Comparative studies of the solution properties of vinyl aromatic polymers Final report

Viscosity and nuclear magnetic resonance studies of vinyl aromatic polymer solution

Study of solution properties of block copolymers Final report

Solution properties of polybutadiene and polystyrene block copolymer

Nanodielectics (A "Universal" Panacea for Solving All Electrical Insualation Problems?)

This text summarizes the keynote presentation that is based on the full-length paper of the same title. Dr. Fréchette's oral presentation should not be seen as a summary of the “Brainstorm paper” but a glance at some major accomplishments, hinrances and still remaining questions relative to nanodielectrics. Are nanodielectrics a “universal” panacea? The answer to that question is no - but they've got a lot of potential

On the toughness of thermoplastic polymer nanocomposites as assessed by the essential work of fracture (EWF) approach

The essential work of fracture (EWF) approach is widely used to determine the plane stress fracture toughness of highly ductile polymers and related systems. To shed light on how the toughness is affected by nanofillers EWF-suited model polymers, viz. amorphous copolyester and polypropylene block copolymer were modified by multiwall carbon nanotube (MWCNT), graphene (GR), boehmite alumina (BA), and organoclay (MMT) in 1 wt% each. EWF tests were performed on deeply double-edge notched tensile-loaded specimens under quasistatic loading conditions. Data reduction occurred by energy partitioning between yielding and necking/tearing. The EWF prerequisites were not met with the nanocomposites containing MWCNT and GR by contrast to those with MMT and BA. Accordingly, the toughness of nanocomposites with homogeneously dispersed and low aspect ratio fillers may be properly determined using the EWF. Results indicated that incorporation of nanofillers may result in an adverse effect between the specific essential and non-essential EWF parameters

Equations of state for polyamide-6 and its nanocomposites. 1. Fundamentals and the matrix

The pressure-volume-temperature (PVT) surface of polyamide-6 (PA-6) was determined in the range of temperature T = 300\u2013600 K and pressure P = 0.1\u2013190 MPa. The data were analyzed separately for the molten and the noncrystalline phase using the Simha-Somcynsky (S-S) equation of state (eos) based on the cell-hole theory. At Tg(P) 64 T 64 Tm(P), the \u2018\u2018solid\u2019\u2019 state comprises liquid phase with crystals dispersed in it. The PVT behavior of the latter phase was described using Midha-Nanda-Simha- Jain (MNSJ) eos based on the cell theory. The data fitting to these two theories yielded two sets of the Lennard-Jones interaction parameters: e*(S-S) = 34.0 \ub1 0.3 and e*(MNSJ) = 22.8 \ub1 0.3 kJ/mol, whereas v*(S-S) = 32.00 \ub1 0.1 and v*(MNSJ) = 27.9 \ub1 0.2 mL/mol. The raw PVT data were numerically differentiated to obtain the thermal expansion and compressibility coefficients, \u3b1 and \u39a, respectively. At constant P, j followed the same dependence on both sides of the melting zone near Tm. By contrast, \u3b1 = \u3b1(T) dependencies were dramatically different for the solid and molten phase; at T < Tm, \u3b1 linearly increased with increasing T, then within the melting zone, its value step-wise decreased, to slowly increase at higher temperatures.NRC publication: Ye

Microphase Separation Induced by Differential Interactions in Diblock Copolymer/Homopolymer Blends

Phase behavior of diblock copolymer/homopolymer blends (AB/C) is investigated theoretically. The study focuses on a special case where all three binary pairs, A/B, B/C and C/A, are miscible. Despite the miscibility of the binary pairs, a closed-loop immiscible region exists in the AB/C blends when the A/C and B/C pair interactions are sufficiently different. Inside the closed-loop, the system undergoes microphase separation, exhibiting different ordered structures. This phenomenon is enhanced when the homopolymer (C) interacts more strongly to one of the blocks (A or B).Comment: 19 pages, 7 figures, submitted to J. Chem. Phy

Dielectric Properties of Polypropylene Containing Nano-Particles

Peer reviewed: NoNRC publication: Ye

The effect of organoclay addition on the properties of an acrylate based, thermally activated shape memory polymer

Shape Memory Polymers (SMPs) exhibit the intriguing ability to change back from an intermediate, deformed shape back to their original, permanent shape. In this contribution a systematic series of t-butylacrylate-co-poly(ethyleneglycol) dimethacrylate (tBA-co-PEGDMA) polymers have been synthesised and characterised prior to incorporation of organoclay. Increasing the poly(ethyleneglycol) dimethacrylate (PEGDMA) content in increments of 10% increased the storage modulus from 2005 to 2250 MPa, reduced the glass transition temperature from + 41 to − 26 °C and reduced the intensity of the associated tan δ peak. The tBA-co-PEGDMA crosslinked networks displayed useful shape memory properties up to PEGDMA contents of 40%. Above this PEGDMA percentage the materials were prone to fracture and too brittle for a realistic assessment of their shape memory capability. The system containing 90% t-butylacrylate (tBA) and 10% PEGDMA was selected as the host matrix to investigate how the incorporation of 1 to 5 mass% of a benzyl tallow dimethylammonium-exchanged bentonite (BTDB) influenced the shape memory properties. X-ray diffraction data confirmed that BTDB formed a microcomposite in the selected matrix and exerted no influence on the storage modulus, rubbery modulus, glass transition temperature, Tg, or the shape or intensity of the tan δ peak of the host matrix. Therefore, it was anticipated that the presence of BTDB would have no effect, positive or negative, nor on the shape memory properties of the host matrix. However, it was found that the incorporation of clay, especially at the 1 mass% level, significantly accelerated the speed, compared with the clay-free SMP, at which the microcomposite returned to the original, permanent shape. This accelerated return to the permanent shape was also observed when the microcomposite was coated onto a 100 μm PET film