Structure property relationships in polyolefins

Changes in the amount of the rigid, semi-rigid, and soft fractions, chain dynamics, and domain thickness of isotactic polypropylene (iPP) were investigated as a function of temperature, storage temperature, storage time, draw ratio, drawing temperature, drawing rate, ethylene propylene rubber content and addition of nucleating agents. Those changes are studied with high sensitivity using low and high field solid state nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), infrared spectroscopy (IR) and X-ray diffraction (XRD). The results obtained by NMR are in good agreement with those measured by the above techniques. The small difference between the results can be quantitatively explained by the presence of interface which is not taken into account in DSC, IR, TEM and XRD data analysis. The structural changes due to storage time and temperature are considered to be associated with a molecular rearrangement generally similar to secondary crystallization accompanied by a decrease in segmental chain mobility of the amorphous chains involved in the diffusion process. A decrease in the chain mobility has been observed in all fractions with increasing the drawing rate, draw ratio, and drawing temperature. The increase in the thickness of the lamellae with increasing draw ratio and drawing temperature can be explained by partial melting and recrystallization, as well as immobilization of the amorphous phase. A decrease in the heat of fusion, yield stress, flexural modulus has been observed with increasing rubber content. The addition of nucleating agents however, caused an increase in the crystallization temperature, heat of fusion, yield stress, flexural modulus, and rigid fraction.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2007

Author dc:creator

• Hedesiu, Cristian Eugen

Contributors dc:contributor

• Blümich, Bernhard

• info:eu-repo/classification/ddc/530
• Magnetische Kernresonanz
• Kernspinrelaxation
• Polypropylen
• Polyethylene
• Durchstrahlungselektronenmikroskopie
• Physik
• Low field NMR
• Polypropylene
• Aging
• Mechanical Properties

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112481%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A49913