Molecular Weight Dependence of Overall Crystallization

Molecular weight dependence of overall crystallization rate (k) seems to be very complicated as seen in Fig. 19.2 for PE. The Avrami constant of k is a function of nucleation rate of (1) and crystal growth rate of (G) as expressed by following equation, 

Molecular weight (p/mol) dependence of common logarithm of the overall crystallization rate constant (1/sec) as a function of the contribution factor c ranging from zero to one. Curves are calculated on the bases of PESU data [76  

Step-scan Alternating Differential Scanning Calorimetry Studies on the Crystallisation Behaviour of Low Molecular Weight Polyethylene 

Department of Chemistry and Technology of Pol3rmers, Cracow University of Technology, ul. Warszawska 24, 31-155 Krakow, Poland kpielichQusk.pk.edu.pi 

Crystallisation behaviour of polyethylene (PE) has been intensively studied from both fundamental and application reasons [1-3]. One of the most commonly used techniques is differential scanning calorimetry (DSC). New information on PE crystallisation can be gained if modulated temperature DSC (MT-DSC), which uses a periodical temperature modulation over a traditional linear heating or cooling ramp, is applied. It makes it possible to separate reversing and non-reversing components of the total heat flow because of this characteristics of the MT-DSC technique, it can be regarded as a useful tool to study polymer crystallisation behaviour. 

---