Tensile properties crystallinity, effects

DTA was used [31] to determine the melting temperature (r ), the heat of fusion AHm) and the degree of crystallinity (%C). PLLA with draw ratios of 3 1 to 8 1 exhibits good tensile properties. Crystallinity affects the mechanical properties and DSC was used [31] to consider the effect of the draw ratio on the crystallinity and, ultimately, the tensile strength of the fibres. 

Although structurally Kevlar fibres are highly crystalline or ordered it is interesting to note that appreciable moisture is absorbed at equilibrium. For example in variant T950 the moisture uptake is about 5 % at 22 °C and 55 % relative humidity. As discussed in Sect. 4.1.4.1 it is likely that the water is retained in microvoids distributed close to the surface of the fibres. Certainly in the short term there appears to be little effect of moisture on the tensile properties. 

We have studied the effect of heating on the color, on the dry and wet tensile properties, on the abrasion characteristics, and on the dyeing and resultant color properties of the linen. We also examined the effect of heat treatment on the crystallinity of flax by wide angle X-ray scattering (WAXS) and on the surface morphology of flax fibers by scanning electron microscopy (SEM). 

Duvdevani(40) have been directed at modification of ionomer properties by employing polar additives to specifically interact or plasticize the ionic interactions. This plasticization process is necessary to achieve the processability of thermoplastic elastomers based on S-EPDM. Crystalline polar plasticizers such as zinc stearate can markedly affect ionic associations in S-EPDM. For example, low levels of metal stearate can enhance the melt flow of S-EPDM at elevated temperatures and yet improve the tensile properties of this ionomer at ambient temperatures. Above its crystalline melting point, ca. 120°C, zinc stearate is effective at solvating the ionic groups, thus lowering the melt viscosity of the ionomer. At ambient temperatures the crystalline additive acts as a reinforcing filler. 

The miscibility of olefin copolymers such as ethylene-a-olefin copolymers was found to be controlled by the structural composition and the primary strucmre of the copolymers. Using these copolymers, binary blends with various compatibilities were prepared and the effects of compatibihty on mechanical properties in the binary blends were investigated. The tensile properties in binary blends of iPP with rubbery olefin copolymers are considerably influenced by the miscibility between iPP and the copolymers. The miscibility of iPP with other polyolefins is described in detail based on the dynamic mechanical properties, morphology observation, and solidification process. It is found that EBR, EHR, and EOR having more than 50 mol% of a-olefin are miscible with iPP in the molten state. In the solid state, the miscible copolymers are dissolved in the amorphous region of iPP, although the copolymers are excluded from crystalhne lattice of iPP. The isotactic propylene sequence in the EP copolymers with a propylene-unit content of more than 84 mol% participates in the crystallization process of iPP, resulting that a part of the EP copolymers is included in the crystalline lattice of iPP. 

It Is of Interest to point out the Figure 2 spin line capillary diameter effect on the FOY yarn structure, where the 7 mil (0.018 cm) diameter capillary yielded no amorphous orientation change, but a significant crystallinity reduction relative to the 15 mil (0.38 cm) capillary. From the above discussion, the generally equal FOY tensile properties for yarns spun from the two capillaries are predicted from the equal amorphous orientation values at equivalent spinning speeds (Table I). The greatly reduced PTY broken filament count for the yarn textured from the higher crystallinity FOY spun from the 15 mil capillary I also consistent with the above discussion. 

The effects of fillers on tensile properties have been investigated by Godard and Bomal [34], Canova [35]. Skelhorn [36], and Meddad et. al. [37] amongst others. Where crosshead movement is used to estimate extension, the correction for the finite compliance of the test machine has been reported by Turek [38]. The effect of crystalline and amorphous phases in a semicrystalline polymer has been reported by Carraher [39]. Some of the... 

Abbate M, MartusceUi E, Ragosta G, Scarinzi G (1991) Tensile properties and impact behaviour of poly(D(-)3-hydroxybutyrate)/rubber blends. J Mater Sd 26 1119-1125 Abe H, Doi Y (2002) Side-chain effect of second monomer units on crystalline morphology, thermal properties, and enzymatic degradability for random copolyesters of (R)-3-hydroxybutyric add with (R)-3-hydroxyalkanoic acids. Biomacromolecules 3 133-138 Abe C, Taima Y, Nakamura Y, Doi Y (1990) New bacterial copolyester of 3-hydroxyalkanoates and 3-hydroxy-co-fluoroalkanoates produced by Pseudomonas oleovorans. Polym Commun 31 404 06... 

Keywords crystal structure, process variables, molecular weight, molecular weight distribution (MWD), polydispersity, copoljoners, nucleating agents, melt spinning, spinline, effects of molecular variables, effects of processing variables, tensile properties of filaments, birefringence, take-up velocity, conformationally disordered structure, amorphous orientation, crystalline orientation. 

Tensile properties are, by far, the most widely studied mechanical properties of eco-friendly polymer nanocomposites. Overall, the mechanical performance of CNC-reinforced composites depends on the aspect ratio, crystallinity, processing method, and CNC/matrix interfacial interaction. The mechanical properties are proportional to aspect ratio and crystaUinify of nanoreinforcement and it has been shown that increase in aspect ratio and crystaUinify results in increase in mechanical properties. Slow processing methods which encourage water evaporation result in composites with improved properties. This is because nanoparticles have suflticient time to interact and connect to form a continuous network, which is the basis of their reinforcing effect. Nanoreinforcement which is compatible with the biopolymer matrix also exhibits improved mechanical properties of the nanocomposites. 

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