Polyester fibres structure modification using some organic solutions
The treatment causes only minor decrease in fi bre, i.e. yarn strength, while breaking elongation increases signifi cantly, almost up to 150 % in comparison to the untreated sample. Organic solvents, i.e. plasticizer solutions in the organic solvents mixture infl uence fi bre properties in a very favorable way, i.e. they can enable better dyeing, better moisture absorption, easier treatment in further phases of textile products manufacture and generally better usability. X-ray structural analysis was used to examine the infl uence of the treatment of polyester fi bres in the form of fi lament yarn, fi neness 75/26 dtex, with solutions 0.3, 0.6 and 0.9 % hydroquinone and α-naphtole in the solvent mixture which contained chlorophorm and methanol (solubility parameter δ=11.7) on changing of crystalline degree and crystallite size. It was found that treated fi bres showed sharper refl exion on diffractograms than untreated ones, i.e. they showed higher crystalline degree but smaller crystallite size.
Chemical Surface Modification of Poly(ethylene terephthalate)
Reactions of semicrystalline poly(ethylene terephthalate) (PET) film with ester-selective reagents at the film−solution interface can be controlled to produce modified film samples containing a thin (less than ∼ 40 A) surface layer of the reagent-induced functionality. Hydrolysis of PET yields a surface mixture of alcohol and carboxylic acid groups. Reduction with lithium aluminum hydride and transesterification with ethylene glycol (glycolysis) both produce surfaces with alcohol functionality (PET−OHR and PET−OHG, respectively). Each of these modification reactions involves chain cleavage and can lead to significant sample degradation (reactive dissolution); for each modification reaction, conditions were optimized to maximize conversion and minimize degradation. The reactivity of surface alcohols (PET−OH) was assessed for samples prepared by both reduction and glycolysis, and a comparative analysis was made:  the presence of benzylic alcohols in reduced samples and their absence in glycolyzed samples as...
The measurement of the crystallinity of polymers by DSC
The procedures adopted and the inherent assumptions made in the measurement of crystallinity of polymers by differential scanning calorimetry (DSC) are reviewed. The inherent problem in all DSC measurements is concurrent recrystallisation and melting of the polymer sample on heating to the melting point and the variation of the enthalpies of crystallisation and melting, heat capacities and degree of crystallinity with temperature. A First Law procedure is suggested which involves heating the sample between two set temperatures, T1 and T2. T1 is selected by the requirement that the degree of crystallinity of the sample should not change either with temperature or time, and be representative of the sample during its use. T1 is taken to be ambient or just above the glass transition temperature. T2 is taken to be just above the observed last trace of crystallinity. Integrating the observed specific heat difference between the sample and the completely amorphous material during these two temperature ranges determined the residual enthalpy of fusion at T1. Problems are noted in the use of this procedure in that the specific heat of the liquid should not be arbitrarily chosen since this leads to systematic errors in the heat of crystallisation. 
 
The degrees of crystallinity of metallocene polyethylene (m-PE) and polyethylene terephthalate (PET) measured by this procedure have been compared with values measured by density, determined at room temperature.