Accelerated physical ageing of poly(1,4-cyclohexylenedimethylene-co-2,2,4,4-tetramethyl-1,3-cyclobutanediol terephthalate)

Abstract

Successfully evaluating plastic lifetime requires understanding of the relationships between polymer dynamics and mechanical performance as a function of thermal ageing. The relatively high T g (T g ¼ 110 C) of poly(1,4-cyclohexylenedimethylene-co-2,2,4,4-tetramethyl-1,3-cyclobutanediol terephthalate) (PCTT) renders it useful as a substituent for PET in higher temperature applications. This work links thermal ageing and mechanical performance of a commercial PCTT plastic after exposure to 40-80 C for up to 2950 h. No chemical or conformational changes were found while pronounced physical ageing, measured as enthalpic relaxation, caused yield hardening (28% increase in yield strength) and embrittlement (80% decrease in toughness). Enthalpic relaxation increased with temperature and time to 3.8 J g À1 and correlated to the determined toughness and yield strength. Finally, a 9% increase in Young's modulus was observed independent of temperature and with no correlation to enthalpic relaxation. Enthalpic relaxation followed Vogel-Fulcher-Tammann behaviour, while yield strength and charpy v-notch toughness followed Arrhenius behaviour enabling prediction of the different properties with time and temperature. View Article Onlinewhere M C and M T are the molecular weights of the CHDM and TMCD repeating units (both 274 g mol À1 ), respectively. TMCD/CHDM ratio (f T/C ) was calculated from the carbonyl 13 C-NMR CHDM (1, 167.8 ppm) and TMCD (7, 168.4 ppm) peaks as given in eqn (4):This journal is

Terephthalic Acid Copolyesters Containing Tetramethylcyclobutanediol for High‐Performance Plastics

“…However, Young′s modulus increased from 1.47 to 1.59 GPa on aging for 42 days irrespective of temperature (40–80 °C), and tensile strength at yield increased from 46 to 47 MPa, 48 to 52 MPa, and 51 to 58 MPa on aging for 42 days at 40, 60 and 80 °C, respectively. [42] The yellowness index after 2500 h of UV exposure (340 nm) was markedly lower for TPA‐TMCD/BDO copolyester (+29 %) than commercial polycarbonate (+2800 %) in the absence of any UV stabilizer. The notched Izod impact strength of the copolyester decreased from 390 to 110 J/m (−72 %) while that of polycarbonate decreased from 990 to 70 J/m (−93 %) after UV ag.…”

“…13 C NMR can be employed for calculating cis/trans ratio (81.9/ 82.9 ppm for TMCD and 34.3/36.9 ppm for CHDM) and dyad sequences (133.7 from TPA). [42]…”

Predicting nonlinear physical aging of glasses from equilibrium relaxation via the material time

“…Understanding this type of aging is crucial for applications of noncrystalline materials such as oxide glasses (4,(6)(7)(8), polymers (2,5,(9)(10)(11)(12)(13), metallic glasses (14)(15)(16)(17)(18), amorphous pharmaceuticals (19), colloidal suspensions (20), etc. For instance, the performance of a smartphone display glass substrate is controlled by details of the physical aging during production (21), and some plastics eventually become brittle as a result of physical aging (22). Noncrystalline or partly noncrystalline states play a role in modern materials science, e.g., in connection with metal-organic frameworks (23) and high-entropy alloys (24), and physical aging is also important in connection with active matter (25)(26)(27).…”

Surface Mechanical Properties and Topological Characteristics of Thermoplastic Copolyesters after Precisely Controlled Abrasion

“…To put this in perspective, the tensile modulus of PCTT at ambient temperature has been measured , to be 1.50 GPa on average. Corresponding results obtained under identical testing conditions with the conospherical indenter tip are included in Figure .…”