Accelerated hydrolytic degradation of glass fiber-polyamide (PA66) composites

IF 6.3 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability Pub Date : 2025-02-08 DOI:10.1016/j.polymdegradstab.2025.111256

K. Gkaliou , M.V. Ørsnæs , A.H. Holm , A.E. Daugaard

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引用次数: 0

Abstract

In this work, we investigated the accelerated hydrolytic degradation behavior of unfilled polyamide 66 (PA66) and glass fiber (GF)-reinforced PA66 composites by use of thin injection molded samples. The primary goal of this study was to decrease the required evaluation time of GF-PA66 compounds for use in heating applications, targeting faster qualification of new or recycled materials and also addressing the critical factors of composite durability. According to the data, hydrolysis leads to a linear reduction in molar mass with time until reaching an equilibrium point of 10 kg/mol at 2500 h at 95 °C. The effect of thickness was significant: thin samples exhibited uniform bulk erosion, while thick samples experienced surface erosion with hydrolysis progressing inward to the core. Hydrolytic aging most significantly affected the PA66 matrix, while the glass fiber sizing was shown by X-ray Photoelectron Spectroscopy to be partially removed. The presence of glass fibers had a stabilizing role in the dimensional stability of the composites and limited embrittlement. Last, rheological analysis identified degradation mechanisms in the melt state, revealing that the primary process involved the recombination of fragmented chains and post-condensation reactions, leading to an increase in storage modulus. These findings highlight the need for additives to enhance interfacial adhesion between damaged GF and the polymer matrix, and reactive additives to suppress cross-linking and increase PA66 molar mass. These modifications are crucial for upgrading degraded materials for potential secondary applications, making recycling viable.

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来源期刊

Polymer Degradation and Stability 化学-高分子科学

CiteScore

10.10

自引率

10.20%

发文量

325

审稿时长

23 days

期刊介绍： Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology. Deteriorative reactions occur during processing, when polymers are subjected to heat, oxygen and mechanical stress, and during the useful life of the materials when oxygen and sunlight are the most important degradative agencies. In more specialised applications, degradation may be induced by high energy radiation, ozone, atmospheric pollutants, mechanical stress, biological action, hydrolysis and many other influences. The mechanisms of these reactions and stabilisation processes must be understood if the technology and application of polymers are to continue to advance. The reporting of investigations of this kind is therefore a major function of this journal. However there are also new developments in polymer technology in which degradation processes find positive applications. For example, photodegradable plastics are now available, the recycling of polymeric products will become increasingly important, degradation and combustion studies are involved in the definition of the fire hazards which are associated with polymeric materials and the microelectronics industry is vitally dependent upon polymer degradation in the manufacture of its circuitry. Polymer properties may also be improved by processes like curing and grafting, the chemistry of which can be closely related to that which causes physical deterioration in other circumstances.