 1-10 microns for conventional PDLC's where the illumination is homogeneous. Using this technique, the transmission Bragg gratings can be electrically switched leading to a new class of PDLC electro-optic devices based on switchable holograms. On/off switching ratios > 25 dB were measured with response times of 20-40 us (which varies quadratically with droplet size). Applications include: switches for optical fiber networks, recording of projection images in PDLC'S, switchable holographic lenses (where a suitable voltage switches the focal length between a few mm and infinity), electrically switchable reflection holograms which can function as notch color filters, and potentially full color reflective displays which are under development. (Polymer Preprints, 38 (2), 634, 1997).

Catalysis-A potentially important new method of synthesizing highly branched macro-molecules from AB type monomers was introduced at the Fall Meeting of the American Chemical Society. The method involves cationic, self-condensing, vinyl polymerization which yields hyperbranched structures similar to the interesting and useful dendrimers which require lengthy multistep synthesis. In another development, ring-opening metathesis polymerization (ROMP) has led to new amphiphilic architectures via the macromonomer technique including sequential PS and PEO macromonomer copolymerization, and branched assemblies via PS-block-PEO based macromonomers which could serve as unimolecular micelles or associative thickeners.

• Profs. R.B. Grubbs and J.M.J. Frechet at U. Cal., Berkeley have shown that the self-condensing, vinyl polymerization of styrene derivatives is an effective route to high molecular weight branched polymers. The effect of various system components in a living, cationic styrene polymerization including monomer/initiator ratios, Lewis acid type, and quenching agent were evaluated to provide the basic data for further work. This will utilize surface functionalization to produce a variety of readily accessed and potentially useful hyperbranched materials. It is hoped that the properties of these materials will resemble those of the interesting and useful dendrimers which require lengthy multistep syntheses and as a result have limited availability. (PMSE, 77, 197, 1997).

   

• V. Heroguez and coworkers at CNRS, U. of Bordeaux, France have built on the discovery that highly strained cyclic olefins such as norborene can be polymerized under living conditions via ROMP, and macromonomer polymerization proceeds well via living ROMP to complete conversion in the presence of appropriate initiators of metathesis reactions. In this work, ROMP is applied to copolymerize either sequentially or statistically two macromonomers of different chemical nature or homopolymerize macromonomers that are themselves block copolymers. Two amphiphilic architectures have been constructed including Janus type structures derived by sequential copolymerization of PS and PEO macromonomers. Branched assemblies which could serve as unimolecular micelles or associative thickeners become accessible by ROMP of PS-block-PEO based macromonomers. (Macromolecules, 30, 4791, 1997).

Alloys & Blends-Compatibilization of potentially important polyester/poly(phenylene oxide) (PPO) blends was demonstrated using a unique compatibilizer of poly(4-vinyl phenol)-polystyrene (PS) copolymer which also promoted the dispersion of inorganic particles and adhesion to inorganic surfaces. The polyester component could enhance key properties of Noryl type blends including chemical resistance with possible automotive applications.

• T.E Long and coworkers at Eastman Kodak Co. in Rochester have shown the utility of poly(4-vinyl phenol)-PS copolymers (e.g., block, tapered random, and graft) as effective compatibilizers for polyester/PPO blends. Typical polyesters employed consisted of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol. The compatibilizers reduced the particle size of the dispersed phase resulting in enhanced mechanical properties. The poly(4-vinyl phenol)-PS compatibilizers were also effective in dispersing inorganic particles and in promoting adhesion to inorganic surfaces. The utility of these copolymeric compatibilizers is thought to be derived from the ability of phenol to form intermolecular hydrogen bonds. The alloy could have important commercial potential such as in exterior automotive parts. (Polymer Preprints, 38(2), 385, 1997).

Alloy & Blend Patents-Among 1500 patents reviewed during this period, several noteworthy inventions include: protective film for automotive bodies, transparent polysulfone/fluorene carbonate blends with an excellent balance of properties, vapor deposited metal-oxide/propylene gas barrier film, a depolymerization process for unzipping nylon in waste material, and silicon oxide coated PET gas barrier film for packaging.

• "Protection Of Coated Automobile Bodies, And Protecting Films And Pressure-Sensitive Adhesive Films For The Protection". A. Dobashi et. al. (Hitachi Chemical Co.) JP 09 94,532, April 8, 1997. Title bodies are protected by covering polymer films containing > 10% CaCO₃ and having Munsell color system > 8 and bonding the film edges to the bodies by using adhesive films comprising a base film with UV transmission < 5% at 190-370 nm and Munsell color system > 8 and containing propylene copolymers with 5-40% ethylene, and a pressure-sensitive adhesive layer containing polyisobutylene (I), butyl rubber or polybutene. The protecting film which does not soil the coated bodies, is manufactured inexpensively, and is easily removed after use. Thus, a coated automobile body was covered with a film containing Mirason 12 (polyethylene), Whiton SB (CaCO₃), and TiO₂ by using an adhesive film containing 8:92 ethylene-propylene copolymer, Oppanol B 80 (I) and Tinuvin 327 (UV absorber) and left outdoors for 3 months. The film was easily peeled off from the body. (Chem. Abs. 127: 19174x).

   

• "Blends Of Polysulfones With Diaryl Fluorene Carbonate Polymers Having Improved Transparency" K. Nichols et. al. (Dow Chemical Co.) US 5,633,331, May 27, 1997. Polymer blends having an excellent combination of optical properties, physical properties, and hydrolytic stability comprise, in admixture, (a) a diaryl fluorene carbonate polymer and (b) a polysulfone. Preferably, the diaryl carbonate polymer is a copolycarbonate of bisphenol A with bis(hydroxyphenyl)fluorene, preferably 9,9-bis(4-hydroxyphenyl) fluorene. Optionally, the blend compositions also comprise a second non-fluorene carbonate polymer (c). Preferably, the polysulfone is a bisphenol A polysulfone or a polyether polysulfone. In preferred aspects of this invention, the polysulfone and diaryl carbonate polymer components are selected to provide a transparent blend composition. (Chem. Abs. 127: 51570j).

   

• "Metal Oxide Vapor-Deposited And Unoriented Propylene Polymer Film With High Gas Barrier Property". S. Tanaka et. al. (Toray Industries) JP 09,143,294, June 3, 1997. Title film is obtained by vapor-depositing a metal oxide on a film comprising a propylene (I) random copolymer 85-99, high density polyethylene (II) 1-15, and a lubricant 0.05-0.5% and shows unidirectional flexural modulus of the metal oxide film > 0.7 GPa, light transmittance 60-90%, and water vapor transmission rate (R) < 2.5 g/m² - day. The film is applicable to heat-sealing materials or other secondary moldings, e.g., laminating with other plastic films etc. Thus, butene-l-ethylene-I random copolymer [showing ethylene content 2.0%, butene-1 content 5.0%, and melt flow index (MFI) 3.6 g/10 min] 95, II (showing density 0.937 g/cc, m.p. 130C, and MFI 4.5 g/10 min) 5, and SiO₂ 0.1 part were blended and molded to give 25 um unoriented film, which was treated with corona discharge to give a film showing wet tension (JIS 6768) 45 mN/m. Then, an Al oxide film was formed by vapor deposition on the film to give a test piece showing longitudinal flexural modulus 0.8 GPa, light transmittance 80%, and R of 1.5 g/m²-day. (Chem. Abs. 127: 51995b).

   

• "Process For Depolymerizing Nylon-Containing Waste To Form Caprolactam By Superheated Steam In The Absence Of Catalysts". S. Sifniades et. al. (Allied Signal) WO 97 20,813, June 12, 1997. An efficient process for depolymerizing multicomponent waste material comprising polycaprolactam and non-polycaprolactam components to form caprolactam comprises contacting the waste material, in the absence of added catalyst, with superheated steam at ~250-400C and ~1-100 atm and substantially less than the saturated vapor pressure of water at the temperature wherein a caprolactam-containing vapor stream is formed. The formed caprolactam may then be used in the production of engineered resins and fibers. (Chem. Abs. 127: 82490n)

   

• "Gas-Barrier Plastic Films Or Sheets Coated With Organic Silicone Polymer And Silicon Oxide Layers For Packaging". T. Namiki (Toyo Seikan Kaisha) US 5,641,559, June 24, 1997. Title film or sheet, useful for packaging, comprises a plastic film or sheet, a first layer of organic silicone polymer containing Si >15%, C >20%, and O, formed over the plastic film, and a second silicon oxide layer covering the first layer. Thus, a biaxially oriented PET sheet (100 um thick) was coated (0.053 um) on its surface with a first layer containing Si 16, O 36, and C 48% formed by chemical vapor deposition of hexamethyldisilane, ethylene and oxygen with a low temperature plasma CVD method, and a second layer (0.7 um) with composition ratio Si/O = 1/1.8 was formed over the coated film with a high frequency ion plating method to give a film showing permeation of steam (at 40C, 90%RH) 0.3 g/m²-day. (Chem. Abs. 127: 110019m).

New Polymer/Plastic Ventures-Three important polymer-based ventures were recently announced by Shell Chemical, DuPont/Hitachi Chemical, and Bayer/GE Plastics including, respectively: a new polyester product line for blends and composites; a joint venture (JV) on polyimide coatings for microelectronics: and a JV involving polycarbonate windows for automotive applications. The business rationales appear to be based on, respectively: competitive property advantages with captive monomer; combined partner strength, with focused market driven globalization; and combined partner technical/sales & marketing strength, with major global market potential.

• Shell Chemical introduced their compounded polyester product line (Corterra) at the NPE show in Chicago to complement their previously announced Corterra carpet fiber and film products. The material-polytrimethylene terephthalate (PTT)-offers the processibility of polybutylene terephthalate (PBT) with the tensile and impact properties of PET and could be employed in new blends and composites. The intermediate 1,3 propanediol which Shell supplies in market development quantities from a Gusmer, LA plant provides the route to this new polymer. A commercial monomer plant (160 million lb/yr) is planned for 1999 along with a 200 million lb/yr PTT polymer plant. These engineering resin compounds address applications such as automotive (under the hood), electrical, appliances and furniture. This is a good example of exploiting a captive monomer in a known polymer with material/process advantages. (Plastics World, July, 1997, p. 1). In a competitive development, DuPont has made an agreement with Degussa Corp. to obtain 20 million lb/yr of 1,3 propanediol thru 1998 and Degussa will build and assist DuPont in the start-up of a 100 million lb/yr 1,3 propanediol plant. This arrangement will give DuPont a ready source of monomer to manufacture PTT for carpet fiber and possibly engineering resin compounds. With DuPont's recent agreement to buy ICI's polyester business to improve its already strong position in this area, the purchase of Degussa's technology will further strengthen DuPont's polyester position and allow it to more quickly compete with Shell Chemical which is the only other producer of PTT worldwide. (M. Reisch, C&EN, Aug. 4, 1997, p. l2).

   

• DuPont and Hitachi Chemical are combining their polyimide coating operations in a joint venture - HD Microsystems. The new venture will provide materials to the microelectronics industry via: DuPont's Pyralin and Hitachi Chemical's polyimide coating product line. The business will include all polyimide R&D, manufacturing, sales, and technical service of the parent companies. Management and manufacturing will be located in the US and Japan. Sales are projected at $100 million in 1998. This is a good example of a focused market driven, globalized venture. (C&EN, Sept. 8, 1997, p. 15).

   

• Meanwhile Bayer and GE Plastics have entered into an agreement to form a joint venture to produce coated polycarbonate automobile windows with the abrasion resistance of glass. The objective is to develop the materials, the abrasion resistant coatings, and the process technologies to enable the broad use of polycarbonate windows in new vehicles. Advantages of polycarbonate glazing over glass windows include greater design freedom such as increased window curvature, better impact resistance, and weight reduction with better gas mileage. The company will be based mainly in the Detroit area. A development and engineering center is planned in Michigan to demonstrate the feasibility of polycarbonate glazing, with the capability to manufacture more than one million polycarbonate windows for customer evaluation. A development and marketing center in Germany will serve Europe and an office will be opened in Asia. Bayer will provide a composite technology involving hard nanometer sized particles embedded into the polycarbonate via a solvent process. GE Plastics plans to focus on plasma coating technology wherein a ceramic hard coating is applied through a vacuum process. The goal is to achieve a hard-coated polycarbonate with its rigidity, strength, and superior impact resistance while retaining the optical clarity and scratch resistance of glass. (V. Wigotsky, Plastics Engineering, Aug., 1997, pp. 12, 19).