In
today’s competitive manufacturing environment, ensuring the quality,
durability, and compliance of plastic materials is critical. Adhering to
recognized plastic testing standards not only boosts product credibility but
also reduces failure risks. Whether you're in packaging, automotive, medical,
or construction, understanding these standards is essential. Here are the plastic
testing standards every manufacturer must know.
Tensile Properties of Plastics
The behavior of plastic
and polymer materials in response to pulling or stretching forces describes their tensile properties.
One of the critical property is found to be “Tensile
Strength”, the way the plastic acts with respect to the force exerted,
under tension. How far the material will resist the breaking phenomena, concerning the force exerted. “Elongation at Break”, the way the plastic
material stretches from its original length before it fails. Helps to find out
the kinds of deformations occurring within the plastic materials such as
plastic deformation (deformation is irreversible, where the material doesn’t
return to its original position) and elastic deformation (deformation is
reversible, valid for a small amount of strain).
There are three types of tensile strength;
A] Yield
Strength: the level of stress a material can withstand before getting
permanently deformed
B] Ultimate
Strength: the highest level of stress that a material can withstand before
getting deformed.
C] Breaking
Strength: the point at which the failure occurs with respect to the load
applied and the strain that occurs in it. This is referred as the ultimate tensile
strength.
These properties are important for plastic
part manufacturers when evaluating new material for a specific application;
ultimately benefit the end users with the best properties at low cost. This is
one important property for analyzing the material, quality control, which helps with
the structural design, modeling, and failure analysis.
Izod Impact Strength
The way the plastic
material behaves with respect to an application of unforeseen/instant/unnoticed stress or force, especially when the material has a high
concentration of stress in it, with a notch made on its surface.
This Izod impact strength of polymeric testing
or plastic testing of materials seems to be a crucial or indispensable property
for evaluating the polymeric material toughness and appropriateness for applications utilising unrealized
impacts.
This polymeric testing or plastic testing of Izod
impact strength of polymeric materials specifies how effectively a polymer can
resist the phenomena of fracture under instant high force.
The specimens are made with a notch before exerting
a sudden impact, which inherently makes the polymeric material have high
stress and makes polymeric testing or plastic testing of Izod impact more
delicate towards the material's brittleness.
The plastic testing of Izod impact strength of
polymeric materials helps to estimate/quantify the energy absorbed by the
sample before it breaks or meets with a catastrophic failure.
The factors affecting the Izod impact strength goes with:
Type of material
Temperature of the used material
The amount of moisture content with the material
The sensitivity of the notch made or occurs with the material during
usage
The way the material got manufacture.
Charpy Impact Test
The charpy impact test is regarded as one of
the most common in polymer testing or plastic testing of materials, where the
material’s ability towards fracture and deformation can be determined.
The charpy impact test helps to evaluate a
notched polymeric or plastic material in quantifying the energy associated with
it before facing a failure owing to a high impact associated with it.
This charpy impact test was regarded as one of the most inexpensive in
polymeric testing or plastic
testing of materials; where the polymeric materials in material science field
gets differentiated to the terms such as hardness (how well the
materials behave to the level of friction applied), strength (how
much the force can be handled before getting deformed) and toughness (how well
the material can resist the breaking to a sudden load).
This charpy impact test in polymeric testing or plastic testing of materials
was found to be a valuable one with respect to evaluation of suitable polymers
for certain specific applications; to judge and differentiate the toughness of
various polymeric materials, helpful in analyzing the crucial factors
associated with the failure behavior of materials.
Also, it highlights the manufacturing defects
like voids or fractures associated with the materials.
Flexural Properties
In polymeric testing or flexural property
testing of plastic material’s we can understand the stiffness and resistance to
the bending behavior of materials under the applied stress.
The flexural strength and flexural modulus are
the two key flexural properties in plastic testing.
The maximum amount of stress that a material
can withstand before breaking under bending is described by the term “Flexural
Strength”. Where the term “Flexural Modulus” shows how stiff or the capability
to resist bending is quantified. On the whole, the material's stiffness
and bending behavior are assessed and observed. The higher the stiffness, higher
will be the flexural modulus of a material.
Parameters associated with altering the flexural behavior of polymeric materials are related to the nature of the polymer used, the temperature at which it finds its application, the type of reinforcements it has, the level of loading, and the environmental conditions in which it prevails.
Melt Flow Index (MFI)
With polymer testing or plastic testing of
material’s flow characteristics, the term “Melt Flow Index” shows how well the
material flows or at what temperature it gets to the molten stage and starts to
flow. It seems to be an indicator of the material's processability and to
evaluate its molecular properties.
It specifies the nature of polymeric material,
where a higher MFI value shows that the polymer is more fluid and the
processing can be done quickly; whereas, with the more viscous and hard, and
rigid material, the MFI values go to a lower level.
much mass of a polymeric material in grams that flows through a die in a specific time (say 10 minutes) under certain specific
conditions of temperature and pressure is defined as the melt flow index.
The various factors associated with altering
the melt flow index of material include molecular weight, molecular weight
distribution, the kind of branches prevailing with the polymeric material, the
level of crystallinity, and the temperature and pressure. Higher molecular
weight fetches a lower melt flow index. Higher levels of variations in the chain
length (a wider distribution of polymeric chains) can affect the melt flow
index. More number of entanglement, owing to the higher branches, reduces the
melt flow rate.
Water Absorption of Plastics
Capability of a plastic or polymer material to absorb the moisture from
its environment describes its water absorption characteristics. This character
with polymeric testing or plastic testing of material shows how well the
plastic performance can be deteriorated owing to the level of moisture
absorbance nature of the polymer. Factors associated with the absorbing nature
were influenced by environment temperature, thickness, the level of humidity it
prevails in and the time it gets exposed to that atmosphere.
With the moisture absorbing character, the
following effects can be realized such as change in the dimension, change in
mass (swelling), extraction of water soluble components, change in mechanical
properties like elasticity, tensile strength, impact strength, and electrical
performance.
The factors associated with the moisture-absorbing nature of polymers lies with;
The type of plastic
material
Crystalline and
amorphous nature of polymer, with their proportions
The kind of additives
and the proportions
The nature of
additives, the type of fillers, and the reinforcement used
Relative humidity and
temperature, and
The length of exposure
Specific Gravity (Density)
In polymer testing or plastic
testing, of material's specific gravity enumerates its relative density, a
dimensionless character. It’s an indicating parameter of a polymer or plastic
to show how dense it is. For certain applications where the material needs to float, the design is to be buoyant, and for selecting the
right polymeric material with a specific density requirement.
Density measures the mass per unit volume. For plastics, it is usually
expressed in g/cubic centimeter.
The various factors associated with affecting
the density of the plastic materials seem to be;
The molecular structure
and the arrangement of polymeric chains within the structure
Temperature – higher
temperature leads to expansion of materials, whereby the
Volume increases with a decrease in density
Absorption of solvents and loss of plasticizers may also change the density of the material.
Shore Hardness
In polymer testing or plastic testing of material hardness, the
resistance of a plastic material that resists the indenter to get penetrating under a specific force is defined as shore hardness.
Various scales were used owing to the hardness nature of the material,
where the higher the number higher the hardness rate.
The device used to measure the hardness is a “Durometer”. The depth of the penetration depends on the hardness of the material, the viscoelasticity of the material, the shape of the
indenter and the duration of the test.
Factors affecting the hardness of the material:
Density of the material
Grade of the material
used
Molecular weight,
Molecular weight
distribution,
The kind of branch that prevails with the polymeric material, and
The level of
crystallinity
Conclusion
Understanding
and applying these plastic testing standards is a vital step for manufacturers
looking to ensure product performance, durability, and compliance. By working
with an NABL-accredited plastic testing lab, businesses can confidently
validate their materials and gain a Competitive advantage.
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