On the effect of stress on oxidative destruction of polymers. The action of ozone on polyolefines

Попов, А. А.; Krisyuk, B. E.; Blinov, N N; Заиков, Г. Е.

doi:10.1016/0014-3057(81)90051-3

Cited by 30 publications

(8 citation statements)

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“…On analyzing the results for the samples not exposed to degradation (neat PP and modified PP), slightly lower crystallinity values were observed for the modified samples compared with the unmodified samples. This may be due to the presence of the organic pro‐degradant additive in the modified samples, which could increase the free volume, reducing the crystallinity …”

Section: Resultsmentioning

confidence: 99%

Study on the accelerated biodegradation of PP modified with an organic pro‐degradant additive

Montagna

Forte

Santana

2014

J of Applied Polymer Sci

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In order to reduce the environmental impact of the accumulation of synthetic polymer waste, especially in the case of products with a short shelf life, such as disposable diapers and sanitary napkins, this study evaluated the biodegradation of samples of polypropylene (PP) modified with an organic additive free of transition metals. The samples were prepared using a single-screw extruder, then ground with liquid nitrogen and processed by thermal compression molding into the form of plates. They were then submitted to a respirometric test involving biodegradation carried out at 58 C for 120 days. The samples were characterized according to their physical, thermal, and morphological properties. The results verified that the modified PP showed evidence of enhanced degradation through increased CO 2 generation and weight loss during incubation. The thermal analysis revealed an increase in the degree of crystallinity and a decrease in the melt temperature. SEM micrographs showed exfoliation, the appearance of holes, and surface deterioration.

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Section: Resultsmentioning

confidence: 99%

Study on the accelerated biodegradation of PP modified with an organic pro‐degradant additive

Montagna

Forte

Santana

2014

J of Applied Polymer Sci

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“…14,15,33,34 Mechanical forces have been implicated in not only bond scission reactions, but also bimolecular reactions such as polyamide hydrolysis 35 and polyolefin ozonolysis. [36][37][38][39][40][41][42] These examples of mechanochemical activation are best viewed as destructive, and only recently has the idea of productive mechanochemistry in polymers taken shape. Nonetheless, that history validates two critical foundations of the current work in the area of productive polymer mechanochemistry: (i) macroscopic forces in polymers can be enormous-large enough to induce 90 kcal mol À1 bond scissions and suggesting that an applied mechanical force of the correct magnitude might be able to direct almost any organic transformation of interest; (ii) mechanochemistry in polymers can be made selective, by strategically coupling the applied force to the desired reaction mechanism.…”

Section: Introductionmentioning

confidence: 99%

From molecular mechanochemistry to stress-responsive materials

2011

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Current activity in, and future prospects for, the incorporation of mechanochemically active functional groups (''mechanophores'') into polymers is reviewed. This area of research is treated in the context of two categories. The first category is the development of new chemistry in the service of material science, through the design and synthesis of mechanophores to provide stress-sensing and/or stress-responsive elements in materials. The second category is the reverse-the development of new material architectures that efficiently transmit macroscopic forces to targeted molecules in order to generate chemical reactivity that is inaccessible by other means. IntroductionThe mechanical forces typical of daily life have the potential to induce dramatic reactivity at the molecular level. The force between an infant's clenched finger and thumb, for example, is more than ten billion times that of the force between atoms in a carbon-carbon bond. Not only are macroscopic forces many orders of magnitude greater than atomic forces, they are also directional, and therefore differ from conventional forms of energy input such as heat and light. In the past four years, several studies have demonstrated that macroscopic mechanical forces can be harnessed at the molecular level, creating a new tool for the organic and materials chemist alike. Broadly, the opportunities in this area can be divided into two categories. First, there is the opportunity to develop new chemistry in the service of material science by designing and synthesizing mechanically activated functional groups (''mechanophores'') and incorporating them as stress-sensing and/or stress-responsive elements in materials. The second opportunity is the complement of the first-the development of new material architectures that efficiently transmit macroscopic forces to targeted molecules and, in so doing, open up a world of chemical reactivity that is inaccessible by other means. We will refer to these as ''chem / mat'' and ''mat / chem'' mechanochemistry, respectively (Fig. 1). The field of mechanochemistry therefore touches on materials chemistry from the point of view of each of its principle progenitors with potential utility in areas ranging from stoichiometric reactivity and catalysis to stress-responsive and selfhealing polymers.We see the greatest opportunities in mechanochemistry arising from situations in which the mechanical force is directly applied to the mechanophore, so that a directional coupling between the vector of applied force and the reaction of interest is possible. The focus of this paper, then, will be on the mechanochemistry of polymers under tension, where the mechanical coupling is most obvious and, therefore, most amenable to the chemist's intuition. Other aspects of mechanochemistry, such as those involved in the milling of crystals, metals, and alloys, 1 are well known and important fields, but they will not be discussed here. A comprehensive review of mechanochemistry in polymers has been published recently by Caruso et al., 2 and it is ...

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“…In this context, it was pointed out by Costa et al17 that although high forces on a molecular level are necessary to mechanically break covalent bonds in polymers, moderate forces may catalyze the scission of bonds when superimposed by chemical reactions. Nevertheless, the most highly loaded bonds will be those also most likely to react 18, 19. As a result, under practical conditions, local aging mechanisms are frequently coactivated by defects or residues of metallic catalysts 20, 21…”

Section: Introductionmentioning

confidence: 99%

Effect of stabilization on creep crack growth in high‐density polyethylene

Pinter

Lang

2003

J of Applied Polymer Sci

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Polyolefins, particularly polyethylene, are known to fail via crack initiation and crack propagation when exposed to multiaxial long-term static stresses at elevated temperatures. Using concepts of linear elastic fracture mechanics, this article describes and discusses the effects of stabilization on the kinetics of creep crack growth (CCG) in high-density polyethylene (PE-HD) and the failure micromechanisms involved. As for the influence of stabilization, six PE-HD formulations (two polymer types, each with three stabilizer systems) were investigated. CCG initiation times and CCG rates were determined at 60 and 80°C in distilled water as functions of the crack tip stress field characterized by the stress intensity factor. Although no influence of the stabilizer type was found in either polymer type for CCG initiation times and CCG rates at high crack speeds, significant effects of the added stabilizer type and concentration were detected for low CCG rates. The observed phenomena were explained in terms of local aging processes in the immediate vicinity of the crack tip, which were controlled by the presence and content of various stabilizers.

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On the effect of stress on oxidative destruction of polymers. The action of ozone on polyolefines

Cited by 30 publications

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Study on the accelerated biodegradation of PP modified with an organic pro‐degradant additive

Study on the accelerated biodegradation of PP modified with an organic pro‐degradant additive

From molecular mechanochemistry to stress-responsive materials

Effect of stabilization on creep crack growth in high‐density polyethylene

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