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Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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TL;DR: In this article, the performance of polymeric dicyclopentadiene (pDCPD) was compared with two epoxy resin/diamine systems with comparable glass transition temperatures.
61 citations
Cites background from "Mechanical Properties of Polymers a..."
...Epoxy resins that have high stiffness and strength required for structural applications are heavily exploited in fiber reinforced composites, but they are notoriously brittle [5]....
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TL;DR: In this article, a-BPDA-derived polyimides were used as matrix polymers for semirigid polyimide homo-polymers for the present purpose.
Abstract: Asymmetric biphenyl type polyimides (PI) derived from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA) and p-phenylenediamine (PDA) or 4,4′-oxydianiline (ODA) show higher Tgs, and much better thermoplasticity than the corresponding isomeric PIs from symmetric 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA). In addition, a-BPDA-derived PIs are completely amorphous owing to their bent chain structures and highly distorted conformations, whereas the PIs from s-BPDA are semicrystalline. a-BPDA-derived PIs possessing these properties or the a-BPDA monomer were used as a flexible blend component or a comonomer to improve the insufficient thermoplasticity of semirigid s-BPDA/PDA homo polymer. The blends composed of s-BPDA/PDA (80%) with a-BPDA-derived PIs (20%), as well as the s-BPDA/PDA-based copolymer containing 20% a-BPDA, showed a certain extent of thermoplasticity above the Tgs without causing a decrease in Tg. In addition, these blends and copolymer provided comparatively low thermal expansion coefficient (ca. 18 ppm). The improved film properties for the blends are related to good blend miscibility. On the other hand, when s-BPDA/ODA was used as a flexible matrix polymer instead of a-BPDA-derived PIs, the 80/20 blend film annealed at 400°C exhibited no prominent softening at the Tg. This result arises from annealing-induced crystallization of the flexible s-BPDA/ODA component. Thus, these results revealed that a-BPDA-derived PIs are promising candidates as matrix polymers for semirigid s-BPDA/PDA for the present purpose. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2499–2511, 1999
61 citations
TL;DR: In this article, the effects of BA-a content on the thermal, mechanical and shape memory properties of epoxy-based shape memory polymers (SMPs) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), flexural test and shape recovery test.
Abstract: Novel shape memory polymers (SMPs) were prepared from benzoxazine-modified epoxy resin. Specimens consisting of aromatic epoxy (E), aliphatic epoxy (N), Jeffamine D230 (D) and BA-a benzoxazine monomer (B) were evaluated. The mole ratio of D/B was used as a mixed curing agent for an epoxy system with a fixed E/N. The effects of BA-a content on the thermal, mechanical and shape memory properties of epoxy-based shape memory polymers (SMPs) were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), flexural test and shape recovery test. The results revealed that the obtained SMPs exhibited a higher flexural strength and flexural modulus than those of the unmodified epoxy-based SMP at room temperature and at 20?? C above glass transition temperature (Tg). The presence of 1?mol BA-a as a curing agent provided the specimen with the highest Tg, i.e. about 72?? C higher than that of epoxy-based SMP cured by Jeffamine D230. All SMP samples needed only a few minutes to fully recover to their original shape. The samples exhibited high shape fixity (98?99%) and shape recovery ratio (90?100%). In addition, the recovery stress values increased with increasing BA-a mole ratio from 20 to 38?kPa, when BA-a up to 1?mol ratio was added. All of the SMP samples exhibited only minimum change in their flexural strength at the end of a 100 recovery cycles test.
61 citations
TL;DR: The PHB/nHA composite scaffolds investigated in this study tend to be favorable for bone tissue engineering applications.
61 citations
TL;DR: In this paper, a mixture of polypropylene and nylon-6 extruded into ribbons at varying draw ratios generated laminar morphologies under different draw ratios for the binary system and the compatibilized system.
Abstract: Blends of polypropylene and nylon-6 extruded into ribbons at varying draw ratios generated laminar morphologies under our conditions. For the binary system, the size and distribution of the dispersed phase is coarse. The addition of an ionomer to the nylon prior to blending compatibilized the phases and produced much finer domains. The tensile properties of the virgin matrix material respond to the draw ratio in a parabolic manner attaining a maximum at intermediate values. Blending with nylon-6 attenuates the effect without improving the tensiles markedly. The compatibilized system however demonstrates greatly improved mechanical properties.
60 citations