Polypropylene/calcium carbonate nanocomposites

Toughening of polypropylene with calcium carbonate particles

Polypropylene/Calcium Carbonate Nanocomposites

Stereoregular Polymers and Stereospecific Polymerizations Edited by Giulio Natta and Ferdinando Danusso. (The Contributions of Giulio Natta and his School of Polymer Chemistry.) Vol. 1: Pp. xxii + 1 + 466. Vol.2: Pp. xx + 467–888. (Oxford, London and New York: Pergamon Press, Ltd., 1967.) 315s. net per set of two volumes. Heteroatom Ring Systems and Polymers By H. R. Allcock. Pp. xi + 401. (New York: Academic Press, Inc.; London: Academic Press, Inc. (London), Ltd., 1967.) 132s.

Advances in Polymer Science

In this review we highlight new developments in tough hydrogel materials in terms of their enhanced mechanical performance and their corresponding toughening mechanisms. These mechanically robust hydrogels have been developed over the past 10 years with many now showing mechanical properties comparable with those of natural tissues. By first reviewing the brittleness of conventional synthetic hydrogels, we introduce each new class of tough hydrogel: homogeneous gels, slip-link gels, double-network gels, nanocomposite gels and gels formed using poly-functional crosslinkers. In each case we provide a description of the fracture process that may be occurring. With the exception of double network gels where the enhanced toughness is quite well understood, these descriptions remain to be confirmed. We also introduce material property charts for conventional and tough synthetic hydrogels to illustrate the wide range of mechanical and swelling properties exhibited by these materials and to highlight links between these properties and the network topology. Finally, we provide some suggestions for further work particularly with regard to some unanswered questions and possible avenues for further enhancement of gel toughness.

Progress toward robust polymer hydrogels

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/28299/0000053.pdf;sequence=1

Toughening mechanisms in core-shell rubber modified polycarbonate

The use of a rubber modified thermoplastic resin has been investigated as a method to improve the Mode I interlaminar fracture toughness of a unidirectional continuous carbon fiber composite. Test results show that the improvement in the fracture toughness is less than expected due to rubber particle agglomeration, solvent and molding induced crystallization of the matrix and poor fiber/matrix adhesion. The plastic zone in composites utilizing tough matrices can extend well beyond a single interfibrillar spacing. However, the development of the plastic zone is limited due to the failure of the fiber/matrix interface. In order to fully evaluate the potential of tough composites using toughened matrices, any improvement made in the matrix toughness must be coupled with improvements in the fiber/matrix adhesion.

/pdf/factors-influencing-the-mode-i-interlaminar-fracture-2lof16ieie.pdf

Factors Influencing the Mode I Interlaminar Fracture Toughness of a Rubber Toughened Thermoplastic Matrix Composite

The development of tough high-peformance composites often employs a variety of analytical methods that correlate morphological, yield and fracture characteristics to the corresponding properties of a composite. Most of these techniques can be severely limited due to the high concentration of fibres used in high performance composites (nominally 60 wt %). Several light microscopy techniques can be used to identify relationships between morphological features and composite properties, for example fracture surface studies using reflected light microscopy, microtomed sections, cast films and etched surfaces. These techniques are limited for the following reasons: reflected light microscopy is restricted to surfaces, cast films do not necessarily reflect properties of the bulk material, microtomed sections are very difficult to produce with such a high concentration of fibres, and etched surfaces can be difficult to interpret because artefacts may be created by the use of the etchant. Petrographic thin sectioning has been used in conjunction with transmission polarized light microscopy for microstructural and deformation mechanism characterizations in a variety of polymer systems such as: identifying the failure modes in glass-filled polycarbonate and toughened nylon [1], evaluating the toughening mechanisms in rubber-toughened epoxy [2], and observing the development of the plastic zone in front of a crack tip in toughened polycarbonates and epoxy resins [3]. The technique used for preparing petrographic thin sections is described by Holik et al. [1]. This paper will focus on adaptations of this technique to facilitate the examination of high performance composites. We have adapted a transmitted light microscopy thin sectioning technique for use in studying high performance composites which overcomes several of the limitations associated with the more standard techniques. Thin sectioning of composites is extremely useful for identifying the presence of spherulites within a composite matrix and relating the effect of thermal treatment on spherulite morphology. This technique is also applicable to subsurface deformation analysis for identifying the plastic zone within a high performance

/pdf/a-petrographic-thin-sectioning-technique-for-evaluating-3n0prc2b3m.pdf

D. S. Parker

Papers

Toughening mechanisms in core-shell rubber modified polycarbonate

Factors Influencing the Mode I Interlaminar Fracture Toughness of a Rubber Toughened Thermoplastic Matrix Composite

A petrographic thin sectioning technique for evaluating composite materials