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Plastic modification methods are complete, you must know!
- Nov 30, 2018 -

In practical application, few plastics can fully meet the specific application requirements; this requires us to make some appropriate adjustments to the physical properties of plastics; on the other hand, according to the actual situation of the market, we will meet the requirements, as far as possible to reduce the cost, so as to take the lead in the fierce competition! Four o'clock, you must know how to make plastic!

1. How to reduce the cost of plastics?

Method 1. Filling of Inorganic Material

For thermoplastics, the main purpose is to reduce costs; for thermosetting plastics, both cost reduction and modification are necessary. In addition to reducing cost, filling can also improve some properties of products. Generally, it can improve the rigidity, heat resistance (inorganic filler), dimensional stability, reducing shrinkage and creep resistance, and some can also improve insulation, flame retardancy, smoke suppression and sound insulation.

Common fillers

Class CaCO3 packing

Talc filler

Wollastonite packing

Kaolin filler

Mica filler

Diatomite filler

Key points of formula design

Oil absorption of fillers

When liquid additives are contained in the formulation system, fillers with low oil absorption should be selected.

Resin absorption of fillers

When liquid resin is contained in the formulation system, fillers with low resin absorption should be selected.

METHOD II. BLENDING OF LOW-PRICE RESIN

Blending to reduce the cost of plastics refers to the process of mixing low-cost resins or waste plastics into high-price resins in order to achieve the goal of reducing costs. Compared with the cost reduction of filling plastics, the cost reduction of filling plastics is not very large, but it has the advantage of less influence on its own performance.

Among the resins used, the resins with relatively low price are mainly PVC, LDPE, LLDPE, HDPE, PP and PS. The so-called low-cost resin is blended with these resins.

2. How to strengthen plastics?

Fiber Reinforcement with Plastic Addition

Fiber reinforced plastics is one of the most common and effective reinforcement methods. Fiber reinforced materials are the most important reinforcing materials for plastics, which can account for more than 90% of the total reinforcing materials. Fiber materials for reinforcement include fibers and whiskers.

Inorganic: such as glass fibers, asbestos fibers, carbon fibers, whiskers, quartz fibers, graphite fibers and ceramic fibers, etc.

Organic: such as PAN fiber, polyethylene fiber, PA fiber, PC fiber, PVC fiber and polyester fiber, etc.

Metals: such as boron fibers and metal whiskers such as aluminium, titanium and calcium.

3. How to change the heat resistance of plastics?

Method 1. Plastic Filling

In all fillers, except organic fillers, most inorganic mineral fillers can significantly improve the heat resistance temperature of plastics.

The commonly used heat-resistant fillers are calcium carbonate, talc powder, wollastonite, mica, calcined ceramics, bauxite and asbestos. For example, mica can be used at a maximum temperature of 1000 degrees Celsius and is the most effective heat-resistant modified filler.

Method 2. Reinforcement of plastics

The effect of plastic reinforcement on heat resistance is better than that of filling, mainly because the heat resistance of most fibers is very high, and the melting point of most fibers is more than 1500 degrees Celsius.

The commonly used heat-resistant fibers are asbestos fibers, glass fibers, carbon fibers, whiskers, polyamide fibers and acrylate fibers.

4. How to improve the flame retardancy of plastics?

Combustibility of plastics

The flame retardancy of most plastics is not very good. To measure the flame retardancy of resins, the following indicators are generally used:

Oxygen index (OI)

U.S. UL Standard (UL-94)

The test method of UL standard in USA is to observe the combustion of plastics in direct contact with fire source and to analyze its flame resistance.

A.V-0 level is extinguished within 10 seconds after fire, and does not ignite cotton powder 30 cm below it.

Grade b.V-1 will be extinguished within 10-30 seconds after Fire detachment and will not ignite cotton powder 30 cm below it.

C.V-2 level is extinguished within 30 seconds after fire, but it can ignite cotton powder 30 cm below it.

Flame Retardant Materials for Plastic Addition

Flame retardant is a common component in plastics adding flame retardant formula. It is a kind of additive that can prevent plastics from igniting or inhibiting flame propagation. Flame retardant is a commonly used additive in plastics formulation. Its consumption is second only to filler and plasticizer, and it has become the third largest additive variety of plastics. There are many kinds of flame retardants. At present, thousands of flame retardants have been reported, and more than 100 kinds of flame retardants are frequently used.

The commonly used flame retardants can be divided into halogen compounds, phosphorus compounds, nitrogen compounds, organosilicon compounds and various inorganic compounds, such as AI (OH) 3, Mg (OH) 2 and Sb2O3.