Toughened blend of polycarbonate and epoxidized ethylene propylene diene rubber

A super-tough polycarbonate (PC) blend was obtained by using epoxidized ethylene propylene diene (eEPDM) rubber as modifier. The notched Izod impact strength of PC/eEPDM (96/4) blend shows a great improvement, with a value about 25 times of that of pure PC. Finely and homogeneously dispersed rubber particles (0.2-0.8 mu m) in the PC matrix indicated good adhesion between the eEPDM rubber phase and the PC matrix. (C) 1997 Elsevier Science Ltd.

In situ epoxidation of ethylene propylene diene rubber by performic acid

In this paper, epoxidation of ethylene propylene diene rubber by in situ generated performic acid is discussed. The samples have been characterized by infra-red and H-1-nuclear magnetic resonance analyses. Quantitative analysis of the reaction products is made possible by using the methyl deformation band at 1377 cm(-1) as internal standard. The conversion of double bonds increases rapidly within the first 1 h, then gradually, over 2 h, has only a slight increase. The maximum conversion ratio of double bonds is about 70%. The relative content of epoxy groups has a top value at about 7 h. The side reactions are also discussed. (C) 1997 Elsevier Science Ltd.

Toughening of poly(butylene terephthalate) with epoxidized ethylene propylene diene rubber

In this paper, unepoxidized ethylene propylene diene rubber (uEPDM) was first epoxidized with formic acid and H2O2, and then the epoxidized ethylene propylene diene rubber (eEPDM) was melt-mixed with PET resin in a Brabender-like apparatus. Toughening of PET matrix was achieved by this method. The dispersion of rubber particles and phase structure of the blends were also observed by SEM. It has been suggested that the epoxy groups in the eEPDM could react with PET end groups to form a graft copolymer which could act as an interfacial compatibilizer between the PBT matrix and eEPDM rubber dispersed phase. This is beneficial to the improvement of the impact performance of PBT. (C) 1997 Elsevier Science Ltd.

Toughened poly(butylene terephthalate) by epoxided ethylene-propylene-diene-rubber

Blends of poly (butylene terephthalate) (PBT) and epoxided ethylene-propylene-diene terpolymer (EEPDM) were prepared. Their mechanical properties and morphology were studied by Izod impact test machine and scanning electronic microscope respectively, It was found that the notched Izod impact strength of blend PBT/EEPDM was as about 23 times as that of pure PET and about 10 times as that of blend PBT/EPDM at room temperature, The dispersed rubber particles were much smaller and the phase boundary was more blurred in blend PBT/EEPDM than in blend PBT/EPDM. The toughness of blend PBT/EEPDM was much more better than that of blend PET and PBT/EPDM, which was in good agreement with the difference between their morphologies.

RADIATION VULCANIZATION OF HYDROGENATED ACRYLONITRILE-BUTADIENE RUBBER (HNBR)

Raw polymer and compound of hydrogenated acrylonitrile butadiene rubber (HNBR) were subjected to gamma-ray irradiation. Crosslinking was found to be the main chemical reaction induced by irradiation; the ratio of chain scission to crosslinking as well as

EFFECT OF REPTATION ON FRACTURE-MECHANICS OF RUBBER NETWORKS

End-linked hydroxyl-terminated polybutadiene containing unattached linear polybutadiene was used to study the effect of reptating species on the fracture mechanics of rubber networks. The concentration of reptating species in the networks ranged from 0 to 100%. The fracture mechanics of the networks was described using the critical strain energy release rate in mode III testing, i.e. the tearing energy. The tearing energy was measured at room temperature using a 'trouser' specimen at a strain rate spanning five logarithmic decades. When the strain rate was as low as 10(-4) s-1, the tearing energy of the networks increased with reduction in reptating species. In this case the reptating species did not contribute to the tearing energy of the networks due to relaxation. Hence, the tearing energy increased with the number of crosslinked chains per unit volume in the networks. At a strain rate ranging from 10(-3) to 10(-1) s-1, the tearing energy of the networks was governed by local viscosity. The tearing energies of the networks containing various amounts of reptating species were superimposed to give a master curve based on the Williams-Landel-Ferry equation.

Preparation of a novel polysulfone/polyethylene oxide/silicone rubber multilayer composite membrane for hydrogen-nitrogen separation

A novel poly sulfone/polyethylene oxide/silicone rubber (PSOPEO/SR) multilayer composite membrane was fabricated by double coating polysulfone substrate membrane with polyethylene oxide and silicone rubber. Gas permeation experiments were performed at 30 degrees C for hydrogen and nitrogen. PSf(PEO/SR membrane displayed high and steady performance for H-2/N-2: permeances of H-2 and N-2 of 49.51 and 0.601 GPU, respectively, and H-2/N-2 ideal separation factor of 82.3. It was explained that layer interfaces due to the introduction of PEO layer act as the permselective media and are responsible for the higher H-2/N-2 ideal separation factor which has exceeded the intrinsic permselectivities of the three polymers used in this study. (c) 2005 Elsevier B.V. All rights reserved.

Subset Warping: Rubber Sheeting with Cuts

Image warping, often referred to as "rubber sheeting" represents the deformation of a domain image space into a range image space. In this paper, a technique is described which extends the definition of a rubber-sheet transformation to allow a polygonal region to be warped into one or more subsets of itself, where the subsets may be multiply connected. To do this, it constructs a set of "slits" in the domain image, which correspond to discontinuities in the range image, using a technique based on generalized Voronoi diagrams. The concept of medial axis is extended to describe inner and outer medial contours of a polygon. Polygonal regions are decomposed into annular subregions, and path homotopies are introduced to describe the annular subregions. These constructions motivate the definition of a ladder, which guides the construction of grid point pairs necessary to effect the warp itself.

Replacing rubber plantations by rain forest in Southwest China - Who would gain and how much?

The cultivation of rubber trees in Xishuangbanna Prefecture in China’s Yunnan Province has triggered an unprecedented economic development but it is also associated with severe environmental problems. Rubber plantations are encroaching the indigenous rainforests at a large scale and a high speed in Xishuangbanna. Many rare plant and animal species are endangered by this development, the natural water management is disturbed and even the microclimate in this region has changed over the past years. The present study aims at an assessment of the environmental benefits accruing from a reforestation project partly reversing the deforestation that has taken place over the past years. To this end a Contingent Valuation survey has been conducted in Xishuangbanna to elicit local residents’ willingness to pay for this reforestation program that converts existing rubber plantations back into forest. It is shown that local people's awareness of the environmental problems caused by increasing rubber plantation is quite high and that in spite of the economic advantages of rubber plantation there is a positive willingness among the local population to contribute financially to a reduction of existing rubber plantations for the sake of a partial restoration of the local rainforest. These results could be used for the practical implementation of a PES (Payments for Eco-System Services) system for reforestation in Xishuangbanna.

Correlating Additives to Deterioration and Assessing the Effectiveness of Acrylic Coatings for the Protection of Rubber

Conservators have long been aware of the problems associated with the preservation of rubber objects due to inherent instability that can be attributed, in part, to the presence of additives. Inorganic additives, such as fillers, accelerators, stabilizers, and special ingredients are necessary in manufacturing to alter the properties of natural rubber. These materials all have different interactions with the rubber, and each other, and differing effects on the ageing process. To date, the most effective and accepted methods to preserve rubber are cold, dark storage of objects, or the use of low oxygen environments. While these methods are effective, they greatly limit access. The application of coatings to the surface of rubber objects can slow deterioration and greatly increase the ability of an institution to handle and display rubber objects. While numerous coatings for preventive and interventive treatment have been tested, none have been so successful to warrant routine use. The first section of this research highlighted the relationship between the inclusion of certain additives in natural rubber objects and the accelerated or slowed down overall degradation. In the second part of this research, the acrylic varnishes Golden Polymer Varnish with UVLS, Lascaux Acrylic Transparent Varnish-UV, Sennelier Matte Lacquer with UV Protection, and Liquitex Soluvar Varnish containing ultraviolet light absorbers or stabilizers were tested as a preventative coating for rubber. Through testing the visual and physical properties of the samples, as well as compound analysis the results of this research suggest that acrylic varnishes do provide protection, each to varying degrees. The results also provided insight into the behavior of rubber and these varnishes with continuing light exposure.