Search Results

You are looking at 1 - 10 of 37 items for :

  • "polycaprolactone" x
  • Refine by Access: All Content x
Clear All

Abstract  

Cellulose acetate-based polycaprolactones (CAPCL's) were synthesized by the polymerization of -caprolactone which was initiated by non-substituted OH group in cellulose acetate. The CL/OH (mol mol–1) ratios of the CAPCL's were changed from 2 to 20. Thermal and viscoelastic properties of the CAPCL sheets were studied by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Glass transition, cold crystallization and melting were determined by DSC. Dynamic modules (E'), dynamic loss modules (E'') and tan were measured in a temperature range from –150 to 50°C by DMA. Apparent activation energy of a dispersion was calculated from the frequency dependency of E'' peak temperature. It was found that the main chain motion of both CA and PCL is observed in a CL/OH ratio from 0 to 10 mol mol–1. However, when CL/OH ratio exceeds 10 mol mol–1, the crystalline region which is rearranged by the PCL chain association is observed and only the main chain motion of PCL can be detected.

Restricted access

Abstract  

Pyrolytic process has a promising potential for the environmentally friendly upgrading of lignocellulosic and plastic waste. Thermogravimetry and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) were used to get information about the reactive decomposition of PCL in binary mixtures with microcrystalline cellulose (MC) or sisal fibres (SF). Preliminary thermogravimetric investigation showed that biomass is thermally degraded at lower temperatures than PCL and this process has a predominant influence on the thermal behaviour of the mixtures. Discrepancies between the experimental and predicted TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis. It was found that reactivity of PCL was slightly increased in PCL-SF binary mixtures. Evolution of acidic products from cellulose and hemicelluloses decomposition may promote PCL degradation in binary mixtures with SF. It seems that the co-pyrolysis process could have potential for the environmentally friendly transformation of biocomposites.

Restricted access

Polycaprolactone (PCL) is a new material used in orthopedics. It is characterized by an endothermic melting peak at about 61‡C, an endothermic decomposition peak at about 380‡C and an exothermic peak at about 453‡C. These three observed phenomena and the corresponding thermodynamic data made it easily possible to identify PCL among the other polymers previously examined with Differential Thermal Analysis (DTA).

Restricted access

about polymer blends containing one crystallizable component and a thermosetting component [ 9 ]. In previous articles, the miscibility of the systems formed by linear UP resin and poly(∊-caprolactone) (PCL) [ 10 – 13 ] were studied. For the

Restricted access

Abstract  

Thermal degradation behaviour of alcoholysis lignin-based polycaprolactones (ALPCL's) with various molar ratios of β-caprolactone monomer to each hydroxyl group of lignin (CL/OH ratios) was studied by TG-FTIR. The temperature was varied from 20 to 800C. Thermal degradation temperatures (Td's) of alcoholysis lignin (AL) and ALPCL's were determined using TG curves. Td increased with increasing CL/OH ratio, suggesting that AL becomes thermally stable after the derivatization with PCL chains. Mass residue (MR) at 500C was also determined using TG curves. MR values decreased with increasing CL/OH ratios. The evolved gases formed by thermal degradation of ALPCL's at various temperatures were simultaneously analyzed by FTIR. The main peaks observed for the samples are as follows: wavenumber (assignment): 1160 cm-1 (vC-O-), 1260 cm-1(-C(=O)-O-C-), 1517 and 1617 cm-1 (vC=C), 1770 cm-1 (vC=O), 2345 cm-1 (vCO2), 2945 cm-1 (vC-H) and 3700 cm-1 (vOH). It was found that the peak intensities for C=O, CH, C-O-C, OH peaks, which were observed for evolved gases at 430C, increased with increasing CL/OH ratios, suggesting that the evolved gases at 430C are mainly formed by thermal degradation of PCL chains in ALPCL's.

Restricted access

Introduction Polycaprolactone (PCL) is a semi-crystalline aliphatic polyester. Both biocompatible and biodegradable PCL is used in a wide range of applications including tissue engineering scaffolding, bioabsorbable sutures and

Restricted access

Abstract  

The isothermal crystallization behavior of layered silicate/starch-polycaprolactone blend nanocomposites was studied by means of differential scanning calorimetry (DSC) measurements. The theoretical melting point was higher for the matrix than for nanocomposites. At low clay concentration, the induction time decreased and the overall crystallization rate increased acting as nucleating agent whereas at higher concentrations became retardants. Classical Avrami equation was used to analyze the crystallization kinetic of these materials. n values suggested that clay not only affected the crystallization rate but also influenced the mechanism of crystals growth. An Arrhenius type equation was used for the rate constant (k). Models correctly reproduced the experimental data.

Restricted access

Abstract  

The soft segment crystallinity and morphology of poly(ester-urethanes) (PEUs) based on poly(&-caprolactone) (PCL) as a soft segment and an aliphatic diisocyanate in the hard segment were studied. It was found that the restriction of the crystallization of the PCL soft segment depends on the hard segment concentration, the length of the soft segment, and the total molecular mass of the PEUs. The PEU based on a low molecular mass PCL (M=2000) is an amorphous elastic material during a long time after casting from solution or after melt crystallization. A soft-hard segment endothermal mixing transition (Tmix) of about 70-80C is observed in the DSC curves of this PEU sample.

Restricted access

extensively used in biomedical applications. In this direction, poly(caprolactone) (PCL) is one of the most promising polymers, and it can be used in many medical applications, such as drug delivery, scaffolds, and guided bone regeneration [ 14 ]. PCL has been

Restricted access

Abstract  

Non-isothermal crystallization of MaterBi-Z (starch-polycaprolactone blend) and its nanocomposites with different clay contents (0, 2.5 and 5 mass%) was studied. The experimental data show that clay can be act both as nucleating or retarding agent depend on the clay content. Kinetic parameters obtained by using a non-linear regression method, i.e., Kamal’s model and Dietz’s modification, were able to describe the non-isothermal crystallization behavior of the studied materials. A full model that takes into account the induction and growth of the crystal during cooling under non-isothermal conditions was used to obtain a continuous cooling transformation diagrams.

Restricted access