A Day of Caring

We find it important to stay active in our communities, to do what we can as individuals and as a company to help those in need. Over the course of  two days, we had 18 employees take a leave from work and assist a local organization - Girl's Inc. - in converting their living room into a technology center.

"This new technology center will allow Girls, Inc to run classes surrounding cyber bullying, social media safety, and math/science/engineering," said Christina McMahon, Instron Assistant Controller. "The first day of our project was a huge success. The passion, leadership & teamwork I witnessed are a fundamental reason why I love working at Instron."

Girl's Inc has been providing mentoring and the building blocks for young women to succeed and be “strong, smart, and bold” for 100 years.

Does your organization participate in community events? We’d love to hear your stories ……… Read more

Geometry and Stiffness: What's the Connection?

Last month we posted a blog article on compression testing various eggs and compared the findings of these eggs to each other. Although we were testing to see how much load an egg could uphold before cracking, I recently read an article were researchers at MIT, as well as a team of researchers at the University of Lyon in France, are using "experimental and theoretical methods to better understand how the geometry of nonspherical shells relates to their stiffness."

Read the article ...

Have you ever tested specimens to understand how their shape impacts their properties? Read more

The New Alchemy

Scientists are trialing transmutation for the modern age. No, not lead into gold, and no Philosopher’s stone is involved. A simple bacterium is proving to be an effective, yet peculiar agent in producing high-quality plastics ideally suitable for medical and disposable applications.

Previously, the bio-plastic PHB has been grown in glucose by microbes with disappointing results. However, trials using waste cooking oil instead of glucose as a raw material have shown a tripling in yield in the same time period. This is great news for the waste recycling industry and the environmental community, firstly because un-recycled waste oil can be a major hazard to freshwater wildlife, but secondly because PHB has very useful properties. This makes it suitable for use in a variety of applications and attractive to the polymer industry. Interestingly, some sources claim that PHB can be used as a component in bio-degradable sutures that do not need to be removed, but dissolve harmlessly.

Producing bio-polymers, such as PHB, in the past has been expensive due to the use of glucose as the feedstock. But given the relatively low-cost of waste cooking oil, the production process is not only more effective than with a Glucose feed-stock, but also much cheaper. This makes the production of PHB from waste cooking oil a breakthrough for the 21st century - environmentally friendly, but also economically viable.

This blog-post was inspired by an article posted here. Read more

Making an Impression... or Not

Every few years, scientists come up with a wacky new material with properties that defy all sense. As a case in point just look at the eerie ferro-fluids – liquids that respond to magnetic fields; or aerogels that can support the weight of a brick but weigh only 2 grams. Well, the latest ‘fad’ (if you can call it that) in ‘out-there’ science projects is a little something called a hydrogel. Hydrogels have been around since the sixties, but are more recently coming into their own in the bio-medical sciences. They hold a variety of potentially useful properties including the ability to self-heal and can be made from a range of polymers. But you’ve yet to see the most astonishing thing of all.

I should say first of all that we’ve seen plenty of impact tests. Our drop-towers will rip through many common household and industrial materials. But I was surprised to see this video. Ordinarily, testing a film (in plastics testing, any polymeric material less than 1mm thick is a film) is a somewhat delicate operation.

But not with this mysterious concoction of compounds, which can absorb impacts of 9,000 joules per square meter and stretch up to 20 times its original length without breaking. Just to give you some perspective – if a bag of sugar weighed 1 kg, and you had just a square meter of this hydrogel – you could drop the bag of sugar onto the hydrogel from nearly a kilometre above and not penetrate it.

We’ve already seen hydrogels performing well in a variety of applications including contact lenses, tissue engineering and nappies (of all things!), but until now their lack of sufficient mechanical properties limited their versatility for widespread use. But with recent developments producing promising results, the future is looking bright for hydrogels.

Read more

Composite Cars?

Professor Dan Adams (University of Utah, Salt Lake City) has been at the forefront of the effort to bring composite materials into the automotive industry. The main driver behind this (no pun intended!) is the need to make cars lighter overall in order to reduce fuel consumption, all while maintaining or increasing safety.

Adams has been working with international organizations to develop unique and novel new “crashworthiness” tests and fixtures to better understand how composite materials will behave under impact conditions.

Check out this article… Read more

The Future of Green Fuel

Hemmed in by strong oceanic currents forming a ‘gyre’, the Great Pacific Garbage Patch is a stretch of relatively still water in which plastic waste gathers, floating just under the surface. Estimates of its extent vary from Hawaii-sized right up to twice the size of the United States. The ambiguity arises from complications in the sampling process and definitions of the problem area. Definitions are typically based on ‘above normal’ levels of pollution – although there is some sadness in acknowledging any level of pollution as normal, with the potential association that normal is therefore acceptable. The problem is also somewhat counter-intuitive; larger matter like bottles and containers are broken down by photo-degradation, due to exposure to the ultraviolet light found in sunlight. You might think this would help to dissolve the plastic but in reality, this only cuts down the size of the particles. The plastic, once broken down into millimetre-sized pieces can then take hundreds of years to decompose. Meanwhile, at the millimeter scale, the plastic is unfortunately perfectly sized and placed to find its way into the bodies of animals as diverse as Jellyfish, Sea Turtles, and Albatross. Often the plastic particles wash up on shore and ruin picturesque landscapes while causing a hazard to native wildlife.

Aside from ecological concerns, there are other serious issues facing the global community. In particular, the world economy is predominantly driven by crude oil, which is rapidly running out. Some estimates predict as little as 40 years of oil remaining. Wouldn’t it be great if we could solve both problems of ocean pollution and oil depletion with one sweeping motion? Project Kaisei seems to think so.

This non-profit organization is focused on the research of marine debris, particularly in the Pacific ocean. One of their long-term goals is to create technology to ‘harvest’ the waste plastic from the ocean so that it can one day become a useful resource. The idea of waste plastic as a resource could serve as a vital incentive to the world’s industry captains to clean up the seas. What happens when the material is actually harvested? This is where companies like Cynar come in. Cynar has developed highly successful technology for transforming used-up plastic waste into useful diesel fuel. So successful, in fact, that adventurer Jeremy Roswell is planning to fly from Sydney to London on 100% recycled fuel. But how does this process actually work?

First the recyclate is collected together in bales and sent to the central processing plant. There it is ground into small flakes, approximately 15 mm in diameter. Now the plastic must be transformed from a heap of flakes into a consistent fluid melt for processing at later stages. In practice this is achieved with an extruder, a machine fed by a hopper of plastic flakes that drives material through a heated screw mechanism. It is at this point that our testing machines come in to play. To achieve optimum efficiency and quality of product, the ground recyclate must be adequately tested so that the best extrusion conditions can be determined. This is particularly true in the recycling industry where the raw material can vary significantly in composition. The CEAST Series of Melt Flow Testers are well positioned to deliver this testing. Ranging from basic budget models all the way up to advanced, automated premium variants, our machines are easy to use and conform to the main international melt flow standards.

Once the material is melted, it is pumped by the extruder into the Pyrolysis chamber. Pyrolysis is a process of breaking down the long chain hydrocarbons into small constituent molecules similar to the raw crude oil from which the plastics were made. In order to do this, the polymers are heated at temperatures of up to 420° in the absence of Oxygen to prevent burning. The primary product of this process is a high-quality diesel fuel. Cynar produces 800 liters of diesel per ton of recycled plastic and even uses gases harvested from the process to power the process. The ‘synthetic’ diesel produced burns more ‘cleanly’ than regular diesel with a much better rate of emission production.

Could we see waste differently in the future? Could today’s eye-sores and environmental disasters be tomorrow’s gold-mines? Only time will tell. Read more

The Evolution of String

Taking a look at the evolution of string: From the legendary days of Robin Hood and his ability to handle a bow and arrow made out of hard wood and strings made from rawhide, linen or hemp to the bows and arrows of today, which are made from advanced composite material and synthetic fibers. 

Crary Brownell (Brownell & Co.) was one of the first to take a look at alternative materials for making bow string, both because he enjoyed the sport and because he owned a textile manufacturing facility. It is desirable to have a very strong and durable string with minimal stretch so that all of the bow power can be used to propel the arrow.

In 1928, Brownell introduced a string made from linen that was durable and had a low stretch. In 1957, he revisited the archery market and thought of improving the string performance by making it out of Dacron, which was a synthetic fiber made by DuPont. After some trial and error, Brownell was able to successfully use Dacron fiber to make strings for bows called Brownell’s B-50, which became the standard bowstring material well into the 1980s.

In 1985, Allied Signal introduced Brownell to a new fiber called Spectra and asked that they should try to use it to make their string. Spectra is much lighter and strong as steel, exhibiting very little stretch. Although it was a challenge to get Spectra to work well, Brownell’s engineers succeed, testing to ASTM Standards F1752 (Standard Test Method For Archery Bow Component - Cord Material) and ASTM F1648 (Standard Test Method for Archery Bow Component - Serving String Material). This product, Fast Flight, was introduced in 1986.

Over the last few years, Brownell  has been using High Modulus Polyethylene (HMPE), which is sometimes also referred to as Ultra High Molecular Weight Polyethylene (UHMWPE). This material has similar characteristics, but is lighter, stronger, and tends to be more durable. Additionally, Brownell developed blended fiber products from both HMPE and Vectran (a product of Kuraray Co LTD). Read more

What is the Bagley Correction and Why do I Need to Perform One?

When testing using a capillary rheometer, it is desirable to know the pressure drop along the capillary. Realistically, it is not possible to test for this inside the die itself, and pressure transducers are typically located just above the die. While this makes the machine design much simpler and more budget-friendly, it does introduce a very particular kind of error that affects readings of pressure drop, shear stress, and viscosity.

When the melt is pushed through the die, there are two drops in pressure that it experiences. First of all, the pressure drop due to the ‘entrance’ effects experienced at and around the die-mouth. This is related to the shape and size of the die and the compaction of the melt from a large to a small geometry. Additionally, there is a second pressure drop experienced between the start and end of the capillary. It is this second quantity that we are really interested in, and the separation of the two quantities is the product of the Bagley correction. The Bagley correction is unique for each configuration and set of parameters; it is only changed in die length that does not require a new correction to be performed.

Performing a Bagley correction might seem daunting, but it’s actually rather simple involving two basic rheology tests. Each test should be set up with identical parameters (a simulation of the anticipated testing conditions) and dies of the same geometry, but differing lengths. The analysis then consists of a mere pinch of high school algebra. Essentially, the two tests (ideally performed simultaneously on a dual bore machine) produce data that can be expressed as simultaneous equations:

E + A = x   (1)

E + B = y   (2)

Where E is the pressure drop due to entrance effects; A and B the drop in pressure in each barrel due to the lengths of the dies; x and y the pressure drop recorded by the transducers in each barrel. 

Then:

B = cA   (3)

Because:
1. The ratio of the length of one die to the other is known (c).
2.  The drop in pressure across the die is proportional to the shape, size and length of the die.
3.  The dies have the same shape and size.
4.  Thus the ratio of the die lengths is also the ratio of the pressure drops between the two dies.

Then taking equation 2 from equation 1:

A – B = x – y   (4)

A – cA = x – y   (5)

As c, x and y are known, you can now work back through the equations and calculate A, B and E. Software can be used to automatically perform the necessary calculations and execute a Bagley correction on all data collected following the procedure.

Having said this, if the data is purely for Quality Control purposes, then you won't need to perform the Bagley correction. As long as each test is executed using strictly the same equipment in the same configuration, then the results are comparable. 

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