Tech Talk Blog

Tivar® HOT is a good alternative when standard UHMW is unable to withstand your operating temperature.  As the name implies, it is engineered to withstand high operating temperatures up to 220°F.  It is a diverse material that can be modified to fit a broad scope of applications.

Tivar HOT has near-zero water absorption, so it can be used in scalding and submerged applications.  It gives superior wear and chemical resistance, offers good impact strength, low friction, and is self-lubricating. It is also incredibly abrasion-resistant.

Tivar is a good solution for food processing and packaging equipment.  It meets FDA/USDA guidelines and is 3A Compliant.  We see it used in the production of sugar and candy.  Also many industrial applications such as pipe saddles, hopper liners, and conveyor guides.

It is available in sheet, rod or tube form, can be made to order, and is easily machined.  We can custom fabricate a part to match your print.

UHMW Polyethylene is an interesting material in the polymer world.  It’s one of the lowest cost plastics on the market yet it offers some properties that few other polymers do. UHMW is best known for it’s abrasive wear resistance and impact strength but even within this small polymer family there are variations. UHMW stands for ultra high molecular weight and under this description UHMW is produced with a molecular weight range of 3.5 to 6 million. The molecular weight has a fairly dramatic impact on several key properties. For instance, a 4 million molecular weight grade has an abrasion resistance of 100 when measured using a sand slurry test. A 6 million molecular weight is 75 which is a further 25% improvement! Compare this with steel which has a resistance of 160 and you can see why UHMW is the material of choice for abrasive wear environments.

There are several other variations on UHMW including cross linked, glass and moly enhanced and even a high temperature grade.

Check out our Materials Resources Guide to see the entire selection.

Tivar HOT is a unique UHMW grade that has a dramatically higher continuous operating temperature (275F) than standard UHMW. Tivar HOT still has excellent wear and abrasion resistance, doesn’t absorb moisture, has excellent chemical resistance and meets FDA, USDA and 3A guidelines. We have found this product to be excellent for higher temperature zones in food processing and packaging equipment but it has also proven to be a great material in down-hole oil drilling applications!

Pretty diverse material. If you need excellent abrasion resistance, low friction, self lube bearing material with all of the other attributes mentioned, consider Tivar HOT from TriStar! And while you are looking around the site – stop by the Video Learning Center for some more information!

Gamma Radiation is commonly used to sterilize polymer devices. But some polymers do not hold up well to this form of sterilization.

The following plastics cannot be sterilized by radiation:

• Polyacetals (turns to dust)
• Polyacetals(turns to dust)
• Polypropylene (unstabilized)
• Teflon (turns to wax)
• PVDF

Polypropylene Syndrome

• Natural unstabilized PP undergoes a slow degradation process after irradiation where over two years the elongation may drop from 600% to zero and parts will shatter
• PP is both crosslinked and scissioned
• Embrittlement and discoloration can occur
• Radiation stable PP is available

 Polyethylene

• Polyethylene is predominantly crosslinked but acceptable to irradiation
• LDPE < LLDPE < HDPE < UHMWHDPE
• PE can be stabilized to make it gamma stable

If you are unsure if your material will hold up to this sterilization technique, please visit the TriStar Plastics Corp. website for contact information.

We have recently developed a new adhesive for UHMW adhesion. This adhesive is a hot melt adhesive with a glass transition (Tg) of -4 F and a shear failure at 246 F. This means that the hot melt adhesive can expand and contract with the UHMW when bonded to a rigid backing (i.e. UHMW bonded to steel). The use of mechanical fasteners to hold down large pieces of UHMW and the problems of buckling are nearly eliminated. Moreover, the UHMW needs only to be clean for the adhesive to work effectively; no surface treatments or special primers are needed. Our lab tests have shown bonding UHMW to steel in lap shear:

Max (psi) = 83.928         Break (psi) = 75.685     Ext @ Brk = 0.131 in

Other adhesive in development is a new epoxy designed for underwater applications to compliment our existing epoxy product line. Specifically, this underwater epoxy is engineered for submerged bearings for water treatment plants or anywhere where our bearing are used or exposed to water or washing.

You want to learn a little more about surface modification, right?

What say ‘ye?