Effect of foaming temperature and rubber grades on properties of natural rubber foams

Abstract

Foaming temperature and grade of dry natural rubber were varied to evaluate their effects on the morphology and mechanical properties of natural rubber (NR) foams. Three different grades of NR were used; namely ENR-25, SMR-L, and SMR-10. NR foams from these grades were produced at three different foaming temperatures, i.e. 140, 150, and 1608C. The study was carried out using formulated compositions containing sodium bicarbonate as the chemical blowing agent and were expanded using conventional compression molding technique via a heat transfer foaming process. The NR foams were characterized with respect to their relative foam density, density of crosslinking, cell size, compression stress, and compression set. Increase in foaming temperature resulted in lower relative density and larger cell size.It was also discovered that the crosslink density slightly decrease with increasing foaming temperature. For mechanical properties, the highest foam density resulted in the highest compression stress. Compression stress at 50% strain increased with increasing foaming temperature and ENR-25 foam has the highest compression stress among the produced foams. The results showed that the morphology, physical, and mechanical properties of the rubber foams can be controlled closely by the foaming temperature and rubber grades.

Influence of the irradiation dose in the cellular structure of natural rubber foams cross-linked by electron beam irradiation

“…Salmazo). (Ariff et al, 2008;Joon-Hyung et al, 2006;Joon-Hyung et al, 2007;Najib et al, 2009;Najib et al, 2011).…”

Effect of different curing systems on cell structure, mechanical properties and aging resistance of nitrile butadiene rubber foam coating with liquid compounds

“…Using sulphur and dicumyl peroxide (DCP) as curing agents was the common processing for unfoamed rubber and rubber foams; there are substantial literature for discussing S and DCP. 6,[8][9][10] Whereas few results were reported concerning the combined curing agent of S with DCP. 11,12 It was useful to form a complex cross-link structure including S-S and C-C linkage in the elastomer matrix for improving the mechanical property and processability of single peroxide cured foams.…”

Processing of Kaolinite and Alumina Loaded in Natural Rubber Composite Foams

“…Alumina (Al 2 O 3 ) particles which are inorganic material or ceramic powders have good thermal properties, creep resistance, high melting temperature, chemical stability, and excellent hardness and strength. Both alumina and kaolinite particles have been used as rigid fillers or as a dispersed phase to reinforce the mechanical, thermal, and electrical properties of NR foams via the vulcanization process at a curing temperature of 150 C by a two-roll mill [5][6][7][8][9][10].…”

“…means scorch time: time required for the increase of point 1 (T s1 ) from minimum torque or in order to indicate time required for the beginning of the crosslink process[6,10]. means scorch time: time required for the increase of point 2 (T s2 ) from minimum torque or in order to indicate time required for the beginning of the crosslink process[6,10].means time corresponding to 10% curing. d à means time corresponding to 50% curing.…”