a) A neat polymer and its fibre reinforced composite undergo isothermal crystallisation separately under three different...

Transcribed Image Text:

a) A neat polymer and its fibre reinforced composite undergo isothermal crystallisation separately under three different temperatures 260 °C, 280 °C and 300 °C. The relative volume crystallinity generated during the isothermal crystallisation is plotted against time as shown in Figure 2a. Compare and explain the isothermal crystallisation behaviours of i) the neat polymers at three different temperatures and ii) the same polymers reinforced with fibre at each temperature. Neat unreinforced polymer Relative crystallinity vs. time b) Relative volume crystallinity 0.8 0.6 0.4 0.2 Relative volume crystallinity 0.8 0.6 0.4 22 5 10 260°C <-280°C 300 C 15 20 25 Time (min) Composite (Polymer + Carbon Fibre) Relative crystallinity vs. time 0 5 10 15 20 20 Time (min) 260°C <-280°C 300°C 25 25 Figure 2a A grade of polypropylene is found to have the following tensile creep compliance, D(t), when measured at 35 °C: D(t) = 1.2t01 GPa, where t is expressed in seconds. It exhibits time-temperature superposition and obeys the Arrhenius equation with an activation enthalpy of AH = 170 kJ.mol-1. Calculate the tensile creep compliance of this grade of polypropylene at 40 °C. a) A neat polymer and its fibre reinforced composite undergo isothermal crystallisation separately under three different temperatures 260 °C, 280 °C and 300 °C. The relative volume crystallinity generated during the isothermal crystallisation is plotted against time as shown in Figure 2a. Compare and explain the isothermal crystallisation behaviours of i) the neat polymers at three different temperatures and ii) the same polymers reinforced with fibre at each temperature. Neat unreinforced polymer Relative crystallinity vs. time b) Relative volume crystallinity 0.8 0.6 0.4 0.2 Relative volume crystallinity 0.8 0.6 0.4 22 5 10 260°C <-280°C 300 C 15 20 25 Time (min) Composite (Polymer + Carbon Fibre) Relative crystallinity vs. time 0 5 10 15 20 20 Time (min) 260°C <-280°C 300°C 25 25 Figure 2a A grade of polypropylene is found to have the following tensile creep compliance, D(t), when measured at 35 °C: D(t) = 1.2t01 GPa, where t is expressed in seconds. It exhibits time-temperature superposition and obeys the Arrhenius equation with an activation enthalpy of AH = 170 kJ.mol-1. Calculate the tensile creep compliance of this grade of polypropylene at 40 °C.