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Welcome to the MCA Services blog
1:51pm - 04/11/2016

Welcome to the MCA Services Blog

 

Welcome to the MCA Services blog and thank you for taking a look at our first entry.

 We will be adding new entries on a regular basis and we hope that we will be able to give lots of information on our services to help everyone better understand the techniques we have here, how they work and their applications.

 We would like to start by giving an introduction to what we offer and a little on the history of MCA Services.

 

MCA Services: Who we are and what  we offer.

 MCA Services is a contract analytical laboratory and consultancy specialising in the physical characterisation of materials, notably porosimetry. The analytical techniques are applied to a wide and diverse range of materials and industries but are also quite specialised. We have decades of experience and are always happy to lend a hand with understanding them, recommending the best options and interpreting data.

 What is porosity?

 The Oxford English Dictionary [1] gives the following definitions:

 Porosity  The quality or state of being porous; porous consistency. Also: the degree to which a substance is porous.

 Porous  Full of pores; containing minute interstices through which water, air etc., may pass.

 Pore  A minute interstice between particles of matter especially in soil or rock; a minute hole or channel in a surface, fabric, natural or artificial membrane, etc.

 A useful, everyday way of deciding whether a cavity is a pore or not is maybe this: “if it is deeper that it is wide, then it’s a pore”

 It is the extent of porosity, the size of the pores and their volume, which influences the properties of a material.

 Pore sizes are conveniently classified as micropores, mesopores and macropores, depending on their size.

The IUPAC classification [2] is:

Micropores = <2 nm

Mesopores =  2 – 50 nm

Macropores = >50 nm

 

These sizes relate to the diameter of a cylindrical pore or the width of a slit shaped pore.

 To make things a little more complicated, there are a few different units that are commonly used to quote pore sizes;

Nanometre (nm)

Micrometre or Micron (mm)    

Angstrom (Å)

 This chart is helpful to understand the different units and we’ve also included  millimetres which are perhaps more familiar.

 

 

Å

nm

mm

mm

      Angstrom

-

10

10, 000

10, 000, 000

 Nanometre

0.1

-

1,000

1, 000, 000

Micrometre

0.0001

0.001

-

1,000

Millimetre

0.0000001

0.000001

0.001

-

 

What is Porosimetry ?

 Porosimetry is the study of the porous nature of materials and includes information on the size, volume and area of pores, for example; 

  • Pore size distribution
  • Pore volume distribution
  • Total pore volume
  • % Porosity
  • Pore area distribution
  • Surface area
  • Bulk density
  • Absolute density

 Why is porosimetry significant ?

 The extent of porosity, or even the lack of it, in a material can very often have profound effects on its performance and functionality. Understanding the porous nature of a material – whether it is a precursor, an intermediate or a finished product – can often help in maximising performance, identifying failures, directing the formulation process or improving manufacturing processes.

 How are pores characterised ?

 There is no single analytical technique for investigating micropores, mesopores and macropores in one go and so it is necessary to use a combination of techniques.

 The most common techniques are gas adsorption, mercury porosimetry and pycnometry (density measurement). Of course, the most appropriate technique for a sample and its anticipated porosity can also be chosen if we know a little about the sample type, its history (how it was made or used) and the intended application of the results.

 We have a comprehensive suite of the latest, state-of-the-art instrumentation for investigating pores from nanometres to microns. Some of the techniques are:

 

  • BET surface area by nitrogen adsorption
  • BET surface area by krypton adsorption (for particularly low surface area samples)
  • Gas adsorption for investigating micropores
  • Gas adsorption for investigating mesopores and macropores up to approximately 300 nm
  • Mercury porosimetry for investigating pores of 0.003 – 600 microns
  • Mercury pycnometry for measuring bulk density
  • Helium pycnometry for measuring absolute density

 

The diagram below shows the relationship between pore sizes and the analytical technique used to characterise them.

 pore sizes and corresponding analytical option

 

What do the results mean ?

 Our analytical techniques together and their reporting options are incredibly powerful, they are really rather specialised too and can be applied to almost any material – porous or non-porous.

 Results can be reported in a wide variety of graphical representations, the distribution of pore characteristics can be calculated in different ways and many data reduction models can be applied. This can produce a great deal of data but it is important to select which is the most appropriate for the material being analysed and also for its intended application.

 This process can very involved and at MCA Services we have decades of experience with our analytical techniques and their application to a very wide range of materials and industries. We are always keen to ensure that our clients gain the very most from our services and are able to relate the information directly to the understanding of their materials.

 We know about our characterisation techniques and our clients know about their materials, products and applications. Through combining this knowledge and expertise the maximum information is gained from our characterisation services. 

 Through our blog we hope to provide information on the techniques themselves: how they work, some background theory and also some case studies for the analysis of specific materials.

 More about MCA Services.

 MCA Services was founded in 1978 as a laboratory-based consultancy and analytical service specialising in surface area, porosimetry and porosity measurement. On 28th March 2015 the partnership was converted into a Limited Liability Partnership, designated MCA Services Cambridge LLP, Regn. No. OC399113. The LLP continues to use the trade name MCA Services for continuity.

 

Our fully equipped laboratories are based about 15 miles from Cambridge, UK and house the latest equipment for the provision of analytical services to a wide variety of clients, both in the UK and abroad. The scope of our analytical activities has expanded over the past thirty years to encompass physical characterisation techniques such as pore size distribution by gas adsorption, mercury porosimetry, particle size distribution, density testing and catalyst metal area by chemisorption. 

 We are proud of our extensive experience in our analytical techniques and their application. Of great benefit to our clients is our offer of assistance with interpretation of results at no extra charge. 

 The staff at MCA Services are professionally qualified and senior staff are members of the Royal Society of Chemistry and hold Chartered Chemist status.

 In the late 1980’s, MCA’s expertise in particle technology led to diversification into the production of biosensor grade materials where high purity, ultra-fine particulate materials were required.

 Our initial focus was on a fine grade silver chloride powder specifically designed for screen printable biosensor reference electrodes and this was followed by other fine grade powder such as platinum on carbon and ruthenium on carbon for advanced sensor systems. 

 MCA’s technology was successful in gaining four DTi SMART awards for innovative technology and we now supply our materials to a world market. The use of our materials has extended beyond bio-sensors to encompass a diverse range of electrochemical applications.

 References:

 [1] Oxford English Dictionary online. www.oed.com

[2] Pure and Applied Chemistry 57, 4 (1985) 603

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