10. November 2015   7:46 pm
Wally Hansen

Wally Hansen
Belmont, CA

Cleaning, wetting, and surface activation is necessary to guarantee robust and reliable adhesive bonding of plastic and composite materials.

In a previous post, We Have a Water Problem, liquid cleaning was shown to be an inferior choice due to consumable costs, process control issues, and energy required to clean and dry the parts or components. The old adage of, “You are only as clean as your last rinse,” is really true.

For bonding preparation of low-surface-energy plastics, adhesion promoters and primers are well known and have been a common choice for decades. The adhesive providers have done a good job in making these primers work for a wide variety of materials and applications. There are many approaches and chemistries offered, including aggressive acid or alkali etching and some aqueous systems.

However, the most common priming systems for plastics contain high percentages of solvents, such as toluene, acetone or methanol, with the addition of highly profitable “Pixie Dust” chemistry additives. These liquid solvents typically attack (solvate) the plastic surface leaving the “Pixie Dust” chemistry on the surface.

Keep in mind that when you purchase a consumable primer, you are mostly buying solvents, with their associated hazards and process inefficiencies. You own that chemical for its entire life cycle, from the receiving dock to emissions and hazardous waste streams. Again and again.

Other undesirable attributes of a wet priming process are application issues such as mixing and masking, and energy costs to apply and cure the primer.

Time to apply and cure the primer may be the worst deficiency of wet primers. I have detailed some of these issues directly from the MSDS and Data sheets of typical and popular liquid primers for plastics.


  1. HANDLING AND STORAGE – Store in cool, dark place preferably between 60-75 degrees, away from sparks, flames and sources of ignition. Storage conditions can adversely affect properties.
  2. HEALTH HAZARDS – EYES: Can cause severe irritation, redness and tearing.
  3. HEALTH HAZARDS – SKIN: Prolonged contact can cause severe irritation and rash.
  4. HEALTH HAZARDS – INHALATION: Can cause nasal and respiratory irritation dizziness, weakness, fatigue and nausea. Also can causes kidney damage, liver damage in lab animals with chronic expos.
  5. FIRE/EXPLOSION HAZARDS: Vapors are heavier than air & may travel along ground and be ignited by pilot lights, other flames or sparks.
  6. SPILLS: Eliminate all possible sources of ignition such as pilot lights and flames. Absorb liquid. Stop spill at source.
  7. STABILITY/MATERIALS TO AVOID: Avoid contact with strong oxidizing agents. May form toxic materials such as carbon monoxide, various hydrogens and nitrogen compounds.
  8. WASTE DISPOSAL: Destroy by liquid incineration or dispose in approved landfill in accordance with local, state, and federal regulations.
  9. TIME: Apply and cure per instructions. Wait and watch it dry. Do you really have the time to prime?
  10. THERE IS A BETTER WAY: Plasmatreat’s Openair® Atmospheric Plasma cleaning and activation can replace wet primers. Using only compressed air and electricity, Openair® priming activation is fast, touchless and dry.

Save Time

Stay Dry

-Wally Hansen

22. October 2015   11:15 am
Andy Stecher

Andy Stecher
Elgin, IL

Photo courtesy Plasmatreat.

Photo courtesy Plasmatreat.


The World Solar Challenge, taking place this week in Australia, features hyper-efficient solar cars traveling from Darwin to Adelaide—some 3000 kilometers (over 1800 miles) to the south. The event represents the ultimate in automotive lightweighting. As the World Solar Challenge website notes:

It’s all about energy management! Based on the original notion that a 1000W car would complete the journey in 50 hours, solar cars are allowed a nominal 5kW hours of stored energy, which is 10% of that theoretical figure. All other energy must come from the sun or be recovered from the kinetic energy of the vehicle.

Plasmatreat is thrilled to have a horse in this race, so to speak. Atmospheric plasma pretreatment of carbon-fiber-reinforced plastic (CFRP) components for the Punch Powertrain Solar Team’s racing car, Punch One, is an integral part of the car’s speed and strength.

Stiffening ribs in previous iterations of the car, necessary to protect it from strong race-condition vibrations, had been laminated—but this process required multiple layers and lengths of prepeg strips, a labor-intensive process  that also increased weight. Plasma pretreatment enabled the use of Loctite EA 466 instead, a fast-curing two-component epoxy resin adhesive.

The production manager of the 16-strong solar car team – who is just 23 years old – enthusiastically backs his team’s decision to use atmospheric pressure plasma in the new car to improve the adhesion of the CFRP components. This approach not only greatly reduced the time taken to pretreat the CFRP, but also achieved a 3 kg weight savings compared with the previous method.

CFRP is 60 percent lighter than steel and around 30 percent lighter than aluminum, but extremely stable. The total weight of Punch One is just 165 kg (around 364 lbs.), with the heaviest single component being the solar battery.

Needless to say, we are excited and proud to cheer on our contender as it traverses Australia this week. Go Punch One!

Category: Miscellaneous
15. October 2015   8:17 pm
Andy Stecher

Andy Stecher
Elgin, IL

In 1998, Plasmatreat launched the very first Openair® plasma jet for inline surface treatment. This technology was a revolutionary new approach in industrial assembly operations to improve bonding and facilitate perfect adhesion of materials such as non-polar Elastomers.

Since then, thousands of Openair® plasma systems have been installed and operating around the globe. Systems with up to 16 plasma jets can be positioned around complex profile shapes for complete, fast inline treatment. However, treating job runs of irregularly shaped profiles in small quantities has remained a time-consuming challenge—until now.

The new Openair® Plasma Automatic Profile System, PlasmaXCT, is fully automated and controlled by a high-performance XYZ-axis. All plasma jet positions can be programmed for precise applications and then permanently kept as “recipes” that are easily accessible through the HMI. Calling up these recipes allows any operator to effortlessly precision-adjust the plasma jets in 2 minutes or less.

The result: A reproducible, safe, and high-quality surface treatment. You can see a brief demonstration of how it works on our Plasmatreat YouTube channel .

For a more in-depth presentation, we’d like to cordially invite you to an online Product Feature Exposition on Tuesday, October 20th, hosted by our colleagues in Europe:

  • 11 am Eastern/ 10 am Central U.S. Daylight Time
  • (5 pm Central European Standard Time)


Just click here to register. We hope to see you there!

Category: Miscellaneous
9. October 2015   5:19 am
Andy Stecher

Andy Stecher
Elgin, IL

Just a quick note today to let you know about Surface Science Corner, a recurring feature here on the PlasmaBlog courtesy of Professors K.L. Mittal and Robert H. Lacombe.

Drs. Mittal and Lacombe write fascinating, in-depth pieces for us on the science behind plasma technology. Their most recent installment has the dual purpose of presenting a book review on the recently published Adhesion Science: Principles and Practice while simultaneously diving into the ubiquitous world of adhesives technology. It’s an illuminating read.

We are lucky to have the expertise of Drs. Mittal and Lacombe in our corner, in addition to the fine talent we possess in house. As always, please let us know if you have any manufacturing challenges—adhesion-related or otherwise—that Plasmatreat’s technologies may be able to help with.

Dr. K. L. Mittal, Dr. Robert H. Lacombe

Dr. K. L. Mittal, Dr. Robert H. Lacombe

Editorial September 2015

This issue of the SURFACE SCIENCE CORNER has the dual purpose of presenting a book review on a recently published volume while simultaneously having a look at the amazingly ubiquitous world of adhesives technology. The volume in question is:

Steven Abbott, (DEStech Publications, Inc., 2015)

Though the title would give the impression of dealing with the broad topic of adhesion science the volume is in fact closely focused on the topic of adhesives technology. This is not only a good thing but a necessary one also since dealing with the general topic of adhesion would require an encyclopedia series as opposed to a relatively compact volume.

What struck me most upon reading the volume was the amazing ubiquity of adhesive applications which we encounter in our everyday lives and the broad range of thermal-mechanical requirements that these applications require. Have a look around your local supermarket if you are not convinced about pervasiveness of adhesives in our day to day lives. Every glass jar has an adhesive attaching the label, every cardboard box is held together with an adhesive, all the bubble pack packages containing everything from paperclips to cutlery are sealed with an adhesive. Even going over to the fresh produce tables with fruits and vegetables laid out completely bare of any packaging materials whatever one finds sneaky little labels adhered to nearly everything with the items PLU code printed on it. It is not an exaggeration to say that the entire contents of the store are held together with an adhesive of one kind or another.

Looking around my office I see the ever present Postit® notes plastered on nearly every vertical and horizontal surface as well as interleaving the pages of most of the volumes on my bookshelf. Thinking about it one realizes the that the Postit note is a rather remarkable technology in that the note must adhere quickly to a broad range of surfaces without any surface pretreatment whatever and must also be cleanly removable without damaging the surface in question. Thus the Postit note puts a stake in the ground at one end of the adhesive performance spectrum which requires rapid easily reversed adhesion to a wide range of surfaces without regard to any sort of surface treatment other than perhaps blowing off some dust.

Going to the other end of the spectrum we find the adhesives which are used to glue together high performance aircraft. The requirements for this application are totally the opposite from those of the Postit note. All surfaces are carefully cleaned and treated with special primers. Maximal joint strength is required over a wide range of temperature and environment conditions giving a bond that needs to be totally irreversible.

Sitting between the extremes of the Postit note and aircraft glue is a vast range of intermediate applications ranging from gluing together the common cereal box to gluing the windshield onto your automobile. Consider the cereal box. Here fairly strong adhesion is required since the container cannot fall apart too easily but the adhesion cannot be too strong since the consumer has to be able to open the package without excessive force. On top of these requirements the adhesive material must be inexpensive and easily applied without surface preparation since the manufacturing volumes involved are enormous.

The case of adhering to windshield glass presents an entirely different set of requirements. In case you are not aware, many windshields in the newer car models are glued to the frame. Not only that but you also find that the rearview mirror is also glued to the glass. I can attest directly to this fact since the rearview mirror on my car fell off recently and needed to be reattached. The requirements here are dramatically opposite to the cereal box. First the bond must be permanent. Second the bond must withstand a wide range of temperature cycling from say 10 degrees F below zero in Winter to over 100 F in summer for a vehicle parked in the sun. Third the adhesive must withstand extensive exposure to ultra violet radiation from the sun. Given these requirements I thought it best to go to the auto parts store and purchase an adhesive specially formulated for attaching rearview mirrors.

The procedure for attaching my mirror was more like using aircraft glue than bonding a cereal box. First the glass and the attachment button were cleaned with acetone to remove all residual adhesive. Second a primer layer had to be applied to the glass and allowed to set for a specific time. Finally I was directed to apply only a thin layer of the adhesive to the attachment button which was then pressed in place for a full minute to get initial attachment. An hour or so or curing time was needed to achieve full strength before the mirror could be attached to the button.

Getting back to the volume under review it is clear upon cursory reading that the author has spent considerable time in the adhesives formulation business. The table of contents gives an indication of the flavor of the topics covered:
1. Some basics: Reviews the rudiments of adhesion measurement and adhesion failure mechanisms.
2. The Myths around Surface Energy and Roughness: An entertainingly provocative review of the concepts of surface energy and surface roughness as applied to adhesives technology.
3. Intermingling and Entanglement: Brings into focus the critically important role of the adhesive bulk properties on its adhesion performance. In particular the crucial role of polymer molecular weight and chain segment mobility are discussed in regard to achieving high adhesion strength.
4. Time is the Same as Temperature: Discusses the critical importance of the concept of Time Temperature Superposition in determining the thermal-mechanical properties of all adhesive formulations.
5. Strong Adhesion with a Weak Interface: Review of the important topic of pressure sensitive adhesives.
6. Formulating for Compatibility: Discusses the importance of polymer solution thermodynamics in the development of adhesive formulations.
7. Measuring Adhesion: Perils and Pitfalls: Gives a review of the most common adhesion measurement methods used for evaluating adhesive formulations.
8. Putting Things into Practice: Gives a comprehensive summary of how all the above topics can work together in the “scientific” design of adhesive formulations.

Topics 2 and 3 above are of most interest to the subject of applying plasma technology to improving adhesion to polymer substrates. The essential point of chapter 2 is that the role of surface energy in promoting adhesion to crystalline polymers is basically misunderstood. It is well known that it is difficult to adhere anything to crystalline polymers such as poly(ethylene) PE, poly(ethylene-terepthalate) PET and poly(propylene) PP. It is also well known that plasma treatment greatly improves the adhesibility of all of these materials. The question is what is going on?

The standard answer is that plasma treatment is improving the surface energy of these materials thus allowing greater wetting as well as stronger interactions at the interface via the creation of functional groups. The author argues persuasively that this is unlikely to be the case. Looking at polyethylene for example, standard analysis reveals the surface energy to be roughly 32 mJ/m2 (milli joules per square meter). Plasma treatment will typically raise the surface energy to something like 42 mJ/m2 or about a 30% increase. This figure, however, does not square with the observed increase in peel test adhesion which can be in the range of 10 to 100 J/m2 (joules per square meter) or several orders of magnitude larger than the increase in surface energy.

Further suspicion is cast on the surface energy argument by the comparison of poly(ethylene terephthalate)PET to poly(vinyl chloride) PVC. The surface energies of these two polymers are close to 43 mJ/m2 but it is well known that it is difficult to adhere to PET compared to PVC. Again we have wonder what is going on?

A clue begins to emerge in the case of PE. This polymer comes in two basic forms one of low density LDPE and one of high density HDPE. The high density form is essentially one long completely linear chain of CH units and therefore tends to be highly crystalline. The low density form, however, is composed of linear strings of CH units broken up at intervals by short side chains of CH units terminating in a CH3 group. The many side chains of the LDPE prevent it from attaining the same level of crystallinity as its HDPE cousin thus resulting in lower density. It is also known that it is easier to adhere to low density PE than the high density form. If we combine this with the fact that the poorly adhesionable PET is a highly crystalline polymer and the easily adhesionable PVC is totally amorphous then we have to suspect that it is the level of crystallinity that is key in determining adhesability.

It is at this point that the mechanisms of chain intermingling and chain entanglement enter the picture. In essence amorphous polymers have a high degree of chain segment mobility which allows them to interpenetrate and form entanglements which give rise to high levels of energy dissipation when trying to pull them apart. Think of trying to pull part two lengths of string that have been randomly jumbled together. It is these strongly dissipative effects that give rise to the apparent strong adhesion observed in peeling apart these intermingled and entangled layers.

Now the question becomes what is the role of plasma treatment in improving the adhesionability of crystalline polymers? Aside from improving the wettability of the treated surface the most obvious mechanism is the disruption of the surface crystalline layers of the polymer. Plasma treatment always involves the making and breaking of chemical bonds and in the case of crystalline polymers we postulate that the plasma field breaks up a significant amount of surface crystallinity creating an amorphous layer with highly mobile chain segments capable of intermingling and entangling with applied surface layers. The existing level of surface energy must be sufficient to allow for a reasonable amount of wetting, but beyond that it does not add significantly to the overall peel removal energy which is dominated by the dissipative effects of chain interpenetration and entanglement.

Prof. Abbott points out that the adhesion mechanisms described above have a strong influence on how the typical adhesive is formulated. The redoubtable formulator is generally faced with the prospect of joining two poorly or wholly uncharacterized surfaces and his customer wants an inexpensive and easily applied glue that will hold these surfaces together with just the right amount of strength and durability called for. He has to assume that the surface energies will be in a reasonable range to give sufficient wetting without the need to perform any sort of involved surface analysis or surface preparation aside from a perfunctory cleaning. Plasma treatment will be a very handy tool when dealing with difficult surfaces such as the crystalline polymers but it must be remembered that all that is required is to sufficiently break up the crystallinity of just the top most surface layer in order to get chain interpenetration. Over treatment must be avoided so that one does not create a layer low molecular weight rubble that could act as a weak boundary layer and thus give even poorer adhesion than the original untreated surface.

As luck would have it not only did my rearview mirror fall off but also the soles of my cycling shoes delaminated. Thus I got to try out a totally different kind of adhesive from what I used to attach my mirror. Commonly called shoe goo it is apparently some kind of silicone polymer formulation. No surface preparation is required other than blowing out any loosely adhered debris. Contrary to the rearview mirror formulation there is no primer layer required and the glue is applied in a fairly thick layer and spread out as evenly as possible with a stick to give good coverage and penetration into all the nooks and crannies of the mating surfaces. After application of the glue I pressed together the mating surfaces under the weight of an inverted 10 pound sledge hammer in order to make maximal contact and then allowed everything to set and cure over a period of a day or two.

Thus the world of adhesives turns out not only to be very commonplace in our day to day lives but also rather subtle, deceptive and non-intuitive in terms of the science and technology required to create truly effective and useful formulations. The requirements from one application to another can be diametrically opposite and the formulator has but a limited number of theoretical tools available which must be carefully handled. The reader interested in further exploring this most engaging topic is encourage to refer to Prof. Abbott’s fine volume.

For my part I can confirm that both my rearview mirror and cycling shoes remain completely intact. So despite the subtle and intricate nature of adhesive technology good adhesives are available for nearly all practical purposes and Prof. Abbot’s volume is a most instructive guide for anyone faced with the problem of developing a working adhesive.

The author is happy to entertain any questions or comments concerning this topic and may be contacted at the coordinates below.

Dr. Robert H. Lacombe
Materials Science and Technology
3 Hammer Drive
Hopewell Junction, NY 12533-6124
Tel. 845-897-1654; 845-592-1963
FAX 212-656-1016
E-mail: rhlacombe@compuserve.com

24. September 2015   2:00 pm
Andy Stecher

Andy Stecher
Elgin, IL

We have lots of exciting news around here these days. As I mentioned in my last post, Plasmatreat turned 20 on September 1.

In addition to this big milestone, Plasmatreat has also just been honored as one of the 100 “Best of German Mittelstand” companies at the 2015 Ambassadors’ Conference hosted by the German Foreign Office in Berlin. (In this context, “Mittelstand” refers to the small and mid-sized German companies that have achieved global market-leader status in their respective sectors.)

Closer to home, we are shaking things up with a move to a larger and better equipped facility in the East Bay for our California-based division. Stay tuned for more details once we get settled.

Despite the upheaval of the impending move, Khoren Sahagian, our Senior Applications Manager, has just written a new post that helps you cross-correlate a water contact angle and dyne surface tension.  I encourage you to give it a read if you’re trying to calculate surface energy for wettability or adhesion purposes.

Finally, last but certainly not least, Plasmatreat North America has appointed Mercedes Tur Escriva as Territory Manager for Mexico and Central America. She has over 15 years’ experience working with clients in the area of industrial surface treatment technologies, and we are excited to offer our Spanish-speaking prospects a fast response and assistance in their native language. Welcome to the team, Mercedes!

Until next time, we hope your autumn is as busy and productive as ours has been so far.

23. September 2015   5:49 am
Khoren Sahagian

Khoren Sahagian

Contact angle and dyne inks are commonly accepted methods for probing surface energy. Surface energy is a good first indicator of a clean, bondable, or wettable surface.

For typical plastic and composite materials, the surface begins with low surface energy or a high water contact angle. Aqueous solutions and many adhesives have difficulty wetting onto materials with low surface energy.

Plasma processing incorporates the surface with reactive groups that promote wetting and adhesion. But not every material responds the same to every plasma treatment. With some materials, you have to find the correct plasma gas or plasma source to achieve the desired response. A contact angle or dyne ink will quickly show you if you have that response, or if you should try a different variable.

Brighton Technologies in Cincinnati, Ohio has created a graph that cross-correlates between a water contact angle (WCA) and dyne surface tension mN/m, which they have allowed us to reproduce here. This is helpful for those trying to replace their dyne inks, or those who wish to convert their contact angle data into an engineering unit.

We hope it’s helpful to you (click on the chart to expand it).


Category: Miscellaneous
17. September 2015   2:02 pm
Andy Stecher

Andy Stecher
Elgin, IL

On September 1, Plasmatreat turned a very proud 20 years of age—a true entrepreneurial success story that I, and my team, are extremely proud to be part of. We appreciate all of your support and could not have done it without you!

The company was launched by Christian Buske (our current CEO) and Peter Foensel back in 1995, and our very first customer was Hella Headlamps. Fast-forward twenty years, and we are now a global leader for all kinds of plasma surface treatment technologies with subsidiaries and representation in over 20 countries all over the world.

Earlier this month, I was among 300 employees, spouses, customers, suppliers, and friends who gathered together in Germany for the 20th anniversary celebration. It was a very inspiring, fun evening, and I’ve attached a few photos.



As I mentioned earlier, we owe our success to you and are deeply grateful for your business and your belief in our technology. Thank you. Plasma’s applications are growing every day, and we’re excited to be a longstanding pioneer in this industry.

To the next 20 years and beyond!

27. August 2015   3:56 pm
Andy Stecher

Andy Stecher
Elgin, IL


Nondisclosure agreements often prevent me from sharing the details of many of our exciting developments—understandable yet frustrating!—but today I am pleased to talk in a general sense about an application that has the potential to improve the daily lives of countless people (and animals) around the world.

Plasma can improve the “wettability” of microsampling devices used to collect fluids for lab analysis, including well water, waste water, blood, tears, and synovial fluid.

Companies are using gas plasma in manufacturing to develop new devices that can quickly and consistently collect a fixed volume of the fluid to be tested. No special skill is required to collect the sample, and once the fluid’s analyte has dried on the tip, it can later be extracted using common solvents and analyzed—no centrifuge, transfer, or freezing are required.

Samples obtained in this manner are minimally invasive, resulting in less trauma to test subjects (including children and laboratory animals). Additionally, as compared with wet samples, samples obtained in this manner are easy to ship via regular mail as no dry ice or expedited delivery are needed to preserve the samples’ integrity.

This also means that people around the world, even in very remote areas, can participate in groundbreaking—and potentially life-saving—medical studies.

Amazing and inspiring stuff indeed!

Oftentimes, industry engineers are not fully aware of all the options (both in service and technology) Plasmatreat offers. But we have the infrastructure in application support and continue to strengthen it to support solution developments in the medical and life sciences markets—as well as many others.

As always, please feel free to get in touch if we can provide any additional information for you.

Category: Aerospace
13. August 2015   2:00 pm
Andy Stecher

Andy Stecher
Elgin, IL



I’ve been doing a lot of traveling lately (primarily for work, but some pleasure, too), so airplanes have been on my mind as I’ve been spending much of my time aloft!

Plasmatreat’s Openair technology plays a key role in the safe and stable adhesion of coatings and bondings on aircraft components made of carbon-fiber reinforced plastics, as well as metals and composites.

What’s great about this technology, in addition to its reliability, is the fact that it’s both environmentally friendly and cost-effective. It’s also suitable for treatment of airplane parts of all sizes, from the very smallest (including those with complex geometries) all the way up to huge wings and fuselage components.

How does it work? The process is threefold: Plasma activates a surface via selective oxidation processes, eliminates static charges, and cleans at a microfine level. Our laboratory trials have revealed that surface energy values of more than 72 dyne are achievable, leading to improved bonding and enabling adhesion of water-based adhesive or paint systems to traditionally adhesive-resistant surfaces.

If you’d like more details on the process, please check out our article in the June 2015 issue of Products Finishing magazine. We’re always happy to answer any questions you may have at our end, too.