Nondestructive testing of defects in adhesive joints

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Use of deproteinized and normal skim rubbers for property improvement in natural rubber K. Mariamma George*, Rosamma Alex, Salini K.S and K.T. Thomas Rubber Research Institute of India, Rubber Board, Kottayam -9, India Email: *mariamma@rubberboard.org.in, mgpattani@yahoo.co.in Abstract Skim rubber is the rubber recovered from skim latex, which is obtained as a by-product during the centrifugal concentration of natural rubber (NR) latex. Blending skim rubber with natural rubber is a method of taking advantage of the relatively low price of skim rubber while minimizing its disadvantages. In addition, it seems possible that in such blends the fast curing characteristics of the skim can be utilized. We have examined the cure behaviour and technological properties on adding 20 p.h.r (parts per hundred rubber) each of deproteinized skim rubber (DPSR) and normal skim rubber to ISNR 20 without further addition of curatives and comparing the properties to that of a similar ISNR 20 mix. Two cure systems, one which contain usual dosage of accelerator and antioxidant and the other system which contain comparatively lower level of accelerator without any antioxidant were studied. In the former case, the cure characteristics showed that there is attainment of good level of cure and cure rate even after addition of 20 p.h.r skim rubber or DPSR to ISNR 20 with no extra curatives, compared to the conventional ISNR 20 mix. Also the ISNR 20 vulcanizate and the vulcanizate containing additional 20 parts of skim rubber showed comparable values of moduli, tensile strength, tear strength and abrasion resistance and these values were higher than that observed for ISNR 20 vulcanizate containing 20 parts DPSR. Skim rubber incorporated mix showed a slightly higher resistance to crack initiation and crack failure when compared to ISNR 20 mix. Blend which contain 20 parts DPSR showed slightly better dynamic properties and improved air ageing characteristics as compared to normal skim rubber. For the mixes which contain lower level of curatives, cure characteristics were comparable but the values were lower than that which contain the usual dosage. Same trend was observed for the mechanical properties and ageing characteristics. The study has shown that incorporation of 20 parts skim rubber or deproteinized skim rubber to ISNR 20 imparts cure characteristics and mechanical properties similar to that attained by ISNR 20 without the incorporation of additional curatives. Introduction Skim rubber is obtained by the coagulation of skim latex, the secondary fraction of natural rubber latex, from the centrifugal concentration process. The processing of skim latex has many associated problems due to the peculiar physical and chemical characteristics of the same and is an issue of environmental concern. Skim latex has very low dry rubber content (4-8%) and rubber particles are smaller in size with high specific surface area 1, 2 . It has higher proportion of non-rubber solids which is mostly proteinaceous in nature. It is difficult to coagulate skim latex 3 and there is considerable loss in skim rubber during processing. Acid coagulation and auto coagulation are used to recover rubber from skim latex 4 . To improve the raw rubber properties of skim rubber, attempts have been made by deproteinization using certain enzymes 5 and subsequent creaming 6 of skim latex. The proteolytic enzyme stabilized liquid papain used for deproteinization followed by creaming results in quick and easy coagulation of skim latex 7 . The type and high level of non-rubbers present in the skim rubber give rise to scorchy cure and generally give vulcanizates of high modulus. The latter can be considered to arise at least in part due to the protein present in the rubber acting as a reinforcing filler and participation in the curing process. Despite these adverse features, skim rubber has low dirt content, often accompanied by light colour and relatively low cost. Blending skim rubber with natural rubber is a method of taking advantage of the relatively low price of skim rubber while minimizing its disadvantages. In addition, it seems possible that in such blends the fast curing characteristics of the skim can be utilized 8 .
In this work we have examined the cure behaviour and technological properties on adding 20 phr (parts per hundred rubber) each of deproteinized skim rubber (DPSR) and skim rubber to ISNR 20 mix without further addition of curatives and comparing the properties to that of a similar ISNR 20 mix. Two cure systems, one which contain usual dosage of accelerator and antioxidant and the other system which contain comparatively lower level of accelerator without any antioxidant were studied. Experimental ISNR 20 - From the Pilot Crumb Rubber Factory, Rubber Board DPSR - Prepared at the Rubber Technology Division, RRII Skim rubber - From the Central Experiment Station, Chethackal, Rubber Board The other ingredients used were of commercial grade Preparation of deproteinized skim rubber Liquid papain of 0.25 phr as 5% solution was initially treated with 0.5 phr potassium oleate. This was then mixed with the skim latex, stored for 48 h at room temperature, treated with potassium oleate (0.01% w/v on latex as 10% solution) and stored for further 24 h. It was then subjected to creaming with ammonium alginate (0.3% w/v on latex as 3% solution), coagulated the cream with 5% H2SO4, the coagulum soaked for 24 h in oxalic acid solution and dried 7 . The fatty acids present in both DPSR and skim rubber were determined using gel permeation chromatograph (GPC – Waters 510) attached to a 410 diffraction refractometer. The solvent used was THF/water/acetonitrile in the ratio 25/35/45 (v/v) at a flow rate of 2ml/min. Raw rubber properties of ISNR 20, DPSR and skim rubber were determined and are given in Table 1. Preparation of mixes In order to study the cure behaviour and technological properties, two cure systems were selected. Mixes were prepared as per the formulations given in Table 2 using a laboratory model two roll mixing mill. Cure characteristics of the samples were determined using Tech Pro Rheo Tech MD + at 150°C. Vucanizates were moulded using an electrically heated hydraulic press to their respective optimum cure. Properties of the vulcanizates were determined as per the relevant ASTM standards. Ageing of the vulcanizates was carried out at 70°C for 7 days in an air oven as per ASTM standards. Results and discussion Fatty acids Fig.1 shows the chromatogram of the fatty acids present in the skim rubber prepared by conventional method and that obtained after deproteinization and creaming. The fatty acids present include linoleic, oleic, stearic, linolenic and lauric. There is a reduction in the quantity of fatty acids after deproteinization and creaming. Higher quantity of fatty acids retained in skim rubber adversely affects the ageing characteristics. Raw rubber properties Results in Table 1 show that ISNR 20 has nitrogen content of 0.37 % where as skim rubber has nitrogen content of 2.3 %. DPSR prepared by using the protelytic enzyme papain has reduced the nitrogen content to 0.62 %. Being a protease, this enzyme catalysis the hydrolysis of proteins which are bound to the latex particles in to water soluble polypeptides and amino acids, which get removed during the creaming process 9 . Ash content was more for the skim rubber than ISNR 20. During deproteinization and creaming some of these mineral materials were removed and hence the value for the ash content of DPSR was lower than skim rubber but higher than ISNR 20. Initial plasticity, Po for the three samples were within the limit specified by Bureau of Indian Standards (BIS). Comparatively low PRI was recorded by the skim rubber while DPSR recorded a PRI comparable to that of ISNR 20. The low PRI of skim rubber could be attributed to the presence of high proportion of copper and unsaturated fatty acids that accelerate the oxidation of rubber 10 . It is reported that the PRI can be improved by immersion of the coagulum in 1% oxalic acid solution and the improvement observed for the enzyme treated sample may be due to the extraction of free copper from the rubber
Page 1 and 2:
Design of experiments for optimizin
Page 3 and 4:
Verification Experiments Confirmato
Page 5 and 6:
Fig 3 Overlaid contour plots for te
Page 7 and 8:
processing variables on the adhesio
Page 9 and 10:
NR / CR TSC (%) 100 / 0 75 / 25 50
Page 11 and 12:
the observed high values of its T-p
Page 13 and 14:
Nondestructive testing of defects i
Page 15 and 16:
visible impact damage (BVID). The c
Page 17 and 18:
Fig 2. Photograph of the spliced ne
Page 19 and 20: Electrical studies on silver subsur
Page 21 and 22: temperatures exhibited by the 50 nm
Page 23 and 24: Figure 1: Variation of ln R with 1/
Page 25 and 26: Experimental Polyamide6 (PA6 with z
Page 27 and 28: Table 1: Sample code and compositio
Page 29 and 30: Blends of unsaturated polyester res
Page 31 and 32: in comparison to that of the base r
Page 33 and 34: Fig. 1 Tensile strength of rubber m
Page 35 and 36: characterization of PTT/m-LLDPE ble
Page 37 and 38: organoclay into the blend matrix re
Page 39 and 40: Figure: 5 - DSC cooling thermogram
Page 41 and 42: polypropylene exhibits β-chain sci
Page 43 and 44: ehavior. Here two possible effects
Page 45 and 46: Complex modulus (KPa) Complex visco
Page 47 and 48: has been carried out using thermogr
Page 49 and 50: Weight (%) 80 40 0 Table 1. Sample
Page 51 and 52: Mechanical properties of natural ru
Page 53 and 54: due to adsorption on rubber particl
Page 55 and 56: Preparation and Characterization of
Page 57 and 58: 2.7. Fabrication of curcumin elutin
Page 59 and 60: Table 2. Effect of curcumin content
Page 61 and 62: Biodegradable nanocomposites can be
Page 63 and 64: crystallization temperature of PBAT
Page 65 and 66: Biomimetic synthesis of nanohybrids
Page 67 and 68: 3.3. Thermogravimetric analysis (TG
Page 69: Fig 2: 31 P-NMR Spectra of as-synth
Page 73 and 74: 7. George, K.M, Alex, R, Joseph, S
Page 75 and 76: Reinforcement studies - Effect of t
Page 77 and 78: Results and Discussion Immersion an
Page 79 and 80: Stress (MPa) 26 24 22 20 18 16 14 1
Page 81 and 82: Effect of plasticizer, filler and s
Page 83: Results and Discussion Properties o
Page 86 and 87: prepolymers having higher percentag
Page 88 and 89: Table2. Formulation for Peroxide cu
Page 90 and 91: Elongation at Break The elongation
Page 92 and 93: All-PP composites based on β and
Page 94 and 95: a T E'(T) = (1) E'(T ) ref The shif
Page 96 and 97: We tried the classical WLF equation
Page 98 and 99: Figure 2. Schematic of time-tempera
Page 100 and 101: Intercalated poly (methyl methacryl
Page 102 and 103: them. The nanocomposites prepared u
Page 104 and 105: Table 1: Mechanical Properties of P
Page 106 and 107: Abstract A Review on thermally stab
Page 108 and 109: processing of different commercial
Page 110 and 111: d(%Mass)/dT ( 0 d(%Mass)/dT ( C) 0
Page 112 and 113: composites has been reported to imp
Page 114 and 115: (a) (b) Figure 2: WAXD of a) PVC/mi
Page 116 and 117: Storage Modulus (M Pa) 3000 2500 20
Page 118 and 119: 17. Peprnicek, T.; Duchet, J.; Kova
Page 120 and 121:
constraint of several nanometers, t
Page 122 and 123:
The FT-IR spectrum .ER-Epoxy resin,
Page 124 and 125:
GLASS TRANSITION TEMPERATURE (Tg) V
Page 126 and 127:
AFM image of Amine containing PDMS
Page 128 and 129:
8. A.Al.Abrash, F.Al.Sagheer, A.A.m
Page 130 and 131:
2. Experimental Details Polypropyle
Page 132 and 133:
5. Acknowlegements We would like to
Page 134 and 135:
Synthesis and characterization of p
Page 136 and 137:
pristine polypropylene during cooli
Page 138 and 139:
a Figure 2: Typical TEM micrographs
Page 140 and 141:
potassium ditelluratoargentate (III
Page 142 and 143:
found to be 80.51 and 77.31, respec
Page 144 and 145:
14. G. Canche-Escamilla, J.I. Cauic
Page 146 and 147:
2.2. Characterization of electrospu
Page 148 and 149:
eported that tortuosity decreases w
Page 150 and 151:
Abstract: Effect of nano TiO2 in co
Page 152 and 153:
3. Results and Discussion : The wid
Page 154 and 155:
This is further evidenced from the
Page 156 and 157:
Transducer using Terfenol-D/epoxy c
Page 158 and 159:
esults were compared. Measurements
Page 160 and 161:
500 400 300 200 100 0 Magnetostrict
Page 162 and 163:
Experimental Materials Natural crum
Page 164 and 165:
It is known that for alkali and alk
Page 166 and 167:
Polymer sample Table1. Ion uptake b
Page 168 and 169:
Abstract Protein functionalized pol
Page 170 and 171:
2.4 Analysis of Particle size of ul
Page 172 and 173:
Table 1 Nano particle preparation o
Page 174 and 175:
As the particle size is reduced, su
Page 176 and 177:
Figure- 3 SEM micrograph of EFNP of
Page 178 and 179:
Excess PVA solution was drained off
Page 180 and 181:
Figure 1. IR spectra of (I) PSF bas
Page 182 and 183:
Photodegradable polypropylene film
Page 184 and 185:
were observed as a broad peak in th
Page 186 and 187:
Fig. 1. Carbonyl index variation of
Page 188 and 189:
Abstract Swelling behaviour of hydr
Page 190 and 191:
Swelling experiment Circular shaped
Page 192 and 193:
⎛ hθ D = π⎜ ⎜ ⎝ 4Q ∞
Page 194 and 195:
21. Bajsic G, Rek V. J Appl Polym S
Page 196 and 197:
log (C α - C t ) 1.0 0.9 0.8 0.7 0
Page 198 and 199:
esistance [2]. For converting it to
Page 200 and 201:
References 1. Bob RJ, Underwater El
Page 202 and 203:
Figure-2 Insertion Loss behavior 0.
Page 204 and 205:
Development of epoxy based material
Page 206 and 207:
NOTATIONS USED A→E-55, AL-45.S.g-
Page 208 and 209:
The Samples E, I, H and pure epoxy
Page 210 and 211:
The combination B The combination I
Page 212 and 213:
Graft-copolymerization of cellulose
Page 214 and 215:
Once the free-radical species (A
Page 216 and 217:
References 1. Margaret I.P, Sau L.L
Page 218 and 219:
Design of experiments for optimizin
Page 220 and 221:
Verification Experiments Confirmato
Page 222 and 223:
Fig 3 Overlaid contour plots for te
Page 224 and 225:
processing variables on the adhesio
Page 226 and 227:
NR / CR TSC (%) 100 / 0 75 / 25 50
Page 228 and 229:
the observed high values of its T-p
Page 230 and 231:
Nondestructive testing of defects i
Page 232 and 233:
visible impact damage (BVID). The c
Page 234 and 235:
Fig 2. Photograph of the spliced ne
Page 236 and 237:
Electrical studies on silver subsur
Page 238 and 239:
temperatures exhibited by the 50 nm
Page 240 and 241:
Figure 1: Variation of ln R with 1/
Page 242 and 243:
Experimental Polyamide6 (PA6 with z
Page 244 and 245:
Table 1: Sample code and compositio
Page 246 and 247:
Blends of unsaturated polyester res
Page 248 and 249:
in comparison to that of the base r
Page 250 and 251:
Fig. 1 Tensile strength of rubber m
Page 252 and 253:
characterization of PTT/m-LLDPE ble
Page 254 and 255:
organoclay into the blend matrix re
Page 256 and 257:
Figure: 5 - DSC cooling thermogram
Page 258 and 259:
polypropylene exhibits β-chain sci
Page 260 and 261:
ehavior. Here two possible effects
Page 262 and 263:
Complex modulus (KPa) Complex visco
Page 264 and 265:
has been carried out using thermogr
Page 266 and 267:
Weight (%) 80 40 0 Table 1. Sample
Page 268 and 269:
Mechanical properties of natural ru
Page 270 and 271:
due to adsorption on rubber particl
Page 272 and 273:
Preparation and Characterization of
Page 274 and 275:
2.7. Fabrication of curcumin elutin
Page 276 and 277:
Table 2. Effect of curcumin content
Page 278 and 279:
Biodegradable nanocomposites can be
Page 280 and 281:
crystallization temperature of PBAT
Page 282 and 283:
Biomimetic synthesis of nanohybrids
Page 284 and 285:
3.3. Thermogravimetric analysis (TG
Page 286 and 287:
Fig 2: 31 P-NMR Spectra of as-synth
Page 288 and 289:
In this work we have examined the c
Page 290 and 291:
7. George, K.M, Alex, R, Joseph, S
Page 292 and 293:
Reinforcement studies - Effect of t
Page 294 and 295:
Results and Discussion Immersion an
Page 296 and 297:
Stress (MPa) 26 24 22 20 18 16 14 1
Page 298 and 299:
Effect of plasticizer, filler and s
Page 300:
Results and Discussion Properties o
Page 303 and 304:
prepolymers having higher percentag
Page 305 and 306:
Table2. Formulation for Peroxide cu
Page 307 and 308:
Elongation at Break The elongation
Page 309 and 310:
All-PP composites based on β and
Page 311 and 312:
a T E'(T) = (1) E'(T ) ref The shif
Page 313 and 314:
We tried the classical WLF equation
Page 315 and 316:
Figure 2. Schematic of time-tempera
Page 317 and 318:
Intercalated poly (methyl methacryl
Page 319 and 320:
them. The nanocomposites prepared u
Page 321 and 322:
Table 1: Mechanical Properties of P
Page 323 and 324:
Abstract A Review on thermally stab
Page 325 and 326:
processing of different commercial
Page 327 and 328:
d(%Mass)/dT ( 0 d(%Mass)/dT ( C) 0
Page 329 and 330:
composites has been reported to imp
Page 331 and 332:
(a) (b) Figure 2: WAXD of a) PVC/mi
Page 333 and 334:
Storage Modulus (M Pa) 3000 2500 20
Page 335 and 336:
17. Peprnicek, T.; Duchet, J.; Kova
Page 337 and 338:
constraint of several nanometers, t
Page 339 and 340:
The FT-IR spectrum .ER-Epoxy resin,
Page 341 and 342:
GLASS TRANSITION TEMPERATURE (Tg) V
Page 343 and 344:
AFM image of Amine containing PDMS
Page 345 and 346:
8. A.Al.Abrash, F.Al.Sagheer, A.A.m
Page 347 and 348:
2. Experimental Details Polypropyle
Page 349 and 350:
5. Acknowlegements We would like to
Page 351 and 352:
Synthesis and characterization of p
Page 353 and 354:
pristine polypropylene during cooli
Page 355 and 356:
a Figure 2: Typical TEM micrographs
Page 357 and 358:
potassium ditelluratoargentate (III
Page 359 and 360:
found to be 80.51 and 77.31, respec
Page 361 and 362:
14. G. Canche-Escamilla, J.I. Cauic
Page 363 and 364:
2.2. Characterization of electrospu
Page 365 and 366:
eported that tortuosity decreases w
Page 367 and 368:
Abstract: Effect of nano TiO2 in co
Page 369 and 370:
3. Results and Discussion : The wid
Page 371 and 372:
This is further evidenced from the
Page 373 and 374:
Transducer using Terfenol-D/epoxy c
Page 375 and 376:
esults were compared. Measurements
Page 377 and 378:
500 400 300 200 100 0 Magnetostrict
Page 379 and 380:
Experimental Materials Natural crum
Page 381 and 382:
It is known that for alkali and alk
Page 383 and 384:
Polymer sample Table1. Ion uptake b
Page 385 and 386:
Abstract Protein functionalized pol
Page 387 and 388:
2.4 Analysis of Particle size of ul
Page 389 and 390:
Table 1 Nano particle preparation o
Page 391 and 392:
As the particle size is reduced, su
Page 393 and 394:
Figure- 3 SEM micrograph of EFNP of
Page 395 and 396:
Excess PVA solution was drained off
Page 397 and 398:
Figure 1. IR spectra of (I) PSF bas
Page 399 and 400:
Photodegradable polypropylene film
Page 401 and 402:
were observed as a broad peak in th
Page 403 and 404:
Fig. 1. Carbonyl index variation of
Page 405 and 406:
Abstract Swelling behaviour of hydr
Page 407 and 408:
Swelling experiment Circular shaped
Page 409 and 410:
⎛ hθ D = π⎜ ⎜ ⎝ 4Q ∞
Page 411 and 412:
21. Bajsic G, Rek V. J Appl Polym S
Page 413 and 414:
log (C α - C t ) 1.0 0.9 0.8 0.7 0
Page 415 and 416:
esistance [2]. For converting it to
Page 417 and 418:
References 1. Bob RJ, Underwater El
Page 419 and 420:
Figure-2 Insertion Loss behavior 0.
Page 421 and 422:
Development of epoxy based material
Page 423 and 424:
NOTATIONS USED A→E-55, AL-45.S.g-
Page 425 and 426:
The Samples E, I, H and pure epoxy
Page 427 and 428:
The combination B The combination I
Page 429 and 430:
Graft-copolymerization of cellulose
Page 431 and 432:
Once the free-radical species (A
Page 433 and 434:
References 1. Margaret I.P, Sau L.L
Page 435 and 436:
Studies on processing of styrene bu
Page 437 and 438:
3 Results 4. Swelling index - Tolue
Page 439:
4. Swelling index The swelling indi
Page 442 and 443:
Effect of post drawing parameters o
Page 444 and 445:
Drawing the fiber at 100 0 C, which
Page 446 and 447:
Table 1: Experimental details of va
Page 448 and 449:
and the primary variables in the go
Page 450 and 451:
The equ (3.2) is linearized and we
Page 452 and 453:
Initial Deformed coordinates coordi
Page 454 and 455:
As 'C' channel structures is non-sy
Page 456 and 457:
Figure 3: Von-mises stress distribu
Page 458 and 459:
Synthesis, curing and characterizat
Page 460 and 461:
Results and Discussion: . Table 4.1
Page 462 and 463:
TGDDM/DDM SYSTEM: There are 2 trans
Page 464 and 465:
Table 4.6: DSC Results DSC thermo g
Page 466 and 467:
CONCLUSION: 1. Tetraglycidyl Diamin
Page 468 and 469:
Studies on processing of styrene bu
Page 470 and 471:
3 Results 4. Swelling index - Tolue
Page 472:
4. Swelling index The swelling indi
Page 475 and 476:
Effect of post drawing parameters o
Page 477 and 478:
Drawing the fiber at 100 0 C, which
Page 479 and 480:
Table 1: Experimental details of va
Page 481 and 482:
and the primary variables in the go
Page 483 and 484:
The equ (3.2) is linearized and we
Page 485 and 486:
Initial Deformed coordinates coordi
Page 487 and 488:
As 'C' channel structures is non-sy
Page 489 and 490:
Figure 3: Von-mises stress distribu
Page 491 and 492:
Synthesis, curing and characterizat
Page 493 and 494:
Results and Discussion: . Table 4.1
Page 495 and 496:
TGDDM/DDM SYSTEM: There are 2 trans
Page 497 and 498:
Table 4.6: DSC Results DSC thermo g
Page 499 and 500:
CONCLUSION: 1. Tetraglycidyl Diamin
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