How do you read a rheometer graph?

The lowest torque value recorded on the graph, measured in dN*m, is called ML (Moment Lowest). It is a measure of stiffness of uncured rubber compound at a given temperature. As the curing starts, the torque rises. When the torque increases 2 dN*m units above ML value, the time is recorded.

What are uses of rubber?

Uses of Rubber

• Rubber moulded products are widely used industrially (and in some household applications) in the form of rubber goods and appliances.
• Rubber is used in garden hoses and pipes for small scale gardening applications.
• Most of the tyres and tubes used in automobiles are made up of rubber.

What is the relationship between rheology and viscosity?

Rheology is a general term referring to the science of studying flow and deformation of materials. Viscosity is defined as the resistance of a liquid to flow. For example, ketchup has a higher viscosity than water.

What does rheology measure?

To measure the rheological properties of a material, rheometers are used. They measure the torque and the deflection angle of the measuring bob. This means that in a viscosity measurement the rheometer presets a certain current that correlates to a defined torque. The speed is then measured.

What is Scorch safety?

Scorch has a quite specific meaning in rubber technology where it is the term for premature vulcanisation of the mix before the final shaping can be accomplished. Scorch inhibits flow and results in scrap. The challenge of the rubber technologist is to introduce adequate process safety into the cure formulation.

Is viscosity a rheological property?

The rheological parameters were viscosity (cp), torque%, shear stress (dyne/cm2) and shear rate (s-1).

What is the meaning of rheological properties?

Rheology is the branch of physics in which we study the way in which materials deform or flowin response to applied forces or stresses. The material properties that govern the specific way in which these deformation or flow behaviors occur are called rheological properties.

What is rheology used for?

Rheology is used to describe and assess the deformation and flow behavior of materials. Fluids flow at different speeds and solids can be deformed to a certain extent.

Why Rheology is important in food technology?

Study of rheological properties is important in food science due to its utility in food processing operations and sensory characteristics. It gives information about the microstructure of a food. Rheology properties are manifestation of the rate and nature of the deformation that occurs when a material is stressed.

What is ML and MH in rheometer?

The minimum torque (ML) is a measure of the extent of mastication, whereas the maximum torque (MH) is an indication of the cross-linking density of the fully vulcanized rubber.

What is a vulcanizing agent?

Vulcanization is a chemical process that converts natural rubber and other polydiene elastomers into cross-linked polymers. The most common vulcanization agent is sulfur. It forms bridges between individual polymer molecules when heated with rubber.

What is vulcanisation of rubber?

Vulcanisation is the process of curing elastomers. It involves the treatment of natural rubber with sulphur or other curatives (such as peroxide and metal oxides) to form cross-links between sections of a polymer chain to produce a rubberised material boasting excellent rigidity and durability.

What are the advantages of vulcanization of rubber?

Advantages of Vulcanization: It has good tensile strength and extensibility. It has excellent resilience i.e.it returns to the original shape, when the deforming load is removed. It possesses low water absorption tendency. It has higher resistance to oxidation, wear and tear abrasion.

What is the function of cure rate in rheometer checking?

The rate of cure is an important vulcanization parameter since it determines the time the compound must be cured i.e. the cure time. The Thermoplasticity is derived from the difference of initial viscosity & minimum viscosity.

What is vulcanizing process?

Vulcanization is a chemical process in which the rubber is heated with sulphur, accelerator and activator at 140–160°C. The process involves the formation of cross-links between long rubber molecules so as to achieve improved elasticity, resilience, tensile strength, viscosity, hardness and weather resistance.

What is difference between rheometer and viscometer?

What’s the difference? Typically a viscometer employs a mechanical bearing that limits the speed and torque capabilities of the instrument, whereas a rheometer uses a low friction air bearing. A viscometer can offer portability for field or remote testing.

Why is rheology important in pharmacy?

Rheology is therefore crucially important as it will directly affect the way a drug is formulated and developed, the quality of the raw and finished product, the drug efficacy, the way a patient adheres to the prescribed drug, and the overall healthcare cost.

How do you calculate curing time?

1. Cure time is a time required by the sample to reach a desired state of cure, usually to reach 90% of the maximum cure.
2. Cure rate is the rate at which x-linking & the development of compound stiffness (modulus) occur after scorch point.
3. Use of accelerator also increases cure rate.
4. Cure rate Index = 100/(tc90 – ts2)

How much does a rheometer cost?

Capillary rheometers can range in price from $30,000 to $45,000 for entry-level, benchtop QC units up to $100,000 for more advanced models. There are also on-line capillary rheometers that measure viscosity of material as it passes through an extruder.

What scorch means?

(Entry 1 of 3) transitive verb. 1 : to burn a surface of so as to change its color and texture. 2a : to dry or shrivel with or as if with intense heat : parch.

Why Sulphur is used in vulcanization of rubber?

Vulcanization of rubber involves heating it in the presence of sulphur. This results in cross-linking of the chains of rubber and sulphur to form a stable polymer which is more strong and stable.

What is rheometer for rubber?

A Rubber Rheometer is a device that is used in laboratories to test raw rubber flow in response to applied forces. The Rheometer measures the change in the properties of the rubber compound during the course of vulcanization.

What does thixotropy mean?

: the property of various gels of becoming fluid when disturbed (as by shaking) … says that blood liquefaction can be explained in terms of a phenomenon called thixotropy.

What is scorch time?

[′skȯrch ‚tīm] (chemical engineering) In rubber manufacture, the time during which a rubber compound can be worked at a given temperature before curing begins.

What do you know about rheology?

Rheology is the science of measurement of deformation. Virtually all materials deform in response to an imposed stress (‘everything breaks if you hit it hard enough’) and the materials present in the eye range from liquid-like to soft-solid behaviour.

What is the difference between rheology and viscosity?

Rheology is not a measure of viscosity but an area of physics focused on the study of a substance’s change in flow characteristics under applied stress or force. The term rheology modifier is being used erroneously to refer to chemicals that modify the viscosity of any material.

Why do we study rheology?

Rheology of Polymer Melts Rheology is the study of how materials flow or deform under an applied force. Stress relaxation and creep recovery experiments are used to show how constitutive equations are developed to relate stress to rate of strain for viscoelastic materials.

What is viscosity of rubber?

Mooney viscosity is defined as the shearing torque resisting rotation of a cylindrical metal disk (or rotor) embedded in rubber within a cylindrical cavity. The dimensions of the shearing disk viscometer, test temperatures, and procedures for determining Mooney viscosity are defined in these test methods.

What is used to measure viscosity?

viscosimeter

What is Moving Die Rheometer?

The Moving Die Rheometer MDR- 3000 measures the change in stiffness of a rubber sample. The sample is compressed between two heated platens and by an applied oscillating force. Our Moving Die Rheometer offers affordable testing and stunning results.