PCL blends

In the matrix of PLA/ polycaprilactone (PCL)/OMMT nano-composites, the silicate layers of the organoclay were intercalated and randomly distributed (Zhenyang et at, 2007). The PLA/PCL blend significantly improved the tensile and other mechanical properties by addition of OMMT. Thermal stability of PLA/PCL blends was also explicitly improved when the OMMT content is less than 5%wt. Preparation of PLA/thermoplastic starch/MMT nano-composites have been investigated and the products have been characterized using X-Ray diffraction, transmission electron microscopy and tensile measurements. The results show improvement in the tensile and modulus, and reduction in fracture toughness (Arroyo et ah, 2010). 

Poly-e-caprolactone fibers have been used to control the release of herbicides into an aquatic environment (76,77). A PCL blend with... 

Fig. 5.31 Schematic illustration of the morphology formed by blends and copolymers of two crystallizable polymers (Nojima et al. 19926) (a) a PEG/PCL blend, (b) a PCL-PEG-PCL triblock. In the blend, PEG and PCL are phase-separated into domains in which each homopolymer crystallizes in a lamellar texture. In the copolymer, PEG and PCL blocks cyrstallize in the same domain due to chain connectivity.

Fig.10 Composition dependence of Tg and Tm, compared for two series of CB/PCL blends. Open and filled symbols represent the data for CB(DS = 1.2)/PCL blends and CB(DS = 2.4)/PCL blends, respectively. (Reproduced from [133])...

The compatibility, mechanical properties, and segmental orientation characteristics of poly-e-caprolactone (PCL) blended with poly (vinyl chloride) (PVC) and nitrocellulose (NC) are described in this study. In PVC blends, the amorphous components were compatible from 0-100% PCL concentration, while in the NC system compatibility teas achieved in the range 50-100% PCL. Above 50% PCL concentration, PCL crystallinity was present in both blend systems. Differential IR dichroism was used to follow the dynamic strain-induced orientation of the constituent chains in the blends. It was found for amorphous compatible blends that the PCL oriented in essentially the same manner as NC and the isotactic segments of PVC. Syndio-tactic PVC segments showed higher orientation functions, implying a microcrystalline PVC phase. 

Dynamic Mechanical Properties. The dynamic mechanical properties of the PVC/PCL and NC/PCL blend systems are shown in Figures... 

Figure 3. Tg data for PVC/PCL and NC/PCL blends plotted according to the Gordon-Taylor equation. The lines are fit to the quenched data (1).

Figure 3 shows that the Gordon-Taylor equation fits the quenched data for the PVC/PCL blends quite well. The thermograms for the blends of 25, 35, and 50% PVC display PCL heats of fusion, and conse-... 

The orientation functions for a 75/25 PVC/PCL blend are presented in Figure 5, which shows that the PCL chains in the 75% PVC blend orient in essentially the same way as the isotactic segments and the other folded-chain PVC segments represented by the 693 cm 1 peak. This peak is shifted from 691 cm 1 for pure PVC. The shape and magnitude of the orientation functions for the carbonyl and 693-cm"1 C-Cl peak are similar to the orientation functions shown for the amorphous 50% NC blend. 

Blends of PCL with PVC were shown to exhibit only one glass-transition temperature (Tg), which for blends quenched from the melt could be represented as a function of composition by the Gordon-Taylor Tg equation. By similar criterion, the PCL blends with NC were shown to be compatible for the composition range 0-50% NC by weight. With higher concentrations of NC, both thermal and mechanical testing indicated that multiple amorphous phases were present, even though the films were clear. 

Differential IR dichroism was used to follow the dynamic strain-induced orientation of the constituent chains in PVC/PCL and NC/PCL blends. It was found for amorphous compatible blends that PCL oriented in essentially the same manner as NC and the isotactic segments of PVC. Syndiotactic PVC segments showed much higher orientation functions, which implied the existence of a microcrystalline PVC phase. 

Addition of starch has a nucleating effect, which increases the rate of crystallisation. The rheology of starch/PCL blends depends on the extent of starch granule destruction and the formation of thermoplastic starch during extrusion. Increasing the heat and shear intensities can reduce the melt viscosity, but enhance the extrudate-swell properties of the polymer. 

Powell HM, Boyce ST (2009) Engineered human skin fabricated using electrospun collagen-PCL blends morphogenesis and mechanical properties. Tissue Eng A 15(8) 2177-2187... 

Mirau and White applied the HETCOR pulse sequence to PMA/PVPh, PMMA/PVPh and PC/polycaprolactone (PCL) blends [26, 124]. Figure 10.16(b) shows the HETCOR spectrum for PMA/PVPh = 1/1 cast from methyl ethyl ketone. The combined use of WIM-24 and MAS allows CP for H and C spins in close proximity, therefore, most of the cross-peaks appear between directly bonded C— H pairs. Interestingly, a cross-peak was observed for the nonprotonated carbonyl carbon of PMA. The spectrum shows... 

This is a phenomenon often observed in PCL blends. In DSC scans as a function of crystallization time (i) a single melting behavior is observed... 

For example, the ellipsometric technique was used to determine the interfacial thickness in SAN/PA blends, compatibilized by addition of SMA [Yukioka and Inoue, 1991, 1993]. A thin bi-layer film of SMA/SAN was prepared then mounted on a thick PA substrate. The interfacial thickness varied with the compatibilization time from A1 = 2 to 30 nm. The method was also used to study the interphasial thickness variation in PCL blends with CTBN or CTBR. Without a reactive modifier (aminopropyltriethoxysilane, APS), the measured thickness was A1 = 3 nm, upon addition increasing to 6 nm [Okamoto and Inoue, 1993]. 

In the PVC/PMMA blend, the chlorine and the mass loss of the PVC increased in the presence of PMMA. Similarly, in the PVC/PCL blend also... 

Blends of the commodity polymers with more specialty polymers are limited although many specific examples exist in the patent/open literature. In the design of polymer blends for specific application needs, countless opportunities can be envisioned. Examples may include PE/poly(s-caprolactone) (PCL) blends for biodegradable applications (proposed), polyolefin (PO)/poly(vinyl alcohol) (PVAL) blends for antistatic films, PO/silicone rubber blends for biomedical applications, PO/thermoplastic polyurethane TPU (or other thermoplastic elastomers) for applications similar to plasticized PVC, functionalized PO/thermoset blends. 

KIM 01] Kim C.H., Cho K.Y., Park J.K., Effect of poly(aciyhc acid>g-PCL microstructure on the mechanical properties of starch/PCL blend compatibUized with poly(acryhc acid)-g-VCL , Polymer Engineering Science, vol. 41, no. 3, pp. 542-553, 2001. 

Cadebo, L., Feijoo, J. L., Villanueva, M. R, Lagaron, J. M., Gimenez, E. Optimization of biodegradable nanocomposites based on aRLA/PCL blends for food packaging applications. Macromol. Symp., 2006, 233, 191-197. 

Poly(8-caprolactone) (PCL), on the other hand, is a semi-ciystaUine biodegradable polymer. This material is commonly used as plasticizer. The P(3HB)/ PCL blend exhibited partial miscibility, however, the elongation at break was increased about 81 % in comparison with pure P(3HB) [43]. 

In accordance with a concept derived from the SBS/PCL blend, Wang et al. developed a series of novel biodegradable SMP blends consisting of... 

Schematic figures of the shape memory mechanism of the styrene-butadiene-styrene (SBS) triblock copolymer/poly(e-caprolactone) (PCL) blend in (a)-(d). (Adapted from Zhang, H., Wang, H., Zhong, W, and Du, Q. 2009. A novel type of shape memory polymer blend and the shape memory mechanism. Polymer 50 1596-1601. Copyright Elsevier Ltd. Reproduced with permission.)...

---