Surface energy of styrene-butadiene rubbers

J of Applied Polymer Sci

Ślusarski

Głąb

2007

The activity of iodoform (CHI 3 ) toward unsaturated rubbers was examined. Special attention was devoted to cis-1,4-(poly)isoprene (IR). The thermal decomposition of CHI 3 was studied by ion mass spectroscopy, and the obtained data were used for the identification of pyrolysis products of CHI 3 vulcanizates by pyrolytic gas chromatography. The kinetics of the chemical crosslinking of rubber were studied with a cure meter. The changes observed in the chemical structure of rubber were explained on the basis of 13 CNMR and Fourier transform infrared spectroscopy, differential scanning calorimetry, equilibrium swelling, and chemical microanalysis data. Apart from crosslinking, a simultaneous modification of the rubber macromolecules took place, specifically the cistrans isomerization of IR. This resulted in a significant increase in the rubber hardness, especially after a postheat treatment accompanied by oxidation. CHI 3 -IR vulcanizates behaved like thermoplastics because of the presence of a trans-1,4 phase, as confirmed by dynamic mechanical thermal analysis. The structure of the macromolecules treated with CHI 3 and its effect on the physical properties of the material were compared with those of peroxide-IR vulcanizates. The influence of the modification on the surface energy, bacteriostaticity, and mechanical properties of the vulcanizates was examined.

Section: Methodsmentioning

confidence: 99%

Modification of rubber by iodoform

J of Applied Polymer Sci

Ślusarski

Głąb

2007

“…z o.o., Polska). Uzyskane wartooeci wykorzystano do obliczenia energii powierzchni wulkanizatów oraz jej sk³adowych, postêpuj¹c wed-³ug procedury opisanej w literaturze [20,21].…”

Section: Energia Powierzchniunclassified

Modification of styrene-butadiene rubber with polymethylsiloxanes

Głąb²,

Chruściel³

2007

Polimery

Streszczenie -Przedstawiono wyniki badañ dotycz¹cych strukturalnych aspektów modyfikacji kauczuku butadienowo-styrenowego (SBR) polimetylowodorosiloksanami (PMHS) i polidimetylosiloksanami (PDMS). Modyfikatory te ró¿ni³y siê reaktywnooeci¹, mierzon¹ ilooeciowym stosunkiem merów metylowodorosiloksanowych do merów dimetylosiloksanowych. Okreoelono wp³yw reaktywnooeci modyfikatora na kinetykê rodnikowej reakcji sieciowania kauczuku wobec ditlenku dikumylu (DCP) a tak¿e wulkanizacji siarkowej. W przypadku zastosowania DCP szybkooeae i wydajnooeae sieciowania rosn¹ wraz ze zwiêkszaniem reaktywnooeci u¿ytego modyfikatora, natomiast w wulkanizacji siarkowej najwiêksz¹ szybkooeci¹ reakcji odznacza³y siê uk³ady zawieraj¹ce najmniej reaktywny PMHS. Nie zaobserwowano równie¿ ¿adnego wp³ywu modyfikatora na wydajnooeae wulkanizacji siark¹ i wyjaoeniono przyczyny tego zjawiska. Sieciowaniu wobec DCP towarzysz¹ reakcje szczepienia PMHS na elastomerze oraz jego polimeryzacji w kauczukowej matrycy. Modyfikatory krzemoorganiczne przejawiaj¹ tendencjê do migracji i segregacji powierzchniowej w kauczuku. Obok zmiany morfologii uk³adu, wp³ywa to na w³aoeciwooeci mechaniczne i trybologiczne usieciowanego SBR. Mianowicie, wprowadzenie modyfikatora powoduje zmniejszenie wytrzyma³ooeci na rozci¹ganie, zw³aszcza w przypadku kauczuku usieciowanego wobec DCP. Wspó³czynnik tarcia wulkanizatów siarkowych zwiêksza siê pod wp³ywem modyfikacji, natomiast w przypadku SBR usieciowanego za pomo-c¹ DCP mo¿na zmniejszyae ten wspó³czynnik u¿ywaj¹c do modyfikacji PDMS lub PMHS o ma³ej reaktywnooeci. S³owa kluczowe: kauczuk butadienowo-styrenowy, polimetylowodorosiloksany, polidimetylosiloksany, modyfikacja, sieciowanie, morfologia, wytrzyma³ooeae mechaniczna, energia powierzchni, tarcie. MODIFICATION OF STYRENE-BUTADIENE RUBBER WITH POLYMETHYLSILOXANESSummary -The results of investigations on structural aspects of styrene-butadiene rubber (SBR) modification with polymethylhydrosiloxanes (PMHS) or polydimethylsiloxanes (PDMS) were presented. The modifiers varied in reactivity, measured as a ratio of methylhydrosiloxane and dimethylsiloxane units ( Table 1). The effects of modifier reactivity on the kinetics of radical reaction of rubber curing in the presence of dicumyl peroxide (DCP) as well as on the sulfur-induced vulcanization were determined (Table 2-5, Fig. 2 and 3). In case of DCP use the curing rate and efficiency increase with increasing reactivity of modifier used. However, in case of sulfur-induced vulcanization the systems containing less active PMHS showed the highest reaction rate. No modifier effect on the efficiency of sulfur-induced vulcanization was observed. It can be the result of active complex blocking by polysiloxanes, wetting the surface of ZnO being an activator of sulfur curing system. The curing in the presence of DCP is accompanied with the reactions of PMHS grafting onto elastomer and its polymerization in the rubber matrix. Organosilicon modifiers show the tendency to surface migration and segregation in the rubber. Togethe...

Influence of chemical modification on tribological properties of elastomers

J of Applied Polymer Sci

Ślusarski

Affrossman

et al. 1995

SYNOPSISPhysical properties of surface modified synthetic elastomers were studied to understand the factors that reduce friction and provide advantages in practical use. Bromination, iodination, sulfonation, and chlorination were investigated. The coefficient of friction p was measured using a modified version of the pin-on-disc apparatus. The surface energy, morphology, mechanical properties, and extent of chemical modification were also measured. An increased stiffness and microroughness were found to correlate with changes in the coefficient of friction. Sulfonation (100% H,SO,) was found to be the most effective and universally acceptable method of chemical treatment from a tribological point of view.