Mechanical properties, compositional effects weight effect

Mahlberg etal. (2001) studied the effect of acetylation of wood fibres (20 % WPG) upon the mechanical properties of wood fibre PP fibre composites, with and without the addition of a novalak PF. Acetylation resulted in significant improvements in MOR, MOE and IBS in a composite containing 20 % by weight of PP fibre. With a combination of PF and PP (both 10 % by weight) and acetylated wood fibre, MOR was unchanged, MOE decreased and only IBS showed a significant improvement. Acetylation also contributed to a better dispersion of the wood fibres in the PP matrix. 

A polymer electrolyte with acceptable conductivity, mechanical properties and electrochemical stability has yet to be developed and commercialized on a large scale. The main issues which are still to be resolved for a completely successful operation of these materials are the reactivity of their interface with the lithium metal electrode and the decay of their conductivity at temperatures below 70 °C. Croce et al. found an effective approach for reaching both of these goals by dispersing low particle size ceramic powders in the polymer electrolyte bulk. They claimed that this new nanocomposite polymer electrolytes had a very stable lithium electrode interface and an enhanced ionic conductivity at low temperature. combined with good mechanical properties. Fan et al. has also developed a new type of composite electrolyte by dispersing fumed silica into low to moderate molecular weight PEO. 

The prime object of the present study was to determine the compositional polydlspersity of commercial cellulose triacetate and to examine the effect of molecular weight and molecular weight distribution on the mechanical properties of the fibres. 

Fig. 17. Effect of interdiffusion of the functionalized polymer with the matrix on the mechanical properties of PP/cellulose composites. Molecular weight of MA-PP (O) non-treat-ed, (A) 350, (V) 4500, ( ) 3.9X10 ...

In the present study, the effects of composition, molecular weight, and heat treatment on the relaxation behavior of styrene—butadiene-styrene (SBS) block polymers are investigated. There is evidence (e.g., 6,7,8) that these types of multicomponent multiphase systems exhibit unusual phenomena in their dynamic mechanical behavior and in other physical properties. These are apparently related to the presence of the so-called interphase mixing region between the elastomeric and glassy domains. Similar evidence has been obtained by gas diffusion and sorption studies on the copolymer samples used in this investigation (9). 

Numerous studies have been made of the mechanical properties of fibrous composites these include recently published papers on impact properties by Izod (1,2, 3,4) and Charpy (5,6) and drop weight (7) tests. We reported the Charpy impact fracture behavior of various glass-polyester composites regarding the effects of temperature (8,9,10), specimen size (8), and fiber orientation (10). This paper describes the effects of the tough-brittle transition in the impact behavior of glass-polyester composites which occurs with a variation of temperature and specimen size. 

The synthesis and properties of poly(imide-siloxane) polymers and copolymers based on 5,5 bis(lyly3,3-tetramethyl-l,3-disiloxane-diyl)norbornane dicarboxylic anhydride are described. High-molec-ular-weight thermoplastics and elastoplastics were prepared readily in solution from aromatic diamines, organic dianhydrides, and this unique anhydride-terminated siloxane. The thermal and mechanical properties of a variety of copolymer compositions are described. Average siloxane block length and overall siloxane content had the greatest effect on these properties. 

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