Some polymers have mechanical properties that make them useful in various areas of applications. Examples of such polymers are polypropylene. Common applications of polypropylene include textiles, parts for refrigerators and dishwashers, furniture, toys, syringes, body panels for automobiles, and so much more.
With such versatile polymers, we only need to tweak their properties with some additives, and they can become suitable for even more areas of applications. Examples of additives for such polymers are nucleating agents and clarifiers.
What Are Nucleating Agents?
Nucleating agents are chemicals that encourage the formation of crystals in semi-crystalline polymers. The presence of nucleating agents in polymers improves their toughness, molecular stability, and clarity. Clarifying agents are only nucleating agents that enhance transparency.
The most common area of application of nucleating and clarifying agents is in polypropylene (PP) polymer. And because the crystal size, rate of crystallization, and degree of crystallization of these polymers play huge roles in their optical, thermal, and mechanical properties, nucleating agents are also very important because they allow us to modify these factors.
How Nucleating Agents Work
Nucleating agents increase the rate at which crystallization takes place in semi-crystalline polymers. Nucleating agents do this by this is by creating a suitable surface for the growth of polymer crystals. The consequence of this is that the time required for the polymer to cool down after processing is reduced. And when it takes less time to process polymer, its production rate increases.
There are three major ways through which nucleating agents are added to the polymer matrix. The first is by melt mixing. The second is solution blending, and the third is in-situ polymerization. During mix melting, the nucleating agents are mixed with the polymer matrix at temperature levels that are higher than the melting point of the polymer. Solution blending involves the dissolving of the polymer in a solvent before adding the nucleating agents to the solution.
Finally, the in-situ polymerization mixing involves the synthesizing of the polymer from its monomer. And while the polymerization reaction takes place, we add the nucleating agents.
Categories of Nucleating Agents
We have more than one way of categorize nucleating agents. But the most common classifications are these:
- Soluble nucleating agents
- Particulate nucleating agents
Let’s discuss each class in a little more detail.
1. Soluble Nucleating Agents
Soluble nucleating agents are characterized by their low melting points and how quickly they dissolve in polymers. During the melting process of polymers, soluble nucleating agents are the first to crystallize out. They then form a network that has a wide surface area in the process. On further drop in the temperature of the polymer melt, the polymer itself begins to melt, with the nucleating agent forming a network of nuclei. The nuclei are often so many that they force the polymer crystals to be small. And with the formation of these tiny crystals, the polymer becomes more transparent.
Examples of these nucleating agents are trisamides, nonitols, and sorbitols.
2. Particulate Nucleating Agents
Unlike their soluble counterparts, particulate nucleating agents have high melting points. During polymer processing, the particles of these nucleating agents scatter themselves in the polymer melt. There, they form nuclei “hotspots” for the crystals of the polymers to grow from.
Examples of particulate nucleating agents include minerals and salts.
Factors that Affect The Effectiveness of Nucleating Agents
Nucleating agents have varying levels of effectiveness in polymers, depending on the following factors:
1. The acid scavenger used in the polymer
Some acid scavengers negate the effects of some kinds of nucleants. They should never be used together in the same polymer. Examples of incompatible acid scavengers and nucleant are calcium stearate and sodium benzoate, respectively.
2. Polymer melt temperatures
Nucleating agents have varying melt temperatures. Those that have high melt temperatures help us derive the best clarity from the polymers they are added to. Sorbitols are examples of such polymers.
3. Size of nucleant particles
The smaller the particles of nucleants, the more clarification they bring to the polymer. The disadvantage of nucleants with small particles, however, is that the particles are harder to disperse. Smaller nucleant particles tend to re-aggregate even after dispersion. A suitable example of such a nucleant is sodium benzoate.
Other factors that determine the effectiveness of nucleating agents in the polymer matrix are the shape of the nucleant particles, the method of adding the nucleant to the polymer, and the degree of dispersion of the nucleant particles.
Shipping Nucleating and Clarifying Agents in Liquid Bulk
Nucleating agents are not as popular as other polymer additives. The reason is that only a handful of polymers use these additives. As a result, not many logistics companies would want to ship these chemicals. But even if you run out of logistics service options for your nucleating agent transport, Total Connection still has your back.
Total Connection logistics company offers you the best liquid bulk shipping solutions for your nucleating agent and clarifier shipments. We are a third-party logistics company with the experience and expertise to ship all kinds of industrial chemicals. Our services are tailored to your needs and your budget, so you can rest assured that you’re making the best supply chain decision for your company.
Enjoy the premium, yet affordable, services than other companies enjoy when they have us handle their supply chain by filling out the brief quote form below.