Comparison of Mechanical Properties between Thai Orthodontic Elastics with Different Ammonia Contents and Commercial Orthodontic Elastics

Introduction: The most widely used preservative system for natural rubber latex to date is the ammonia-based system preventing spontaneous coagulation and putrefaction due mainly to bacteria contamination. Objectives: The study compared 2 types of Thai orthodontic elastics, produced from natural rubber latex with different ammonia contents with commercial orthodontic elastics in terms of initial extension force, residual force, force loss, swelling index, breaking strength and maximum displacement. Materials and Methods: Thai orthodontic elastics were developed from 2 types of natural rubber latex; low ammonia < 0.15% (Thai-L), and high ammonia not < 0.6% (Thai-H). The mechanical properties of Thai orthodontic elastics were compared with commercial elastics (Ormco). Mechanical properties were tested using a universal testing machine (Instron 5566). Data were analyzed by One-way ANOVA and Tukey’s test compared the measurements among groups. Results: Ormco had the highest initial extension force and showed significant differences with Thai-L and Thai-H. Thai-L had the highest residual force but showed no significant difference compared with Ormco. Thai-L had the lowest percent of force loss and showed significant differences with Thai-H and Ormco. Thai-L had lower force loss than Thai-H. For swelling index, Thai-L had the highest elasticity. For breaking strength and maximum displacement, both Thai elastics met the Australian Standard (AS) for breaking strength and maximum displacement, similar to Ormco elastics. Conclusion: All elastics met the specifications of the AS for breaking strength and maximum displacement. Thai-L had comparable properties with commercial orthodontic elastics in terms of mechanical properties. Thai-L had comparable properties with Ormco in terms of mechanical properties and may be developed for orthodontic purposes.

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Comparison of Mechanical Properties of Three Different Orthodontic Latex Elastic Bands Leached with NaOH Solution

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.730.135 ◽

2017 ◽

Vol 730 ◽

pp. 135-140

Author(s):

Thipsupar Pureprasert ◽

Niwat Anuwongnukroh ◽

Surachai Dechkunakorn ◽

Surapich Loykulanant ◽

Chaveewan Kongkaew ◽

...

Keyword(s):

Mechanical Properties ◽

Breaking Strength ◽

Testing Machine ◽

New Method ◽

Maximum Displacement ◽

Elastic Bands ◽

Extension Force ◽

Naoh Solution ◽

Residual Force ◽

Toxic Components

Orthodontic elastic bands made from natural rubber continue to be commonly used due to their favorable characteristics. However, there are concerns associated cytotoxicity due to harmful components released during conventional vulcanization (sulfur-based method). With the co-operation of The National Metal and Materials Technology Center (MTEC) and Faculty of Dentistry Mahidol University, a new method was introduced to reduce toxic components by leaching the orthodontic elastic bands with NaOH solution. The objective of this study was to evaluate the mechanical properties of Thai and commercial orthodontic elastic brands (Ormco and W&H) leached with NaOH solution. Three elastic brands (N =30, size 1⁄4 inch ,4.5 oz.) were tested for mechanical properties in terms of initial extension force, residual force, force loss, breaking strength and maximum displacement using a Universal Testing Machine. The results showed that force loss significantly decreased in Thai-LEACH and W&H-LEACH, whereas the values increased in Ormco-LEACH (P<0.05). The data exhibited a significantly decrease in breaking strength with Thai-LEACH and Ormco-LEACH, whereas all 3 brands revealed a significantly decrease in maximum displacement with the leaching process (P<0.05). In conclusion, leaching with NaOH solution is a new method, which can remove toxic components from orthodontic latex elastic bands. However, this process can affect their mechanical properties. Leached elastic bands from Thai had comparable properties with Ormco and have potential to be developed as a promising product.

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Fabrication of Novel Polyhydroxybutyrate-co-Hydroxyvalerate (PHBV) Mixed with Natural Rubber Latex

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.659.404 ◽

2015 ◽

Vol 659 ◽

pp. 404-408 ◽

Cited By ~ 3

Author(s):

Karndarthip Kuntanoo ◽

Sarunya Promkotra ◽

Pakawadee Kaewkannetra

Keyword(s):

Mechanical Properties ◽

Natural Rubber ◽

Testing Machine ◽

Natural Rubber Latex ◽

Melting Behavior ◽

Melting Transition ◽

Rubber Latex ◽

Scanning Calorimetry ◽

Wide Range ◽

Mixed Films

Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is mixed with natural rubber latex to make better mechanical properties of PHBV. The various ratios between PHBV and natural rubber latex are examined to improve their mechanical properties. The PHBV are solid, easily broken, while natural rubber is excessive elastic materials. Concentrations of the employed PHBV solution are 1, 2, and 3 (%w/v). The mixtures of this solution to natural rubber latex are fabricated the biofilms in three different ratios, 4:6, 5:5, and 6:4, respectively. The films are characterized by electron microscope, universal testing machine, and differential scanning calorimetry (DSC). The electron micrographs of the mixed films and unmixed PHBV yield the lowest void distributions in 3%w/v PHBV. For mechanical properties, the averaged elastic moduli of 1, 2, and 3 (%w/v PHBV) mixed films are 773, 955 and 1,008 kPa, respectively. Their tensile strengths increase with increasing the PHBV concentrations. A similar trend is also found in elastic modulus. The crystallization and melting behavior of pure PHBV and the mixed films are examined by DSC. Melting transition temperatures of pure PHBV exhibit two melting peaks at 154°C and 173°C. In addition, the melting peaks of the mixed films remain in the range of 152-156°C and 168-171°C, respectively. According to their morphology, void distributions reduce twice, compared to the unmixed PHBV. Mechanical properties and thermal analysis indicate that the mixed PHBV can be improved their properties with more resilient and wide range temperature than usual.

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Thermal Insulation Performances of Plaster Composites Based on Embedding Natural Rubber Latex Compound

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.904.441 ◽

2021 ◽

Vol 904 ◽

pp. 441-446

Author(s):

Nuchnapa Tangboriboon ◽

Sarun Muntongkaw ◽

Sompratthana Pianklang

Keyword(s):

Natural Rubber ◽

Thermal Insulation ◽

Water Solubility ◽

Testing Machine ◽

Natural Rubber Latex ◽

Cold Weather ◽

Mechanical And Thermal Properties ◽

Rubber Latex ◽

Universal Testing ◽

Cost Of Energy

Adding 0, 20, and 50 wt% natural-rubber latex compound into the plaster ceiling matrix affected to increase the physical-mechanical-thermal performance properties of plaster ceiling composites. Adding 50 wt% natural rubber latex compound into plaster composites can increase the superior adhesion of the nail-tensile resistance equal to 57.54 N and decrease thermal conductivity equal to 0.0634 W/m.K. In addition, adding natural rubber latex compounds into plaster composites can reduce water solubility, brittleness, impact, and cost of energy consumption due to the exterior temperature. Adequate thermal insulation for roofing, ceiling, and wall systems also reduces radiative losses that chill occupants in cold weather, and reduce interior surface temperatures in the summer, thereby optimizing the comfort of building occupants. The mechanical and thermal properties of plaster composites were investigated by using a Universal Testing Machine (UTM) and heat flow meter, respectively, measured according to TIS 1211-50, TIS 219-2522, and ASTM C518.

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Effect of Bio-Fibrils Incorporating with TiO2 on the Properties of Natural Rubber Foam

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.718.26 ◽

2016 ◽

Vol 718 ◽

pp. 26-29

Author(s):

Kanokwan Seerod ◽

Jantaravan Sangjumpa ◽

Varinrumpai Seithtanabutara

Keyword(s):

Natural Rubber ◽

Smooth Surface ◽

Testing Machine ◽

Natural Rubber Latex ◽

Gelling Agent ◽

Acid Mixture ◽

Rubber Latex ◽

Composite Foam ◽

Physical Strength ◽

Universal Testing

In this study, empty fruit bunch (EFB) was pretreated and bleached with 2.5 M NaOH at 80°C for 8 h and ClNaO for 12 h, respectively. Then it was hydrolyzed in the acid mixture of 5%wt. C2H2O4 and 48%wt. H2SO4 for 24 h. The obtained bio-fibrils and titanium dioxide (TiO2) were filled into the natural rubber latex (NRL) with the help of vulcanizing agent, antioxidant, accelerators, curing agent and gelling agent to get the resulted natural rubber (NR) foams. The morphology properties and physical properties of all foam samples were checked by using scanning electron microscope and universal testing machine, respectively. The properties of EFB fibers and bio-fibrils were also compared. The density of prepared foams was found out. Resulted showed that the bio-fibrils have the smooth surface with smaller size than BFB fibers. Addition of these bio-fibrils and TiO2 particles into NRL latex contributed the significant improvement of density and physical strength of the resulted foams. The composite foam containing 1.0 phr of bio-fibrils and 2.5 phr of TiO2 had the highest value of density and tensile stress.

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