دانلود ترجمه مقاله ترک خوردگی لاستیک اوزون در اثر فشار اتمسفر – مجله الزویر

• فهرست مطالب:

 مقدمه
بیان مسئله
نتایج آزمایش
پیشنهادی برای حل مسئله
کلی
نمونه های آزمایشی
روش تحلیل اوزون

• بخشی از ترجمه:

چهار ترکیب تهیه شدند که برای درجات متوسط ترک برداری اوزون در دوره های مواجهه محفظه ازمایشی ۲ و ۴ ساعت در سطوح اوزون انتخاب شده ارایه شده اند. فرمول ها در جدول ۱ نشان داده شده است. مقادیر SOC اندازه گیری شده در ۲ و ۴ ساعت در اتاقک اوزون برای تهیه نمودار های SOC و غلظت اوزون استفاده شد
جدول ۲ مقادیر SOC را در غلظت های دقیق اوزون ۳۰، ۵۰ و ۷۰ pphm نشان می دهد که از نمودار های log (SOC) v. 03 که در شکل ۱ تا ۴ نشان داده شده است درون یابی شده است. پارامتر log (SOC) بیان کننده درجه آسیب ترک اوزون ناشی از تغییرات در فشار جزیی اوزون در دو ازمایشگاه است که تابع خطی از غلظت اوزون است. این رفتار شبه خطی به درون یابی کمک می کند. تبدیل لگاریتم در دامنه ۳۰ تا ۷۰ pphm بوده و پیامد کاربردی در این وابستگی ویژه وجود دارد. یک مسئله مشهود، مقدار SOC غیر صفر در غلظت اوزون صفر با وابستگی لگاریتمی مشاهده شده است. بر این اساس، مقادیر log (SOC)    بدست آمده و از این داده ها نسبت ها بدست آمده و برای تهیه جدول ۴ استفاده شد.  نسبت ها نشان دهنده تفاوت در درجه  اسیب اوزون در ازمایشکاه  یا در فشار اتمسفر است: ۷۳۶torr(98.1kPa) در ازمایشگاه ۱ و ۶۳۶  torr  (۸۴٫۷  kPa) در ازمایشکاه  ۲اثر مورد انتظار کاهش در فشار زمانی که غلظت اوزون  به صورت ثابت حفظ شود کاهش در سرعت تصادم از مولکول های اوزون با سطح لاستیک است.

• بخشی از مقاله انگلیسی:

The testing of compounded, cured rubbers for ozone cracking resistance occupies a prominent place in the general scheme of polymeric degradation testing. The failure of rubber products in service is often the direct result of the ozone induced surface cracking or alternatively fatigue or mechanical failure is initiated by the surface cracks produced by ozone attack. Rubbers are most frequently evaluated for their ozone crack resistance by exposure to ozonated air in laboratory testing chambers. Such chambers nominally consist of 1. a thermostat and heater system to control testing temperature; 2. a chamber air circulation system in equilibrium with atmospheric pressure (internal fan or other device); 3. an ozone generator, most frequently a mercury vapor UV light source which generates ozone as an air stream is passed through it. Analysis of the ozone content in the chamber air is conducted by a variety of techniques; electrochemical, 1 UV light absorption, 2 chemiluminesence 3’4 and absorption of the ozone by reaction with iodide ion in a neutral buffered aqueous solution. 5″6 The iodide ion is oxidized to free iodine by the ozone and the iodine is titrated with standardized sodium thiosulfate solution. National standard test methods for ozone testing such as ASTM D-1149-77T and BS903 as well as the international standard ISO 1431 express ozone concentration in the air of the chamber on a volume per volume basis. Nominally the ozone concentration is expressed in parts of ozone per 100 million (108) parts of air (by volume). This is abbreviated by the term pphm, parts per hundred million. This paper illustrates a testing error that can occur when the pphm (volume) basis of ozone concentration is used. In intra-laboratory testing (at different times), one source of variation in test results is the fluctuation of atmospheric pressure. In inter-laboratory testing, similar test variations can be attributed to atmospheric pressure differences due to geographical location, i.e. elevation above sea level. The latter effect is especially important in producer v. industrial consumer ozone testing for quality control and specification purposes. BACKGROUND ON THE PROBLEM The rate of ozone reaction with rubber (or the cracking rate of rubber) is a function of the collision rate of ozone molecules with the rubber surface, all other factors constant. A change in barometric pressure, at constant temperature, will alter this collision rate even if the ozone content in the chamber is maintained constant on a volume (ozone) per unit volume (air) basis. Therefore, ozone content or concentration cannot be unambiguously expressed on a volume per volume basis in situations where differences in atmospheric pressure are likely. A method of expressing ozone content that is free of this limitation must be used. This atmospheric pressure effect was discovered by one of us (RLE) as part of a continuing inter-laboratory testing program of the Gates Rubber Co. EFFECT OF ATMOSPHERIC PRESSURE ON OZONE CRACKING OF RUBBER 29 The testing as outlined here was conducted as part of an ASTM sponsored program to modify the ASTMD-1149 Standard. Two laboratories were selected to participate; BF Goodrich R & D Center, designated Lab-l, and Gates Rubber Co., designated as Lab-2 in some of the tables and figures that follow. The nominal pressure differential between these two locations is 13.3 kPa (100 torr). It was realized that there would be two requirements for the successful execution of this inter-laboratory testing program. 1. A quantitative method for measuring the degree of ozone cracking. 2. Accurate measurement of 03 concentration in both laboratories. To meet both of these requirements, actions were taken as outlined in the Inter-laboratory Test Procedure section listed in the appendix. Briefly stated, the degree of ozone cracking was assessed by the SOC technique 7 and tests were conducted at three target ozone concentrations in the range 30-70 pphm and then comparisons made at exact concentrations of 30, 50 and 70± ۱ pphm. This avoids the tedious task of requiting each laboratory to obtain exact ozone concentrations by numerous adjustments. It is suggested that the Inter-laboratory Test Procedure be consulted prior to the next section of test results. The SOC value is a numerical expression of the size of ozone cracks and is measured by a microscopic technique. It is the product of the average length and width of a selected representative sample of the surface ozone cracks. TEST RESULTS Four compounds were prepared that provided for moderate degrees of ozone cracking in test chamber exposure periods of 2 and 4 h at the selected ozone levels. The formulations are listed in Table 1. The measured SOC values at 2 and 4 h of ozone chamber exposure were used to prepare plots of SOC v. ozone concentration. Table 2 lists SOC values at exact ozone concentrations of 30, 50 and 70 pphm as interpolated from plots of log (SOC) v. 03 as shown in Figs. 1 to 4. The log (SOC) transformation gives, in most cases, an essentially linear plot. This quasi-linear behavior assists in interpolation. The log (SOC) parameter expresses the degree of ozone cracking damage due to variations in ozone partial pressure at the two test laboratories that most nearly is a linear function of ozone concentration. The log transformation is intended to apply over the range of 30-70 pphm only and no fundamental implication is intended in this particular dependency. An obvious problem is the non-zero SOC value at zero ozone concentration implied by the observed logarithmic dependence.