Structure-property relationships of an electron beam cured model urethane prepolymer

Journal Article · Thu Oct 01 00:00:00 EDT 1981 · J. Appl. Polym. Sci.; (United States)

DOI:https://doi.org/10.1002/app.1981.070261016· OSTI ID:6260827

Joseph, E ^[1]; Wilkes, G; Park, K

---

1. Virginia Polytechnic Inst. and State Univ., Blacksburg

A semicrystalline urethane prepolymer derived from polycaprolactone was crosslinked below and above the melt to different levels using electron beam radiation. Studies at room temperature on the systems crosslinked under ambient conditions, which is below the melting temperature, show that changes in mechanical properties which occur as the electron beam dose is increased are due principally to the increase in crosslink density and to the changes in the crosslinking mechanism. Specifically, crosslinking takes place mainly at the acrylate double bonds or may also occur along the polymer backbone. All systems, however, are semicrystalline and possess a spherulitic texture. Mechanical and rheo-optical testing above the melt on these same systems indicate that at extensions up to 125% classical rubber elasticity theory and photoelasticity theory is obeyed. Isothermal crystallization kinetics measurements show that the rate of crystallization decreases as the electron beam dose is raised. When the systems are crosslinked above the melt again a spherulitic texture results. Mechanical testing above the melting temperature on the prepolymer crosslinked up to 4 Mrad shows that at elongations up to 125% classical rubber elasticity theory is obeyed. At room temperature these latter crosslinked systems exhibited a lower modulus compared to the materials crosslinked below the melt. Polarizing optical microscopy carried out above the melting temperature strongly suggested that no order was present in these systems during crosslinking in contrast to those crosslinked below the melting temperature.

• OSTI ID: 6260827
• Journal Information: J. Appl. Polym. Sci.; (United States), Vol. 26:10
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
36 MATERIALS SCIENCE
URETHANE
CHEMICAL RADIATION EFFECTS
CALORIMETRY
CROSS-LINKING
CRYSTALLIZATION
ELECTRON BEAMS
EXPERIMENTAL DATA
MEDIUM TEMPERATURE
MOLECULAR WEIGHT
OPTICAL MICROSCOPY
SCANNING ELECTRON MICROSCOPY
STRESSES
YOUNG MODULUS
BEAMS
CARBAMATES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACID SALTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
ELECTRON MICROSCOPY
INFORMATION
LEPTON BEAMS
MECHANICAL PROPERTIES
MICROSCOPY
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLE BEAMS
PHASE TRANSFORMATIONS
POLYMERIZATION
RADIATION CHEMISTRY
RADIATION EFFECTS
400600* - Radiation Chemistry
360406 - Materials- Polymers & Plastics- Radiation Effects- (-1987)