Polypropylene (PP)/layered double hydroxide (LDH) composites were prepared via melt‐compounding using both a carbonate‐LDH and an organo‐LDH (dodecyl benzene sulfonate DBS‐LDH) in different concentrations. Transmission electron microscopy and X‐ray diffraction analysis were used to investigate the morphology. The results showed that only by using DBS‐LDH the intercalation of polymer chains and a partial delamination were obtained. However, the introduction of maleic anhydride‐grafted polypropylene (PP‐g‐MAH), as coupling agent, favored the aggregation of the particles generating localized domains of aggregates. The thermo‐gravimetric analysis showed that PP/DBS‐LDH composites have a higher thermal stability than the pure matrix. Differential scanning calorimetry evidenced that both LDH and DBS‐LDH particles acted as nucleating agents increasing the crystallization temperature, even if, in the case of LDH the effect was observed only with the addition of the compatibilizer. The results collected by dynamic mechanical thermal analysis, beyond showing a significant increase of the matrix stiffness by incorporation of DBS‐LDH, evidenced an increase of the PP glass transition temperature (Tg) indicating a restriction of PP chain segment mobility due to the strong polymer‐particle interactions. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

Narrowly distributed (N‐isopropylacrylamide) (NIPAM) polymers are prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. After successful cleavage of the trithiocarbonate end groups (thiol generation), they can be grafted to styrene‐butadiene rubber (SBR) by a radical thiol‐ene reaction leading to various grafted SBR‐copolymers. During the grafting reaction, no crosslinking or branching of the SBR can be observed. Measurements of the contact angle of water show that the lower critical solution temperature (LCST) properties of the PNIPAM fraction affect the SBR. Films of the graft‐copolymer exhibit a distinct hydrophilicity below the LCST, while they show hydrophobic behavior above the LCST. Rheological measurements reveal a physical crosslinking of the functionalized SBR due to nanophase separation of the PNIPAM chains (hard phase) in the unpolar SBR. Compared with blends of SBR and PNIPAM, the PNIPAM‐grafted SBR possesses a much finer distribution of the PNIPAM domains (10–30 nm) within the matrix. In addition, two novel difunctional chain‐transfer agents are used, leading to difunctional PNIPAM, enabling a covalent crosslinking of SBR.