Tech Talk Blog

Mid-winter is the thick of flu season, and in this age of H1N1, we are all aware that germs on the hands can spread bacteria that cause infection, disease and even food-borne illness.  In fact, the CDC reports that flu viruses can survive for several hours on hard surfaces we touch all the time, such as doorknobs and shopping carts.

But what if there were a permanent treatment for inanimate surfaces to help us avoid — and even eliminate — the spread of bacteria, pathogens, and viruses?  Our R&D team is at work on such a solution.

Although still in the testing stage, our propylene additive will have a permanent anti-bacterial and anti-fungal effect on hard surfaces.  The key to remaining germ-free?  A nano silver additive that keeps hard surfaces hygienic indefinitely.

Look for more information to follow.

Our team is designing a lens that must withstand military extremes such as salt spray, fog, humidity and temperature.  The coating must be abrasion-resistant and anti-reflective – what is the best treatment?

This is a great question — and a multi-step process. Assuming your lens is a polymer lens like polycarbonate or CR-39, currently there is no single surface treatment for both anti-abrasion and anti-reflective (AR) properties.  Instead, one would apply the anti-abrasion coating first, followed by the AR process, which is done in a vacuum for a uniform and consistent result.

Your abrasion-resistant coating options include:

A)    Polyurethane  – This usually is the most economical coating, which is applied by either sprayed or dip method. This is a popular treatment for end user ophthalmics, but also has the least durability and longevity.

B)    DLC (Diamond-like coating) – An extremely hard, durable coating, that is relatively expensive, but most effective for high-end users.  DLC ensures high-performance and impact-resistance as the resulting surface is very close to the hardness of diamond.

Our team can help you explore your best solution.

What is the best process for removing silicone oil from a catheter made of Pebax® tubing prior to a bonding operation?  Would you use plasma or corona?

Your question is one that we are seeing more frequently. And the short answer is that it all depends on the amount of oil.

If you can see a significant oil collection, then you need to wash the tubing in an ultrasonic bath with an emulsifier. Then, you may simply wipe the tubing with an alcohol wipe to remove any excess. It really depends on the level of contamination. Generally speaking, I’ve found that catheters have a superficial level of oil.

If the amount of oil is superficial, plasma can carry away the excess oil via a specific oxygen treatment. We do not advise corona treatment for this application, since it can make the silicone hydrophilic and give a false impression of being clean. Plasma is a more elegant solution and will “superclean” the surface to promote better adhesion.  Learn how we recently solved this challenge.

Previous blog addressed importance of crystallinity control on PTFE as it relates to porosity, changes in physical strength and dielectric values. More Tri Star testing has shown better detail on the effects of processing and crystallinity. Specific gravity is the primary gage of crystalline or amorphous stages of polymers. In the case of PTFE the range is generally between 2.1 and 2.3 for unfilled resin. Testing showed that at 2.1 SpG the crystallinity of the molded product was approximately 38%. At 2.13 it was 47%, 2.15- 53%, 2.17 – 60%, 2.2 – 70%. Remember, the higher the crystallinity the lower the flex life, higher compressive stress, lower recovery, more permeability and lower wear life.

Another part of the equation has to do with microvoids as it relates to crystallinity. Microvoids are generally a result of poor attention to preforming conditions and to a lesser extent the sintering process. Microvoids, or porosity, have a direct bearing on crystallinity. As an example, a low microvoid material at 2.13 SpG would be 47% crystalline. However, if processing problems occur and void content grows you could see a substantial increase in crystallinity.  At a 1% microvoid level the 2.13 sample at 47% crystallinity would increase to 53%. Doesn’t sound like much but could have a great influence on the properties and wear of the material. Additionally, at 1% void content the dielectric strength of the PTFE would drop from it’s normal 500 v/mil to 320 v/mil. This is significant when considering PTFE as a dielectric insulator. For more information on the importance of quality in PTFE, contact Tri Star via this blog site or our website @www.tstar.com.

There is a lot of talk these days about biodegradable plastics, renewable resources, carbon footprints and the like. It’s interesting that as companies look at the feasibility of biodegradable plastics they also look at how it affects the other aspects of the ecology. If it takes more energy and produces more negative effects on nature we have to be able to justify the efforts. Today’s bioplastics technology is catagorized several ways. There are pure bio polymers that are based on polylactides (fermented bacteria), cellulose ( naturally occuring wood product), lignin (a macromolecular by-product of paper), biopolymer blends (combination of bio sources) and finally polymer blends which utilize biomaterials and petroleum products.

Bioplastic products are further classified by either compostable or true biodegradable. Compostable bioplastics degrade by at least 90% within 6 months by natural environmental conditions; i.e. temperature, humidity and pH. This degradation occurs through typical composting breakdowns and the result is by-products such as water, carbon dioxide, methane and humus.  Some biodegradable polymers will break down through naturally occuring micro-organisms such as bacteria or fungi. Today, most of the bioplastics that fall into this category are packaging films and consumables but that is changing. More and more bioplastics are being developed with higher engineering potential. Materials that can withstand loads, can be extruded into shapes and molded or machined into finished parts for things as diverse as musical instruments to display panels in store fronts. It is also available in stock shapes such as rod, sheet, tube and custom profiles. Tri Star Plastics is working closely with bio-partners to develop more and more options in this interesting new world of bio-plastics. For more information on this technology, contact our Technical Department at www.tstar.com or send us a return blog! More interesting things on the way!

The Dixon M-Liners from Saint Gobain have become very difficult to obtain since they come from overseas. Tri Star is now offering a size for size equivalent product in it’s Tri Steel product line called Tri Steel PE. This product is a rolled steel backed polymer lined bearing. The polymer liner is a special PEEK/PTFE combination that has a thicker dimension  than normal steel backed bearings. This allows for post machining of the ID to tighter tolerances without removing the primary bearing source. Learn more from Tri Star’s website www.tstar.com and review the information on Tri Steel Bearings or watch our Tri Steel video on the Video Learning Center.

With the recent spike in air travel over the holidays, I was reminded of some of the aerospace materials that our team often treats, particularly foam. Foam is a common insulation material aboard aircraft, used to fill open crevices between the passenger compartment and the outer shell.  It serves a number of functions such as regulating temperature, reducing engine noise, and protecting the mechanical systems from moisture and temperature variations that may lead to corrosion.

Currently, micro-light fiberglass is used for aircraft insulation, but it has the tendency to absorb moisture, which can add substantial — and unwanted — weight to the craft.  A typical flight may consist of up to 1,500 lbs of water weight.

Our team is working on an alternative to fiberglass insulation . The following materials are foam products that offer good acoustic, insulative, and weight properties, but have a tendency to absorb moisture like the fiberglass. We treat these foam products to inhibit these properties:

1)      AC 530 — a polyimide material, is lightweight, fire resistant and offers thermal and noise insulation.  It is a flexible material, but holds its shape and conforms to structural inlay. But, this foam is prone to moisture absorption.

2)      Melamine foam — is also lightweight, fire resistant, and offers thermal and noise insulation. This foam is flexible and holds its shape and conforms to structural inlay. But, this foam will naturally absorb moisture particularly well.

Our hydrophobic process offers the distinct advantage of penetrating the entire surface of the material, unlike some processes that may sit only on the surface. Our process enhances the properties to form a better water-resistant property that inhibits the absorption of moisture maintaining the dry weight of the aircraft.

As always – if you are still burning with questions, Ask The Experts!