A study was carried out of the tensile strength of plane-oriented amorphous and crystalline polymer films previously acted on by water and aqueous solutions of salts and organic acids. The dependence of strength on the time of exposure to the action
It was established that the action of certain liquid media on polymers leads to orientation-relaxation processes whose character varies with time. To determine the degree of this variation and to elucidate its causes, tests were carried out on polyme
The effect of liquid lubricants on antifriction properties of self-lubricating iron-base composite materials was studied. Crude oil products of the petrolatum type were found to have higher load-carrying capacities and permissible working temperature
The effect of strain rate on the strength of poly (methyl methacrylate) and teflon-4 in liquid media was studied. It was shown that the influence of liquid media on the strength of polymer materials decreases with increasing strain rate.
Investigations of the effect of irradiation on physicomechanical properties of polymers are reviewed, and it is shown that studies of physicomechanical properties of irradiated specimens must be regarded as only the first stage of researches directed
Mechanical properties and swelling of polytrifluorochloroethylene (teflon) in water, oil, kerosene and acetone were studied, The results showed that water and oil have no effect on the mechanical properties of teflon whose strength is substantially r
It is well known [1-3] that the m e c h a n i c a l p r o p e r t i e s of polymers, as of other solid m a t e r i a l s , can be substantially affected by the surrounding medium. The changes produced are e x t r e m e l y diverse and are due not only to c h e m i c a l r e a c t i o n s but also to r e v e r s i b l e physicochemical p r o c e s s e s . In this case, the selectivity of the effect of the working medium is determined by the m o l e c u l a r nature of the m a t e r i a l s , by the i n t e r m o l e c u l a r interaction of the chains of the m a c r o m o l e c u l e s , and by p r o c e s s e s taking place over the c o u r s e of time, such as penetration of the medium into the p o l y m e r under investigation (by volumetric diffusion and by m i g r a t i o n along defects), swelling of the material, orientation of the m a c r o m o l e c u l e s , and other s t r u c t u r a l changes . Consequently, the stability of the p r o p e r t i e s of photopolymeric printing f o r m s which, under the conditions of their use, are subjected to the combined action of mechanical s t r e s s e s and liquid media (coloring agents, solvents and their binders, moisture, etc.), m a y vary, which has a substantial effect on the quality of the printing. T h e r e f o r e , an investigation of the effect of the working media used in printing on the deformability, the s e r v i c e life, and other p r o p e r t i e s of photopolymeric f o r m s is of g r e a t importance for the polygraphic industry. T h e r e are p r a c t i c a l l y no papers devoted to this problem since, at the p r e s e n t time, photopolymeric printing f o r m s are undergoing s e m i - w o r k s t e s t s in s e v e r a l polygraphic e n t e r p r i s e s in the Soviet Union. We give below the r e s u l t s of a study of the effect of working media on some of the p r o p e r t i e s of printing f o r m s made of mixed polyamides, developed at the I. Fedorov Ukrainian P o l y g r a p h i c Institute. The kinetics of the deformation of photopolymeric printing f o r m s , held previously in various media, as well as under various a t m o s p h e r i c conditions, were investigated using a method proposed e a r l i e r . The objective indices of the deformation p r o p e r t i e s of the printing f o r m s were calculated on the basis of data obtained in
~ t, days Fig. 1
Fig. 1. Relative maximal deformation of photopolymeric printing forms, held in various media: 1) water; 2) 96% ethyl alcohol; 3, 4, 5) turpentine, kerosene, mixture of turpentine and kerosene (1 : 1); 6, 7, 8) weak drying oil, medium drying oil, GLF11-300 drying oil. Fig. 2. Change in the fraction of the elastic-resilientdeformation of photopolymeric printing forms, held in various media: 1, 2, 3) turpentine, kerosene, mixture of turpentine and kerosene (1 : 1); 4, 5, 6) weak drying oil, medium drying oil, GLFll-300 drying oil; 7) water; 8) 96% ethyl alcohol.
I. Fedorov Ukrainian Polygraphic Institute; L'vov. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 8, No. 2, pp. 102-104, March-April, 1972. Original article submitted March 9, 1971. 9 Consultants Bureau, a division of Plenum Pu.blistling Corporation, 227 I~'est 17th Street, .Vow }or/,, Y. Y. )0012. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any .form or D) any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission of the p~b/isher. I copy of this ortiele is available from the publisl~er for $15.00.
a study of the kinetics of deformation under a load (30 k g / c m 2) and after r e m o v a l of the load (1 kg/cm2). The change in weight of the photopolymeric f o r m s and the profile of a printing element were also determined. In a m a j o r i t y of the working media (Figs. 1 and 2), the deformation p r o p e r t i e s of photopolymeric printing f o r m s , i.e., the relative maximal deformation emax, the fraction of elastic eelas, r e s i l i e n t e r e s deformations (in %, r e f e r r e d to emax) varied only slightly. Thus, for example, with testing of samples in kerosene, turpentine, a mixture of turpentine and kerosene (1 : 1),and in other media, during the f i r s t 24 h there is observed a certain d e c r e a s e 5 ~ t, days in the plastic deformations of the m a t e r i a l and a corresponding Fig. 3. Kinetms of the swelling of i n c r e a s e in the e l a s t i c - r e s i l i e n t d e f o r m a t i o n s , while in water and photopolymeric printing f o r m s in in 96% ethyl alcohol there is an appreciable i n c r e a s e in emax and the binders of coloring agents and in the fraction o f e r e s . The r e s u l t s of swelling tests c o r r e l a t e with in their solvents: 1) water; 2) 96% these data (Fig. 3): in a m a j o r i t y of working media there is a ethyl alcohol; 3) mixture of turpensmall limited swelling, and in 96% ethyl alcohol and water a contine and kerosene (1 : 1); 4) turpensiderable degree of swelling. The change in the e l a s t i c o - e l a s t i c tine; 5) kerosene; 6, 7, 8) weak p r o p e r t i e s of a m a t e r i a l under the effect of the media is obviously drying oil, medium drying oil, connected with facilitation of the slipping of individual elements G L F l l - 3 0 0 drying oil. in the links of the m a c r o m u l e c u l a r chains, included between the nodes of a joint, with r e s p e c t to one another; this is the r e s u l t of an i n c r e a s e of the i n t e r m o l e c u l a r interaction in the m a t e r i a l in the presence of a sorbed substance, tn addition, the affinity of ethyl alcohol for polyamide, and its ability to form single-ended hydrogen bonds, explain the r e a s o n s for the r e l a t i v e l y high deformability of photopolymeric printing f o r m s held in this medium.
Natural and synthetic binders for coloring agents have practically no effect on the deformation p r o p e r ties of the f o r m s (Figs. 1 and 2), although these media are in continuous cbntact with the photopolymeric printing f o r m s during the printing p r o c e s s . Thus, the stability of the mechanical c h a r a c t e r i s t i c s of photopolymeric f o r m s can vary, depending on the duration of the contact between the m a t e r i a l and the liquid, and on the physicochemical p r o p e r t i e s of the forms. However, since in use the photopolymeric printing f o r m s are, as a rule, subjected only for a s h o r t period of time to the action of wetting agents, i.e., benzene, kerosene, a mixture of kerosene and turpentine, etc., they should not be expected to have any significant effect on the deformation p r o p e r t i e s of the f o r m s , which could be reflected to any considerable extent in the quality of the printing. Actually, an industrial tests of the printing capacity of photopolymeric f o r m s has shown that after 500,000-600,000 i m p r e s s i o n s the quality of the printing r e m a i n s sufficiently high. On the basis of what has been said above, the conclusion m a y be drawn that the physicochemical media used in printing do not worsen the physicomechanical p r o p e r t i e s of photopolymeric f o r m s after 500,000-600,000 i m p r e s s i o n s . LITERATURE 1. 2. 3. 4.
A . N . Tynnyi and A. I. Soshko, Fiz.-Khim. Mekhan. Mat., No. 3 (1965). A . N . Tynnyi, N. A. Oltkhovich-Novosadyuk, A. I. Soshko, N. G. Kalinin, and O. A. Mikityuk, F i z . Khim. Mekhan. Mat., No. 4 (1969). E . D . Shchukin, A. I. Soshko, O. A. Mikityuk, and A. N. Tynnyi, Fiz.-Khim. Mekhan. Mat., No. 2 (1971). F . S . Savitskii, V. M. T r e m u t , S. F. Mikhailishin, and F. S. Martynyuk, Modern Flexographic P r i n t i n g [in Russian], Moscow-Kiev (1969).