What are the factors affecting the melt index of plastic TPE-TPU

There are many types of plastics, among which TPE and TPU are a type of elastomer that can be plasticized by heating and dissolved by solvents. They have excellent comprehensive properties such as high strength, high toughness, wear resistance, and oil resistance, and are commonly used in multiple industries. The measurement of melt index can help determine the purpose of this material. So, what is melt index?
Melt index, also known as MI, is a physical parameter that measures the flowability of a material (usually rubber plastic material) under certain temperature and pressure conditions, usually in g/10min. Melt index, since it is a physical term that characterizes the fluidity of materials, to some extent determines the forming and processing performance of materials. Therefore, it needs to be considered when forming materials. A suitable TPE | TPU material with a suitable melt index should be selected based on comprehensive consideration of product mold and flow channel design, product structure, equipment processing and plasticizing ability, and product performance requirements.
Generally, the melt index of TPE is between 0 and 100, and the material melt index of each TPE manufacturer varies depending on the testing conditions.
There are generally two conditions for weight and melt temperature. Temperature conditions (150 ℃, 190 ℃, 210 ℃), weight (1.2kg, 2.16kg, 5kg). Generally, 2.16kg is used, with a melt index between 0 and 150 at 190 ℃. Usually, if the fluidity is below 0, the conditions for testing will be changed, such as 5kg, 190 ℃ or 2.16kg, 210 ℃, and those above 100 will be tested under 1.2kg, 190 ℃ or 2.16kg, 150 ℃ conditions.
There are generally four factors that affect the TPE | TPU melt index:
1. Molecular weight of the matrix material
The molecular weight is inversely proportional to the melt index. The higher the molecular weight of general matrix materials (such as SBS, SEBS), the lower the TPE | TPR melt index.
2. Reinforced plastic
Reinforced plastics such as PP, PS, PPO, PE, etc. The higher the fluidity, the higher the melting index of TPE mixture
3. Molecular Chain Structure of Matrix Materials
Generally speaking, when other parameters are equivalent, a substrate with a higher degree of molecular chain branching will result in a lower melting index of the TPE mixing system; In addition, TPE | TPU with star shaped structure as the substrate has a low melting index.

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