In actuality, the great majority of polymer-polymer mix systems are either incompatible with thermodynamics or only partially compatible with it. In other words, polymer-polymer blend systems are often not particularly compatible. Compatibilization is a widely used technique for obtaining good physical and mechanical qualities and enhancing polymer-polymer compatibility.
1. Compatibility is physical in nature
Compatibility’s physical characteristics can be summed up in three ways: Reduce the interfacial tension between the blending components; Improve the phase structure’s stability, which stabilizes the performance of the blended modified plastic; and Improve the interfacial bonding between the components, which facilitates the transfer of external field effects between components and enhances the performance of blended modified plastics. It is hoped that the compatibilizer will congregate in the interface zone, where it can completely exert its effects. In actuality, a variety of factors influence how the compatibilizer is distributed in the mix system.In addition to compatibility, it is influenced by blending equipment, process circumstances, the quantity and technique of applying a compatibilizer, and other elements.
2. Guidelines for compatibilizer selection
Compatibilizers frequently use block copolymers, graft copolymers, etc. One segment of the component interacts or reacts with one component of the blend, whereas the other segment interacts or reacts with a different component of the mix. The employed compatibilizers are categorized into homogeneous type compatibilizers and micro-phase separation type compatibilizers based on how they behave differently during micro-phase separation. Block copolymers and graft copolymers serve as representations for the former, while they also serve as representations for the latter. homopolymers, functionalized polymers, and random copolymers are included.
(1) Poly(A-co-B), a copolymer of Poly(A) and Poly(B), can be used to make Poly(A) and Poly(B) more compatible with one another.
(2) Poly(C) can act directly as a compatibilizer for both if it is compatible with Poly(A) and Poly(B) at the same time.
(3) Poly(C) can be utilized as a compatibilizer for both if it is compatible with Poly(A) and its functional group interacts with a specific functional group of Poly(B).
3. Systems for several widely used plastic blending that are compatibilizers
PPO/nylon 6 alloys include PPO-g-MAH and PS-g-MAH.
PC/ABS alloy: ABS, SEBS-g-MAH, SMA, or SBS.
PE, PP, POE, SEBS or ABS, EPDM-g-MAH: Elastomer hardened nylon 6 system
PPO toughened with styrenic elastomer: SBS, SEBS, or SIS-g-MAH
acrylate copolymer PBT/ABS alloy
acrylate copolymer and GMA graft copolymer are elastomer-toughened PBT materials.
Modifying plastic blends is done for this reason.
1. Enhance certain of the mechanical and physical characteristics of plastics and broaden their application range
(1) Increase plastics’ all-around performance. Utilize the unique qualities of each polymer component, build on one another’s benefits, get rid of the performance flaws in each individual polymer component, keep their own advantages, and you’ll get polymer materials with great overall properties. For instance, combining polypropylene and polyethylene maintains the benefits of high tensile and compressive strength of polypropylene and high impact strength of polyethylene while also addressing the drawbacks of polypropylene’s poor impact strength and susceptibility to stress cracking.
(2) Increase impact resistance and plastic toughness. For considerable modification effects, modest amounts of one polymer can be used as a modifier for another polymer. Plastics that have been rubberized are the most prevalent example. For instance, PVC/rubber and PP/rubber blend systems all have strong impact resistance. Another illustration is the PA/PE blend system, which significantly lowers the hygroscopicity of PA and increases its impact strength at low temperatures.
(3) Increase plastics’ capacity to withstand heat. Most polymers have low thermal deformation temperatures. General plastics are not appropriate for particular parts because they operate best at a specific temperature. Its heat resistance can be increased by combining other plastics that have strong heat resistance.
(4) Decrease water absorption and enhance dimensional stability of the product. For instance, the relatively high water absorption rate of PA, which is easily responsible for dimensional changes in goods, is significantly decreased by the PA/PE mix system.
(5) Enhance the effectiveness of stress cracking. For instance, PC that has been converted to PE or ABS, etc.
(6) Enhance various mechanical and physical characteristics. include biocompatibility, damping, adhesion, weather resistance, wear resistance, air tightness, and chemical resistance (solvent resistance).
2. Increase melt fluidity and performance of the molding processing
For instance, plastics that can withstand high temperatures are needed in the field of aerospace science. However, a lot of plastics that can withstand high temperatures also have high melting points and low melt fluidity, making them challenging to mold and process. Technology blending can address this issue. For instance, polyimide (PI), which is insoluble and refractory, can be easily injected when combined with fluid polyphenylene sulfide (PPS).
The blends of these two polymers are still outstanding high-temperature materials because of their good heat resistance. PS and ABS can be blended with polyphenylene ether (PPO) to increase fluidity and processability. To increase its processability, rigid PVC frequently needs to be blended with CPE, ACR, and other resins. Blending is another method for controlling how crystalline polymers behave when they crystallize.
3. Create new plastic alloy materials and provide plastics specific particular characteristics.
Halogen-containing flame-resistant polymers can be combined with flame-retardant plastic alloys to create them. For instance, PVC, chlorinated PE, polyphenylene ether, and polyphenylene sulfide can all be made more flame resistant by adding PS, ABS, polyformaldehyde, etc. Plastics don’t conduct well. To produce plastic materials with anti-static, conductive, and electromagnetic shielding functions to meet the needs of the electronics, home appliance, communications, military, and other industries, some materials that need conductivity and anti-static can be blended with conductive polymers.
varied polymers with vastly varied optical characteristics can be mixed to create beautiful plastics with iridescent brilliance. For instance, iridescent shine can be added to PC products by adding polymethyl methacrylate. By combining a variety of polymers, silicone resin can be used to create polymer materials with good self-lubricating qualities.
It is possible to create multi-layered, porous materials with lovely natural wood grains that can be used as wood substitutes by mixing two resins with drastically differing tensile strengths and poor miscibility.
4. Lower material prices and boost financial gains
In order to lower the cost of the material and improve the molding processability without impacting the usage conditions, some engineering plastics with great qualities but affordable costs can be combined with cheap general-purpose plastics. For instance, SAN and ABS can be added to PC, PSF, etc. to increase performance while lowering material prices.
5. Recycle used polymer materials to lessen pollution
Utilizing blending technology can help recycle used plastics, conserve resources, and lessen environmental damage. In summary, by modifying the blending process, it is possible to increase the variety of plastics with relatively little investment, increase the uses for plastics, lower their cost, and produce high-performance, refined, functional, and functional plastics. The development of the plastic and polymer material sectors, as well as high-tech industries like communications, transportation, electronics, appliances, home appliances, military, and aerospace, is facilitated by specialization and serialization.
