PVC blending system PVC transverse heat shrinkable film production line

日期:2021/7/23 8:33:49 / 閱讀: / 來源:本站

PVC blending system PVC transverse heat shrinkable film production line
EPDM is soft rubber at room temperature. EPDM is a non-polar polymer, so the compatibility between EPDM and PVC is very poor. Therefore, in order to prepare PVC / EPDM blends with certain practical value, the appropriate compatibilizer must be selected first. Add some polymers with certain molecular polarity (such as CPE, EVA, NBR, etc.), or some specific coupling agents (such as mercaptan compounds), or some graft copolymers (such as EP. Dm-g-mma) The compatibility of EPDM and PVC can be improved to a certain extent by introducing proper co crosslinking structure (such as adding a small amount of DCP as co crosslinking agent of EPDM and PVC), so as to improve the properties of the blends. When 10 phr CPE was added into PVC / EPDM Blend, the compatibilization effect was obvious. Mercaptan coupling agent can effectively improve the compatibility of PVC / EPDM system, and the impact strength of PVC / EPDM blends is about 10 times higher than that of simple blends. PVC transverse heat shrinkable film production line www.www.dressup9x.com
EVA is a kind of PVC modifier with excellent impact resistance and weather resistance. The impact strength of PVC can be improved obviously after blending with EVA. EVA does not contain C-C sensitive to oxidation, so it has better anti-aging properties. When the content of EVA is 7.0% ~ 7.5%, the notched impact strength of the blends reaches the maximum value (about 500 J / M). The melt flow rate of EVA and blending process conditions also have some effects on the properties of the blends. The mechanism of toughening PVC with EVA is mainly shear band (about 90%), and there is a certain amount of crazing (about 10%). In addition, appropriate amount of cavitation is also a favorable factor for toughening PVC. When the content of EVA is 7.5%, the impact strength of EVA continuous network structure is the largest. This continuous network structure is conducive to induce more shear bands of matrix PVC under external force, and has a greater toughening effect on the material. With the increase of EVA content in the blends, the impact property, processability, thermal and photo stability of the blends increase, while the modulus, strength and thermal deformation temperature decrease. PVC transverse heat shrinkable film production line www.www.dressup9x.com
MBS resin is a kind of polymer obtained by grafting the copolymer of methyl methacrylate and styrene onto polybutadiene or styrene butadiene rubber. In the polymer chain, styrene is the rigid chain segment, and polybutadiene or styrene butadiene rubber is the flexible chain segment. The synergistic effect of the two gives MBS good flexibility. MBS resin phase MS has good compatibility with PVC resin and can form a uniform continuous phase in which rubber particles are dispersed. MBS not only gives PVC better impact strength and transparency, but also improves its processability. It is mainly used to manufacture hard film, plate, bottle, transparent pipe, instrument shell, etc. The rubber particle size in MBS has a great influence on the toughening effect. When the particle size is large, it will induce non-destructive cracks, absorb energy and prevent material cracking; However, if the particle size is too large, the surface of the material will be rough and the distribution area of the limited amount of rubber will be reduced, resulting in the decrease of the impact strength. When the ratio of PVC / MBS is the same, the impact strength increases with the increase of butadiene content in MBS. The grafting mode and S / M ratio of MBS also have an effect on the impact strength of the blends. It is appropriate to connect s first and then m, and the ratio of S / M is 66.7:33.3. The notch impact strength of MBS is the highest when the dosage of MBS is in the range of 10% ~ 20%. If it is higher than this value, the MBS blends show the properties of PMMA because the outer layer of MBS is m. However, the impact strength of PMMA is lower than that of PVC homopolymer, so it shows brittle failure. PVC transverse heat shrinkable film production line www.www.dressup9x.com
Nitrile butadiene rubber (NBR) is the first commercial toughening modifier for PVC. NBR molecules contain a large number of polar bonds, showing strong polarity. When NBR was blended with PVC, NBR existed as dispersed phase when the content of acrylonitrile (an) was less than 8%; When the content of an reaches 15% ~ 30%, it is dispersed in the form of network; When the content of an is more than 40%, it is completely compatible. PVC transverse heat shrinkable film production line www.www.dressup9x.com
Nbr-29 and NBR-40 were blended with PVC resin by mechanical blending method. The influence of CN group content in NBR on the modification effect of the blend system was discussed. The impact properties of PVC / nbr-29 blends were better than those of PVC / NBR-40 blends. Through dynamic mechanical analysis, there are two loss peaks on the mechanical spectrum of PVC / nbr-29 system, which respectively correspond to the glass transition temperature of the two components. It is a partially compatible two-phase system. The interface layer between the two phases is the internal reason for NBR toughening PVC. Because of the strong intermolecular force between the two phases, the compatibility between the two phases is too good, and there is only a wide loss peak in the dynamic mechanical spectrum, which is a uniform compatible system, so the toughening effect is not obvious. Powdered nitrile butadiene rubber (PNBR) prepared by cross-linking coating method was blended with PVC. PNBR had significant toughening effect on PVC. When the content of PNBR was 10 phr, the notched impact strength of the blends was as high as 71 kJ / m. The cross-linking structure of PNBR macromolecule and the presence of coating agent have little effect on the impact strength of the blends. The brittle ductile transition of the blends occurs when the content of PNBR is 7.5 ~ 10 phr. After the brittle ductile transition, the impact fracture surface of the blends presents a "hook wire" structure, and the toughening mechanism is a typical shear yield mechanism. PVC transverse heat shrinkable film production line www.www.dressup9x.com


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