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Do you use compatibilizers correctly?
- Dec 21, 2018 -

Compatibilizer is also called compatibilizer. The key of plastics blending, modification and alloying is to solve the compatibility of different polymers. Adding appropriate compatibilizers to make them have good compatibility is solving this problem.

How to select compatibilizer correctly, give full play to the performance of different components, and prevent the product from failing in the final use process is very important.

According to the interaction characteristics between matrix polymers of compatibilizers, compatibilizers can be divided into two categories: non-reactive compatibilizers and reactive compatibilizers.

Non-reactive compatibilizer

Non-reactive compatibilizers refer to copolymers that do not contain reaction genes and do not participate in chemical reactions in the mixing process of polymers.

Structurally, most non-reactive compatibilizers are block copolymers, graft copolymers or random copolymers, such as EAA, EEA, EVA, CPE, SEBS, etc.

But this kind of compatibilizer needs to be added in a large amount.

Reactive compatibilizer

Reactive compatibilizers improve their compatibility mainly by chemical bonds formed by chemical reactions between their reaction groups and raw polymer during mixing.

Generally speaking, it is of macromolecular type. Its active functional groups can be at the end of the molecule or on the side chain of the molecule. The main chain of the macromolecule can be the same as or different from at least one polymer matrix in the blend system. However, under different conditions, the main chain of its macromolecule should have good compatibility with at least one polymer matrix in the blend system.

This kind of compatibilizer has the advantages of high efficiency, less amount of additives, but the disadvantages are large side reactions and relatively high requirements for mixing conditions.

Main Classifications and Varieties

01. Cyclic anhydride type (MAH)

Cyclic anhydride type reactive compatibilizer is the most commonly used type of reactive compatibilizer at present. Among them, maleic anhydride is mainly grafted to polyolefin compatibilizer, the grafting rate is generally 0.8% - 1.0%, which is mainly used in the modification of polyolefin plastics. Copolymerization compatibilizer grafting maleic anhydride onto PS or PS matrix can be used in modification, blending or alloying of PA/PC, ABS/GF, PA/ABS. The general dosage is 5%-8%.

02. Carboxylic acid type

The representative product of carboxylic acids is acrylic compatibilizer. Acrylic acid is usually grafted onto polyolefin resins for the same purpose as maleic anhydride.

03. Epoxy type

Epoxy reactive compatibilizer is prepared by graft copolymerization of epoxy resin or epoxy compounds with other polymers. This kind of reactive compatibilizer can play a good compatibility role.

04. Oxazoline

Oxazoline grafted PS, or RPS, is an important compatibilizer with a grafting rate of 1%. It has a wide range of applications. It can not only react with general polymers containing amino or carboxyl groups, but also with carbonyl, anhydride and epoxy groups to form graft copolymers. Therefore, it can be used in PS and a variety of engineering plastics or modified polyolefin resins. In addition, it can also be "in-situ" compatible, directly used in plastic modification, blending and alloys.

05, imide type

The imide type is modified polyacrylate, which is mainly suitable for engineering plastics alloys or blends such as PA/PO, PC/PO, PA/PC, etc.

06, isocyanate type

The composition is m-isopropyl-2,2-dimethylbenzoyl isocyanate. It can be used in engineering plastics alloys containing amino and carboxyl groups.

07, Low Molecular Type

Low molecular compatibilizers are reactive compatibilizers. They are reactive monomers and low molecular weight polymers, including some components compatible with one component synthesized from plastics, and react, cross-link or bond with another component to form organic and inorganic compounds in plastic alloys. In this way, not only the process of manufacturing plastic alloys is simplified, but also the raw materials are easily available and the cost is low. However, the requirement for extruders is high, and the use of mixing extruders is the key to the production of low molecular compatibilizers.

Where compatibilizers are needed

01. Plastic Alloys

The compatibilizer plays a very good role in adjusting and controlling the micro-phase structure of the alloy technology, so as to achieve high performance and functionalization of the blends. Compatibilizers are widely used in PP/PE, PP/PA, PA/PS, PA/ABS, ABS/PC, PBT/PA, PET/PA, PP/POE, PE/EPDM, TPE/PU and other alloys.

02. Polymer Modification

Because the compatibilizer acts as a bridge between non-polar and polar polymers by incorporating carboxyl groups of active free radicals, it is modified into polar polymers, and then blended with polar polymers. The good effect of modification and blending is obtained by the reaction between them.

03. Recycling Waste Plastics

Recycling waste plastics by using compatibilizers to make them new plastic alloys or new modified plastics is a better feasible way of "comprehensive utilization of waste" and can solve the problem of "white pollution", which has great social and enterprise economic benefits. There are many precedents abroad, such as BENNET compatibilizer produced by Dutch National Mining Corporation, which is a special compatibilizer for recycling waste plastics. It can be used to blend two or more kinds of old plastics with different properties, such as polyolefin plastics and engineering plastics, and add 5%-10% compatibilizer as the interface layer between sea and island, so as to play the role of compatibilizer. The bonding force is POLARLY compatible with the group efficiency, and is prepared into a new plastic alloy or modified plastic.

04. Coupling of Plastics with Fillers

The compatibilizer is also called macromolecule coupling agent. Because the polymer is compatible with the polymer, the compatibilizer has excellent coupling efficiency between plastics and fillers. It can be used in PE/CaCO3, PE/talc powder, PA/GF and other coupling treatments, and the effect is good.

05. Toughening of Polar Resin

Thermoplastic elastomer has good softness, high elasticity and low temperature properties. A certain amount of compatibilizer can be used as toughening agent for PP, PE, PS, PA, PC and other plastics. The compatibilizer is the most critical "core" and "shell" compatibility of these tougheners. For example, the toughening agent of EPDM grafted with MAH can maintain excellent physical properties and toughness at - 45 C. The general dosage is 5%-10%.

06. Improving other properties of plastics

The compatibilizer can also be used to improve the adhesion, antistatic, printability, gloss and other properties of plastics.