Hexagonal boron nitride micro particles functionalized by γ-MPS, were used to fabricate PI/BN composites. The thermal conductivity of the composites with 40 wt% m-BN content was increased to 0.748 W m−1 K−1, 4.5 times higher than that of the pure PI.

A novel poly(cyclotriphosphazene-co-bisphenol A)-coated boron nitride (PCB-BN) was synthesized by in situ polymerization on the surface of BN. The epoxy/PCB-BN composites showed the enhanced thermal conductivity with the improved flame retardance.

Poly(methyl methacrylate-ran-styrene) copolymers were synthesized under monomer-starved conditions by emulsion copolymerization. The glass-transition temperatures (T g 's) of the copolymers were measured by differential scanning calorimetry (DSC) and torsional braid analysis (TBA). The results showed that the methyl methacrylate-styrene random copolymers produced an asymmetric T g versus composition curve, which could not even be interpreted by the Johnston equation with different contributions of dyads to the T g of the copolymer considered. A new sequence distribution equation concerning different contributions of triads was introduced to predict the copolymer's T g . The new equation fit the experimental data exactly. Also, the T g determined by TBA (T gTBA ) was higher than the one determined by DSC (T gDSC ) and the difference was not constant. The rheological behavior of the copolymers was also studied. T gTBA Ϫ T gDSC increased with increasing flow index of the melt of the copolymer, and the reason was interpreted.

In the past work, the shear resistance of pure poly(n-butyl acrylate) was low, even incorporation of inorganic filler, silica in the composition. It is well-known that the copolymerization of n-butyl acrylate (BA) with methyl methacrylate (MMA) will increase the glass transition temperature, and enhance the shear resistance of acrylic polymers. In the current work, the preparation of a series of acrylic water-borne pressure-sensitive adhesives (PSAs) with the controlled composition and structure for the copolymerization of BA and acrylic acid (AA) with different MMA contents, poly(BA-co-MMA-co-AA) was reported and its effects on adhesive properties of the latices were investigated. The latices of poly(BA-co-MMA-co-AA) were prepared at a solid content of 50% by two-stage sequential emulsion polymerization, and this process consisted of a batch seed stage giving a particle diameter of 111 nm, which was then grown by the semicontinuous addition of monomers to final diameter of 303 nm. Dynamic light scattering (DLS) was used to monitor the particle diameters and proved that no new nucleation occurred during the growth stage. Copolymerization of BA with MMA raised the glass transition temperature (T g ) of the soft acrylic polymers, and had the effect of improving shear resistance, while the loop tack and peel adhesion kept relatively high. The relationship between pressuresensitive properties and molecular parameters, such as gel content and molecular weight, was evaluated.

ABSTRACT:The properties and morphology of nano-calcium carbonate (nano-CaCO 3 ) modified with the titanate coupling agent isopropyl trioleoyl titanate (IPTT) were characterized by Fourier transform infrared, thermogravimetric analyses, surface tension, and transmission electron microscopy. The results showed that the grafting ratio of IPTT on the surface of nano-CaCO 3 (IPTT-Ca) increased with IPTT content. IPTT-Ca/PBA/PMMA (IPTT-Ca/ACR, PBA/ PMMA core-shell polymer, referred to ACR) latexes were prepared by seeded emulsion polymerization. They were then used to mix with PVC resin. The outer layer (PMMA) enhanced the dispensability of IPTT-Ca/ACR in the PVC matrix by increasing the interfacial interaction of these composite particles with PVC. The notched impact strengths of the blends were influenced by the weight ratio of IPTT-Ca to BA/MMA monomers, the weight ratio of BA/MMA. The relationships between the mechanical properties and the core-shell composite structures were elaborated.