Rubber, thermoplastic natural

Table 6. Typical Properties of Hard Blends of Thermoplastic Natural Rubber...

Roy Choudhury N., Bhowmick A.K., and De S.K., Thermoplastic natural rubber. Natural Rubber Biology, Cultivation and Technology (Sethuraj M.R. and Mathew N.M., eds.), Elsevier, New York, 1992. Elliot D.J., Natural rubber systems. Development of Rubber Technology 3 (Whelan A. and Lee K.S., eds.). Applied Science, New York, 1982. 

Mixing of natural rubber with polyolefin is one of the methods used to prepare thermoplastic natural rubber (TPNR). TPNR behaves like vulcanized rubbers at ambient conditions, but at elevated temperatures they melt and flow like a thermoplastic material. Thus TPNR could be processed using conventional thermoplastic processing machinery without requiring vulcanization, and these materials could be reprocessed. Thus there is low level of wastage, as scrap too can be recycled. 

As natural rubber is a product of nature, its properties are determined by the biochemical pathway by which the polymer is synthesized in the plant. In the case of natural rubber the polymerization process cannot be tailored like that of synthetic rubbers. The only option to modify natural rubber is after it has been harvested from the tree. The important modified forms of natural rubber include hydrogenated natural rubber, chlorinated natural rubber, hydro-halogenated natural rubber, cyclized natural rubber, depolymerised liquid natural rubber, resin modified natural rubber, poly(methyl methacrylate) grafted natural rubber, poly(styrene) grafted natural rubber, and epoxidized natural rubber [33,34]. Thermoplastic natural rubber prepared by blending natural rubber and PP is considered as a physically modified form of natural rubber. 

Nakason, C., Panklieng, Y., and Kamesamman, A. 2004. Rheological and thermal properties of thermoplastic natural rubbers based on poly (methyl methacrylate)/epoxidized-natural-rubber blends. Journal of Applied Polymer Science 92(6) 3561-3572. 

Thermoplastic elastomer (TPE) blends have been broadly studied as a new class of materials. TPEs offer various advantages and require no state-of-the-art processing machinery, while scrap and rejects are recyclable. Blends can be homogeneous, phase separated or both. TPEs are multi-phase polymer systems consisting of hard and soft domains that can be copolymers or mechanical blends. This phase separation leads to materials having unique and viable commercial physical properties. TPEs exhibit the thermoplastic characteristics of the hard thermoplastic phase, and resilience as a result of the rubbery domains. TPEs based on natural rubber (NR) and thermoplastic blends are known as thermoplastic natural rubber (TPNR) blends. There are two types of TPNR, namely thermoplastic polyolefin (TPO) and thermoplastic vulcanizate (TPV).3... 

Figure 17.4 SEM micrograph of thermoplastic natural rubber (TPNR).

H. Anuar, S.H. Ahmad, R. Rasid, and N.S. Nik Daud, Tensile md impact properties of thermoplastic natural rubber reinforced short glass fiber and empty fruit bunch hybrid composites. Polym. Plast. Technol. Eng. 45, 1059-1063 (2006). 

Thermoplastic natural rubber - a TPE Thermoplastic nitrile butadiene rubber Thermoplastic polyolefin... 

H.N. Azlina, H. Norita, H. Anuar, S.N. Surip, N.N. Bonnia, PermeahUity properties of thermoplastic natural rubber (TPNR) nanocomposites, in ISBEIA 2012-IEEE Symposium on Business, Engineering and Industrial Apphcations, 6422983,2012, pp. 714-718. 

H.N. Azlina, H.A. Sahrim, R. Rozaidi, R. Bahri, Y. Yamamoto, S. Kawahara, Oxygen barrier properties of new thermoplastic natural rubber nanocomposites. Polymer - Plastics Technology and Engineering 50 (15) (2011) 1564—1569. 

M.H. Flaifel, S.H. Ahmad, M.H. Abdullah, B.A. Al-Asbahi, NiZn ferrite filled thermoplastic natural rubber nanocomposites effect of low temperature on their magnetic behaviour, Cryogenics, ISSN 0011-2275 52 (10) (October 2012) 523-529. http //dx.doi. org/10.1016/j.cryogenics.2012.06.009. 

L. Mullins, Advances in Thermoplastic Natural Rubber, Rubber Dev. 31(4), 92 (1978). Review of thermoplastic IPNs. 

One of the important families of blended TPEs is thermoplastic natural rubber (TPNR), based primarily on polyolefin and natural rubber (NR). TPNR blends have attracted much attention due to their ease of processability and a broad spectrum of properties available at a competitive price. The TPNR system consists of multi-phases of hard and soft domains from blending thermoplastics with NR. Generally, TPNR is prepared with various type of polyolefin, such as PP, LDPE, LLDPE and HDPE. TPNR is usually prepared by a melt mixing process using an internal mixer or twin-screw extruder. It presents a wide range of useful properties, excellent processing abilities, and can be produced at moderate cost. 

Development of TPEs with various types of elastomers and polyolefins has been extensively reported by many researchers. Ethylene-propylene-diene monomer (EPDM) or its modified form is used as the elastomer in most polyolefin TPEs. Natural rubber (NR) and thermoplastic blends have become an area of interest only recently. These materials are known as thermoplastic natural rubber (TPNR). The development of TPNR was principally based on the criteria set by EPDM blends with thermoplastics. Two types are known, one belonging to the TPO class and the other belonging to the TPV class. 

Acrylate polymers are often used in many applications that require good optical properties. However, they are unsuitable for use in the automotive industry because of their brittle characteristics. Thus, when natural rubber is blended with poly(methyl methacrylate), there is a big improvement in the elasticity of the brittle acrylate polymers. It is of interest that thermoplastic natural rubbers are relatively new products in the rubber industry and are fastgrowing items in the polymer market. The acrylate polymers blended with natural rubber can improve various properties of both the natural rubber and the acrylate polymers such as elasticity, adhesion, processability properties, and transparency. These materials are known for their excellent processability, characteristic of acrylate polymers, and their elasticity property provided by natural rubber, thus they exhibit the typical properties of elastomeric materials and can be processed with thermoplastic processing equipment used to prepare acrylate polymers. Many of their interesting properties have been widely developed for several industrial applications such as in the automotive industry, household appliances, medical devices, electrical cables, and headphone cables. ... 

Kong I, Hj Ahmad S, Hj AbduUah M, Hui D, Nazhm Yusoff A, Puryanti D. Magnetic and microwave absorbing properties of magnetite-thermoplastic natural rubber nanocomposites. J Magn Magn Mater... 

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