Crystalline structure in aliphatic polyketones

• Published in: Polymer (Guilford) Vol. 41; no. 8; pp. 3011 - 3017
• Main Authors: Lagaron, J.M, Vickers, M.E, Powell, A.K, Davidson, N.S
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2000; Elsevier
• Subjects: Aliphatic polyketones; Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Raman spectroscopy; Structure, morphology and analysis; Wide angle X-ray scattering; Wide angle X-ray scattering; Raman spectroscopy; Aliphatic polyketones; Beta form; Crystal form; Aliphatic polymer; Ketone polymer; Experimental study; Polymorphic transformation; Structure composition relationship; Aliphatic copolymer; Ketone copolymer; Alpha form
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(99)00458-9

The crystalline structure of a number of perfectly 1:1 alternating α-olefin:carbon monoxide aliphatic polyketones produced by the polymerisation of ethene with carbon monoxide (ECO polymers) and mixtures of ethene and propene with carbon monoxide (EPCO polymers) have been studied by wide angle X-ray scattering (WAXS), Raman spectroscopy and differential scanning calorimetry (DSC). It is further confirmed that both WAXS and Raman spectroscopy are suitable techniques for the characterisation of the two polymorphs (α and β) reported for these materials. DSC detected the presence of small endotherms around 100°C associated with the transition from the α to the β phase only in the ECO material. In accordance with previous work, it is found that the α/β ratio is the highest for the ECO polymer and decreases with increasing propene content in EPCO polymers. Above 2.9 mol% of propene incorporation, EPCO polymers show exclusively β phase. Heat of fusion (degree of crystallinity) and melting point decreased with increasing propene level, as expected. Accordingly, crystalline density (as determined by WAXS) and lattice interchain interaction (as determined by Raman) were also found to decrease by increasing the propene incorporation.