The modification of general-purpose plastics by POE elastomers is mainly to study its use as a toughener to modify rigid general-purpose plastics, to improve the toughness of rigid general-purpose plastics or to improve the properties of general-purpose polyethylene (PE) by blending. There are few studies on PE/POE systems at home and abroad, and more and more studies are on the report of POE toughened rigid PP.
1. PE/POE system
In recent years, wood-plastic composite materials have received widespread attention due to their low cost, good performance, light weight, and low wear on processing equipment. However, the composite material becomes brittle after filling the wood powder, which limits the application and promotion of wood-plastic composite materials.
Wood-plastic composites were prepared by using high-density polyethylene (HDPE) filled with waste wood powder. The composites were toughened by metallocene polyethylene (mPE) and POE, and the toughening effects of the two toughening agents were evaluated. When the amount of the two is less than 12 parts, the toughening effect of the two is not much different; but after the amount is more than 12 parts, the impact strength and elongation at break of the composites toughened with POE increase very rapidly, and increase with mPE. The increase in toughness is relatively flat; the toughening effect of POE is significantly better than that of mPE. The mechanical properties and thermal properties of HDPE and POE blends were studied. The results of thermal analysis showed that HDPE and POE had certain interactions. When the POE content was ≥5%, the materials were super tough at room temperature.
The foamed material prepared by POE modified PE has good toughness, elasticity and strength and can be used as an adhesive tape. 30 parts of ionic structure-containing PE and 6.5 parts of azodicarbonamide were added to a mixture of 100 parts of 30% POE and 70% of Affinity PL 1845, extruded into sheets, and irradiated and crosslinked at 250 ° C. Under foaming, the obtained 1 mm thick foam sheet had good toughness, and the bending strengths in the transverse and longitudinal directions were 30.2 MPa and 24.3 MPa, respectively.
The POE/PE composite material can be made into a microporous film for use in a separator for a capacitor, a diaper, a sanitary napkin, a separator for a packaging film, and the like.
2. PP/POE system
As a general public plastics, polypropylene (PP) has the disadvantages of poor low temperature toughness and large notch sensitivity. Therefore, in order to improve PP performance, elastomer toughening modification has been regarded as the most effective way. . Although EPDM has a good toughening effect on PP, the price of EPDM is high, the glue is difficult, and the fluidity is not ideal. The advent of POE has made it an advantage that traditional elastomers cannot match in the toughening modification of PP. POE toughened PP can not only overcome the shortcomings of EPDM toughened PP, but also give PP higher toughness, high transparency, high performance / price ratio. The study pointed out that compared with EPDM toughened PP, POE has better toughening effect than EPDM for ordinary PP, copolymerized PP or high flow PP, and the bending modulus and tensile strength decrease are small. The octene content in POE affects the toughening effect of POE on PP. With the increase of octene content in POE, the crystallinity, melting point and density of POE decrease, the flexibility increases, and the toughening effect on PP increases.
Commercialized POE itself is granular and can be directly added to Other materials such as PP for modification. Therefore, POE is easier to process than EPDM rubber modifiers, which greatly reduces production costs. The PP/POE blend system was studied and compared with the PP/EPDM blend system. The results show that the two blends have similar crystallization behavior and similar mechanical properties, but the PP/POE blends have lower torque and better processing performance. As a PP impact modifier, POE has obvious price and performance advantages over EPDM.
The phase structure, toughening mechanism and mechanical properties of the blended system of PP/POE blends were studied. The results show that under the same conditions, the amount of POE added is less than that of EPDM. When the amount of POE is 20 parts, the blended alloy can achieve brittle-ductile transformation. In the PP/POE blend system, POE forms a uniform “sea-island†structure in the PP continuous phase; POE toughening modification of PP conforms to the silver-grain shearing mechanism, which can effectively improve the normal temperature and low-temperature impact strength of PP.
The toughening effect of POE on isotactic polypropylene was studied. When the POE mass fraction is between 15% and 25%, the impact strength of the blend increases slowly; the POE mass fraction continues to increase, and the impact strength increases rapidly; when the POE mass fraction is 40%, the impact strength is the largest. Morphological analysis showed that the size of the dispersed phase increased with the increase of POE mass fraction; the synergistic effect of the blend components significantly increased the impact strength.
3, general plastic / POE / inorganic filler system
How to reduce the amount of toughening agent POE to reduce the cost does not affect the toughening effect, which is the hot spot and direction of the research and development of general plastics/POE system. The addition of inorganic or organic fillers to the blend can reduce the raw material cost of the product to an incremental purpose, or significantly improve the performance of the product. In recent years, it has been reported that inorganic fillers are added to the general plastic/POE blend system. .
In view of the shortcomings of insufficient rigidity of the pipe ring made of recycled high density polyethylene (RHDPE), RHDPE was modified by talc powder and self-made modified POE (MPOE). The mechanical properties of the blending system were studied. The impact of performance.
The results show that when the mass ratio of RHDPE/MPOE/talc is 50/10/40, the comprehensive mechanical properties of the system are the best. When the amount of talc is 40%, the ring stiffness of the obtained RHDPE pipe is 54% higher than that of the unmodified RHDPE pipe. At the same time, they also studied the mechanical properties of PVC/MPOE/inorganic filler system. The results show that when the mass fraction of talc or calcium carbonate in the filler masterbatch is 70%, the comprehensive performance of the ternary composite system is the best.
At home and abroad, PP/elastomers and PP/inorganic nanoparticle systems have been studied. The toughness or rigidity increase of these two systems is at the expense of other properties. Therefore, the increase of elastomers The combination of toughening and strengthening of tough and inorganic nanoparticles simultaneously produces a multiphase composite system of PP/elastomer/inorganic nanoparticles, which is gradually becoming a new research hotspot.
High performance PP/POE/nano kaolin ternary composites were prepared by alloying technology and filling compounding process. The results show that nano-kaolin and elastomer POE have synergistic effect on PP toughening, which is not a simple addition of independent toughening effect; the optimum dosage of nano-kaolin is 5%, using scanning electron microscope (SEM) Observing the impact section of PP/POE (20%)/nano-kaolin (5%), it can be seen that the kaolin particles are coated with the matrix and dispersed in the matrix of the blend in a layered structure, and the interface is firmly bonded.
After studying PP/POE/nano-SiO2 composites, it is concluded that the melt blending method allows POE and SiO2 to be uniformly dispersed in the PP matrix. When the ratio of PP/POE/nano-SiO2 is 100/15/4, the comprehensive properties of the composites optimal. Although the dispersion of nano-SiO2 particles in PP is distributed as agglomerates of particles, it is equivalent to the particle size of the secondary particles of the nano-SiO2 particles and is smaller than the critical particle diameter. Therefore, when the impact is applied, the absorption energy hinders the crack propagation, thereby improving the material. Resilience.
The PP/elastomer/nano-CaCO3 composites were studied and found to have good impact strength. POE has better toughening effect than HDPE, and the tensile strength of the material decreases with the increase of elastomer content. Transmission electron microscopy (TEM) observations show that nano-CaCO3 has reached nanodispersion in the PP matrix. It is concluded that nano-CaCO3 improves the defects caused by the decrease of hardness of POE, and the tensile strength and bending strength are improved. The modification effect of activated nano-CaCO3 is much better than that of unactivated. The dosage is about 8 parts. Good; the composite material achieves both reinforcement and toughening.
The PP/POE system has excellent comprehensive performance, and a variety of products have been developed, especially the automobile bumper has broad market prospects. Generally, the notched impact strength (normal temperature) of the PP bumper material is required to be greater than 500 J/m, and the notched impact strength of -40 ° C is ≥ 50 J/m. Using PP as the base resin, POE is the toughening agent, talcum powder is the reinforcing filler, and the automobile bumper special material with the performance meets the requirements is obtained. The modified PP has ultra high impact strength, its notched impact strength is up to 723 J/m, and it has enhanced softness, excellent heat resistance, low temperature resistance and aging resistance. Based on small bulk polypropylene (PP), it is blended with co-polypropylene (CPP), POE, wollastonite and other additives to produce special materials for bumper and door panels. The analysis showed that the formulation of PP/CPP/POE/wollastonite blending system was reasonable, the process route and parameters were correct. When PP:CPP:POE: wollastonite mass ratio is 45~48:26~29:19~22:4~6, the blending material can fully meet the performance requirements of automobile bumper; when PP:CPP:POE:silicon When the mass ratio of limestone is 45~50:27~29:3~6:17~20, the blending material can fully meet the performance requirements of automotive door panels. The research found that the comprehensive performance of POE modified PP is better than the traditional toughening agent; wollastonite also has a certain toughening function, and some play the role of glass short fiber.
Thermoplastic vulcanizate (TPV) can be obtained by cross-linking PP with elastomer. TPV has high application value in actual production. The POE is grafted with vinyl silane and dispersed in PP, and the blend is crosslinked by hydrolyzed water to obtain TPV; the obtained TPV is easy to process into a product and has excellent surface properties. The product has high breaking strength and elongation at break, a wide range of Shore hardness, very low haze, uses POE and is odorless, and can be widely used in the automotive field.
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