COMPLIMENTARY COPY
Vol. 5, No. 2
PEL PLASTICS UPDATE
By Mort Wallach
http://www.pelassociates.com/
Mar-April 1997
ISSN 1094-656X
RECENT PROGRESS IN POLYMER/PLASTICS TECHNOLOGY
High Performance Polymers-New heat-resistant Si containing polymers are fusible,
moldable, and thermosetting with heat and burn resistant properties similar to the well
known polyimides. They have potential in demanding applications including aerospace,
automotive and electrical/electronic areas. In recent basic studies, the color intensity of
polyimides agrees well with the order of electron-donating properties of the diamine
moiety and electron-accepting properties of the dianhydride moiety in the polymer chain.

Masayoshi and coworkers at Mitsui Toatsu Chemicals in Yokohama, Japan
have developed Si containing polymers, i.e., poly[(phenylsilylene)ethynylene-1,3phenyleneethynylene)s which have excellent thermo-oxidative stability. These
polymers are prepared by two methods (1) the dehydrogenative polymerization
reaction between trihydrosilane (RSiH3 ) and diethynylbenzene using MgO as a
catalyst and (2) the condensation reactions using dichlorosilane (RSiHCl2) and
organic magnesium reagents. The R=phenyl derivative has only a 5% weight loss at
a temperature of 860C and 94% residue at 1000C in Argon- values comparable
with the best known heat resistant polymers. Fiber reinforced composites prepared
with glass, carbon, or SiC fiber showed good mechanical strength even at 400C in
air. The Si-H bond can couple with many reinforcing materials and molding can be
carried out with no byproduct generation. Bending strength and modulus suggested
use temperatures to 400C and the composite did not burn or smoke in the fire of a
gas burner. These polymers have real potential in high temperature applications.
(Macromolecules, 30, 694, 1997)

S. Ando and coworkers at NTT Labs in Tokyo have studied the relation between
the color intensity of polyimide films and the electronic properties of the
monomers-aromatic diamines and aromatic tetracarboxylic dianhydrides. They find
that the arrangement of the diamine moieties in order of color intensity of
polyimides shows good agreement with the order of the electron-donating
properties of the diamines established from 15N NMR chemical shift. On the other
hand, the arrangement of the dianhydride moieties in order of color intensity of
polyimides agrees with the order of the electron-accepting properties of the
dianhydrides estimated from experimental and calculated electron affinity.
However, in some cases inconsistencies are observed e.g., for dianhydrides having
both CF3 groups and a benzophenone carbonyl group. The overall results are
PEL Updates
Mar-April 1997
Page 2
consistent with the formation of a charge transfer complex and indicate that the
electron-donating properties of diamines and electron-accepting properties of
dianhydrides are retained to a significant extent even in polyimide molecular
chains. [Polym. J. (Tokyo), 29, 69, 1997]
Biopolymers-A correlation was established between the body’s defense against cancer
and the gene p53 and its protein product. This led to important work on how this protein
functions and the development of drugs to increase its usefulness. In another advance, new
hydrophobic polymer microspheres provide a potential oral delivery route to therapeutic
drugs and DNA.

p53 discoverers Prof. David Lane at U. of Dundee, Scotland, and Molecular
Biologist Arnold Levine of Princeton U. have initiated what has become one of
the hottest fields of cancer research, and molecular biology. When p53 is
functioning properly the risk of cancer is greatly reduced. However, improperly
functioning p53 is linked to 50-60% of all cancers worldwide. p53 mutations are
present in 40% of them. In other cancer cases the p53 gene appears normal but is
inactivated. The purpose of this gene appears to be the suppression of tumor
formation. If a cell is damaged (e.g., by ionizing radiation or chemical agents), p53
prevents it from continuing to grow and divide. Also, high levels of p53 can cause
unwanted cells to die. At the molecular level p53 (p=protein, 53=MW of 53,000) is
a transcription factor-it binds to regulatory regions of a specific set of genes and
instructs the cell to make more of these genes’ proteins. One of the key areas of
current research is in determining what these genes actually do. For example, one of
these genes p21 triggers p53’s ability to arrest the cell cycle, MDM2 genes produce
proteins that inhibit p53, and another gene BAX plays a role in p53’s induction of
cell suicide. Much work is underway in drug development including the use of
gene therapy to put unmutated p53 genes into tumor cells that lack it. Usually a
virus vector (carrier) is employed. Since p53’s function is to bind to DNA, most of
the mutations that inactivate it occur in the portion of the protein where DNA
binding takes place. The crystal structure of the binding region of p53 suggests that
one of two mutation classes affects the stability of the protein in its folded state.
Tumors with this type of mutation make p53 but it can never fold. As a result small
molecules are being sought (e.g., drug compounds) which will stabilize the folded
configuration so that the p53 will function like the unmutated protein. To date
Prof. Lane’s lab has had some encouraging results with antibody stabilizers and
small peptides. Clearly, much work lies ahead, and the hope is that others will take
up this challenge, in what appears to require a multidisciplinary approach to
determine how this protein functions, and the development of drugs to increase its
usefulness in the search to find a cure for cancer. (R. Rawls, C&EN, 2/17/97, p.
38)

Prof. E. Mathiowitz and coworkers at Brown U. School of Medicine have
developed hydrophobic polymeric microspheres which rapidly degrade and offer a
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Mar-April 1997
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route to the oral administration of bioactive materials. Examples include dicumerol
anticoagulant, the peptide insulin, and a DNA plasmid containing a gene used as a
marker in DNA vector systems. The latter offer the potential for delivering DNA
into cells for gene therapy. At the present time none of these can be given orally.
Oral uptake is improved by encapsulating the drugs in polymers that adhere to the
lining of the stomach and intestines. Encapsulation with a bioadhesive polymer
allows the capsule to reside in the gastrointestinal tract longer and via controlled
release allows more drug molecules to diffuse from it through the intestinal walls.
Meanwhile, encapsulation protects the drug molecules from degradation in the
harsh environment of the gastrointestinal tract. Mathiowitz uses hydrophobic
polymers containing surface carboxylic acid groups. These polymers have the
advantage that they biodegrade into nontoxic byproducts and can be made into very
small and tailored microspheres. Optical and electron microscopic techniques
showed that microspheres < 2 m are most effective in adhesion, mobility, and
adsorption into the circulatory system. The phase-inversion nanoencapsultion
process generates microspheres in the 0.1-5 m size range. This process allows for
the spontaneous encapsulation of sensitive molecules such as proteins or DNA in
very small particles without affecting the structure of the molecules. This important
work could lead to oral gene therapy and drug delivery that was not possible
heretofore. (Nature, 386, 410, 1997)
Smart/Functional Polymers-A new light-emitting diode was developed from a blend of
a fluorine containing carbazole copolymer, and poly(vinylcarbazole) which transforms the
electro- luminescence spectrum from that of white light to a fine blue color.

J. Kim and coworkers at The Korea Institute of Science & Technology in
Seoul have developed an alternating copolymer composed of 9,9’-dihexylfluorene
and N-(ethylhexyl) carbazole for use as an emissive polymer in a light-emitting
diode (LED). The copolymer is soluble in organic solvents and spin-casts to make a
good film. An LED fabricated by sandwiching the alternating copolymer between
indium-tin oxide and Al emits a white color with the full width at half max. of 150
nm. The electroluminescence spectrum becomes simplified to have an emission
peak at 460 nm. for fine blue color when the copolymer is blended with
poly(vinylcarbazole) with a ratio of 1 to 4 before use as an emissive layer. The
forward bias turn-on voltage for the LED is 13, and quantum efficiency is
0.002%.[Polym. Bull. (Berlin), 38, 169, 1997]
Alloys & Blends-Important work continues worldwide including compatibilization of
nylon 6/polyethersulfone blends (S. Korea), and unique crystalline/amorphous PET blends
(Greece).
PEL Updates
Mar-April 1997
Page 4

T. Ahn and coworkers at Seoul National University, S. Korea have synthesized
block copolymer compatibilizers of nylon 6/polyethersulfone (PES)/nylon 6 by
anionic polymerization of -caprolactam using chlorine terminated PES, as a
polymeric activator. The structure and properties of the block polymers were
examined using IR, NMR, DSC, TEM and TGA. The compatibilizing effects of
the block copolymer on PES/nylon 6 blends were investigated by examining
thermal properties, morphology and dynamic mechanical characteristics. When the
block polymer was added, the size of the dispersed phase in the blend decreased
dramatically, and the glass transition temperatures of the constituent polymers
converge. The improvement of dynamic tensile modulus and thermal resistance
due to the dispersed PES phase was enhanced. (Polymer, 38, 207, 1997)

In interesting work from N. Kalfoglou and coworkers at Patra U. in Patra,
Greece, the compatibility behavior of melt-mixed blends of an amorphous
copolyester (ethylene glycol-cyclohexane-1,4-dimethanol-terephthalic acid
copolymer), (PETG) with poly(ethylene terephthalate) (PET), was investigated over
the complete composition range. The techniques applied were dynamic mechanical
analysis, tensile testing and differential scanning calorimetry. The effect of thermal
history was also examined. In quenched blends tensile properties were good in all
compositions. Suitable treatment of thermal data allowed for the determination of
the polymer-polymer interaction parameter 12 whose value supports the view that
the blend is miscible at increased PETG levels. (Polymer, 38, 631, 1997)
Alloy & Blend Patents-Among 1,050 patents evaluated during this period, key
developments include: a process for new PET/PEN bottle compositions, tough and
transparent amorphous copolyesters and blends, new compatible polyolefin graft
copolymer/polycarbonate blends, and recycled compact disk/polycarbonate blend
compositions for molded products.

“Injection Molding Of Hollow Containers From Poly(ethylene terephthalate)
and Poly(ethylene naphthalenedicarboxylate) Compositions”, Y. Yoshida et al,
(Teijin Ltd) JP 08,309,833, Nov. 26, 1996. The process for the preparation of
transparent containers (bottles), is carried out by mixing poly(ethylene
terephthalate) and poly(ethylene naphthal-enedicarboxylate) compositions at 260340C for 100-220 sec. in an injection cylinder and injection blow-molding, wherein
the melted compositions satisfy with one or both of the two given process
conditions. (Chem. Abs. 126: 105077d).

“Cyclobutanediol-Based Copolyester Compositions With Superior Impact
Resistance And Transparency”, D. R. Kelsey, (Shell Internationale Research
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Mar-April 1997
Page 5
Maatschappij B.V.), EP 745,628, Dec. 4, 1996. An amorphous copolyester is
prepared by polymerizing an aromatic dicarboxylic acid, ester, or anhydride with
2,2,4,4-tetraalkyl-1,3-cyclobutanediol, and optionally alkylene diols. Thus, di-Me
terephthalate, 1,3-propanediol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol are
copolymerized in the presence of Bu2SnO. Injection molded articles prepared from
the polyester exhibit less yellowness, low shrinkage, and improved toughness, and
can be blended with polycarbonates, and other polyesters. (Chem. Abs. 126:
0227b).

“Blends Of Polyolefin Graft Copolymers And Polycarbonates Having Good
Compatibility And Physical Properties”, A. Denicola et al, (Montell North
America), EP 745,647, Dec. 4, 1996. Title blend comprises (a) ~94-30% graft
copolymer of propylene and monomers being selected from the group consisting of
(i) styrene and acrylonitrile, and (ii) styrene and maleic anhydride or alphamethylstyrene, styrene and maleic anhydride, (b) ~5-40% > 1 aromatic
polycarbonate, and (c) ~1-15% > 1 aliphatic polyester, optionally also ~5-20% > 1
rubber components, ~1-50% a propylene polymer material or both. A blend of
acrylonitrile-propylene-styrene graft copolymer 68.25, Calibre 302-22 bisphenol
polycarbonate 29.25, and polycaprolactone 2.5 parts had notched Izod impact
strength 1.13 ft-lb/in, tensile yield 6910 lb/in2 , flexural strength 11,830 lb/in2,
elongation at break 14.3%, and Rockwell Hardness 111. (Chem. Abs. 126:
90210r).

“Aromatic Polycarbonate Compositions Containing Waste Compact Disks
And Molded Products Thereof Showing Metallic Appearance”, T. Oda et al,
(Teijin Chemicals Ltd), JP 08,311,326, Nov. 26, 1996. The compositions contain
(A) mixtures of 10-100% of pulverized compact disks whose substrates are
aromatic polycarbonates and 0-90% aromatic polycarbonates and (B) thermoplastic
graft copolymers comprising diene rubber components grafted with aromatic vinyl
compounds and vinyl cyanides at A:B 15-95:5-85. Alternatively, the compositions
contain 100 parts of 20:80-95:5 A-B mixtures and 1-10 parts of (C) elastic
polymers. Alternatively, the compositions contain 100 parts of A and
3-20 parts of C. Pulverized compact disks (containing 99.6% aromatic
polycarbonate prepared from bisphenol A) 70, Santac UT 61 (ABS resin) 30,
Me3PO4 0.05, and MA 100 (carbon black) 0.05%, were mixed, pelletized and
injection molded to give test pieces showing melt flow rate 18.5 g/10 min, impact
strength 5.0 kg-cm/cm, deflection temperature under load of 115C, and metallic
appearance. (Chem. Abs. 126: 132229m).

_______________________________________________________________________
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Mar-April 1997
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Dr. Mort Wallach has over twenty-five years experience in the plastics industry beginning
at DuPont’s Experimental Station, and ranging from resin, film, and plastic manufacture, to
consumer products, transportation and aerospace. His contributions include twenty-two
publications, numerous patents, and key roles in commercial developments, such as Kapton
polyimide film, high performance composites, novel consumer products, and engineered
materials. Presently, he is President of PEL Associates, a successful consulting firm in
polymer/plastics science and technology. He is a member of: ACS, SPE, IUPAC, Sigma
Xi, and The Boston Computer Society. Dr. Wallach is affiliated with: Teltech Network of
Experts, UNIDO Roster of Experts, The NIH Consulting File, Massachusetts
Manufacturing Partnership, and PST International.
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PEL PLASTICS UPDATE highlights recent progress in key areas of polymer/plastics
technology including: catalysis, biopolymers, smart/functional polymers, alloys & blends
and polymer modification.