New resins make their debut at NPE 2000

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