Air-intake ducts are now made from Forprene, a PP/EPDM   TPV. The TPVs were developed in Italy by So.F.teR, but are now available   in the U.S. through a joint venture with M.A. Hanna Co.

Air-intake ducts are now made from Forprene, a PP/EPDM TPV. The TPVs were developed in Italy by So.F.teR, but are now available in the U.S. through a joint venture with M.A. Hanna Co.


A new family of thermoplastic-metal composites, Polymetals, are poised to replace lead and other high-gravity metallics. Potential uses include radiation shielding for nuclear medicine, medical imaging, and radiation therapy; weighting and ballast applications for industrial machinery, sporting goods, and instrumentation; and nontoxic projectile inserts for small-caliber ammunition.

The high-density composite, called Ecomass, consists of powdered tungsten dispersed in a thermo-plastic matrix. The composite provides a high level of radiation shielding and dense mass comparable to lead without the negative health effects and environ-mental concerns over toxicity. Currently, eight Eco-mass compounds are commercially available, ranging in specific gravity from 6.0 to 11.0 gm/cc. A special radiation-shielding formulation is said to provide shielding efficiency comparable to lead with approximately only two-thirds the density.

Another resin system crosses the Atlantic after a successful 15-yr run in Europe. Forprene, a thermo-plastic vulcanate (TPV) elastomer, expands M.A. Hanna's Co., Cleveland, portfolio of thermoplastic elastomers (TPEs). The Forprene TPV compounds consist of a polyolefin phase with a cross-linked ethylene-propylene-diene monomer (EPDM) rubber phase dispersed throughout. The TPV has rubberlike properties such as softness, elastic memory, and flexibility, but is melt processible.

The Forprene product line covers a broad hardness range extending from Shore 35A to 60D. Resins are tailored for injection and blow molding, extrusion, and calendering. Special grades are stabilized against heat, copper, and UV degradation, while others are flame resistant, high-flow, and antifogging.

Hanna also debuts a new line of thermally conductive composites under the Edgetek family of high-performance compounds. Called Therma-tech they sport a high coefficient of thermal conductivity and target thermal management applications. Custom-molded heat sinks on circuit boards, and innovative heat exchangers in appliances, telecommunication devices, business machines, and other related industrial equipment are possible.

The easily recyclable compounds are designed to replace metal and nonrecyclable metallized plastics in shrouds, heat sinks, thermostats, heat exchangers, and radiant heating coils. Thermal qualities are said to rival those of commonly used metals such as steel, tin, and aluminum. Other formulations combine both thermal and electrical conductivity, permitting both heat dissipation and electrical management in a single part.

Typical mechanical properties of standard-grade Forprene TPV
PROPERTY
TEST METHOD
A35
A45
A55
A65
A75
A85
Hardness @15 sec, Shore A
ASTM D 2240
38
47
57
67
77
87
Tensile strength, psi
ASTM D 412-C
580
754
811
956
1,160
1,594
Elongation at break, %
ASTM D 412-C
550
500
450
450
460
510
Modulus at 100%, psi
ASTM D 412-C
145
203
246
333
449
652
Modulus at 300%, psi
ASTM D 412-C
304
377
464
565
623
870

Typical physical properties of Ecomass NJ-96TP/000
PHYSICAL PROPERTY
TEST
NJ-96TP/000
Density, gm/cm 3
D-792
11.0
Melt point, °F
D-789
351
Flexural modulus, psi
D-790
790,000
Tensile strength, psi
D-638
6,000
Ultimate elongation, %
D-638
< 1.0
Deflection temperature @264 psi, °F
D-648
311
(High-density thermoplastic, nontoxic alternative to lead)

Preliminary mechanical properties of Therma-Tech composites
PROPERTY
TEST METHOD
LC-6000 TC
(Thermally conductive liquid-crystal polymer, LCP)
NY-4515 TC
(Thermally conductive nylon 6)
Tensile strength, psi
D638
15,100
15,544
Tensile elongation, %
D638
0.9
0.53
Tensile modulus, psi
D638
5,400,000
75.520
Flexural strength, psi
D790
2,600
27,150
Flexural modulus, psi
D790
4,300,000
29,785

M.A. Hanna Co., 200 Public Square, Suite 36-5000, Cleveland, OH 44114, (216) 589-4000, www.mahanna.com