Durability of HDPE geomembranes

This work reports on the nucleation of the β-phase of poly(vinylidene fluoride) (PVDF) by incorporating CoFe2O4 and NiFe2O4 nanoparticles, leading in this way to the preparation of magnetoelectric composites. The fraction of filler nanoparticles needed to produce the same β- to α-phase ratio in crystallized PVDF is 1 order of magnitude lower in the cobalt ferrite nanoparticles. The interaction between nanoparticles and PVDF chains induce the all-trans conformation in PVDF segments, and this structure then propagates in crystal growth. The nucleation kinetics is enhanced by the presence of nanoparticles, as corroborated by the increasing number of spherulites with increasing nanoparticle content and by the variations of the Avrami’s exponent. Further, the decrease of the crystalline fraction of PVDF with increasing nanoparticle content indicates that an important fraction of polymer chains are confined in interphases with the filler particle.

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Influence of ferrite nanoparticle type and content on the crystallization kinetics and electroactive phase nucleation of poly(vinylidene fluoride).

Laboratory-accelerated ageing tests have been conducted to examine the depletion of antioxidants from high-density polyethylene (HDPE) geomembranes as a result of their exposure to various environm...

Effects of exposure conditions on the depletion of antioxidants from high-density polyethylene (HDPE) geomembranes

Melting behaviour of poly (phenylene sulphide): 2. Multiple stage melt crystallization

The rigid amorphous phase of semicrystalline poly(phenylene sulfide) (PPS) has been studied as a function of thermal history using scanning calorimetry, dielectric relaxation, density, and small-angle x-ray scattering (SAXS). Based on the new heat of fusion of perfect crystalline PPS, which is 26.7±0.8 cal/gram, the weight fraction of rigid amorphous phase is shown to be nearly twice as large as previously reported [1]. The mass fraction of the rigid amorphous phase ranges from 0.24 to 0.42 and is dependent upon thermal treatment. We have taken the approach of assuming a three-phase model for the morphology of semicrystalline PPS consisting of crystalline lamellae, mobile amorphous, and rigid amorphous components. Using this three-phase model, we determine that the average density of the rigid amorphous fraction is 1.325 g/cc, which is slightly larger than the density of the mobile amorphous phase fraction and was insensitive to thermal history. From the SAXS long period, the layer thicknesses of the mobile amorphous phase, rigid amorphous phase, and crystal lamellae were estimated. Only the lamellar thickness shows a systematic variation with thermal history, increasing with melt or cold crystallization temperature, or with decreasing cooling rate.

Effects of thermal history on the rigid amorphous phase in poly(phenylene sulfide)

Crystallization kinetics of poly(p-phenylene sulphide): the effect of branching agent content and endgroup counter-atom

A process for preparing arylene sulfide polymers which comprises the steps of contacting at least one first alkali metal aminoalkanoate with a molar excess relative to the aminoalkanoate of hydrogen sulfide in an enclosed reaction vessel under reaction conditions of time and temperature sufficient to react the hydrogen sulfide with the first alkali metal aminoalkanoate to produce alkali metal bisulfide and thereby form a first reaction product comprising hydrogen sulfide, alkali metal bisulfide, water and lactam, venting the enclosed reaction vessel to remove hydrogen sulfide present in the first reaction product, contacting the alkali metal bisulfide with at least one second alkali metal aminoalkanoate under reaction conditions of time and temperature sufficient to produce a second reaction product comprising water, lactam and a polymerizable complex of the second alkali metal aminoalkanoate and the alkali metal bisulfide, dehydrating the second reaction product, contacting the dehydrated second reaction product with at least one dihaloaromatic compound to form a polymerization mixture, and subjecting the polymerization mixture to polymerization conditions of time and temperature sufficient to produce the arylene sulfide polymer.

Process for preparing arylene sulfide polymers

A process is provided for producing a high molecular weight poly(arylene sulfide) polymer employing at least one dihaloaromatic compound, a sulfur source, a polar organic compound, a lithium salt which is soluble in the polar organic compound, and water in an amount less than about 1.75 moles of water per mole of sulfur under polymerization conditions. The pressure and temperature are chosen to allow the volatile reactants to be maintained in liquid form in the reaction mixture.

Process for preparing high molecular weight poly(arylene sulfide) polymers using lithium salts

A process to form a fiber-reinforced composite having a continuous thermoplastic matrix of poly(arylene sulfide ketone) resins is provided. The composite is useful to form shaped articles with high temperature resistance. The composite can be prepared by consolidating under heating a multi-layer stack of resin sheets and fiber reinforcement sheets. The poly(arylene sulfide ketone) resins can be melt-stabilized through treatment with a water-soluble salt of an alkaline earth metal. The composite has excellent thermal properties such as heat distortion temperature.

Jon F. Geibel

Papers

Crystallization kinetics of poly(p-phenylene sulphide): the effect of branching agent content and endgroup counter-atom

Process for preparing arylene sulfide polymers

Process for preparing high molecular weight poly(arylene sulfide) polymers using lithium salts

Poly (arylene sulfide ketone) composites

Crystallization behaviour of poly(p-phenylene sulfide): Effects of molecular weight fractionation and endgroup counter-ion