How does swelling water-blocking yarn achieve rapid expansion to prevent water penetration after contacting water?
Publish Time: 2025-06-30
Swelling water-blocking yarn is a functional yarn developed based on polymer water-absorbing materials. It is widely used in fields with extremely high requirements for waterproof performance, such as communication cables, optical cables, and power cables. Its core principle is to use polyester fiber filaments as skeleton materials and dip-coat and bond highly absorbent polyacrylic acid resin on its surface to form a composite structure that can rapidly expand and form a gel-like substance after contacting water.1. Basic composition and characteristics of swelling water-blocking yarnThe core component of swelling water-blocking yarn is polyester fiber filaments, which has excellent mechanical strength and chemical corrosion resistance and is suitable as a supporting skeleton. A layer of highly absorbent resin, usually modified polyacrylic acid salt material, is evenly coated on its surface. The resin has super strong water absorption capacity and can quickly absorb and expand to several times or even dozens of times the original volume after contacting water, while forming a stable gel.This gel has good sealing and adhesion. Once generated, it can effectively block the water penetration path and prevent water from diffusing along the inside of the cable. Even under long-term immersion conditions, the expanded gel can still remain stable and will not dissolve or flow away, thus achieving a lasting water-blocking effect.2. Analysis of the mechanism of swelling in waterWhen the swelling water-blocking yarn comes into contact with water molecules, the polyacrylic resin begins to absorb water. This process mainly relies on the hydrogen bonding between the hydrophilic groups (such as carboxylate ions) on the resin molecular chain and the water molecules. As water continues to penetrate, the resin particles quickly absorb water and expand in volume, eventually forming a dense gel layer.This swelling process is usually completed within a few seconds to a few minutes, with a fast response speed, which can prevent water from continuing to invade in the first place. In addition, because the expanded gel structure has a certain elasticity, it can adapt to the slight deformation that may occur in the cable during use, ensuring the stability of the sealing performance.3. Application advantages in communication cablesIn communication cables, swelling water-blocking yarn is widely used to fill the gap between the cable core and the sheath. Traditional waterproofing methods mostly use grease filling, but this method has problems such as heavy weight, complex construction, and difficult later maintenance. The swelling water-blocking yarn is not only lightweight and environmentally friendly, but also provides more efficient waterproof protection without increasing manufacturing costs.Especially in submarine optical cables and underground communication lines, facing long-term humid or even high-pressure water environments, the rapid response ability and long-term water-blocking performance of swelling water-blocking yarn are particularly important. It can quickly form a barrier at the joints or damaged parts, effectively preventing moisture from entering the cable core and causing signal attenuation or equipment damage.4. Application performance in power cablesIn cross-linked polyethylene insulated power cables, swelling water-blocking yarn is often used in the design of longitudinal waterproof structures. By winding it between the conductor shielding layer or the metal sheath, it can quickly absorb water and swell and close the water inlet channel when the cable is damaged by external force or the joint seal fails, preventing moisture from spreading along the length of the cable, thereby causing insulation degradation or even short circuit accidents.In addition, in the fields of submarine cables and urban rail transit power supply systems, swelling water-blocking yarn is also used as an important component of the comprehensive waterproof layer. It is used in conjunction with water-blocking tapes, water-blocking powders and other materials to build a multi-level waterproof system, significantly improving the safety and reliability of the cable system.5. Choice under the trend of environmental protection and sustainable developmentWith the promotion of the concept of green manufacturing, swelling water-blocking yarn is gradually becoming an ideal choice to replace traditional waterproof materials because it does not require the use of traditional filling media such as mineral oil or silicone oil, reducing the risk of environmental pollution. Its degradability and low toxicity also meet modern environmental standards and are suitable for various engineering projects with strict requirements on ecological impact.In summary, swelling water-blocking yarn plays an important role in multiple industries such as communications and electricity with its unique water swelling mechanism, excellent water-blocking performance and convenient construction method.
