Strength of adhesive joints from functionalized polyethylene and metals

International Journal of Adhesion & Adhesives 18 (1998) 351 — 358

Strength of adhesive joints from functionalized polyethylene and metals S.S. Pesetskii , B. Jurkowski
*, A.I. Kuzavkov Metal-Polymer Research Institute of Belarussian Academy of Sciences, 32a Kirov Street, 246 652 Gomel, Republic of Belarus.
Division of Rubbers and Plastics, Poznan University of Technology, Institute of Material Technology, Piotrowo 3, 61-138, Poznan, Poland Accepted 10 March 1998

Abstract LDPE and functionalized LDPE (FLDPE) adhesive interaction with copper, steel and aluminum was studied. Polyethylene grafted with a non-saturated dicarboxylic acid displays elevated adhesion to all metals. The maximum adhesion strength is shown by joints with steel. The reasons of FLDPE effect on adhesion are discussed proceeding from regularities observed at structural and chemical transformations in the adhesive and metal boundary layers and the analysis is proposed of differences in destruction topography in LDPE and LDPE-g-IA adhesive capability are determined by oxidative transformations going at the metal—adhesive interface at the stage of the contact formation, than by their physical structure. Carboxylic group grafting to LDPE macromolecules results in acceleration of macromolecules oxidation in the adhesive boundary layers on copper and steel, and its inhibition. For aluminum substrates an oxidation process for LDPE-g-IA and LDPE is practically identical, though concentration of carboxylic groups is higher in the first one. At a mild heat regime of the adhesive contact formation with copper (low temperature of the contact formation) the oxidation degree is lower for LDPE-g-IA than for the initial polyethylene. When adhesive joints from FLDPE and metal are broken, a predominantly cohesive character is observed along the adhesive boundary layer. Topography of the polymer layer remaining on the metal surface is determined by the latter nature. Continuous layers are formed on steel and aluminum without a noticeable structural flaw. Copper shows overlayer from hollow micro drops 100—400 nm high, 1000—2000 nm long and 30—150 nm cavity depth. Change of adhesive strength in LDPE-g-IA at varying technological conditions is caused mainly by the altered concentration of low-molecular substances in the contact zone. The presence of a non-grafted IA in the adhesive layer leads to the reduction of adhesive strength.  1998 Elsevier Science Ltd. All rights reserved Keywords: Polyethylene; B. Metal; B. Steel; Copper; Aluminum; D. Boundary layers; Adhesive strength; Functionalization; Grafting

1. Introduction As has been shown earlier [1, 2], lack of interaction of polar functional groups inside polyolefin macromolecules participating in adsorption is one reason of low adhesive strength of their joints with metals. Based on model calculations [3] it has been established that the presence of polar groups results in a considerable increment of adhesive strength. One of the most widely spread technological solutions of the problem on introduction of polar functional groups into polyolefin consists in polymer oxidizing. This oxidizing process can be a preliminary (before the adhes-

*Corresponding author. Tel.: 0048 61 8782771; fax: 0048 61 8782217: e-mail: jurkowsk@sol. put. poznan. pl.

ive contact formation) polymer exposure to different oxidizers, namely, air oxygen at activation by corona discharge, plasma, IR or UV radiation, and so on, or this can be done immediately while adhesive contact formation. The number of such works, especially that relating to the study of the contact thermooxidation of polyolefin films on different-nature metals and their adhesive interaction, is rather numerous. Between the earliest investigations and those important ones that help to interpret the processes of thermooxidation and adhesion, the papers [4—9] and monographs [10, 11] should be mentioned. These publications unambiguously prove the decisive role of contact oxidation of polyolefin in the formation of strong adhesive joints and show the effect of a metal surface on transfomations of oxidized macromolecules. It was found that out [12] the cohesive character of failure of the polyethylene-steel adhesive

0143-7496/98/$—see front matter  1998 Elsevier Science Ltd. All rights reserved. PII: S0143-7496(98)00018-9

352

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

joints formed in air. The fact of predominantly cohesive fracture of adhesive joints has been many times confirmed later on [11, 13]. Practical application of polyolefin contact thermal oxidation aimed at regulating adhesive strength is often limited by the necessity of high temperatures, prolonged formation of adhesive joint and difficulty in attaining the necessary adhesive strength due to, mainly, low cohesion of adhesive layers bordering to metal [11]. Oxygen-containing functional groups can be introduced into the polyolefin macromolecules by grafting to them non-saturated monomers containing the mentioned groups by, for example, the method of reactive extrusion [14]. As it follows from patent literature [15—19], macromolecule grafting by monomers of olefin polymers containing polar functional groups in their composition can be looked upon as a highly efficient means of regulating their adhesive interaction with different-nature solid surfaces, including metals. Systematic investigations in the field of metals adhesive interaction with polyolefins functionalized by polar monomer grafting is, however, not numerous [20—24]. Thus, it has been established [20, 21] that LDPE modified by grafting adhesively active functionalized groups, that is, functionalized polyethylene (FPE) displays a much higher adhesion to steel in contrast to the initial polymer. Work [20] marks that FPE adhesive activity depends, under all other conditions being equal, on the chemical origin of the metal substrate. The formation and failure regularities of FPE adhesive contact with unlike metals have not been extensively studied according to information available. The aim of this work is to examine closely the rules of FPE adhesive interaction with metals based on experimental investigations of adhesive strength and physicochemical transformations of macromolecules at the interface of adhesive — metal substrates.

2. Experimental techniques 2.1. Materials LDPE produced at Novopolotsk PO Polymir (Republic of Belarus) was used as an adhesive. Its parameters are as follows: density 0.92 g/cm, melting point 105°C, melt flow index 17.8 g/min at 10 kg loading and a temperature of 190°C. Functionalized LDPE (LDPE-g-IA) was obtained by grafting about 1 wt% of itaconic acid (IA) (Chem.Div. Pfiser Inc., NY) to its macromolecules by using the reactive extrusion. The method of LDPE-g-IA production based on IA grafting in the presence of dicumyl peroxide (produced at Kazanorgsintez AO, Russia) as reaction initiator is described in detail else-

where [25]. Brabender’s plastograph with a static mixer allowing the grafting reaction under a shear rate of 50 s\ in the polymer melt was used as an extrusion reactor. The efficiency of grafting, determined as the ratio of the grafted acid weight portion to its total amount, [25, 26] was 70—75%. The substrate was the 50 lm thick steel foil (carbon content about 0.8 wt%) that of 50 lm thick copper (copper content, 99.8 wt%) or 100 lm thick aluminum (aluminum content, 99.9 wt%).

3. Methods First, 350$10 lm thick films were produced from LDPE and LDPE-g-IA granules by compression molding at 150°C. The films were then applied on to thoroughly degreased and heated to 110—120°C a foil surface and, next, rolled down by a metal roller through antistick laying from a fluoroplast-4 film [20]. Metal foils were degreased, first, by multiple washing in toluene, then in chemically pure acetone. Degreasing was verified by spreading ethanol on the substrate surface [11]. The wetting angle on a well-degreased surface by absolute ethanol was zero, and on its evaporation no grease traces were observed. After removal of anti-adhesive fluoroplast laying the polymer film samples on metal foil was placed into a thermostatic chamber with free air circulation. Here, the adhesive was brought into the thermal contact with the substrate under a given temperature and time regime. Adhesive strength was estimated by peeling the foil off the polymer at an angle of 180°. A peeling rate was 50 mm/min. 3.1. Physico-chemical analysis Physico-chemical transformations occurring in adhesive layers bordering on metal at a thermal contact underwent IR spectral (M-80 spectrophotometer of Karl—Zeiss, Jena, Germany) analysis and differential scanning calorimetry (DSM-3A calorimeter of Biological Instrument-Making Institute of RAS). Fine layers (slices) of adhesive up to 10—12 lm thick were removed after a tensile test by microtoming the substrate adhesive next to the surface of fracture. The film 50$5 lm thick of samples obtained by compression molding at 150°C of the mentioned slices was subjected to IR analysis. Also, films obtained by remolding the whole layer of the adhesive by peeling off from the substrate were used in IR investigations. DSC analysis was done on adhesive slices bordering directly on metal. Concentration of carboxylic groups (C) in LDPE-g-IA and final product of both LDPE and LDPE-g-IA oxidation on metal was determined from optical density (D) of absorption band 1710—1720 cm\: C"D/eol,

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

353

where e is extinction coefficient of a C"O group entering carboxylic group and is equal to 514 dm (mol cm)\; [27] o the polymer density (g/cm), l the polymer film thickness (cm). Values of l for each sample studied were determined from the calibration curve for the dependence of an LDPE absorption band optical density at 4360 cm\ versus film thickness [28]. The character of joint fracture was studied by atomicforce microscopy (AFM) and image analysis by using the computer system NANOTOP-2 developed and manufactured at MPRI, sector of Probe Analysis.

4. Results and discussion 4.1. The effect of metal nature As is seen from Fig. 1, the most prominent effect of adhesion intensification at the acid-containing group grafting to a carboxylic group of macromolecules is observed on steel. For copper and steel substrates kinetic dependencies of adhesive strength (A) for both LDPE and LDPE-g-IA display an expressed extreme character with a maximum. Aluminum-LDPE joints show the reduction of adhesive strength on reaching a maximum, while those with LDPE-g-IA practically preserve the strength within the whole time of the thermal contact (Fig. 1). The analysis of physicochemical transformations in the adhesive boundary layers [7—11] has been done, bearing in mind that oxidation processes taking place in them exert a critical effect on the formation of the adhesive contact between polyethylene and metals in air. When in thermal contact, LDPE-g-IA and metals show the reduction of carboxylic groups concentration in the boundary layers at initial contacting. This is probably related to the removal of a non-grafted acid from the adhesive bulk (Fig. 2). Then, concentration of the carboxylic groups starts growing, its highest velocity being in joints with steel. The initial period of oxidation runs faster on copper than on aluminum. This is because either in the case of LDPE-g-IA, or pure LDPE, both copper and steel substrates catalyze oxidative transformations in macromolecules. At a longer endurance period accumulation of carboxylic groups in the boundary layers is noticeably retarded, which proves oxidation inhibition. Note, that under conditions of this experiment on copper and steel, inhibition was expressed under less thermal contact duration for LDPE-g-IA than for LDPE. As a result, the amount of carbonyl groups in LDPE-g-IA layers next to steel is much lower than in LDPE (Fig. 2a). The curvature of kinetic curves of aluminum oxidation for both LDPE-g-IA and LDPE above a 5 min contacting time is identical. It can be anticipated that the grafted carboxylic groups and acids formed at PE oxidation form metal-containing compounds on

Fig. 1. Effect of the thermal contact duration of LDPE and LDPE-g-IA films with steel, copper and aluminum substrates at 210°C on adhesive strength.

copper and steel surfaces, which at their low concentration accelerate oxidative transformations of macromolecules and inhibit them at a higher amount. [6,7,10,11,29,30] So, LDPE-g-IA oxidizes faster as compared with the initial polyethylene, though oxidation inhibition starts earlier. For aluminum substrates oxidation kinetics of both adhesives is similar. A considerable variation of adhesive strength of polyolefin joints with metals could be caused by a difference in the physical structure of their boundary layer [11]. As it follows from calorimetry data (Table 1), a difference in LDPE-g-IA and LDPE adhesive capability, and also a character of adhesive strength kinetic dependencies and its value could not be explained by the role of a structural factor. The reasons are the following. At close values of melting heat and, therefore, crystallinity, various metals differ much in adhesive strength. Besides, at close values of the same metal melting heat, LDPE-g-IA and LDPE can differ several times in the adhesive strength value (see Fig. 1, Table 1). Consequently, the determining

354

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

thermooxidative degradation and cross-linking of macromolecules [11,31,32]. A high degree of LDPE-g-IA oxidation on aluminum (Fig. 2c) is one reason of the elevated adhesive strength magnitude under prolonged (530 min) formation of the adhesive contact (Fig. 1c) [6, 33]. Stable adhesive strength might be due to the reduced crystallinity of adhesive boundary layers (Table 1) because of dominating thermooxidative process of macromolecular cross-linking. 4.2. Character of adhesive joint failure

Fig. 2. Time of LDPE and LDPE-g-IA film thermal contact with steel, copper and aluminum substrates versus carbonyl groups concentration in layers adjoining metal.

Table 1 Time of the thermal contact with metal at 210°C versus melting heat (*H) in the adhesive layers adjoining the metal Substrate

Aluminum Copper Steel

Adhesive

LDPE LDPE-g-IA LDPE LDPE-g-IA LDPE LDPE-g-IA

*H (J/g) depending on t (min) 2 0

5

30

60

28 27 26 25 27 26

26 40 38 31 44 37

18 16 39 34 34 28

17 16 37 32 30 22

contribution into kinetics of the adhesive strength variation is made not by the structural but by the chemical transformations in the adhesive boundary layers. The presence of maximum on the kinetic dependencies of adhesive strength is due to two competing processes running in the adhesive boundary layers, i.e.

The analysis of adhesive joint failure has shown that both types of adhesive joint with all metals display cohesive breaking in the adhesive boundary layer within the region of a maximum of adhesive strength (Fig. 3). AFM microscopy of the polymer layer transferred on peeling on the foil confirms a strong difference in the topography of fracture surfaces. Aluminum and steel substrates show almost alike fracture surfaces. This points to the fact that the boundary layer experiences a high-elastic strain during breaking. The resulting strands, cracks and other structural flaws are, probably, self-healing at lamination (Fig. 3 a and c). The thickness of the layer that remained on the metal is 100—150 nm. The AFM-image of a copper substrate on peeling is a combination of droplet islets of the material (Fig. 3 b). Most likely, the formation of micro drops occurs at the stage of adhesive contact damage due to the structural heterogeneity of the oxidized boundary layer of the polymer. Cavities inside micro drops can be the result of portions of material that were pulled out from them while the copper foil peeled off. Micro drop dimensions are: height 100—400 nm, length 1000—2000 nm, cavity depth 30—150 nm. The formation of adhesive micro drops at copper substrate lamination must be accompanied by the reduction of a fracture surface, which is, presumably, one of the reasons of its impaired adhesive strength in contrast to joints with steel. 4.3. Adhesive strength of joints with a copper substrate According to the results reported earlier [34], when a polymeric adhesive is in the thermal contact with a copper substrate in air, the copper surface can form a thick and weak oxide layer, which leads to adhesive strength reduction due to its low cohesive strength. The formation of thick oxide films on a copper surface under the polymer layer accelerates at a temperature of more than 200°C. Since in the above experiments, the temperature was 210°C, it was of interest to compare adhesive capabilities of LDPE and LDPE-g-IA toward copper under a more mild heat exposure. The results of experiments are given in Tables 2 and 3. Their analysis proves that in spite of LDPE-g-IA having a much higher adhesive capability as compared with LDPE, its limiting adhesive

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

355

Table 2 The effect of the thermal contact temperature on adhesive strength (A) and concentration of carboxylic groups (C) in the adhesive layer adjoining copper (t "10 min) 2! Adhesive

Parameter

A (kN/m) C;10 (m/g) LDPE-g-IA A (kN/m) C;10 (m/g) LDPE

¹ (°C) 2! 160

180

190

200

0.04 0.30 0.40 2.0

0.20 0.60 0.90 1.60

0.30 1.00 1.30 1.60

0.50 1.50 1.40 2.0

Table 3 The effect of the thermal contact time at 170°C on adhesive strength and concentration of carboxylic groups in the adhesive layers adjoining copper Adhesive

Parameter

A (kN/m) C;10 (m/g) LDPE-g-IA A (kN/m) C;10 (m/g) LDPE

t (min) 2! 10

30

40

60

0.05 0.20 0.75 0.75

0.20 1.0 1.10 0.70

0.25 1.60 2.20 0.70

0.40 5.70 2.25 0.70

strength values remain still lower than in joints with steel. Note, that at the adhesive strength the 52 kN/m an expressed cohesive character of fracture is observed. At lower adhesive strength values in LDPE-g-IA and LDPE joints they show adhesive—cohesive or adhesive types of failure. It should be noted that at a contact temperature of 170°C an increase in the carboxylic group concentration in the boundary layer does not occur in LDPE-g-IA and at a prolonged contact (t "40 min) with the sub2! strate the oxidation degree of LDPE layer adjoining a copper substrate is much higher than that of LDPE-gIA. The probable cause of inhibited oxidation is the presence of copper-containing compounds in the zone of the adhesive contact formed through interaction with carboxylic groups introduced into the adhesive. A lower degree of oxidation and, perhaps, a lower concentration of unstable low-molecular products in the contact that weaken the adhesive joint [11,30] are the reason for higher adhesive strength in LDPE-g-IA joints formed at ¹ "170°C and t "40—60 min 2! 2! (Table 3). 䊴 Fig. 3. AFM images of substrates from steel (a), copper (b) and aluminum (c) after LDPE-g-IA film peeling. Conditions of the adhesive joint formation: (a) ¹ "190°C, t "5 min; (b) ¹ "210°C, t " 2! 2! 2! 2! 20 min; (c) ¹ "210°C, t "10 min; after scanning: (a) 8 mm, (b) 2! 2! 25 mm, (c) 14 mm.

356

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

Variation kinetics of carboxylic group concentration in LDPE-g-IA adhesive layers next to catalytically inactive aluminum is shown in Fig. 4. As with copper, oxidation of macromolecules at 150°C is evidently not observed during the study. At 190°C the accumulation of carboxylic groups is less intense than at ¹ "210°C 2! (Figs. 2 and 4). 4.4. Non-grafted IA effect on adhesive strength As it has been stated in the previous section, the applied LDPE-g-IA contained up to 25—30 wt% of a non-grafted IA as to its total amount introduced in LDPE. It can be anticipated that non-grafted IA might affect adhesive interaction and adhesive strength values due to, for example, adsorption on the substrate, formation of a weak boundary layer or influence of adhesive’s macromolecules on oxidative transformations at the stage of contact formation. To estimate such an effect, a series of experiments has been undertaken by using LDPE-g-IA as an adhesive from which non-grafted IA has been removed by extraction or thermal treatment. The substrate was steel foil. The effect of a non-grafted IA on adhesive interaction and kinetics of carbonyl group accumulation in the adhesive layer (LDPE-g-IA film) abutting against steel foil can be understood from Fig. 5. IA was extracted in boiling ethanol over 7 h. In conformance with [26], nongrafted IA was fully removed from the LDPE-g-IA bulk. As it is seen from Fig. 5, IA extraction stimulates the adhesive interaction. As far as IA extraction does not lead to a noticeable variation in the kinetics of carbonyl group accumulation in the adhesive as compared with the initial LDPE-g-IA (Fig. 5b), so the formation of weak boundary layers because of a non-grafted acid adsorption on metal is the main reason for adhesive strength

Fig. 4. The effect of thermal contact with aluminum on the carbonyl group concentration in LDPE-g-IA layers adjoining metal.

Fig. 5. Time of thermal contact with steel versus adhesive strength (a) and carbonyl group concentration in adhesive layers next to the metal (b).

Fig. 6. The effect of LDPE-g-IA - steel joint pretreatment for a minute at 220°C (o), 230°C (䉭) and 250°C (䊉) on adhesive strength depending on thermal contact time at 160°C; (䉱) is preliminary non-treated LDPE-g-IA

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

357

reduction (all compounds cohesively decompose along the adhesive boundary layer at adhesive strength values close to the maximum). Since IA is not heat-resistant (IA melts and decomposes at 172°C [35]), it can be assumed that its the non-grafted portion that will be removed from the bulk by a short-term thermal treatment under elevated temperatures. Here, as with extraction, adhesive interaction must be intensified. As it follows from Fig. 6, shortterm high-temperature treatment of LDPE-g-IA on metal in a mild thermal regime before the adhesive contact formation will contribute to the considerable increase in the adhesive strength. At an excessive temperature increase (up to 250°C) the effect of the adhesive strength growth reduces, probably because of the intensified oxidative degradation of macromolecules leading to the additional accumulation of low-molecular products in the adhesive. The comparison of data on adhesive strength (Fig. 6) and kinetics of carboxylic group storing in the adhesive bulk at its heat treatment at 160°C (Fig. 7) shows that the adhesive strength variation cannot be attributed to bulk oxidation of the adhesive (direct correlation between kinetics of carbonyl group concentration and adhesive strength is not observed). It should be noted that at 190°C LDPE-g-IA oxidation accelerates in contrast to LDPE and that containing non-grafted IA (Fig. 7). The governing effects of low-molecular products on adhesive interaction in the studied systems agree well with experimental results on determining adhesive strength in foil—polymer—foil systems (Fig. 8). These compounds are obtained by rolling the steel foil down to both sides of the film adhesives at 110—120°C followed by the adhesive contact formation at 190°C. As is seen from Fig. 8, for open adhesive systems, where low-molecular product removal through the adhesive layer is practically excluded [11], the effect of an adhesive strength increase at functional groups is not achieved by grafting.

Fig. 7. Variation of carbonyl group concentration in LDPE layer bulk (a), LDPE with 1 wt% addition of a non-grafted IA (b), LDPE-g-IA (c) and LDPE-g-IA extracted in ethanol (d) while thermal contact with steel.

Fig. 8. Effect of the adhesive contact formation time on adhesive strength of closed joints.

358

SS. Pesetskii et al. / International Journal of Adhesion & Adhesives 18 (1998) 351—358

5. Conclusions Based on investigations carried out, it can be stated that differences in LDPE and LDPE-g-IA adhesive capability are determined by oxidative transformations going at the metal-adhesive interface at the stage of the contact formation, than by their physical structure. Carboxylic group grafting to LDPE macromolecules results in acceleration of macromolecules oxidation in the adhesive boundary layers on copper and steel, and also its inhibition. For aluminum substrates an oxidation process for LDPE-g-IA and LDPE is practically identical, though concentration of carboxylic groups is higher in the first one. At a mild heat regime of the adhesive contact formation with copper (low temperature of the contact formation) the degree of oxidation is lower for LDPE-g-IA than for the initial polyethylene. When adhesive joints from functionalized polyethylene and metal are broken, a predominantly cohesive character is observed along the adhesive boundary layer. Topography of the polymer layer remaining on the metal surface is determined by the latter nature. Continuous layers are formed on steel and aluminum without a noticeable structural flaw. Copper shows overlayer from hollow micro drops 100—400 nm high, 1000—2000 nm long and 30—150 nm cavity depth. A change in adhesive strength of LDPE-g-IA at varying technological conditions is caused mainly by the altered concentration of low-molecular substances in the contact zone. The presence of a non-grafted IA in the adhesive layer leads to the reduction of adhesive strength.

[3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27]

Acknowledgements The authors express their gratitude to Polish Committee of Scientific research, grant No. 7.TO8E.014.11, and Found of Fundamentals Researches of Republic Belarus, grant No. T 95-294, for financial support. References [1] Backhoff FI, Mc Donel ET, Rutzler IE. Industr Engng Chem 1958;50(6):904—7. [2] Matting A, Ulmer K, Kautch Gummi Kunstst Asbest 1963;16(4):213—24.

[28]

[29] [30] [31] [32] [33] [34] [35] [36]

Taylor D, Rutzler IE. Industr Engng Chem 1958;50(6):928—34. Arlit HA, Grisser EE, Heine WA. Tappi 1957;40(3):161—9. Baker RG, Spencer AT. Industr Eng Chem 1960;52(12):1015—7. Sykes IM, Hoar TP. J Polym Sci 1969;A-1:1385—91. Bright K, Malpass BW. Eur Polym J 1968;4:431—7. Bright K, Malpass BW, Packham DE. Nature 1969;223:1360—1. Bright K, Malpass BW, Packham DE. Brit Polym J 1971;3(9):205—8. Belyi VA, Egorenkov NI, Pleskachevsky Yu M. Polymer adhesion to metals. Minsk: Nauka i Tekhnika, 1971. (in Russian). Kalnin MM. Adhesive interaction between polyelifines and steel Riga: Zinatne, 1990:345. (in Russian). Kupfova I. Plasticke Hmoty Kaucuk 1970;5:133—6. Egorenkov NI, Kuzavkov AI. Vysokomol Soedin 1986;28A(6):1317—24. Xanthos M, editor. Reactive extrusion: principles and practice. Munich: Hanser, 1992. USA Patent, 2838437, 154—139, 10 June 1958. Japanese Patent Application 2-173040, C 08 23/10, 04 July 1997. Japanese Patent Application 2317142, C08L 23/04, 25 January 1991. Finland Patent 80893, C08L 255/02, 10 August 1990. USA Patent 4857600, C08L 255/02, 15 August 1989. Pesetskii SS, Kasperovich OM, Kuzavkov AI. In: Proc. Europ. Adhes. Conf. ‘Euradh’96’, Cambridge, 1996:629—33. Pesetskii SS, Kozelskaya VV, Kasperovich OM, Kuzavkov AI, Proc. Belarussian AS, 1995:39(2):56—9. Rajasekharan PV, Mathew B. Indian J Technol 1993; 31(4):302—16. Pesetskii SS, Makarenko OA, Fedorov VD, Krivoguz Yu M. In: PPS. European Meeting, Stuttgart, Germany, September, 1995: 3. Kinloch E. Adhesion and adhesives: science and technology. Moscow: Khimia, 1992. (Russian translation). Pesetskii SS, Jurkowski B, Urbanowicz R, Krivoguz Yu M. J Appl Polym Sci 1997;65:1493—502. Pesetskii SS, Kuzavkov AI, Kasperovich OM, Krivoguz Yu M. Trans of Belarussian AS, Ser Chem Sci 1997;(2):15—8. Fodor ZS, Iring M, Tudos F, Kelen T. J Polym Sci. Polym Chem 1984;22:2539—50. Dechant I, Danz R, Kimmer W, Schmolke R. Ultrarotspektroskopische Untersuchungen an Polymeren, Berlin: Akademie Verlag, 1972:470. Cichetti O, Desimone R, Gratani F. Eur Polym J 1973;9:1205—29. Kuzavkov AI, Ugolev II, Egorenkov NI. Vysokomol Soedin 1991;33A(8):1723—30. Berlin AA, et al. Plast Massy 1962;10:3—5. Borisova FK, et al. Kolloid Zh 1996;28:792—9. Briggs SS, Brewis DM, Konieczko MV. Europ Polym J 1978;14:1—4. Pesetskii SS, Alexandrova ON. Kolloid Zh 1992;52(2):302—8. Kirk—Othmer Encyclopedia. 3rd ed. Vol. 13. New York: USA, 1981: 865. Osawa Z, Saito T. Amer Chem Soc: Polym Prepr 1977; 18(1):420—5.