Chemical and Physical Analysis of Plastic and Rubber
The Physical and Chemical testing, of polymers is a vital part of the product development and production process. Mechanical, thermal, optical, rheological and chemical behaviour and climate testing allow the developers to better understand their product, and introduce stronger quality control. Testing of polymers ensures that material complies with industry specifications. This applies to aerospace, automotive, consumer, medical and defence industries, amongst others. With the vast array of product types and additives available, understanding the capabilities and limitations of a material is a key concern to suppliers, manufacturers and product developers on every level of the polymer industry supply chain. Testing can help raw material suppliers and manufacturers to determine the properties of their products through vast range of testing methods. Knowing when to apply the most relevant technique to obtain the data needed requires specialist insight, knowledge and experience. When a material or additive does not meet the user’s specifications, expert interpretation and advice are highly required. Tests such as FTIR, Ash content for chemical analysis and a very vivid range of physical tests some of which are, Tensile test, longation at break, density and specific gravity, hardness shore A & D, longitudinal reversion, resistance to sulphuric acid, dichloromethane test, compressive strength, and many more to lists.
- FTIR spectroscopy offers a vast array of analytical opportunities. Deeply ingrained in everything from simple compound identification to process and regulatory monitoring, FTIR covers a wide range of chemical applications, especially for polymers and organic compounds such as rubbers and plastics.
- The Hardness Testing of plastics and rubber is most often measured by the Rockwell hardness test or Shore (durometer) hardness test. Both methods measure the resistance of the plastic toward indentation, thereby providing an empirical hardness value. These hardness values do not necessarily correlate to other properties or fundamental characteristics.
- An Ash Content test is used to determine inorganic residues in materials. Inorganic residues found in polymer may be in the form of antiblock agents, fillers, reinforcements, catalyst residues, and pigments.
- Tensile Tests measure the force required to break a polymer sample specimen and the extent to which the specimen stretches or elongates to that breaking point. Such tests produce stress-strain diagrams used to determine tensile modulus. The resulting test data can help specify optimal materials, design parts to withstand application forces, and provide key quality control checks for materials.
- Density measures the mass per unit volume. It is calculated by dividing the mass of the material by the volume and is normally expressed in g/cm3. The density of a polymer sample may change due to change in crystallinity, loss of plasticizers, absorption of solvent, etc. It is important to note that density varies with temperature.
- Flattening Tests are commonly made on specimens cut from tubular PVC products and is conducted by subjecting rings from the tube or pipe to a prescribed degree of flattening between two parallel platens. The severity of the flattening is the measured distance between the platens under a certain load must not be greater than the requirements. A Pass/Fail test, tube flattening is used to determine whether or not the tube will fracture upon flattening.
- The Melt Flow Index (MFI) or melt flow rate (MFR) is a measure for the ease of flow of melted plastics. It is often used in the plastic industry for quality control of thermoplastics.
- The Izod/Charpy Impact Test is used to measure the relative susceptibility of standard test specimen to the pendulum type impact load. The Izod/Charpy impact meter is having an energy range from one joule to twenty-five joules in five different scales.
- Thermogravimetric Analysis (TGA) is conducted on an instrument referred to as a thermogravimetric analyser. A Thermogravimetric Analyser continuously measures mass while the temperature of a sample is changed over time. Mass, Temperature & time are considered base measurements in thermogravimetric analysis while many additional measures may be derived from these three base measurements. A Typical Thermogravimetric Analyser consists of a precision balance with a sample pan located inside a furnace with a programmable control temperature. The temperature is generally increased at constant rate (or for some applications the temperature is controlled for a constant mass loss) to incur a thermal reaction. The thermal reaction may occur under a variety of atmospheres including: ambient air, vacuum, inert gas, oxidising/reducing gases, corrosive gases, carburising gases, vapours of liquids or "self generated atmosphere"; as well as a variety of pressures including: a high vacuum, high pressure, constant pressure, or a controlled pressure. The Thermogravimetric data collected from a thermal reaction is compiled into a plot of mass or percentage of initial mass on the Y - axis versus either temperature or time on the X - axis. This plot, which is often smoothed, is referred to as a TGA curve. The first derivative of the TGA curve (the DTG Curve) may be plotted to determine inflection points useful for in-depth interpretations as well as differential Thermal Analysis. A TGA can be used for materials characterisation through analysis of characteristic decomposition patterns. It is an especially useful technique for the study of polymeric materials, including thermoplastic, thermosets, elastomers, composites, plastic films, fibers, coating, paints & fuels.