A series of novel hybrid poly(acetoxylstyrene-co-isobutylstyryl-POSS)s (PAS−POSS) and poly(vinylpyrrolidone-co-isobutylstyryl-POSS)s (PVP−POSS) are synthesized and characterized. The POSS content in these hybrids can be controlled by varying the monomer feed ratio. The polyhedral oligosilsesquoixane (POSS) moiety can effectively increase the T g of the resultant organic/inorganic hybrid polymer at a relatively high POSS content and produce the hybrid copolymer with narrower molecular weight distribution. The FTIR spectra are used to investigate the structure−property relationship of these hybrid polymers, and the T g enhancement mechanism is discussed in detail.

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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.

This study examines the efficacy of core-shell structure impact modifiers, having different particle sizes and core/shell compositions, for modifying PVC's impact strength. The core and the shell's main compositions are polybutyl acrylate and polymethyl methacrylate, respectively. Also, the TSC is used to obtain the fundamental states of the blended impact modifier/PVC systems, thereby allowing them to be correlated to the above observed efficacy. Results of this study can provide valuable information toward exploring the feasibility of using the TSC data as a product development guide for designing PVC impact modifiers.