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Ningbo Davison Machinery Manufacture Co.,Ltd

Address: No. 199, Xinmei Road, Gaoxin Zone, Ningbo City, Zhejiang Province, China

Manager: Ms Lisa

Tel: 0086-1886-866-7352



PVC Structure Increase The Toughness Of Products

1, PVC Structure physical properties: hard PVC its density is usually 1.38 ~ 1.46g / cm3, water absorption of less than 0.5%, soaked in water, 24 hours, water absorption rate of less than 0.05%;

2, mechanical properties: hard PVC mainly tensile strength, tensile touch, elongation, impact strength, hardness, creep performance, and so on;

2.1 Tensile properties

2.1.1 Stress-strain curve of the influencing factors:

A, with the speed of the test speed: the increase in tensile speed, increased yield stress, increased fracture stress;

B, with the test temperature: the sensitivity to temperature, PVC Structure the temperature decreases, the tensile strength, tensile touch, yield elongation, hardness increases, elongation at break and impact strength decreases; the contrary is the opposite.

2.1.2 Effects on tensile strength and elongation:

A.PVC molecular weight effects: increased molecular weight, then increased;

B.PVC Structure  The effect of toughening agent: the use of toughening agent, will increase the toughness of the product, elongation will increase, but other properties such as tensile strength will be reduced;

C. The effect of plasticizer: usually can improve the processing flow properties of the compound, but the tensile strength will be significantly reduced;

D. The impact of filler: usually the use of filler will reduce the tensile strength and impact strength of products, except for individual fillers (such as glass fiber, etc.).

2.2 Impact performance

The impact of the impact of the main factors are the following:

2.2.1 Test loading speed:

2.2.2 Notch sensitivity:

2.2.3 Temperature effects: Strongly dependent on temperature changes

2.2.4 The impact of ingredients: the composition of the composition and the amount will affect the impact strength of products

A. The impact of molecular weight: molecular weight increases, the impact strength increases

B. Effect of modifier: Under normal circumstances, the amount of modifier increases, the impact strength of the product increases, but the increase in the amount reached a critical value, the amount of modifier increased, the impact of the magnitude of the increase in intensity is significantly reduced, The effect is not very obvious, and the modifier must also be increased to a certain amount before the obvious effect of modification;

C. The effect of plasticizer: the existence of anti-plasticizing effect, the amount of plasticizer in the anti-plasticizing effect, with the increase in the amount of impact strength also increased;

D. The impact of the filler: usually the use of filler will make the impact of products reduced performance. But also in the use of a small amount of ultrafine filler and reinforcing filler can increase the impact of the product strength;

E. The impact of processing conditions: the main requirement to achieve uniform plasticization, control the degree of plasticization between 55% to 65%.

2.3 Hardness

2.4 heat resistance

3 processing rheological properties:

Mainly refers to the PVC compound in the process of melt viscosity changes and its influencing factors.

The rheological properties of PVC - typical pseudoplastic fluid - shear thinning phenomenon,PVC Structure  that is, the shear speed, melt viscosity becomes smaller.

3.1 Factors that affect shear viscosity and flow curves:

A, PVC molecular weight size: high molecular weight, high melt viscosity, is not conducive to processing

B, PVC resin particle morphology: the resin surface morphology of the loose type, is conducive to plasticizers, lubricants and additives absorption, which is conducive to plastic, good processing performance

C, plasticizer: reduce the melt viscosity, improve the melt flow processing and processing performance

D, lubricant: reduce the melt viscosity

E, processing aids: different types of processing aids can play a different role, PVC Structure (see the role of processing aids in detail)

F, shear rate: shear rate increases, viscosity decreases

3.2 Elastic effect of the melt: The melt of the polymer is accompanied by a highly resilient deformation that can be reversed during the flow, including the normal stress effect (the envelope phenomenon), PVC Structure the Baras effect (outlet expansion), and the melt fracture phenomenon.

A, extrusion expansion phenomenon: refers to the melt extrusion die, the cross-sectional area of the extrudate is greater than the cross-sectional area of the phenomenon.

Usually the molecular weight is high, the melt viscosity is large, the relaxation time of the segment takes a long time, the elastic relaxation becomes slow, PVC Structure the elastic effect is obvious, the degree of expansion of the outlet is relatively small, and the expansion ratio is small.

B, unstable flow - melt fracture phenomenon: