High-strength polypropylene filament purchase: Drawing strength is 2000N. How much remains after knotting? The strength of the knot is the key factor. 

When purchasing High-strength polypropylene filament, many people tend to consider the breaking strength as the core indicator. A direct tensile strength of 2000N sounds good, but in actual usage - especially in scenarios such as sewing, binding, and rope net weaving - the yarn often needs to be knotted or bent to bear force. At this point, the real determinant of the firmness is not the direct tensile strength, but the knot strength. Below, from two perspectives, we will help you understand why the knot strength is more worthy of attention. 

1. Direct drawing strength vs. nodule strength: What's the difference? 

The direct drawing strength is the breaking force tested under standard conditions, while the knot strength is the actual load-bearing capacity of the wire after knotting. The difference between the two lies in the bending and stress concentration caused by the knotting, which significantly reduces the carrying capacity of the wire. 

Strength loss rate: When high-strength polypropylene yarn is knotted, the strength loss is usually between 30% and 50% or even higher. That is to say, for a yarn with direct drawing strength of 2000N, after knotting, it may break at a force of 1000-1400N. The lower the loss rate, the better the flexibility and anti-bending fatigue performance of the yarn. 

Why the knot strength is closer to reality: In scenarios such as sewing, binding, and weaving, the thread usually needs to be knotted or wound around other components. For example, the sewing thread for container bags is subjected to force at the corners, and the knot points of the safety rope net are also under force. These positions bear the exact strength of the knotted state. When purchasing, the direct pull strength can be used as a reference, but the knot strength is the more direct indicator to determine whether the thread is suitable for your purpose. 

II. How to assess and select wire with high strength of the nodules? 

Since the strength of the nodules is so crucial, how should we ensure quality during the procurement process? 

The supplier is requested to provide the data on the strength of the knots: During the procurement process, it is advisable to proactively inquire of the supplier whether they have tested the knot strength and require them to provide comparative data of the direct drawing strength and knot strength for the same specification wires. By calculating the strength loss rate (the lower the loss rate, the better), the flexibility and bending resistance of the wire can be preliminarily judged. Suzhen Tongjia New Materials Co., Ltd. specializes in the production of High-strength polypropylene filaments and high-strength polypropylene wires. The product specifications cover 250D - 3000D. It can match appropriate twist and strands according to the purpose to optimize the knot strength. 

Pay attention to the twist degree and surface smoothness of the wire: The strength of the knot is related to the twist degree of the wire, the surface friction coefficient, and the number of strands. An appropriate twist degree can make the wire more evenly stressed when tying the knot, reducing local stress concentration; a smooth-surfaced wire is easier to uniformly tighten when tying the knot, avoiding excessive local friction that leads to premature breakage. When purchasing, you can explain your specific knotting method (such as fisherman's knot, flat knot, reverse hand knot, etc.) to the supplier, so that the supplier can recommend a more suitable specification. 

Summary and Selection Suggestions 

When purchasing high-strength polypropylene yarn, it is recommended to follow the steps below for confirmation: 

Please provide the data on the strength of the nodules: Do not merely focus on the direct pulling strength; you must request the data on the strength of the nodules or the rate of strength loss. 

Actual knotting test: After the sample is made, conduct a manual tension test in your actual knotting method to feel the force exerted on the thread at the knotting point. 

Specify the purpose and knotting method: Inform the supplier of your specific usage (sewing, binding, weaving) and the typical knotting method, so as to match the appropriate twist and specifications. 

Suining Tongjia New Materials Co., Ltd. specializes in the production of polypropylene industrial yarn, high-strength polypropylene industrial yarn, polypropylene thread, high-strength polypropylene yarn, and polypropylene high-strength yarn. The product specifications range from 250D to 3000D. It has the ability for double twisting processing and an annual output of over 5,000 tons. It can optimize the knot strength according to the application requirements. Please feel free to request samples for testing. 

Official website: www.tongjiahx.com