Elongation rate
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I work in the film industry. The middle layer is made of Dow’s 2045G material, which accounts for 70% of the total thickness; the two outer layers are made of PP using Singapore’s FS6612 material. The elongation rate for both types of material is around 880%. My production process involves two stages of inflation – the material is first extruded through a circular die, then inflated, followed by a first stage of stretching. After preheating, it undergoes a second stretching stage, after which it is cooled and wound up. The problem I’m facing is that the elongation rate is 90% at a thickness of 15 um, whereas it should be around 115–125%. I would like to know which parameters (process factors, equipment) affect the elongation rate. Thank you very much
It’s not very large; reducing the stretch ratio to 0.8 doesn’t have a significant effect, and reducing it further makes the membrane bubbles unstable； Question: What impact do the temperature of the film tube before stretching (i.e., after preheating), the cooling temperature after stretching, the water temperature used for rapid cooling after it exits the die, and the structure of the die have on the elongation rate?
The elongation at break is correlated to certain mechanical properties, especially being closely related to tensile strength. Only by having a high tensile strength, which ensures that the material does not break during deformation, can a high elongation rate be achieved; therefore, a high tensile strength is a necessary condition for obtaining a high breaking elongation rate. Generally, as the set stress and hardness increase, the tear elongation decreases ； It has high resilience and low permanent deformation, as well as a high elongation at break. Different types of rubber have varying tensile elongation rates for their vulcanized products. Molecules with good chain flexibility and high elastic deformation capacity exhibit a higher elongation at break. Natural rubber is most suitable for producing products with high tear elongation, and this elongation increases as the rubber content rises ； When the gel content is around 80%, the tear elongation can reach up to 1000%. Rubbers that are prone to plastic flow after deformation also exhibit high tear elongation; for example, butyl rubber can achieve high tear elongation as well. The tear elongation decreases as the crosslinking density increases; therefore, to produce products with high tear elongation, the degree of vulcanization should not be too high. Rubber compounds with a slightly insufficient level of vulcanization exhibit higher tear elongation. Reducing the amount of vulcanizing agent can also increase the tear elongation. The addition of reinforcing fillers significantly reduces the tear elongation, especially with carbon black that has a small particle size and a high degree of structure, where the reduction in tear elongation is even more pronounced. As the amount of filler increases, the tear elongation decreases. Increasing the amount of softener can also yield a higher tear elongation. The permanent deformation of rubber falls within the realm of rubber elasticity. In addition to factors such as the magnitude of the deformation, the duration of application, and temperature, the structure of the rubber molecules as well as various compounding systems also have an impact, to varying degrees. As the crosslinking density increases, the elasticity of the vulcanized rubber increases and reaches a maximum value; as the crosslinking density continues to increase, the elasticity shows a downward trend.
It generally needs to reach over 95°.
Thank you all for your answers. The raw materials used for producing this type of film remain basically unchanged in China. After increasing its strength, the elongation rate during testing (for the 6 samples) was not particularly low; it was relatively consistent, but it remained low overall. I was wondering if anyone could analyze this from the perspective of process adjustments
Moderator, please help! Hehe, could you assist in analyzing it?
I’m sorry, but due to the peak production period, I’ve been very busy lately and don’t have time to devote energy to other things.
Hahaha, so it was the moderator who created the POF, huh. It’s okay; everything’s fine now, thanks
Come and take a look, moderator. Hello, original poster
I came by today to see if there was any new content, but still nothing, haha. I also extend my greetings to the strangers here; hello