Polymer chain rupture and the fracture behavior of glassy polystyrene

Abstract

Uniform latexes of anionically polymerized polystyrene, Mn = 180 000, Mn = 250 000, and M" = 420 000, were prepared by direct miniemulsification. The 1200-A-diameter particles were cleaned, dried, and sintered, and the resulting films were annealed for various periods of time at 144 °C. The films were fractured with fine dental burr instrumentation at a depth of 4000 A/pass. The number of chain ruptures and consumed energy per unit area were measured, as well as tensile strength. Plots of chain scissions and energy consumed vs 0.5 power of annealing time showed three regimes: mixed, peak, and recovery. Data in the mixed regime confirm portions of the de Gennes and Tirrell theory which predicts a 0.5 power dependence on annealing time and portions of the Wool theory. Using the Lake-Thomas theory, rubber elasticity theory, and bond dissociation energy, the contribution of the several mechanisms consuming energy were estimated on the basis of an energy balance approach. A mechanism involving the scissor-action opening of the 109s carbon-carbon bond and concomitant bond stretching of the about 300 bonds trapped between entanglements is consistent with the consumption of most of the energy in the later annealing stages and/or fast fracture processes. Tensile strength and the fracture energy per unit area of the films increase linearly with the number of chain scissions per unit fracture area in the first regime, as predicted by Peppas.

Film Formation from Nanosized Copolymeric Latex Particles: A Photon Transmission Study

“…Here ρ(r ) can be defined as a volume ratio of polymeric material to voids where, as r goes to zero, ρ(r ) increases; however, for large r values ρ(r ) decreases. Equation [1] is quite similar to one which was used to explain the time dependence of the minimum film formation temperature during latex film formation (12,36). If the viscosity is constant in time, integration of Eq.…”

“…The mechanical properties of latex films are dependent on the molecular weight, its distribution (1,2), and sensitivity to stabilizers (3) and surfactants (4). In addition, the quality of these films, for a given molecular weight, depends on the annealing time and annealing temperature (5)(6)(7)(8).…”

Functional latex and thermoset latex films

“…Their most impressive result demonstrates, as predicted by theory, 44 that the film achieves full mechanical strength when the diffusion length is comparable to the radius of gyration of the latex polymer. [45][46][47] In ET experiments, a fraction (typically half) of the latex particles are labeled with a small fraction of one fluorescent dye such as phenanthrene (Phe) or naphthalene (N) that can serve as a donor in an energy transfer experi-ment. The remaining particles are labeled with a second dye such as anthracene (An) that can act as the acceptor.…”

How do soft nanoparticles affect temperature-induced nonlinearity of a UCST copolymer blend?

“…Film formation from colloidal systems presents a suitable approach regarding elucidation of nanostructure evolutions in polymers and their nanocomposites [11][12][13][14]. There are also plenty of applications for latex systems, ranging from paper coatings to adhesives and sealants, textiles, paints, etc.…”

“…Here, mixing can be simply implemented through latex blending followed by drying, which is influenced by the components miscibility and size disparity. Accordingly, enormous property improvement can be achieved through nanoassembly with huge interfacial area and strength [12][13][14]. Therefore, a great deal of effort has been devoted to understanding the main involved parameters through system manipulation via phase separation/dissolution [16].…”