scholarly journals Development of natural rubber foam with water as a blowing agent via microwave and convection heating methods

2022 ◽  
Vol 16 (3) ◽  
pp. 296-317
Author(s):  
Nur Syuhada Ahmad Zauzi ◽  
Zulkifli Mohamad Ariff ◽  
Raa Khimi Shuib
Keyword(s):  
Natural Rubber ◽  
Blowing Agent ◽  
Convection Heating

Effect of carbon allotropes on foam formation, cure characteristics, mechanical and thermal properties of NRF/carbon composites

2020 ◽  
pp. 0021955X2097954
Author(s):  
Pollawat Charoeythornkhajhornchai ◽  
Wutthinun Khamloet ◽  
Pattharawun Nungjumnong
Keyword(s):  
Natural Rubber ◽  
Bubble Diameter ◽  
Carbon Composites ◽  
Mechanical And Thermal Properties ◽  
Foam Formation ◽  
Carbon Filler ◽  
Composite Foam ◽  
Carbon Allotropes ◽  
Blowing Agent ◽  
Rubber Composite

Natural rubber composite foam with carbon such as carbon black (CB), carbon synthesized from durian bark (CDB), graphite (GPT), graphene oxide (GO), graphene (GPE) and multi-walled carbon nanotubes (MWCNT) was studied in this work to investigate the relationship between foam formation during decomposition of chemical blowing agent mechanism and crosslink reaction of rubber molecules by sulphur. Natural rubber composite foam with carbon particle was set at 3 parts per hundred of rubber (phr) to observe the effect of carbon allotropes on foam formation with different microstructure and properties of natural rubber composite foam. The balancing of crosslink reaction by sulphur molecules during foam formation by the decomposition of chemical blowing agent affects the different morphology of natural rubber foam/carbon composites leading to the different mechanical and thermal properties. The result showed the fastest cure characteristics of natural rubber foam with 3 phr of graphene (NRF-GPE3) which was completely cure within 6.55 minutes (tc90) measured by moving die rheometer resulting in the smallest bubble diameter among other formulas. Moreover, natural rubber foam with 3 phr of MWCNT (NRF-MWCNT3) had the highest modulus (0.0035 ± 0.0005 N/m2) due to the small bubble size with high bulk density. In addition, natural rubber foam with 3 phr of GPT (NRF-GPT3) had the highest thermal expansion coefficient (282.12 ± 69 ppm/K) due to high amount of gas bubbles inside natural rubber foam matrix and natural rubber foam with 3 phr of GO (NRF-GO3) displayed the lowest thermal conductivity (0.0798 ± 0.0003 W/m.K) which was lower value than natural rubber foam without carbon filler (NRF). This might be caused by the effect of bubble diameter and bulk density as well as the defect on surface of graphene oxide compared to others carbon filler.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

Effect of Filler Types on Properties of the Natural Rubber Closed Cell Foam

2019 ◽  
Vol 886 ◽  
pp. 213-218
Author(s):  
Ekaroek Phumnok ◽  
Jakkrit Boonphang ◽  
Orrachorn Bourkaew
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Precipitated Calcium Carbonate ◽  
Elongation At Break ◽  
Blowing Agent ◽  
Compression Set ◽  
China Clay ◽  
Closed Cell ◽  
The Difference ◽  
Cell Foam

In this research, effects of filler types and their loading on properties of the natural rubber closed cell foam were investigated. The azodicarbonamide was used as a blowing agent in 4 phr loading. The filler types that are the N-330 grade of carbon black, precipitated calcium carbonate and rubber grade china clay, their loading was varied from 0 to 50 phr (part per hundred dried rubber). The physical properties of the rubber foam that are the difference torque from the oscillating disk rheometer, hardness, tear strength, 300% modulus, tensile strength, elongation at break and compression set were analyzed. The results were found that the carbon black was yielded the highest of all properties in every loading. In conclusion, the suitable filler for closed cell rubber foam is the carbon black.

Effect of Foaming Temperature and Blowing Agent Content on Cure Characteristics, Mechanical and Morphological Properties of Natural Rubber Foams

2013 ◽  
Vol 844 ◽  
pp. 454-457 ◽  
Author(s):  
Worawan Pechurai ◽  
Tatsanee Muansupan ◽  
Petcharat Seawlee
Keyword(s):  
Natural Rubber ◽  
Foam Cell ◽  
Large Cell ◽  
Morphological Properties ◽  
Maximum Torque ◽  
Cure Characteristics ◽  
Blowing Agent ◽  
Foaming Process ◽  
Cure Time ◽  
Foaming Temperature

Influences of foaming temperature (i.e. 150 and 160OC) and blowing agent content on cure characteristics, mechanical and morphological properties of natural rubber (NR) foams were investigated. The blowing agent used in this study was oxybis (benzene sulfonyl) hydrazide (OBSH). The expandable rubber samples were prepared using a conventional compression molding technique via a heat transfer foaming process and an air-circulating oven. For cure behavior, it was found that maximum torque and torque difference tended to decrease with increasing the OBSH content for both processing temperatures. Decreasing of cure time was observed at 3 phr of the OBSH content and then it tended to increase. Moreover, cure time and scorch time decreased with increasing foaming temperature. As a result, the NR foam with large cell size and non-uniform foam cell distribution was observed. Mechanical properties of the NR foam in a term of hardness gradually decreased upon increasing the OBSH content. Whilst compression set increased with increasing the OBSH content up to 6 phr after that it decreased.

The Effect of Kaolin Clay on Fire Retardancy and Thermal Degradation of Intumescent Flame Retardant (IFR)/Natural Rubber Composite

2013 ◽  
Vol 844 ◽  
pp. 334-337 ◽  
Author(s):  
Thiranan Thuechart ◽  
Wirunya Keawwattana
Keyword(s):  
Thermal Degradation ◽  
Natural Rubber ◽  
Flame Retardant ◽  
Cone Calorimeter ◽  
Intumescent Flame Retardant ◽  
Kaolin Clay ◽  
Fire Retardancy ◽  
Blowing Agent ◽  
Rubber Composite ◽  
Synergistic Agent

Study the effect of kaolin clay as a synergistic agent on flame retardancy and thermal degradation in natural rubber based on intumescent flame retardant (IFR); consisting of ammonium polyphosphate (APP) as acid source, pentaerythritol (PER) as a carbonization agent and melamine (ME) as a blowing agent was undertaken. The intumescent was examined at different loading (60, 80 and 100 phr). Kaolin clay was incorporated into flame retardant at four different concentrations (0.5, 1.0, 1.5 and 2.0 wt% of flame retardant) to investigate the synergism between the flame retardant materials. The flammability and thermal degradation of composites were characterized by UL-94 rating (vertical burning) test, cone calorimeter (CONE) and thermogravimetric analysis (TGA). All composites could meet the UL94V-0 standard. A synergist effect was observed when kaolin clay is used in combination with the intumescent flame-retardant through the TGA and CONE results. Moreover Scanning Electron Microscope (SEM) was done for the char morphology.

Effect of azodicarbonamide on microstructure, cure kinetics and physical properties of natural rubber foam

2016 ◽  
Vol 53 (3) ◽  
pp. 287-303 ◽  
Author(s):  
Pollawat Charoeythornkhajhornchai ◽  
Chavakorn Samthong ◽  
Kanoktip Boonkerd ◽  
Anongnat Somwangthanaroj
Keyword(s):  
Natural Rubber ◽  
Physical Properties ◽  
Bubble Size ◽  
Cure Kinetics ◽  
Expansion Ratio ◽  
Gas Content ◽  
Rubber Matrix ◽  
Volumetric Expansion ◽  
Blowing Agent ◽  
Amine Fragment

The effect of azodicarbonamide as chemical blowing agent on the morphology, cure kinetics and physical properties of natural rubber foam is investigated. From the morphology, when the amount of chemical blowing agent increases from 3 to 4 phr, the bubble size in the rubber matrix slightly decreases due to the increase of vulcanization reaction rate from the presence of amine fragment species as by-products from the decomposition of azodicarbonamide. The coalescence between bubbles is observed in the specimen with 5 and 6 phr of azodicarbonamide owing to high gas content in the rubber matrix. Moreover, the scorch time slightly reduces and cure rate increases as a function of azodicarbonamide content. The autocatalytic model can be used to explain the curing reaction and mechanism of this natural rubber foam. Furthermore, the activation energy (Ea) directly relates to the bubble size and microvoid structure of natural rubber foam. When compared with the vulcanized natural rubber without adding chemical blowing agent, it is found that the bulk density of natural rubber foam significantly decreases and the volumetric expansion ratio of natural rubber foam increases at high content of chemical blowing agent. Moreover, natural rubber foam at 4 phr of azodicarbonamide exhibits the lowest thermal expansion coefficient due to the smallest bubble size with less coalescence.

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