简体中文

Why Does PVC Need Stabilizers? Let’s Start with Aging Problems

创建于12.16
Many daily-use items like plastic basins, pipes, and agricultural films are made of PVC (polyvinyl chloride). However, PVC has a critical flaw: it easily releases hydrogen chloride (HCl) gas during high-temperature processing. Like a domino effect, this decomposition triggers a vicious cycle—released HCl accelerates the breakdown of PVC’s molecular structure, forming unstable "polyene structures." When combined with oxygen or metal ions (e.g., iron, zinc, copper), aging speeds up dramatically, leading to discoloration, cracking, brittleness, and reduced strength. Imagine a newly bought plastic bucket cracking in just six months—frustrating indeed!

The Stabilizer Family: Versatile "Plastic Protectors"

To enhance PVC products’ durability, stabilizers are essential additives. Acting like "bodyguards" for plastic, they are categorized into four main types based on their functions: heat stabilizers, antioxidants, UV absorbers, and chelating agents. Manufacturers select and combine these "bodyguard teams" according to product applications (e.g., transparent water cups vs. outdoor pipes) and processing conditions.

1. Heat Stabilizers: "Firewalls" Against High Temperatures

These stabilizers combat thermal decomposition through two key mechanisms: capturing released HCl or repairing unstable molecular structures. Common types include:
  • Lead salt stabilizers
  • Barium-cadmium stabilizers
  • Calcium-zinc stabilizers
  • Organic tin stabilizers
  • Emerging types
  • Auxiliary agents

2. Antioxidants: "Preservatives" Against Oxidation

PVC undergoes oxidation during processing and use when exposed to high temperatures or UV light—similar to apple slices turning brown. Primary antioxidants (e.g., bisphenol A) directly "neutralize" free radicals generated by oxidation, while secondary antioxidants (e.g., triphenyl phosphite) decompose harmful peroxides. Their combination delivers a synergistic effect greater than the sum of individual parts.

3. UV Absorbers: "Sunscreens" for Outdoor Use

PVC products exposed to long-term sunlight (e.g., agricultural films, outdoor plastic decorations) suffer molecular structure damage from UV radiation. UV absorbers act like "sunscreen" for plastic, absorbing specific UV wavelengths:
  • Triazine-5: Most effective but slightly yellowish, adjustable with phthalocyanine blue.
  • UV-9: Commonly used in agricultural films at 0.2–0.5 phr (parts per hundred resin).
  • Salicylates: Mild-acting, suitable for blending with antioxidants.

4. Chelating Agents: "Trappers" for Metal Ions

As metal ions accelerate PVC aging, chelating agents (e.g., phosphites) act like "hunters," binding harmful ions into harmless complexes. Ineffective alone, they are usually combined with metal soap stabilizers, used at 0.5–1 phr in agricultural films.

Future Trends: Dual Upgrades in Environmental Friendliness and Performance

With growing emphasis on health and sustainability, PVC stabilizers are evolving toward non-toxicity, high efficiency, and multi-functionality. Heavy metal-containing stabilizers (e.g., lead salts, barium-cadmium) are declining, while green alternatives (calcium-zinc composites, rare earth, hydrotalcite) have become R&D hotspots. Future stabilizers will not only enhance durability but also offer improved safety and intelligence—such as adaptive protection based on environmental changes. These tiny stabilizers, backed by advanced technology, silently safeguard every PVC product in our daily lives.
Disclaimer: The content of this article comes from the Internet. The purpose of reposting is to share more learning information and for online sharing. The copyright of the article belongs to the original author. We pay tribute to the original author! If you find that the content (including text, images, tables, etc.) infringes on your intellectual property or other legal rights, please contact us promptly.
Contact
Leave your information and we will contact you.