We live in a world of plastics, but not all plastics are created equal. Some are brittle and prone to cracking, while others are flexible and resilient. Some are strong but heavy, while others are lightweight but weak. But what if we could combine the best properties of different plastics, creating materials that are stronger, tougher, more flexible, and more versatile? This is the magic of plastic modification, a field of innovation that’s transforming the world around us.
Supercharging Plastics:
Plastic modification is all about enhancing the properties of plastics, giving them superpowers that make them even more useful and adaptable. It’s like taking a base plastic and giving it a boost, making it tougher, more heat-resistant, more flexible, or more flame-retardant.
The Toolkit of Plastic Modification:
The world of plastic modification is a toolbox filled with ingenious techniques, each designed to achieve a specific outcome. Here are a few of the most common methods:
- Fiber Reinforcement: Adding fibers, like glass or carbon fiber, to plastics increases their strength, stiffness, and durability. Think of it like adding steel rods to concrete, making it stronger and more resistant to bending and breaking.
- Toughening: This process involves adding materials that improve the impact resistance of plastics, making them less prone to cracking and shattering. Imagine a plastic that can withstand a drop or a bump without breaking – that’s the power of toughening.
- Filling Modification: Adding fillers, like minerals or glass beads, to plastics can improve their properties, such as stiffness, strength, and heat resistance. It’s like adding sand to concrete, making it stronger and more durable.
- Blending Modification: Combining different types of plastics can create materials with unique properties. Imagine blending a strong, rigid plastic with a flexible, rubbery plastic – the result could be a material that’s both strong and flexible.
- Flame Retardant: Adding flame retardants to plastics can make them less flammable, improving safety in applications where fire is a concern. Think of it like adding a fire-resistant coating to a material, making it less likely to ignite.
- Graft Modification: This involves chemically attaching new molecules to the plastic, changing its properties in a targeted way. It’s like adding a new feature to a plastic, giving it a specific advantage, like improved heat resistance or chemical resistance.
The Rise of Thermoplastic Elastomers (TPEs):
One of the most exciting areas of plastic modification is the development of thermoplastic elastomers (TPEs). These materials combine the flexibility and resilience of rubber with the strength and processability of plastics. TPEs are finding applications in a wide range of industries, from automotive parts to medical devices to sporting goods.
Plastic modification is a field of innovation that’s constantly evolving, pushing the boundaries of what’s possible with plastics. It’s a testament to human ingenuity, allowing us to create materials that are stronger, tougher, more versatile, and more sustainable. So, the next time you encounter a plastic product, take a moment to appreciate the magic of plastic modification and the incredible possibilities it holds for the future.
Plastic modification is to improve or increase the functions of large quantities of general-purpose resins produced by petrochemical companies through physical, chemical, and mechanical methods, such as electrical, magnetic, optical, thermal, aging resistance, flame retardant, mechanical properties, etc. In order to achieve the functions used under special environmental conditions.
Modified plastics is a plastics industry field with wide coverage and high technological content, and plastic modification technology – filling, blending and enhanced modification has penetrated into the raw materials and molding process of almost all plastic products. From the production of raw resin to modified plastic masterbatch of various specifications and varieties, in order to reduce the cost of plastic products and improve their functionality, plastic modification technology is inseparable.
In order to reduce costs, improve performance and meet different needs, plastics often need to be modified to adapt to various practical requirements. Here are several common plastic modification technologies:
1 Fiber reinforced
Long fiber reinforced thermoplastic (UCRT) is a new type of lightweight and high-strength engineering structural material. Because of its light weight, low price, and easy recycling and reuse, its application in automobiles is developing rapidly. The use of natural fibers such as flax and sisal reinforced plastics to manufacture body parts has been recognized in the automotive industry.
On the one hand, natural fiber is an environmentally friendly material, and on the other hand, plant fiber is 40% lighter than glass fiber. Reducing vehicle weight can reduce fuel consumption. The body floor is made of flax-reinforced PP. The tensile strength of the material is higher than that of steel, and its stiffness is no less than that of glass fiber-reinforced materials. The parts are easier to recycle.
The drive shaft made of fiber-reinforced plastic by the British company GKN Technology is 50%-60% lighter, has a torsional resistance that is 1.0 times greater than steel, and a bending stiffness that is 1.5 times greater. Plastic springs significantly reduce weight. The leaf spring made of carbon fiber reinforced plastic (CFRP) weighs 14kg, reducing weight by 76%. In the United States, Japan, and Europe, leaf springs and cylindrical coil springs have been used to realize fiber-reinforced plastics. In addition to having obvious anti-vibration and noise reduction effects, they also achieve the purpose of lightweighting.
2 Toughening technology
The stiffness (including strength) and toughness of polymer structural materials are the two most important performance indicators that restrict each other. Therefore, the study of enhancing stiffness and toughening at the same time has always been a difficult problem in polymer materials science. The Institute of Chemistry, Chinese Academy of Sciences has developed a new approach to polymer blending, filling, reinforcement and toughening. This achievement has made an important breakthrough in solving the scientific problem of simultaneous reinforcement and toughening of polymer materials. It has successfully prepared ultra-high toughness polyolefin engineering plastics for the first time in China. The upgrade of large varieties of general-purpose plastics provides a new way for engineering plastics and engineering plastics to further improve their performance.
The Supergravity Engineering Technology Research Center of the Ministry of Education successfully developed the national “863” project – “Nano CaCO3 plastic toughening masterbatch and its preparation technology.” This masterbatch can toughen and modify PVC and is mainly used in the production of PVC door and window profiles, as well as in the production of other hard products such as PVC pipes and plates.
From the perspective of development trends, PVC plastic doors and windows have the potential to completely replace steel windows and wooden doors and windows. At present, the annual production capacity of PVC door and window profiles in China is 1 million tons, and it is growing continuously. Using nano- CaCO3 plastic toughened masterbatch to produce PVC door and window profiles can not only comprehensively improve product performance, but also reduce the cost of profiled materials by more than 100 yuan per ton. At the same time, its application areas will also expand to plastic materials such as PP and ABS.
The use of nano-CaCO3 to toughen and modify PVC is a non-elastomeric toughened plastic technology (inorganic rigid particle toughened plastic technology) developed in recent years, which is still in the research stage in China. Directly adding nano-CaCO3 will cause two major problems: First, the nano-particles will agglomerate in the plastic matrix, causing uneven dispersion and affecting the toughening effect; second, because the nano-CaCO3 particles are small, they can easily generate dust and affect the environment. The successful development of nano-CaCO3 plastic toughening masterbatch and its preparation technology has effectively solved these two major problems faced in the same research field at home and abroad.
3 Filling modification (powder filling)
Since plastic filling modification was put on the market in the early 1980s, due to its low price, excellent product performance, and improvement of certain physical properties of plastic products, it can replace synthetic resin, and the production process is simple, the investment is small, and it has Significant economic and social benefits.
The surface modifier of weekly filling-modified inorganic powder materials has achieved certain results from stearic acid to coupling agents. The coupling agents include silane, titanate, aluminate, borate, phosphate, etc. Varieties are emerging.
Talc is commonly used to fill polypropylene. Talc powder has the characteristics of lamellar structure, so talc powder with finer particle size can be used as a reinforcing filler for polypropylene. In the modified polypropylene system, adding ultra-fine talc masterbatch can not only significantly improve the rigidity, surface hardness, heat creep resistance, electrical insulation, and dimensional stability of polypropylene products, but also improve polypropylene products. impact strength.
Adding a small amount of talc to polypropylene can also act as a nucleating agent and improve the crystallinity of polypropylene, thereby improving various mechanical properties of polypropylene. Due to the improved crystallinity of polypropylene, the crystal grains can be refined. , thus improving the transparency of polypropylene. Polypropylene composites filled with 20% and 40% ultrafine talc can significantly improve the rigidity of polypropylene and creep resistance at high temperatures, both at room temperature and high temperature. For polyethylene blown films, filling ultra-fine talc powder masterbatch is better than other fillers, and it is easy to form and has good processability.
4 Blending modification
Plastic blend modification refers to a modification method that incorporates one or more other resins (including plastics and rubber) into a resin to change the properties of the original resin. Plastic blending modification is a common plastic modification method that goes hand in hand with additive modification. The difference between it and plastic additive modification is that additive modification involves mixing small molecular substances into the resin, while plastic blend modification involves mixing high molecular substances into the resin.
Since the blend-modified composite system contains polymer substances, its compatibility is better than that of the additive system, and the modification has relatively little impact on other properties of the original resin. Plastic blends, also known as polymer alloys, are the most effective way to develop new polymer materials and are also the main way to achieve high performance and refinement of existing plastic varieties. Almost all the required properties of plastics can be obtained through blending modification.
For example, PP has the advantages of low density, good transparency, high tensile strength, high hardness, and good heat resistance . However, it has poor impact properties and poor stress cracking resistance. If blended with HDPE, the original properties of PP can be maintained. It also has the advantages of impact resistance, stress cracking resistance and low temperature resistance.
5 Flame retardant technology
Generally speaking, polymer flame retardant technology is mainly divided into two methods: additive and reactive, with additive being the main method. That is, adding a matching flame retardant to ordinary pellets, mixing them thoroughly in a mixer, and then entering the mixing device based on a twin-screw extruder to re-granulate to prepare flame-retardant modified “flame-retardant plastics”.
In the past ten years, intumescent flame retardants pioneered by Professor Camino of the University of Turin in Italy have played a huge role in PP flame retardant technology. This type of PN flame retardant has high efficiency, high thermal and light stability, low toxicity, and low smoke, low corrosion, little impact on processing and mechanical properties, and will not cause environmental pollution.
Commonly used additive flame retardants include decabromodiphenyl ether, octabromodiphenyl ether, tetrabromobisphenol A, hexabromocyclododecane, etc., among which decabromodiphenyl ether is used in the largest amount. The decomposition temperature of brominated flame retardants is mostly around 200-300°C, which matches the decomposition temperature of various polymers. Therefore, it can play a flame retardant role in the gas phase and condensation at the optimal moment, and the addition amount is small. , good flame retardant effect.
6 Graft modification
At present, graft-modified plastics are widely used as macromolecular coupling agents, compatibilizers, toughening agents, etc. Currently, the most common grafting monomers are maleic acid tincture, GMA and acrylic acid, GMA and acrylic acid, all of which have shortcomings such as high polymerization tendency, low grafting rate and grafting efficiency, and acrylic acid is highly corrosive.
The purpose of graft modification of polypropylene is to improve the adhesion or solubility between polypropylene and metals, polar plastics, and inorganic fillers. The grafting monomers used are generally acrylic acid and its esters, maleic acid and its esters, maleimides, etc.
Grafting methods include: ① Solution method, adding peroxide initiator to the solvent for copolymerization; ② Radiation method , grafting under high-energy rays; ③ Melting and mixing method , in the molten state in the presence of peroxide Mixing and grafting are often carried out in a twin-screw extruder.
The properties of graft-modified polymer materials are related to the physical and chemical properties of the graft , as well as the content of the graft, the length of the graft chain, etc. Its basic properties are similar to polypropylene, but different from polar polymer materials. The compatibility of , inorganic materials, rubber, etc. can be greatly improved. The crystallinity and melting point of grafted PP decrease as the graft content increases, while the transparency and low-temperature heat sealability increase.
7 Conductive functional modification
Over the years, there have been numerous studies on composite conductive polymers, but there are still many problems that have not been well resolved. For example, when adding conductive media to improve conductivity, the mechanical properties will decrease. Therefore, the development of composite conductive polymer materials mainly focuses on reducing resistivity and improving the overall performance of the material.
POE is a copolymer of ethylene-octene or ethylene-butene using metallocene catalyst. It has the characteristics of narrow molecular weight distribution, narrow comonomer distribution and long branch chain. It has excellent toughness and good processability. , using POE to blend and modify polyolefins, showing better toughening effects than traditional elastomers.
8 Thermoplastic elastomer
Thermoplastic elastomer (TPE) combines the physical and mechanical properties of thermoplastics with the reprocessability of thermoplastics and the high elasticity of rubber. It also has excellent recyclability. As a new polymer material, the market is developing rapidly. Thermoplastic elastomers have a very wide range of product adaptability.
Due to the adjustability and controllability of the special molecular structure of thermoplastic elastomers, they exhibit a variety of excellent properties. With the continuous emergence of new modification technologies and the continuous improvement of material properties, thermoplastic elastomers will surely have a broader market space. At present, thermoplastic elastomers have developed to more than a dozen varieties and have replaced some natural rubber, synthetic rubber and plastics. Among them, automotive thermoplastic elastomers are the most important application field, accounting for one-third, followed by the construction industry, medical and daily products.