“…The surface of prevulcanized NR evaporated film (PNRev, Figure c) is found to be not so uniform as that of NRev as it constitutes certain spherical granular domains. This may be due to the retention of some original particulate structure formed as a result of the faster cross-linking nature of the surface molecules of the individual particles present in the prevulcanized latex. , 4 Scanning electron micrographs of the cryo-fractured surfaces of (a) Nrev, (b) NRL, (c) PNRev, (d) NCH20ev, (e) NCH20L, and (f) PCH20ev films.…”
Section: Resultsmentioning
confidence: 99%
“…This may be due to the retention of some original particulate structure formed as a result of the faster crosslinking nature of the surface molecules of the individual particles present in the prevulcanized latex. 37,38 Panels d-f of Figure 4 show the fractured surfaces of the composites filled with 20 wt % of chitin whiskers: NCH20ev, NCH20L, and PCH20ev, respectively. In Figure 4d, the chitin whiskers appear as white dots, which are distributed evenly throughout the unvulcanized evaporated matrix.…”
Nanocomposite materials were obtained from a colloidal suspension of chitin whiskers as the reinforcing phase and latex of both unvulcanized and prevulcanized natural rubber as the matrix. The chitin whiskers, prepared by acid hydrolysis of chitin from crab shell, consisted of slender parallelepiped rods with an aspect ratio close to 16. After the two aqueous suspensions were mixed and strirred, solid composite films were obtained either by freeze-drying and hot-pressing or by casting and evaporating the preparations. The processing and swelling behavior of composite films were evaluated. It was concluded that the whiskers form a rigid network assumed to be governed by a percolation mechanism in the evaporated samples only. Comparatively, better resistance of evaporated samples than hot-pressed ones against swelling in an organic solvent medium is good evidence for the existence of a rigid chitin network. The values of diffusion coefficient, bound rubber content, and relative weight loss also supported the presence of a three-dimensional chitin network within the evaporated samples. The mechanical behavior of the composites gives additional insight and evidence for this fact (part 2).
“…The surface of prevulcanized NR evaporated film (PNRev, Figure c) is found to be not so uniform as that of NRev as it constitutes certain spherical granular domains. This may be due to the retention of some original particulate structure formed as a result of the faster cross-linking nature of the surface molecules of the individual particles present in the prevulcanized latex. , 4 Scanning electron micrographs of the cryo-fractured surfaces of (a) Nrev, (b) NRL, (c) PNRev, (d) NCH20ev, (e) NCH20L, and (f) PCH20ev films.…”
Section: Resultsmentioning
confidence: 99%
“…This may be due to the retention of some original particulate structure formed as a result of the faster crosslinking nature of the surface molecules of the individual particles present in the prevulcanized latex. 37,38 Panels d-f of Figure 4 show the fractured surfaces of the composites filled with 20 wt % of chitin whiskers: NCH20ev, NCH20L, and PCH20ev, respectively. In Figure 4d, the chitin whiskers appear as white dots, which are distributed evenly throughout the unvulcanized evaporated matrix.…”
Nanocomposite materials were obtained from a colloidal suspension of chitin whiskers as the reinforcing phase and latex of both unvulcanized and prevulcanized natural rubber as the matrix. The chitin whiskers, prepared by acid hydrolysis of chitin from crab shell, consisted of slender parallelepiped rods with an aspect ratio close to 16. After the two aqueous suspensions were mixed and strirred, solid composite films were obtained either by freeze-drying and hot-pressing or by casting and evaporating the preparations. The processing and swelling behavior of composite films were evaluated. It was concluded that the whiskers form a rigid network assumed to be governed by a percolation mechanism in the evaporated samples only. Comparatively, better resistance of evaporated samples than hot-pressed ones against swelling in an organic solvent medium is good evidence for the existence of a rigid chitin network. The values of diffusion coefficient, bound rubber content, and relative weight loss also supported the presence of a three-dimensional chitin network within the evaporated samples. The mechanical behavior of the composites gives additional insight and evidence for this fact (part 2).
“…The raw shrub controls of the cooked series are included to show that duplicate samples yield less rubber when extracted raw than when cooked before extraction. 6 Start of cooked series. " End of cooked series.…”
A Jordan-type mill may be substituted for the conventional pebble mill for the extraction of rubber from CHEMISTRY Vol. 39, No. II Table VII. Comparison of Guayule Rubbers on A.C.S. II and B.A.I.C. Formulas Before Aging After Aging Curing Elonga-Modulus Tensile
“…In 1928, Sessions (0) reported that he had obtained, at best, a 12.2% yield of theory of maleic acid from furfural. Zumstein (7), in 1929, stated that maleic acid could be produced by the vapor phase oxidation of furfural in yields of 30 to 35% of theory and in 1934 (8), reported a 90% yield of theory. Milas and Walsh (4), in 1935, reported that the vapor phase oxidation of furfuryl alcohol, furfural, furoic acid, and furan produced yields, in the above order, of from 22.5 to 65% of maleic acid of theory.…”
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