The characterization of and formulation development using a novel tyre devulcanizate

The amount of waste tyres being dumped is fast becoming a problem. These stockpiles take up valuable land and are an environmental and health problem. While incineration is the simplest way to recycle the used tyres it isn’t an efficient way to dispose of tyres. This research looks at developing a method for characterizing the New Reclamation Group (NRG) reclaim with the main focus on Hi-Res™ thermogravimetric analysis. Good quantification was possible using this technique. A trade off was established between resolution, sensitivity and time. While increasing the resolution allowed greater separation to be achieved the time for each experiment increased rapidly. Although kinetic models do exist for quantifying rubber components in vulcanized sample, they were not suitable for this study. When devulcanization causes significant molecular changes, such as with NRG reclaim, the decomposition profiles no longer match those of virgin materials. Formulations developed focused on mixing, rheometry, crosslink density and tensile properties. The NRG reclaim acted as a processing aid which lowered the maximum torque. This provides mixing safety as the temperature is decreased as a result of the lower torque. This effect was not seen with conventional reclaim. Rheometry tests indicated that the addition of the devulcanizates decreased the extent of cure. It was demonstrated that this could be linked to crosslink density. Testing of the 100%, 200%, 300% moduli correlated the crosslink density to the maximum torque. Although the addition of NRG reclaim reduced the tensile strength of the formulation, a link between crosslink density and ultimate tensile strength (UTS) couldn’t be made. The decrease in the UTS and increase in extension at break is possibly caused by an increase in low molecular weight material present in the formulations and decrease in crosslink density. This could possibly increase the mobility of polymer chains which could increases flexibility

Carbon Nanotubes as Reinforcing Nanomaterials for Rubbers Used in Electronics

The field of electronics involves complex systems where the active and passive electronic devices are integrated on the rubber substrate, e.g., silicone (Q), which provides, through potting, a strong assembly of these devices on the circuit board. Several other rubbers are employed in the field to strengthen, insulate and seal the components of the electronic machines and instruments, and therefore protect them against damage. These rubbers are typically strengthened and toughened using carbon black (CB). However, due to its noticeable drawbacks, recent research in the field of rubber and electronics has suggested the use of carbon nanotubes (CNTs) as alternative reinforcing fillers to produce electronics rubber composites that do not only have enhanced electrical conductiv¬ity, thermal stability, electromagnetic interference (EMI) shielding, weatherability and insulation properties, but also offer outstanding stretchability, bendability and tear strength under frequent elastic deformation. These performances are similar for both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) in both the functional and structural composites. Although SWCNTs can result in relatively better homogeneity than MWCNTs, most rubbers often constitute MWCNTs because they are relatively cheaper. The great potential of rubber-CNTs composites being extensively used in the field of electronics is explored in this chapter

Catalytic oxidation of thioanisole using oxovanadium (IV)‐functionalized electrospun polybenzimidazole nanofibers

Polybenzimidazole fibers, with an average diameter of 262 nm, were produced by the process of electrospinning. These fibers were used as a solid support material for the immobilization of oxovanadium(IV) which was achieved via a reaction with vanadyl sulfate. The oxovanadium(IV)-functionalized nanofibers were used as heterogeneous catalysts for the oxidation of thioanisole under both batch and pseudo-continuous flow conditions with great success. Under batch conditions near quantitative oxidation of thioanisole was achieved in under 90 min, even after four successive catalytic reactions. Under continuous conditions, excellent conversion of thioanisole was maintained throughout the period studied at flow rates of up to 2 mLh−1. This study, therefore, proposes that electrospun polybenzimidazole nanofibers, with their small diameters, impressive chemical and thermal stability, as well as coordinating benzimidazole group, may be a desirable support material for immobilization of homogeneous catalysts

Phytochemical Profiling and Antioxidant Activity of Dodonaea Viscosa

Antioxidants are compounds that can inhibit free radicals. Herbal medicine is the oldest form of health care known to mankind. Herbal medicines have great importance in maintaining the health of every person. Demands of Herbal medicines are increasing in both developed and developing countries due to growing recognition of natural plants being lesser or of no side effect, easily available in surrounding place with low cost. Different parts of the plant have different active constituents and these active constituents may vary in their extent of activity and concentration. Most of active principles are existing in leaves, root and seeds of the plant. Certain herbs have become popular over the last twenty years, but herbal medicine is still poorly understood by the public, medical practitioners and the media. Africa is not left behind most of the world in this endeavor of utilizing herbal medicine. Dodonaea viscosa is often used traditionally to treat many diseases like fever, cold, malaria, rheumatism, aches, toothaches, headaches, indigestion, ulcers, diarrhea, constipation, dysmenorrheal and irregular menstruation. The plant is 1 2 reported to contain alkaloids, flavonoids, saponins, tannins, steroids, triterpenoids, phytosterols and volatile oil. This research was aimed at describing the medicinal uses, phytochemical components and other important aspects of the plant. The present study focus on antioxidant activity of Dodonaea viscosa, it also reveals that this plant is of therapeutic potential due to their high free-radical scavenging activity. Phytochemical is chemicals that occurs naturally in plants, some are responsible for color and others for organoleptic properties as the aspects of food or other substances as experienced by the sense, including taste, sight, smell and touch. They are found in plant based foods such as fruits, vegetables, beans, and grains. They also contain molecules that inhibit the oxidation of other molecules and oxidation chemical reaction produce free radicals. In turn, these free radicals can start a chain reaction, and when the chain reactions occur in a cell, it can cause damage or death to the cell (e.g. cell membrane contains lipids first defense in the body, if its damage the immune system is compromised). Antioxidant is to terminate these chain reactions by removing free radical intermediates and inhibit oxidation reactio

KNOWLEDGE AND PERCEPTIONS OF SMALLHOLDER FARMERS REGARDING SOLANUM INCANUM L. USE AS A PESTICIDE IN MKOBA COMMUNITY IN GWERU, ZIMBABWE

This study explored the knowledge and perceptions the smallholder farmers in Mkoba village hold regarding the use of extracts of the root and fruit of S. incanum. A questionnaire was administered to 49 sampled respondents (age range 16 to 70 years) from Mkoba village who practiced communal gardening and used Solanum incanum as a pesticide. The data were reported in frequency tables and graphs. The Chi-square was used to determine the associations between the respondents’ perceptions and education level, age, and gender at p = .05. An independent t-test was also used to determine whether there was a statistically significant difference between the different educational groups in their perceptions of S. incanum at p = .05. Of the 49 respondents, 20(40.8%) were in the age range of 30-50 years, and 30 (61.2%) were female. The study found that respondents were knowledgeable about the S. incanum preparations, of which 18 (36.7%) of that indigenous knowledge came from their parents. Many uses of S. incanum were reported which included wound healing 23 (46.9%), toothache 32 (65.3%), and stomach-ache 34(69.3%) remedy. There were mixed opinions reported regarding its environmental user-friendliness, health benefits, and efficacy. Twenty-six 26 (53%) of the respondents believed that S. incanum was non-poisonous and therefore they did not see the need for any precautional measures including the use of personal protective clothing. The most prevalent symptoms of diseases were skin rash 30 (61.2%), nausea 13 (26.5%), headache 15 (30.6%), and poor vision 8 (16.3%) and these symptoms were common in the age group 30 to 60 years. The popular use of S. incanum was attributed to the strong cultural background as well as the unavailability of money to purchase commercial pesticides. Appropriate awareness and education programmes in the community should be organised by the community leaders to increase the level of knowledge to enhance appropriate attitudes and perceptions regarding the hazards S. incanum brings as a pesticide

KNOWLEDGE AND PERCEPTIONS OF SMALLHOLDER FARMERS REGARDING SOLANUM INCANUM L. USE AS A PESTICIDE IN MKOBA COMMUNITY IN GWERU, ZIMBABWE

This study explored the knowledge and perceptions the smallholder farmers in Mkoba village hold regarding the use of extracts of the root and fruit of S. incanum. A questionnaire was administered to 49 sampled respondents (age range 16 to 70 years) from Mkoba village who practiced communal gardening and used Solanum incanum as a pesticide. The data were reported in frequency tables and graphs. The Chi-square was used to determine the associations between the respondents’ perceptions and education level, age, and gender at p = .05. An independent t-test was also used to determine whether there was a statistically significant difference between the different educational groups in their perceptions of S. incanum at p = .05. Of the 49 respondents, 20(40.8%) were in the age range of 30-50 years, and 30 (61.2%) were female. The study found that respondents were knowledgeable about the S. incanum preparations, of which 18 (36.7%) of that indigenous knowledge came from their parents. Many uses of S. incanum were reported which included wound healing 23 (46.9%), toothache 32 (65.3%), and stomach-ache 34(69.3%) remedy. There were mixed opinions reported regarding its environmental user-friendliness, health benefits, and efficacy. Twenty-six 26 (53%) of the respondents believed that S. incanum was non-poisonous and therefore they did not see the need for any precautional measures including the use of personal protective clothing. The most prevalent symptoms of diseases were skin rash 30 (61.2%), nausea 13 (26.5%), headache 15 (30.6%), and poor vision 8 (16.3%) and these symptoms were common in the age group 30 to 60 years. The popular use of S. incanum was attributed to the strong cultural background as well as the unavailability of money to purchase commercial pesticides. Appropriate awareness and education programmes in the community should be organised by the community leaders to increase the level of knowledge to enhance appropriate attitudes and perceptions regarding the hazards S. incanum brings as a pesticide

Three new proaporphine alkaloids from <i>Cissampelos capensis</i> L.f. and their cytotoxic evaluation

Three new proaporphine alkaloids, cissamaline (4), cissamanine (5), and cissamdine (6), along with two known compounds (2 and 3) were isolated from total tertiary alakloidal extracts of the leaves and stems of Cissampelos capensis. The new alkaloids were elucidated through comprehensive spectroscopic analysis, including 1 D, 2 D NMR and High-resolution LCMS. The in vitro MTT cytotoxicity was evaluated on Caco-2 cell lines, where all the isolated compounds exhibited cytotoxic effects at concentrations above 250 µM.</p

Thermal and mechanical properties of cross-linked and uncross-linked linear low-density polyethylene-wax blends

The influence of the wax content and different concentrations of the crosslinking agent on the thermal and mechanical properties of linear low-density polyethylene-wax blends has been investigated. It was found that an increase in wax content induces an increase in elastic modulus and yield stress of the blends. This is a consequence of the higher crystallinity of the blends in the presence of a higher amount of wax. The average tie chain concentration in the blends is estimated in order to explain detrimental effects of the wax on the ultimate properties. A significant correlation was found between stress and strain at break and the concentration of tie chains. Cross-linking improves the ultimate properties of the blends and pure polyethylene. On the other hand, because of its low molecular weight, thermal stability decreases with an increase in wax content and this trend remains unchanged after crosslinking. (C) 2002 Elsevier Science Ltd. All rights reserved