Shearing of Polymer Drops with Interface Modification

Abstract

The influence of block copolymers (BCP) and interfacial reaction on the deformation of 30-100 µm polymer drops inside an immiscible polymer matrix was visualized in a parallel plate, counterrotating apparatus. Symmetric diblock copolymers were blended into polypropylene (PP), poly(methyl methacrylate) (PMMA), and polyethylene (PE) homopolymers. These were dispersed as drops in a polystyrene (PS) matrix. Addition of BCP significantly increased the amount of area the deforming drop generates when subjected to simple shear flow. Polymers with terminal amine groups (PMMA and PS) were coupled with maleic anhydride functional PS and PE. This reaction results in the formation of graft copolymer at the interface. These reactive pairs appear to be even more effective than BCP at generating interfacial area. The enhancement in area may be attributed to reduction in interfacial tension or to reduction in slip, but more likely a combination of both and a gradient in interfacial tension.

Melt rheological properties of polypropylene–polyamide6 blends compatibilized with maleic anhydride‐grafted polypropylene

“…First, with addition of the compatibilizer (PP‐g‐MAH), the surface energy of PA6 droplets decreases. Droplets break‐up becomes much easier thermodynamically; second, the interfacial adhesion between PP and PA6 is strengthened by the in‐situ formed PP‐g‐PA6 graft copolymers located at the interface region, which will largely reduce the interfacial slip during the flow in the fully development zone;59 third, the newly formed surface during droplet break‐up will also be stabilized by the PP‐g‐PA6 graft copolymers. The trend of droplets to break up will be greatly increased.…”

“…The reason for this phenomenon is still not quite clear. Possible answers might be as follows: generally speaking, as in‐situ formed PP‐g‐PA6 copolymers will largely reduce the interfacial slip during flow in the fully development zone,59 and the shear viscosity will increase with increasing shear stress because of the large deformation of the dispersed PA6 droplets in the entrance zone, just like in the case of the blend with 10 wt% PA6 content. However, according to the works of some former researchers,62–64 PP‐g‐PA6 copolymers in PP–PP‐g‐MAH–PA6 blends can be pulled out from the interface and form independent micelles in the matrix, which would act as a plasticizer and reduce the overall shear viscosity of the blends.…”

Evaluation of a new processing method for improved nanocomposite dispersions

“…Additional models based on fluid mechanics have been developed to describe the fragmentation of immiscible fluids in definable flow fields. [50][51][52][53][54] Models based on fluid mechanics incorporate the capillary number of the droplet, as well as the viscosity ratio between the droplet phase and the continuous matrix phase. These models predict that droplet size is a function of shear rate, but only when the viscosity ratio between the droplet and matrix phases is # 1.…”

Morphology Development of Polymer Blends in Extruder: The Effects of Compatibilization and Rotation Rate

“…The blending process is complex due to the complexity of the rheological properties of polymers and slip which could exist at the interfaces between different phases. [61][62][63] Figure 10 shows the viscosity of the polymer blends obtained from location P of the extruder. The predicted viscosity of these blends, h (PS/aPA-av) and h (PSMA/aPA-av) , are calculated using the log-additive mixing rule…”

“…It has been found that significant slip occurs at the interface of different polymers. [54,61,63,64] During blending, slip at the interface of polymers reduces the shear stress transferred from the matrix phase to the dispersed phase, i.e., there is a jump in the tangential stress. This occurs in the uncompatibilized polymer blends.…”