Polyester cord fabric surface treatment process and modelling

Polyester (PE) fibers are one of the mostly used reinforcing materials for rubber goods which exhibit good strength, fatigue resistance, excellent toughness, dimensional stability and low heat generation while sharing the structural load of the vehicle inside of the tire. The reason of polyester preference is the thermal stability, strength and the cost-effectiveness. Fibers are being exposed to the high temperatures during tire production processes and tire running conditions. These cord materials are subjected to heat treatment process at higher temperatures near their melting points and subjected to specified load to reduce residual shrinkage during the vulcanization and operating conditions. The soft surface and low functionality of the synthetic yarns, decrease the chemical bonding between rubber and cord fabric like. For this purpose, cord fabric surface is being coated with special chemical components. In this thesis, presilanizes and nano silica effect on polyester-rubber bonding was studied. The adhesion strength between polyester cord and rubber tested with various adhesion test methods. Previously, heat treatment process had been studied for temperature and load exposures of two zones treatment. Breaking strength (BS), elongation at specified load 6.8 kg (EASL @ 6.8 kg), shrinkage, stiffness, strip adhesion, and fatigue properties were derived according to twist level, heating zone temperature and load and stretch zone temperature and load. In that study, the influence of process variables on the treated cord properties were described. However, the model of the relation of variables and the properties were not driven. The changes in thermo mechanical properties due to heat setting have been correlated to structural and morphological changes like crystallinity, crystal size, orientation, crystal perfection by J. P. Rath and T. K. Chaki, D. Khastgir. The relation between the shrinkage and heat treatment process conditions were explained as well as the relation between the stress-strain curve and heat treatment process conditions. H pull adhesion property of the nylon 6 (NY6), nylon 66 (NY66) and PE cords were studied by M. Jamshidi, F. Afshar, N. Mohammadi and S. Pourmahdian in Iran. The relation of adhesion strength with the temperature increase was explained. The mathematical model of NY66 was studied to correlate the processing conditions and the with resultant cord properties by R. D. Agee and W. T. Pigott in Monsanto Textiles, Alabama. The model that is obtained in that study, would predict values of cord properties independently given processing conditions as inputs. The objective of this study is to understand how cord treating conditions impact final PE cord properties and adhesion between rubber/PE cord interfaces. Heat treatment process was realized with three oven zones. 2. and 3. zone temperature and exposure time correlation with the mechanical and adhesion properties were driven with a mathematical model. The nature of the model is not exact for all industrial treating configurations but it provides the user a relative estimate of how polyester may respond to changes in treating conditions and thus reduces waste by allowing the user to select only the most critical experiments for industrial trials.