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Samui B.K.,Harishankar Singhania Elastomer and Tire Research Institute | Dasgupta S.,Harishankar Singhania Elastomer and Tire Research Institute | Mukhopadhyay R.,Harishankar Singhania Elastomer and Tire Research Institute | Ramesh C.,CSIR - National Chemical Laboratory | Chakrabarty D.,University of Calcutta
Journal of the Textile Institute | Year: 2015

Four major types of polyester industrial yarns, viz. high tenacity (HT), high modulus low shrinkage (HMLS), low shrinkage (LS) and super low shrinkage (SLS) polyester yarns, were studied for their static and dynamic properties. An attempt has been made to establish a linkage between static and dynamic properties of these yarns with its structure and with its end applications. HMLS and HT polyester yarns have lower tan δ and work loss, which are the desired characteristics required for its end applications which include tire and conveyer belt. Higher overall orientation and higher fraction of tie molecules helped to achieve these properties in HT and HMLS polyester yarns. LS and SLS polyester yarns are mostly used for static applications. Low thermal shrinkage is the key requirement for the downstream processes of these yarns. Lower amorphous orientation in these two yarns is primarily responsible for achieving very low thermal shrinkage. A good co-relation has been established between the peak temperature of work loss (in slow speed hysteresis test) and the peak temperature of tan δ (in high-speed dynamic test). © 2015 The Textile Institute Source


Samui B.K.,SRF Limited | Prakasan M.P.,SRF Limited | Chakrabarty D.,Sudan University of Science and Technology | Mukhopadhyay R.,Harishankar Singhania Elastomer and Tire Research Institute
Rubber Chemistry and Technology | Year: 2011

Hysteresis characteristics of high modulus low shrinkage (HMLS) polyester tire yarn and cord were evaluated to determine "specific work loss," which indicate its heat generation characteristics. Test parameters were selectively chosen, considering the service conditions of high-speed passenger radial tires in which HMLS polyester tire cords are predominantly used. Specific work loss was found to increase exponentially with the increase in extent of stress relief. Dynamic property of this yarn and cord was also studied to determine "loss tangent (tan δ)," which influences rolling resistance of tires in service. A good correlation has been found between specific work loss of hysteresis test (a slow speed test) and tan δ of dynamic test (a high-speed test). Dynamic property of polyester dipped cord was investigated for a wide range of temperatures (100-180 °C) and frequencies (5-25 Hz). Tan δ at 100 °C was found to be relatively low and its magnitude remained at the same level for a wide range of frequencies. This is a favorable condition for the high-speed passenger radial tires, made out of HMLS polyester tire yarn. Microstructure of HMLS polyester yarn was analyzed. Crystallinity is around 43% (measured by Wide angle x-ray scattering); crystal width and long period are 61 and 142 A•, respectively. Source


Samui B.K.,SRF Limited | Prakasan M.P.,SRF Limited | Ramesh C.,CSIR - National Chemical Laboratory | Chakrabarty D.,University of Calcutta | Mukhopadhyay R.,Harishankar Singhania Elastomer and Tire Research Institute
Journal of the Textile Institute | Year: 2013

Four major types of polyester industrial yarns (1000 Denier) which are used commercially were studied for their key structural parameters. An attempt has been made to establish a relationship between morphology and properties of these yarns. High tenacity (HT) polyester yarn has the highest birefringence, amorphous orientation, and long period but is relatively less crystalline. High shrinkage characteristic of HT polyester yarn can be accounted for its higher amorphous orientation. High modulus low shrinkage (HMLS) polyester yarn has higher crystallinity and crystal size compared to HT yarn. Fraction of tie molecules of these yarns has been calculated and found that low shrinkage (LS) and super low shrinkage (SLS) yarns have lesser tie molecules. These LS and SLS yarns are tailor-made to achieve lower shrinkage and at the same time maintaining a good level of tenacity. This is achieved with lower amorphous orientation in the final drawn yarn structure. Amorphous orientation was found to have stronger influence than any other structural parameter on the key yarn properties like modulus, tenacity, elongation, and shrinkage. © 2013 Copyright The Textile Institute. Source

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