Relaxation behavior, mechanical poly

Sadanobu, J. and Tsukioka, M., Mechanical relaxation behaviors for homolog poly(alkylenenaphthalate)s, in Proceedings of the 55th SPE ANTEC 97 Conference, May 5-8, 1997, Toronto, ON, Canada, Society of Plastics Engineers, Brookfield, CT, 1997, Vol. 2, pp. 1567-1571. 

The dielectric and mechanical relaxations on poly(l,3-dioxan-5yl-methacrylate) (PDMA) [104], show that this polymer present a variety of absorptions due to the versatility of its structural moiety [105]. Recently this behavior have been studied by molecular dynamic simulation using different methods and force fields [106-109], These polymers are analyzed from molecular simulation using different ways but... 

Mechanical relaxation behavior of poly(n-butyl acrylate) was studied using a freely oscillating torsional pendulum at frequencies of about 1 cycle/sec in the temperature range of 100 to 300 K. Two damping measurements were made every 5°. 

Our approach has been to synthesize the dleplsulflde resin corresponding to the normal blsphenol A type dlepoxlde resins. A polyamide type curing agent (Versamlde 140) was used because of our particular Interest In orthopedic adhesives, l.e. "bone cement". Some of the properties were therefore tailored to be optimum near body temperature. We have found very little prior literature on dleplsulflde resins. As prepared, the dleplsulflde resin analog of DGEBA Is a crystalline solid which must be heated above Its melting temperature for reaction. Charlesworth (2) has reported mechanical relaxation behavior of epoxy-episulfide poly-... 

Keywords Viscoelasticity Glass transition temperature Relaxational processes Dielectric behavior Dynamic mechanical behavior Poly(methacrylate)s Poly (itaconate)s Poly(thiocarbonate)s Spacer groups Side chains Molecular motions... 

The relaxation behavior of poly(trimethylene 2,6-naphthalate)/nanoclay composites has been investigated by DSC and dynamic mechanical analysis [81]. The incorporation of two different types of nanoclays in the polymer matrix intercalates the chains in the... 

Figure 5.31. Effect of absorbed H2O on the storage modulus and mechanical damping behavior (g" or tan 5) of poly(ether sulfone) at IHz curves (a) 0.31% H2O, curve (b) 0.07% H2O the P relaxation in this polysulfone is dependent on the water content of the samples as illustrated the relaxation intensity increases with the amount of moisture present. [From AUen et al. (1971) reprinted with permission of Elsevier.]...

The relaxation behavior of partially crystalline systems is complex and different from amorphous polymers. Observations give the general impression that, in comparison to amorphous systems, partially crystalline samples are much less uniform in behavior. Many of the systems exhibit peculiarities and these can dominate the viscoelastic properties. This is not the place to explore this large field in the necessary depth, which would mean we would have to discuss separately the mechanical behavior of polyethylene, poly(ethylene terephtha-late), polypropylene, it-polystyrene, poly(tetrafluoroethylene) etc. What can be done for illustration is to pick out one instructive example and we select polyethylene. 

Summary In this chapter, a discussion of the viscoelastic properties of selected polymeric materials is performed. The basic concepts of viscoelasticity, dealing with the fact that polymers above glass-transition temperature exhibit high entropic elasticity, are described at beginner level. The analysis of stress-strain for some polymeric materials is shortly described. Dielectric and dynamic mechanical behavior of aliphatic, cyclic saturated and aromatic substituted poly(methacrylate)s is well explained. An interesting approach of the relaxational processes is presented under the experience of the authors in these polymeric systems. The viscoelastic behavior of poly(itaconate)s with mono- and disubstitutions and the effect of the substituents and the functional groups is extensively discussed. The behavior of viscoelastic behavior of different poly(thiocarbonate)s is also analyzed. 

Mechanical and dielectric behavior of poly(methacrylate)s with cyclohexyl groups in the side chain have been reported as it was described above and the viscoelastic information obtained from these polymeric systems is very broad and give confidence about the molecular origin of the fast relaxation processes that take... 

The effects of morphology (i.e., crystallization rate) (6,7, 8) on the mechanical properties of semicrystalline polymers has been studied without observation of a transition from ductile to brittle failure behavior in unoriented samples of similar crystallinity. Often variations in ductlity are observed as spherulite size is varied, but this is normally confounded with sizable changes in percent crystallinity. This report demonstrates that a semicrystalline polymer, poly(hexamethylene sebacate) (HMS) may exhibit either ductile or brittle behavior dependent upon thermal history in a manner not directly related to volume relaxation or percent crystallinity. 

Effects of addition of a compatibilizing block copolymer, poly(styrene-b-methyl methacrylate), P(S-b-MMA) on the rheological behavior of an immiscible blend of PS with SAN were studied by dynamic mechanical spectroscopy [Gleisner et al., 1994]. Upon addition of the compatibilizer, the average diameter of PS particles decreased from d = 400 to 120 nm. The data were analyzed using weighted relaxation-time spectra. A modified emulsion model, originally proposed by Choi and Schowalter [1975], made it possible to correlate the particle size and the interfacial tension coefficient with the compatibilizer concentration. It was reported that the particle size reduction and the reduction of occur at different block-copolymer concentrations. 

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