I. Introduction Conventionally speaking, PVC cable materials generally do not appear to be wet. However, cable material manufacturers, especially some township and village enterprises, are striving to reduce costs by emphasizing efficiency. Such as greatly increasing the amount of filler, the use of plasticizer substitutes and so on. Although it has achieved good economic benefits, it also reduces the performance of cable materials and increases the number of problems in processing. The occurrence of moisture in PVC cable materials during the rainy season is also a product of low-cost cable materials. When the damp cable material is used for cable forming, the surface of the product is rather rough and tarnished. In severe cases, flaws will appear on the surface of the product, accompanied by elongated (opened) bubbles, and there are pores in the cross section. In addition, the processing temperature range also has a tendency to narrow. The application of damp cable materials not only damages the appearance quality of the cable skin, but also affects the internal quality. Cable molding manufacturers will refuse to use it at this time. The moisture-absorbing cable material is simply dried to remove the moisture, and it can be used normally. Its performance will vary somewhat, but it is not obvious. However, after some damp cable materials are dried, the moisture is getting better, but it will soon return to its original state. The underlying cause is not the actual moisture, but the partial degradation of the PVC cable material due to potential degradation and surface coatings. Of course, some of them also have moisture components. The performance of this cable material is very similar to that of a truly wet PVC cable material. In addition, the humid high temperature climate will promote and exacerbate the occurrence of potential degradation and surface layering, making the phenomenon in processing more obvious. Therefore, people often make wrong judgments on them, and it is determined that PVC cable materials are really damp. 2. Prevention measures for moisture in PVC cable materials: The summer rainy season in the north is high and the humidity is high. Certain raw materials and finished products of PVC cable materials are easy to absorb moisture, causing the cable material to be exposed to moisture. In order to prevent the occurrence of moisture, we must first pay attention to the storage of various raw materials, especially the storage of three salts, two salts, resins, clay, etc. that are susceptible to moisture. In order to avoid the moisture, it affects the moisture resistance of PVC cable materials. Secondly, in the production process of PVC cable material, the dry mixing time is appropriately increased, and the exhausting measures during the mastication process, such as vacuuming, are strengthened. Ensure that moisture and other gases are removed before the cable material is formed. Finally, the PVC cable material should be cooled after packaging and sealed in the bag. And pay attention to strengthen the ventilation and drying measures of PVC cable material storage. This generally prolongs the storage time of PVC cable materials in high temperature and humid climate, so that the moisture is less likely to occur, which occurs late or does not occur. III. Analysis and solution to the causes of false dampness of PVC cable materials There are two main reasons for the false damp phenomenon of PVC cable materials: one is the potential degradation, and the other is the surface layer. The phenomenon of false dampness is sometimes caused by one of the reasons, sometimes caused by two reasons. The potential degradation and the occurrence of surface coatings are related to high temperature and high humidity, and the high temperature and high humidity promote and expand the reaction. Because of its performance in cable material re-forming, and the performance of cable materials when it is really wet, it is difficult to distinguish. There are often ingredients that are really damp. Therefore, we call it a fake damp phenomenon. Potential degradation The potential degradation is due to the hydrogen peroxide formed by the oxidation of the plasticizer. It is colorless and tasteless and is not directly reflected. The hydrogen peroxide will cleave and the resulting low molecular weight material will escape, making the "volatility" higher than expected. At the same time, some lysates will cause PVC degradation. Cracked low molecular weight materials that are incompatible with the PVC system also migrate to the same, but unoxidized, PVC product in the same package by migration or even volatilization, causing them to begin to degrade. This destructive effect is already potential in the processing process, but it often does not occur during or immediately after processing, but occurs after being placed, especially after storage in a thermal warehouse for a period of time, giving a damp Illusion. For potential degradation, the amount of stabilizer and lubricant added is appropriately adjusted, and a certain amount of an antioxidant such as bisphenol a is added, and the amount is generally 0.3 to 0.5 PHR. Most can be solved very well. However, it should also be noted that the use of certain pigments and stabilizers, this oxidation phenomenon will be further exacerbated, because a resin stabilizer, and at the same time may be a plasticizer oxidation promoter. 2. Surface layer The surface layer is a viscous deposit deposited onto the metal surface of the processing equipment from the PVC system being processed. When extrusion processing, the surface layer is generally present on the screw, the barrel wall, the inner wall of the die, and the like. The surface layer directly affects the surface quality of the product, which makes the surface rough and tarnished. Seriously, it will cause troubles in operation, and it is easy to cause partial degradation of PVC. It mainly occurs when the cable is formed, causing a false tide of the cable material. In fact, it is lurking in the cable material, more specifically, it is determined by the cable material formulation. The occurrence of surface attachments has a certain relationship with the climate, the production process and the composition of the components, especially the metal ions. Therefore, the solution should start from the following aspects: pay attention to the humidity adjustment of the cable and cable material forming workshop, appropriately reduce the production and processing speed, adjust or replace the stabilizer, adjust the lubrication system, and so on. Some aspects are not well controlled and adjusted during specific operations. Generally, the production speed should be appropriately reduced in the production of PVC cable materials; increase the amount of lubricant stearic acid (but not too large); under the premise of ensuring the stability effect, reduce the amount of stabilizer. Thus, the surface layering phenomenon in the formation of the cable sheath can be substantially eliminated. Of course, adding the right amount of PMMa will make the effect better. In actual production, potential degradation and surface layering are sometimes co-existing, and there is a synergistic effect between them, which together promote the degradation of PVC and cause false tides. This is to be integrated. If the processing speed of the cable material production is appropriately reduced, a certain amount of antioxidant (and acrylate resin) is added, and the amount of the stabilizer and the lubricant is adjusted. After adjustment, in the case of little change in cost, it is generally possible to remove such cable material false tide phenomenon. Conclusion. 1. Affected by the climate, low-cost PVC cable materials are damp in the northern rainy season. 2. PVC cable material in the process of cable skin forming, there are two reasons for the moisture phenomenon: First, the actual absorption of moisture is damp; First, the degradation of PVC and surface damage caused by potential degradation and surface layering should be treated differently. . 3. The cable material that is really damp can be reused by drying. It can be avoided by strengthening preservation measures. 4. The phenomenon of false dampness caused by potential degradation and surface layering should be clearly distinguished. Generally, some adjustments can be made from the process and the formulation, which can basically be solved. 5. Many questions and theories about potential degradation and surface attachments are for further study. Fiberglass woven roving is a versatile composite reinforcement material composed of continuous glass fiber filaments coated with a coupling agent or binder. The glass fibers are woven into a fabric with a plain or twill weave pattern, providing strength and stability. fiberglass woven roving, fiber woven roving, E-Glass Woven roving Jinwu Glass Fiber Co., Ltd , https://www.jinwuwindows.com
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