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Two series of alkylamine-modified (oleylamine and octadecylamine) styrene-butadiene rubber (SBR)/graphene oxide (GO) composites were fabricated through a facile green method involving co-coagulation and in-situ interfacial modification techniques. Both alkylamines were shown to graft onto the GO surface via covalent and ionic-bonding, and GO was partially reduced into graphene during alkylation. The...
High resolution magic angle spinning ( 1 H HR-MAS) NMR spectroscopy has been used to analyze the composition of a set of bioactive hydrogels. Therefore, a set of six hydrogels with different cross linker densities ranging from 1 to 12 mol% were prepared by free radical polymerization. The disulfide based cross linkers of the hydrogels were reduced with dithiothreitol (DTT) to generate free...
By using a special mold technology, it is possible to produce injection molded components with locally graded foam structures and locally different densities. This paper describes general results of foaming polypropylene with chemical and physical blowing agents. Particularly, the characteristics of the density in the different foamed areas and the mechanical properties depend on the process-specific...
We present results of molecular dynamics simulations for coarse-grained polymers confined in nanopores in a wide temperature range to investigate the factors that affect the glass transition. We focus on the influences of interaction strength, confinement size and the mobility of boundary on the static and dynamic properties of confined polymers, and further study their influences on the glass transition...
This paper studies the effect of carbon nanotube (CNT) alignment on anisotropy of electrical conductivity of CNT enhanced polymer composites. A new CNT percolation network model is developed by considering structural distortion of CNT walls at crossed junctions. The structural distortion is modeled by a pseudo-potential energy that consists of the Lennard-Jones potential of Van der Waals interaction...
This paper is focused on demonstrating that it is possible to reduce the thermal conductivity of polymeric foams by reducing the average cell size below the micron. For this purpose, a wide set of samples with cell sizes from 90 nm to 100 μm and relative densities from 0.12 to 0.6 has been produced and analyzed. In addition, a characterization procedure that allows identifying independently some of...
This paper presents a novel method and the underlying mechanisms of improving the ductility and toughness of polymer blend components using microcellular injection molding. By producing a special microcellular structure and morphology in polymer blends of proper material formulations, the ductility and toughness of the foamed parts can be significantly improved compared to those of solid parts. The...
Cellulose nanocrystals (CNCs), a class of renewable bionanomaterials with excellent mechanical properties, have gained major interest as filler for polymers. However, challenges associated with effective CNC dispersion have hindered the production of composites with desired property enhancements. Here, composites of polypropylene (PP) and low density polyethylene (LDPE) with 5–10 wt% unmodified CNC...
A novel method for synthesizing a microsponge polyimide (PI) film with excellent thermal stability, chemical resistance, and heat insulation performance was developed. The synthesized microsponge PI film has open cells with sizes between 1 and 10 μm and a porosity of 76%. Furthermore, the film contains several layers overlapping in multiple grid structures, which complicates the heat transfer paths...
Conformational characteristics and configurational properties of synthetic biodegradable polyesters, poly(ethylene succinate) and poly(butylene succinate), have been investigated by NMR experiments and molecular orbital calculations on their model compounds and the rotational isomeric state calculations for the two aliphatic polyesters. The results have been related to their crystal structures and...
Due to their high aspect ratio, strength, and modulus, multiwall carbon nanotubes (MWCNT) have attracted interest as a reinforcing filler in the automotive tire industry. In part 1 of this study, we demonstrated that styrene–butadiene rubber (SBR) composites containing up to 15 wt. % of well-dispersed, discreet MWCNTs can be prepared using MWCNTs with a specific surface modification and controlled...
In this work the self-healing behaviour of a supramolecular elastomer showing healing at room temperature was studied by mechanical testing. Tensile experiments on pristine and healed samples were conducted and a critical analysis of the material response under the testing conditions applied pointed out that simple tensile test only allows a restricted quantification of the healing process. A fracture...
A novel amphiphilic acrylamide-based polymer with porphyrin pendants that was prepared from radical copolymerization of 5-(p-acryloyloxyphenyl)-10,15,20-triphenylporphyrin (AOTPP) and N,N-dimethylacrylamide (DMAM) has been first reported as a highly selective and sensitive optochemical sensor for Hg 2+ . The responsive optical properties of the polymer were investigated by UV–vis absorption...
Three polyurethanes (PRX1500Me-PU, PRX4000Me-PU, and PRX6000Me-PU) crosslinked by polyrotaxanes (PRXs), which consist of half-methylated α-cyclodextrins (CyDs) and poly(oxyethylene)glycols with different chain lengths (PEG1500, PEG4000, and PEG6000), were synthesized. The filling ratios of CyD in PRX1500, PRX4000 and PRX6000 are 75, 63 and 37%, respectively. A polyurethane crosslinked by half-methylated...
Thermally reduced graphene oxide (TRG)/thermoplastic polyurethanes (TPU) dielectric elastomer with high dielectric constant (k), low dielectric loss and greatly improved actuated strain at low electric field was prepared by solution blending followed by in situ thermal reduction. The results showed that a good dispersion and alignment of TRG in the TPU matrix was obtained. The k at 10 3 Hz...
This study presents a comprehensive morphological, physical, and shape memory characterization of biocompatible shape memory polymer (SMP) blend foams composed of thermoplastic polyurethane (TPU) and polylactic acid (PLA). The TPU/PLA blend compositions studied were 80/20, 65/35, and 50/50 in weight percentage. The influence of blend composition and processing conditions on the pore morphology of...
Thermally induced phase separation (TIPS) has been widely used to prepare microporous membrane. The interaction and dynamic asymmetry between polymer and solvent sometime make the transition happen through viscoelastic phase separation (VPS) mechanism. Under such condition, cell like structure is obtained with low water permeability. In this paper, a new method is proposed to obtain high permeability...
Here we show that ferroelectric polymeric nanoparticles of a poly(vinylidene fluoride-trifluoroethylene) random copolymer, can be prepared by dialysis nanoprecipitation. By this method semicrystalline particles with mean diameter of 280 nm, as revealed by atomic force microscopy, can be obtained. The ferroelectric nature at room temperature of the nanoparticles has been proven by piezoresponse force...
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