Effect of the core‐shell impact modifier shell thickness on toughening PVC

Abstract

The shell thickness of a core/shell impact modifier is found to be the single most important factor in the toughening of rigid polyvinyl chloride (PVC). When the shell thickness is greater than a critical value of 15.8 nm, these core‐shell elastomeric particles are able to remain structurally intact and well dispersed within the PVC matrix after melt blending. However, too thick a shell thickness results in a hard core (high modulus) of these core/shell particles and loss of the rubbery nature required of an efficient impact modifier. Therefore, these over‐thick particles can act only as rigid fillers, not as efficient rubbery modifiers. On the other hand, when the shell thickness is less than the critical value of 4.9 nm, too thin a shell layer is simply unable to fully protect and cover the inner rubbery core during vigorous processing conditions, and these core‐shell particles tend to connect with one another through the partially exposed core to form a cellular‐like structure, thus resulting in poor toughening efficiency. Regardless of the particle size, as long as the shell thickness of these core/shell elastomers is between these two critical values (15.8 nm and 4.9 nm), they all display high efficiency in toughening rigid PVC. Polym. Eng. Sci. 44:1885–1889, 2004. © 2004 Society of Plastics Engineers.

Effect of the matrix plasticization behavior on mechanical properties of PVC/ABS blends

“…For example, Chen et al [7,8] investigated the effect of the shell thickness of MBS core-shell impact modifiers on toughening PVC, and considered that the shell thickness of MBS played an important role in determining the dispersion of the MBS modifier particles in the PVC matrix. When the shell thickness was too thin, the MBS particles tended to aggregate in the PVC.…”

Progress in polyketone materials: blends and composites

“…Core–shell structured modifiers have been widely used for the toughening of polymers such as poly(vinyl chloride) (PVC), polyamide (PA), POK, etc. A traditional core–shell modifier consists of a crosslinked elastomeric core and a rigid glassy shell.…”

PVC Additives

“…33 Faster fusion permits the partial or complete elimination of oxidized polyethylene, which is frequently used as fusion promoter. 37 Figure 3.28 shows that if the shell thickness is too small (smaller than 4.9 nm) or too large (above critical value of 15.8 nm), impact strength is rapidly reduced. 34 Predesigned particles of impact modifiers are based on core-shell technology.…”