Degradation and Stabilization of Polymers

TL;DR: In this paper, the properties of transformation products formed from thiocompounds, phenols and amines are interpreted from the point of view of their exploitation in complementary or supporting stabilization mechanisms in polymers.

TL;DR: The photochemical equivalent law as discussed by the authors states that each photon or quantum absorbed activates only one molecule, which is the first law of photochemical reac-tion of a certain substance only takes place via the excitation of the mole-cule by the absorption of light quantum of sufficient energy.

Abstract: Abstract Adsorption of alkali on rock surfaces is a well-established phenomenon in high Total Acid Number (TAN) oil reservoirs, particularly noticeable during Alkali Polymer (AP) flooding. Despite this, the influence of alkali on the mechanical degradation of polymers in these environments remains insufficiently understood. This study explores the role of alkali in enhancing the mechanical stability of polymers under shear stress conditions prevalent in porous media. Utilizing polyacrylamide polymer products supplied by two vendors, alkali-polymer slugs were prepared for this work. Core flooding experiments were conducted at injection velocities representative of field-scale operations to induce and study the mechanical degradation of polymer chains. These experiments were enabled assessing the rate of polymer mechanical degradation, for which viscosity measurements served as a primary metric. To encompass a range of field scenarios, injection velocities varied from 1 to 20 feet per day. Additionally, core plugs with both low and high permeability were employed to replicate the diverse shear rates encountered in heterogeneous reservoirs. Our findings demonstrate that the presence of alkali clearly enhances the mechanical stability of polymers. This improvement is likely attributed to the increased anionicity caused by alkali. Another contributor could be the role of alkali as changing rock surfaces to be positively charged, which seems to reduce polymer adsorption, thereby helping to maintain viscosity control. Core plugs with lower permeability exhibited higher shear rates, leading to a marginally greater breakdown of polymer chains and consequently more significant viscosity reduction in effluents. As anticipated, higher injection velocities, which simulate the conditions near wells, resulted in greater viscosity losses. In comparing the two polymer products, Flopaam from vendor-B showed superior viscosity control, whereas the vendor-A product exhibited enhanced injectivity. The injectivity outcomes for core floods in presence of crude oil (two-phase) align with those from single-phase core floods when injecting polymer/alkaline polymer (AP) slugs. The enhanced recovery factor attributed to the AP slug injection (23% vs 2%) is confirmed to result not only from the in-situ saponification process but also from the increased mechanical stability of the AP slug. This study not only sheds light on the flow dynamics of polyacrylamide polymers but also underscores the importance of mechanical stability in situ. Such stability is a critical factor affecting both injectivity and mobility in porous media. Therefore, it is imperative to consider these findings as part of the screening criteria for field applications, especially where AP flooding is employed. This research thus provides a pivotal step forward in understanding and optimizing polymer-based enhanced oil recovery techniques in challenging reservoir conditions.

TL;DR: This work has experimentally achieved concurrent phonon blocking and charge transmitting via the endotaxial placement of nanocrystals in a thermoelectric material host via crystallographic alignment of SrTe and PbTe lattices.

TL;DR: In this article, the most important natural fibers are jute, flax, and coir and their novel processing technics to develop natural fiber reinforced composites are also described.

TL;DR: In this paper, Al-Malaika et al. discuss the effect of the reaction environment upon Oxidation and Antioxidant Mechanisms and the present position of Biological Oxidation.

TL;DR: In this article, the degradation and durability of polymers are reviewed in the presence of nanoparticles/nanocomposites under different environmental conditions, and the nanoparticulates have been incorporated into polymer as " nano-additives" for both purposes: degradation and stabilization.