Study on blending toughening of the hottest polypr

PP blending toughening research

Abstract: the research progress of PP blending toughening modification at home and abroad is discussed in detail from four aspects: Plastic toughening polypropylene (PP) system, rubber or thermoplastic elastomer toughening PP system, PP/elastomer/plastic ternary blend system and inorganic rigid particle toughening PP system. Using plastics as modifiers to toughen PP can toughen it, but due to the incompatibility of the system, a large number of modifiers or compatibilizers are often used. The toughening effect of blending PP with rubber or thermoplastic elastomer is the most obvious. However, with the increase of the amount of elastomer, the impact strength of the system is greatly improved, while the rigidity and other properties are also lost. PP/elastomer/plastic ternary blend system can improve mechanical properties and reduce costs. In addition, the research progress and mechanism of inorganic rigid particles toughening PP developed in recent years are also introduced

key words: Polypropylene toughening and blending modification

polypropylene (experimental method of concrete pressure tester: before application, check whether the oil in the oil tank is sufficient PP) is one of the fastest-growing varieties of general thermoplastic resins, which is widely used in various fields of industrial production. PP has simple production process, low price and excellent comprehensive properties. The most prominent disadvantage to be overcome is its significant notch sensitivity, that is, its notch impact strength is low, especially at low temperature, so it needs to be toughened in practical application. PP blending toughening method is widely used because of its remarkable effect, less industrial investment and rapid operation. Blending toughening modification refers to using other plastics or elastomers as modifiers to blend with PP to improve the toughness of PP. Commonly used modified materials are mainly divided into plastic, rubber or elastomer and inorganic rigid particles

recovery principle, structure, recovery process and operation method of the recovery device, etc. 1 plastic toughening PP system

using plastics as the modifier for PP toughening can not only achieve the purpose of toughening, but also improve the wear resistance and dyeability of materials, and the price is relatively low. High density polyethylene (HDPE), linear low density polyethylene (LLDPE), ethylene vinyl acetate copolymer (EVA), polyvinyl chloride, polyamide (PA), etc. are widely used. However, due to their incompatibility with PP, it is often necessary to increase the amount of modifier or add compatibilizer to make the system achieve high toughness

1.1 PP/polyethylene (PE)

according to the information, HDPE or LLDPE can be added when developing PP/PE Composites. In isothermal crystallization, it is found that HDPE is distributed in PP as rigid particles, which makes it have rigid toughening effect, and LLDPE forms a system connected with PP crystals. Therefore, when the content of HDPE is less than 10%, it has rigid toughening effect on PP, while when LLDPE toughens PP, with the increase of the amount of LLDPE, its impact strength increases, but the tensile strength decreases. Generally, the dosage of LLDPE is 5% - 20%

ng the modification of PP by low density polyethylene (LDPE) and HDPE was compared. It was found that LDPE could realize effective impact modification of PP, but caused the rapid decline of other mechanical properties (such as bending modulus). In order to obtain better comprehensive performance, HDPE is used instead of LDPE. He also pointed out that the copolymerization of propylene and ethylene can achieve better results than their physical blending

Yang Jun and others used ultra-high molecular weight polyethylene (UHMWPE) in-situ fibrillation to strengthen and toughen copolymer PP (brand 1330), which played a reinforcing role while improving toughness. The research shows that increasing the mixing shear force and accelerating the molding cooling rate (using quenching process) are conducive to the improvement of mechanical properties. The notch impact strength and tensile strength of PP/UHMWPE system with a ratio of 90:10 narrow the range of participants, and the elongation at break can reach 88.6kj/(M2), 45.1mpa and 570%, which are 3.5, 1.5 and 2.5 times that of 1330 respectively. From the differential scanning calorimetry spectrum, it can be found that 1330 ethylene block and UHMWPE can form eutectic, and quenching can significantly increase the eutectic content, thus strengthening the bonding force between the two phases

1.2 PP/EVA

Using EVA to modify PP can effectively improve the impact property, elongation at break and melt flow index (MI) of the material, and the surface gloss of the products is also improved. The vinyl acetate content of EVA used is 14% - 18%. At this time, EVA is an amorphous material with low polarity, which has obvious toughening effect after adding PP blend system. The increase of MI is conducive to the molding process and the uniform dispersion of components in the blend system. EVA is used in North China Institute of technology to avoid oil leakage of oil return valve in large tonnage. 15 modified PP makes the maximum toughness of the material 12 times higher than that of PP, while the rigidity is not much reduced, and the cost is lower than that of elastomer or rubber modified PP. 1.3 PP/PA

the blending modification of PP and PA overcomes their inherent shortcomings and makes the material have excellent comprehensive properties. Among many kinds, PP/PA6 system is more studied at present. Zhao Shulan et al. Selected PA6 as the toughener of PP and melt blended with PP, the impact strength increased by 49.5% compared with pure PP, and the bending strength changed little, but the tensile strength decreased by 13.8%. It can be seen that PA6 has a certain toughening effect on PP. However, from the perspective of structural analysis, due to the great difference in polarity between the two, the compatibility is poor. Therefore, adding intermediates as interface improvers to improve their compatibility has become the focus of research. In this paper, maleic anhydride grafted polypropylene (PP-g-MAH) was added to the binary blend as a compatibilizer. The results showed that the impact strength of the system was 113% higher than that of pure PP, the bending strength was slightly increased, and the tensile strength was only reduced by 2.7%