PVC modifications: Savior of my figure models

popular science story-telling contest on May 30th

One day when I was clearing up my stuff, I noticed a “horrible” disaster – that was about my figure models bought five years ago. There are cracks on them. The colours had faded. Some of them even got oily and sticky. I didn’t preserve them well. What a terrible mistake! To learn a lesson from this painful experience, I searched for some information and acquired some knowledge about their material, PVC.

PVC, or polyvinyl chloride. It’s a kind of plastic which is easy to get coloured or be shaped – an ideal ingredient for models. However, some of its substance properties make the PVC crafts very fragile.

At the condition of sunlight or high temperature, PVC will degrade. It will give off hydrogen chloride molecular and form some chemical bonds. During this process, its original colours will fade and the plastic will become very brittle.

Also, PVC needs plasticizer to improve properties during manufacture. If there is too much plasticizer inside or it’s too hot, the plasticizer will separate out and make the PVC surface oily. The oilier it is, the less plasticizer left in the plastic, then we can almost declare the end of its life.

So, let’s think out of box. Besides spending much effort on maintenance, why not improve the ingredient itself to enhance our using experience?

This action is called modification. It changes the physical and chemical properties of substance.

Because PVC is widely used in many aspects, PVC modification has long been studied to find newer and better properties.

Let me show two examples.

The first one is about making PVC more heat resistant. The experimental subject is PVC foam, used in packaging and sound insulation. The general idea is to mix PVC with different additives to get a mixture with the highest heat-resistance temperature, and repeat trails till we get the desired outcomes. Those additives, called heat stabilizers, can absorb HCl molecular and inhibit the production of them, to prevent the crafts from cracking and fading. As is shown in the table, the best solution for multifunctional monomer is 100:8 proportions of BMI and PVC. There are also other kinds of PVC, but the BMI is the most effective one.

The second one is about making PVC more corrosion-resistant. Here’s an interesting high-tech called plasma surface treatment, which can be explained as a mass of electrons, ions, neutrons hit the surface of stuff to transfer energy. In this way, the researcher managed to graft Florine atoms to the surface of PVC plastic. The purpose is to combine the two advantages.  Florine atoms are against chemical-erosion, while the PVC plastic is hard and strong. After strengthening the plastic toughness, we can extend the life span of PVC pipes. It will make a great contribution to the construction industry, to save more resources and set more labour-force free.

Now, after learning all this, let’s return to the case of my models. To improve the properties, I think one possible breakthrough is the plasticizer. Can we find a special kind of plasticizer that is more stable and will not leak out of the plastic? Or, on the other hand, is there a possible manufacture technique that allows less dosage of PVC plasticizer? This is still a problem for us to solve, however, we have known that, modification creates a lot of possibilities for PVC and other kinds of substance to show their capabilities of benefiting mankind, and there are still a long way to go.

That’s all for my story on PVC and its modification. Thanks for your listening!