Nylon shear modulus

Fig. 2. Effect of temperature on the shear modulus of dry nylon-6,6 (—) and nylon-6,6 plus 30% glass fiber (-). To covert MPa to psi, multiply by 145.

Fig. 6. Variation of Young s modulus (-) and shear modulus (—), with cord angle 9 for one-ply nylon—mbber system (88).

Figure 5.71 Dependence of shear modulus on temperature for three common engineering polymers crosslinked natural rubber, amorphous polyvinyl chloride (PVC), and crystalline Nylon 6. The typical use temperatures are indicated by dotted lines. Reprinted, by permission, from N. G. McCrum, C. P. Buckley, and C. B. Bucknall, Principles of Polymer Engineering, 2nd ed., p. 154. Copyright 1997 by Oxford University Press.

Dependence of the shear modulus on temperature for three representative engineering polymers natural rubber (cross-linked) PVC (essentially amorphous and not cross-linkied) and nylon 6 (crystalline). The temperatures at which these polymefS are used in technology are indicated ( - - - - ) (after WolO. 

Figure 6.19 Shear modulus vs. temperature for several BASF Ultramid Nylon 6 resins.

Figure 6.67 Shear modulus vs. temperature for DSM Engineering Plastics Stanyl TE250 Series—fiber glass filled, heat stabilized, fire retardant Nylon 46 resins [5].

At 250°C with saturated steam, the strength retention in PBO is less than 20% of its room temperature value. Therefore, PBO fibers should be stored in humid-free environment. PBO tensile strength also drops sharply with UV exposure. Exposure to visible light also affects PBO strength [85]. PBO fiber has excellent chemical resistance to various organic solvents, acids, and bases [49]. Abrasion resistance of PBO on metal is higher than aramid fiber, while both the PBO and aramid show much lower abrasion resistance than nylon or UHMW-PE [49]. Shear modulus of PBO fibers at room temperature is 1 GPA and for commodity textile fibers are generally... 

The effect of absorbed moisture on shear modulus and damping in nylon 6,12 is seen in Figure 33." With increasing water content the a relaxation shifts to lower temperatures, whereas the effect on the y relaxation is rather small. In dry nylon 6,12, the P relaxation is almost absent, but it increases markedly in magnitude with an increase in water content, supporting the assignment of this transition to CO groups with appended H2O. 

Several authors have given a basic theory for the prediction of the modulus of a composite (16-18). The line In Fig, 4 shows the theoretical curve for the reduction of the modulus (E/Eo) due to Incorporation of a soft rubber phase In a hard matrix at a temperature above the transition region of the soft phase and below the transition region of the hard phase (E > flexural modulus of the modified nylon and E0 flexural modulus of the unmodified nylon). The experimental points of systems 1 and 2 fit fairly well onto the theoretical curve. This proves that they are well-dispersed systems without Inclusions. The difference In Impact strength between system 1 and system 2 Is mainly due to the better lnterfaclal adhesion of system 2, by which crazes are stabilized and/or the formation of small shear bands Is Initiated. 

For most packaging applications, compression cutting or shear cutting are used. LDPE is most often compression cut because its low modulus leads to necking in a shear die, and therefore a ragged edge is formed. For HDPE, PP, PMMA, PS, nylons, and PET, shear cutting can be used very effectively. However, the same die will not work equally well for each material because of the differences in modulus. 

An injection-moulded bar contains 20% (by volume) of short carbon fibres (high strength form) in a matrix of nylon 6.6. A tensile strain of 10 is applied along the axis of the bar. Determine the mean tensile stress carried by the fibres and the overall stress carried by the bar. Assume that the fibres are all of length 400 pim and diameter 6 fim, and are perfect aligned along the axis of the bar and perfectly bonded to the matrix. Take the axial tensile modulus of the carbon fibres to be 230 GPa, and the tensile and shear moduli of nylon 6.6 to be 2.7 GPa and 1.015 GPa, respectively. 

Kooijman et al. calculated the modulus for shear between adjacent chains in the hydrogen bonded plane of PpPTA and found sJs = 4.1 G Nm [177]. This value agrees well with the calculated modulus for the shear between adjacent chains in the hydrogen bonded plane of nylon 6 [180]. The monoclinic (pseudo-orthorhombic) PpPTA crystal has two moduli for the shear between adjacent... 

---