Studies on new processing aids and other compounding ingredients in special purpose rubbers

In the first part of the study we probed the effectiveness of rice bran oil as a multipurpose compounding ingredient for nitrile (NBR) and chloroprene (CR) rubbers. This oil has already been successfully employed in the compounding of NR and SBR in this laboratory.In this context we thought it worthwhile to try this oil in the polar rubbers viz, NBR and CR also. The principle of like dissolves like as applicable to solvents is equally applicable while selecting a plasticiser, elastomer combination. Because of the compatibility considerations polar plasticisers are preferred for polar rubbers like NBR and CR. Although plasticisation is a physical phenomenon and no chemical reaction is involved, the chemical structure of plasticisers determines how much physical attraction there is between the rubber and the plasticiser. In this context it is interesting to note that the various fatty acids present in rice bran oil have a long paraffinic chain, characteristic of waxes, with an acid group at the end of the molecule. The paraffinic end of the molecule contributes lubricating effects and limits compatibility whereas the acid end group contributes some polarity and is also chemically reactive. Because of absorption of acid group on the surface of pigments, these acids will have active pigment wetting characteristics also. These factors justifies the role of rice bran oil as a co-activator and lubricating agent for NBR and CR. In fact in our study we successfully replaced stearic acid as co-activator and aromatic oillDOP as processing aid for CR and NBR with rice bran oil.This part of the study has got special significance in the fact that rubber industry now heavily depends on petroleum industry for process oils. The conventional process oils like aromatic, naphthenic and paraffinic oils are increasingly becoming costlier, as its resources in nature are fast depleting. Moreover aromatic process oils are reported to be carcinogenic because of the presence of higher levels of polycyclic aromatic compounds in these oils.As a result of these factors, a great amount research is going on world over for newer processing aids which are cost effective, nontoxic and performanance wise at par with the conventional ones used in the rubber industry. Trials with vegetable oils in this direction is worth trying.Antioxidants are usually added to the rubber compound to minimise ageing effects from heat, light, oxygen etc. As rice bran oil contains significant amount of tocopherols and oryzanol which are natural antioxidants, we replaced a phenolic antioxidant like styrenated phenol (SP) from the compound recipe of both the rubbers with RBO and ascertained whether this oil could function in the role of antioxidant as well.Preparation and use of epoxidised rice bran oil as plasticiser has already been reported.The crude rice bran oil having an iodine value of 92 was epoxidised in this laboratory using peracetic acid in presence of sulphuric acid as catalyst. The epoxy content of the epoxidised oil was determined volumetrically by treating a known weight of the oil with excess HCI and back titrating the residual HCI with standard alkali solution. The epoxidised oil having an epoxy content of 3.4% was tried in the compounding of NBR and CR as processing aids. And results of these investigations are also included in this chapter. In the second part of the study we tried how RBO/ERBO could perform when used as a processing aid in place of aromatic oil in the compounding of black filled NRCR blends. Elastomers cannot have all the properties required for a particular applications, so it is common practice in rubber industry to blend two elastomers to have desired property for the resulting blend.In this RBO/ERBO was tried as a processing aid for plasticisation, dispersion of fillers, and vulcanisation of black filled NR-CR blends.Aromatic oil was used as a control. The results of our study indicate that these oils could function as a processing aid and when added together with carbon black function as a cure accelerator also.PVC is compatible with nitrile rubber in all proportions, provided NBR has an acrylonitrile content of 25 to 40%. Lower or higher ACN content in NBR makes it incompatible with PVC.PVC is usually blended with NBR at high temperatures. In order to reduce torque during mixing, additional amounts of plasticisers like DOP are added. The plasticiser should be compatible both with PVC and NBR so as to get a homogeneous blend. Epoxidised soyaben oil is reported to have been used in the compounding of PVC as it can perfonn both as an efficient plasticiser and heat stabilizer.At present DOP constitute the largest consumed plasticiser in the PVC compounding. The migration of this plasticiser from food packaging materials made of PVC poses great health hazards as this is harmful to human body. In such a scenario we also thought it worthwhile to see whether DOP could be replaced by rice bran oil in the compounding of NBR-PVC blends Different blends of NBR-PVC were prepared with RBO and were vulcanized using sulphur and conventional accelerators. The various physical and mechanical properties of the vulcanisates were evaluated and compared with those prepared with DOP as the control plasticiser. Epoxidised rice bran oil was also tried as plasticiser for the preparation of NBR-PVC blends. A comparison of the processability and cure characteristics of the different blends prepared with DOP and ERBO showed that ERBO based blends have better processability and lower cure time values. However the elastographic maximum torque values are higher for the DOP based blends. Almost all of the physical properties evaluated are found to be slightly better for the DOP based blends over the ERBO based ones. However a notable feature of the ERBO based blends is the better percentage retention of elongation at break values after ageing over the DOP based blends. The results of these studies using rice bran oil and its epoxidised variety indicated that they could be used as efficient plasticisers in place of DOP and justifies their role as novel, nontoxic, and cheap plasticisers for NBR-PVC blends.

Linear Low Density Polyethylene-Biodegradability Using Bacteria from Marine Benthic Environment and Photodegradability Using Ultraviolet Light

Various compositions of linear low density polyethylene(LLDPE) containing bio-filler(either starch or dextrin)of various particle sizes were prepared.The mechanical,thermal,FTIR,morphological(SEM),water absorption and melt flow(MFI) studies were carried out.Biodegradability of the compositions were determined using a shake culture flask containing amylase producing bacteria(vibrios),which were isolated from marine benthic environment and by soil burial test. The effect of low quantities of metal oxides and metal stearate as pro-oxidants in LLDPE and in the LLDPE-biofiller compositions was established by exposing the samples to ultraviolet light.The combination of bio-filler and a pro-oxidant improves the degradation of linear low density polyethylene.The maleation of LLDPE improves the compatibility of the c blend components and thepro-oxidants enhance the photodegradability of the compatibilised blends.The responsibility studies on the partially biodegradable LLDPE containing bio-fillers and pro-oxidants suggest that the blends could be repeatedly reprocessed without deterioration in mechanical properties.

Short Nylon-6 Fibre/Rubber-Toughened Polystyrene Composites

The thesis describes studies on development of short Nylon-6 fibre composites based on rubber-toughened polystyrene (PS). Toughening was done using natural rubber (NR), styrene-butadiene rubber (SBR) and whole tyre reclaim (WTR). The composites were prepared by melt mixing in an internal mixer at 170 oC. It was found that the optimum blend ratio was 85/15 for PS/NR, 90/10 for PS/SBR and 90/22 for PS/WTR blends. The effect of dynamic vulcanisation on 85/15 PS/NR and 90/10 PS/SBR blends using dicumyl peroxide (DCP) at various concentrations were also studied. The dynamic crosslinking improved the tensile properties, flexural properties, impact strength and dynamic mechanical properties of both the blends. The effect of unmodified and resorcinol formaldehyde latex (RFL)-coated short Nylon-6 fibres on the mechanical properties, morphology and dynamic mechanical properties of 85/15 PS/NR, 90/10 PS/SBR and 90/22 PS/WTR blends were studied. Fibre loading was varied from 0 to 3 wt.%. For 85/15 PS/NR blend, there was a significant enhancement in tensile properties, flexural properties and impact strength with 1 wt.% of both unmodified and RFL-coated fibres. Dynamic mechanical analysis revealed that the storage modulus at room temperature was maximum at 1 wt.% fiber loading for both composites. The surface functionality of the fiber was improved by giving alkali treatment. Maleic anhydride-grafted-polystyrene (MA-g-PS) was prepared and used as a compatibiliser. The effect of MA-g-PS on the composites was investigated with respect to mechanical properties, morphology and dynamic mechanical properties. The compatibiliser loading was varied from 0 to 2 wt.%. The properties were enhanced significantly in the case of treated and untreated fibre composites at a compatibiliser loading of 0.75 wt.%. SEM analysis confirmed better bonding between the fibre and the matrix. Dynamic mechanical studies showed that the storage modulus at room temperature improved for treated fibre composites in the presence of compatibiliser. In the case of 90/10 PS/SBR composites, the addition of short Nylon-6 fibres at 1 wt.% loading improved the tensile modulus, flexural properties and impact strength while the tensile strength was marginally reduced. The surface treated fibers along with compatibiliser at 0.5 wt.% improved the tensile properties, flexural properties and impact strength. DMA reveale that the storage modulus at room temperature was better for composites containing untreated fibre and the compatibiliser. In the case of 90/22 PS/WTR blends, 1 wt.% unmodified fibre and 0.5 wt.% RFL-coated fibres improved tensile modulus, flexural properties and impact strength. Tensile strength was improved marginally. The surface treatment of Nylon fibre and the addition of compatibiliser at 0.5 wt.% enhanced the tensile properties, flexural properties and impact strength. The dynamic mechanical analysis showed that the storage modulus at room temperature was better for untreated fibre composites in conjunction with the compatibiliser. The thermal stability of PS/NR was studied by TGA. Thermal stability of the blends improved with dynamic vulcanisation and with the incorporation of RFL-coated Nylon fibres. The untreated and partially hydrolyzed fibre composites in conjunction with the compatibiliser enhanced the thermal stability. Kinetic studies showed that the degradation of the blends and the composites followed first order kinetics.

Studies on polymer blends with special reference to NBR/PVC and CR/PVC blends

The study is undertaken on PVC blends because of their all-round importance-One of the most prominent needs of PVC in application end-use is permanent plasticizationlo. Butadiene-acrylonitrile rubber (NBR) has been utilized as permanent plasticizer for PVC since the 1940s for wire and cable insulation, food contact, and pondliners used for oil containment23'24. Also plasticized PVC has been added to vulcanizable nitrile rubber, to yield improved ozone, thermal ageing, and chemical resistance resulting in applications including fuel hose covers, gaskets, conveyor belt covers, and printing roll covers. This blend is miscible in the range of 23 to 45 per cent acrylonitrile content in the butadiene-acrylqnitrile copolymerzs. The first phase of the study was directed towards modification blends. These blends, in addition to the polymers, require a host of additives like curatives for the NBR phase and stabilizers for the PVC phase26of the existing PVC blends, especially NBR/PVC. The second phase of the study was directed towards the development of novel PVC based blends. Chloroprene rubber (polychloroprene) (CR) is structurally similar to PVC and hence is likely to form successful blends with PVC32.

Studies on Elastomer Blends with special reference to NBR/Butyl, NR/Butyl and NBR/EPDM Blends

The distribution of curing agents and fillers in the constituents of an elastomer blend is an important factor which determines the curing behaviour and vulcanizate properties of the blend. The distribution of curatives and fillers largely depends on the nature of elastomers. The curatives tend to migrate preferentially to the rubber of higher unsaturation and/or higher polarity, and reinforcing fillers tend to get distributed in the low viscosity phase, resulting in inferior mechanical properties of the blends. The thesis suggests several methods for improving mechanical properties of blends like NBR/butyl, NR/butyl, NBR/EPDM and NR/.

Covulcanization of elastomer blends with special reference to NR/EPDM blends

Attempts have been made to attain satisfactory network structures in each of the phases of a rubber blend by minimising the cure rate imbalance by employing methods such as grafting of accelerators to the slow curing rubber, chemically bonding the crosslinking agents to the rubber in which it has lower solubility, functionalisation of the slow curing rubber, masterbatching of the curing agents to the slow curing rubber etc. Functionalisation of the slow curing constituents of NR/IIR and NR/EIPDM blends is tried using novel reagents as the first part of this study. However, the crux of the present study is a more direct approach to attaining a covulcanized state in NR/IIR and NR/EPDM blends: Precuring the slow curing rubber (IIR or EPDM) to a low level when it can still blend with NR and then to ck) the final curing after blending with NR. TNM3 precuring is also likely to minimise the viscosity mismatch. Since a low level of resmmal crosslink density is likely to be present lJ1 reclaimed rubbers, blending heat resistant reclaimed rubber such as butyl reclaim with NR may also have the same effect of precuring IIR, and then blending with NR. Hence use of IIR reclaim for developing blends with NR is also proposed to be investigated in this study

Numerical Simulation of Two-Part Underwater Towing System

The motion instability is an important issue that occurs during the operation of towed underwater vehicles (TUV), which considerably affects the accuracy of high precision acoustic instrumentations housed inside the same. Out of the various parameters responsible for this, the disturbances from the tow-ship are the most significant one. The present study focus on the motion dynamics of an underwater towing system with ship induced disturbances as the input. The study focus on an innovative system called two-part towing. The methodology involves numerical modeling of the tow system, which consists of modeling of the tow-cables and vehicles formulation. Previous study in this direction used a segmental approach for the modeling of the cable. Even though, the model was successful in predicting the heave response of the tow-body, instabilities were observed in the numerical solution. The present study devises a simple approach called lumped mass spring model (LMSM) for the cable formulation. In this work, the traditional LMSM has been modified in two ways. First, by implementing advanced time integration procedures and secondly, use of a modified beam model which uses only translational degrees of freedoms for solving beam equation. A number of time integration procedures, such as Euler, Houbolt, Newmark and HHT-α were implemented in the traditional LMSM and the strength and weakness of each scheme were numerically estimated. In most of the previous studies, hydrodynamic forces acting on the tow-system such as drag and lift etc. are approximated as analytical expression of velocities. This approach restricts these models to use simple cylindrical shaped towed bodies and may not be applicable modern tow systems which are diversed in shape and complexity. Hence, this particular study, hydrodynamic parameters such as drag and lift of the tow-system are estimated using CFD techniques. To achieve this, a RANS based CFD code has been developed. Further, a new convection interpolation scheme for CFD simulation, called BNCUS, which is blend of cell based and node based formulation, was proposed in the study and numerically tested. To account for the fact that simulation takes considerable time in solving fluid dynamic equations, a dedicated parallel computing setup has been developed. Two types of computational parallelisms are explored in the current study, viz; the model for shared memory processors and distributed memory processors. In the present study, shared memory model was used for structural dynamic analysis of towing system, distributed memory one was devised in solving fluid dynamic equations.

Rice husk ash – A valuable reinforcement for high density polyethylene

This paper presents the results of a study on the use of rice husk ash (RHA) for property modification of high density polyethylene (HDPE). Rice husk is a waste product of the rice processing industry. It is used widely as a fuel which results in large quantities of RHA. Here, the characterization of RHA has been done with the help of X-ray diffraction (XRD), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICPAES), light scattering based particle size analysis, Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Most reports suggest that RHA when blended directly with polymers without polar groups does not improve the properties of the polymer substantially. In this study RHA is blended with HDPE in the presence of a compatibilizer. The compatibilized HDPE-RHA blend has a tensile strength about 18% higher than that of virgin HDPE. The elongation-at-break is also higher for the compatibilized blend. TGA studies reveal that uncompatibilized as well as compatibilized HDPERHA composites have excellent thermal stability. The results prove that RHA is a valuable reinforcing material for HDPE and the environmental pollution arising from RHA can be eliminated in a profitable way by this technique.

Utilization of waste expanded polystyrene: Blends with silica-filled natural rubber

Expanded polystyrene (EPS) constitutes a considerable part of thermoplastic waste in the environment in terms of volume. In this study, this waste material has been utilized for blending with silica-reinforced natural rubber (NR). The NR/EPS (35/5) blends were prepared by melt mixing in a Brabender Plasticorder. Since NR and EPS are incompatible and immiscible a method has been devised to improve compatibility. For this, EPS and NR were initially grafted with maleic anhydride (MA) using dicumyl peroxide (DCP) to give a graft copolymer. Grafting was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. This grafted blend was subsequently blended with more of NR during mill compounding. Morphological studies using Scanning Electron Microscopy (SEM) showed better dispersion of EPS in the compatibilized blend compared to the noncompatibilized blend. By this technique, the tensile strength, elongation at break, modulus, tear strength, compression set and hardness of the blend were found to be either at par with or better than that of virgin silica filled NR compound. It is also noted that the thermal properties of the blends are equivalent with that of virgin NR. The study establishes the potential of this method for utilising waste EPS

Natural Rubber Latex Filler Masterbatch by Soap Sensitised Coagulation-Preparation, Processing and Evaluation

Sensitisation of natural rubber latex by addition of a small quantity of an anionic surfactant prior to the addition of a coacervant results in quick coagulation. The natural rubber prepared by the novel coagulation method shows improved raw rubber characteristics, better cure characteristics in gum and carbon black filled compounds and improved mechanical properties as compared to the conventionally coagulated natural rubber. Compounds based on dried masterbatches prepared by the incorporation of fluffy carbon black in different forms of soap sensitised natural rubber latices such as fresh latex, preserved field latex, centrifuged latex and a blend of preserved field latex and skim latex show improved cure characteristics and vucanizate properties as compared to an equivalent conventional dry rubber-fluffy carbon black based compound. The latex masterbatch based vulcanizates show higher level of crosslinking and better dispersion of filler. Vulcanizates based on fresh natural rubber latex- dual filler masterbatches containing a blend of carbon black and silica prepared by the modified coagulation process shows very good mechanical and dynamic properties that could be correlated to a low rolling resistance. The carbon black/silica/nanoclay tri-filler - fresh natural rubber latex masterbatch based vulcanizates show improved mechanical properties as the proportion of nanoclay increased up to 5 phr. The fresh natural rubber latex based carbon black-silica masterbatch/ polybutadiene blend vulcanizates show superior mechanical and dynamic properties as compared to the equivalent compound vulcanizates prepared from the dry natural rubber-filler (conventional dry mix)/polybutadiene blends

A Study of a Comprehensive Career Services System in Chinese Universities

Since 1999, with the adoption of expansion policy in higher education by the Chinese government, enrollment and graduate numbers have been increasing at an unprecedented speed. Accustomed to a system in which university graduates were placed, many students are not trained in “selling themselves”, which exacerbates the situation leading to a skyrocketing unemployment rate among new graduates. The idea of emphasizing career services comes with increasing employment pressure among university graduates in recent years. The 1998 “Higher Education Act” made it a legislative requirement. Thereafter, the Ministry of Education issued a series of documents in order to promote the development of career services. All higher education institutions are required to set up special career service centers and to set a ratio of 1:500 between career staff and the total number of students. Related career management courses, especially career planning classes, are required to be clearly included as specific modules into the teaching plan with a requirement of no less than 38 sessions in one semester at all universities. Developing career services in higher education has thus become a hot issue. One of the more notable trends in higher education in recent years has been the transformation of university career service centers from merely being the coordinators of on-campus placement into full service centers for international career development. The traditional core of career services in higher education had been built around guidance, information and placements (Watts, 1997). This core was still in place, but the role of higher education career services has changed considerably in recent years and the nature of each part is being transformed (Watts, 1997). Most services are undertaking a range of additional activities, and the career guidance issue is emphasized much more than before. Career management courses, especially career planning classes, are given special focus in developing career services in the Chinese case. This links career services clearly and directly with the course provision function. In China, most career service centers are engaging in the transformation period from a “management-oriented” organization to a “service-oriented” organization. Besides guidance services, information services and placement activities, there is a need to blend them together with the new additional teaching function, which follows the general trend as regulated by the government. The role of career services has been expanding and this has brought more challenges to its development in Chinese higher education. Chinese universities still remain in the period of exploration and establishment in developing their own career services. In the face of the new situation, it is very important and meaningful to explore and establish a comprehensive career services system to address student needs in the universities. A key part in developing this system is the introduction of career courses and delivering related career management skills to the students. So there is the need to restructure the career service sectors within the Chinese universities in general. The career service centers will operate as a hub and function as a spoke in the wheel of this model system, providing support and information to staff located in individual teaching departments who are responsible for the delivery of career education, information, advice and guidance. The career service centers will also provide training and career planning classes. The purpose of establishing a comprehensive career services system is to provide a strong base for student career development. The students can prepare themselves well in psychology, ideology and ability before employment with the assistance of effective career services. To conclude, according to the different characteristics and needs of students, there will be appropriate services and guidance in different stages and different ways. In other words, related career services and career guidance activities would be started for newly enrolled freshmen and continue throughout their whole university process. For the operation of a comprehensive services system, there is a need for strong support by the government in the form of macro-control and policy guarantee, but support by the government in the form of macro-control and policy guarantee, but also a need for close cooperation with the academic administration and faculties to be actively involved in career planning and employment programs. As an integral function within the universities, career services must develop and maintain productive relationships with relevant campus offices and key stakeholders both within the universities and externally.

Object Detection in Images by Components

In this paper we present a component based person detection system that is capable of detecting frontal, rear and near side views of people, and partially occluded persons in cluttered scenes. The framework that is described here for people is easily applied to other objects as well. The motivation for developing a component based approach is two fold: first, to enhance the performance of person detection systems on frontal and rear views of people and second, to develop a framework that directly addresses the problem of detecting people who are partially occluded or whose body parts blend in with the background. The data classification is handled by several support vector machine classifiers arranged in two layers. This architecture is known as Adaptive Combination of Classifiers (ACC). The system performs very well and is capable of detecting people even when all components of a person are not found. The performance of the system is significantly better than a full body person detector designed along similar lines. This suggests that the improved performance is due to the components based approach and the ACC data classification structure.

WAIS seminar: The Domain Name System: a magical mystery tour

Wednesday 12th March 2014 Speaker(s): Dr Tim Chown Organiser: Time: 12/03/2014 11:00-11:50 Location: B32/3077 File size: 642 Mb Abstract The WAIS seminar series is designed to be a blend of classic seminars, research discussions, debates and tutorials. The Domain Name System (DNS) is a critical part of the Internet infrastructure. In this talk we begin by explaining the basic model of operation of the DNS, including how domain names are delegated and how a DNS resolver performs a DNS lookup. We then take a tour of DNS-related topics, including caching, poisoning, governance, the increasing misuse of the DNS in DDoS attacks, and the expansion of the DNS namespace to new top level domains and internationalised domain names. We also present the latest work in the IETF on DNS privacy. The talk will be pitched such that no detailed technical knowledge is required. We hope that attendees will gain some familiarity with how the DNS works, some key issues surrounding DNS operation, and how the DNS might touch on various areas of research within WAIS.

La migración y los nuevos retos para el Estado-nación: relativismo ético y de identidad

Existe una fuerte preocupación por parte de los Estados acerca de la cuestión migratoria. En tanto en que ésta se convierte de una fuerza generadora de transformaciones sociales, políticas y económicas, también representan un reto para el Estado tradicional que bajo contextos democráticos no favorece sin embargo institucionalmente la implantación de modelos más pluralistas que favorezcan la inclusión de los migrantes bajo ciertas condiciones. La dificultad de implementar estos modelos radica no sólo en los posibles resultados de las nuevas relaciones que se generan, sino también en la combinación sistemática de hábitos y estructuras sociales que generan una cultura, siendo el significado simbólico de la identidad —pública y privada— la que da sentido al proceso adaptativo y asimilatorio de esos migrantes. Por lo que la migración ha tenido un efecto bipolar, por una parte favorece la propiciación de flexibilidad institucional que favorezca un sistema más plural en sentido político, por parte de los estados, pero también ha impulsado la idea de que existen identidades colectivas ajenas a lo nacional, que ponen en riesgo la cohesión social dentro de un Estado-nación.-----There is a deep concern of the Governments with respect to the migration issue. While it is moving from being a force generating social, political, and economical transformations, it also represents a challenge to the traditional State which despite its democratic framework, it however does not institutionally favor the implementation of more pluralist models which promote the inclusion of migrants under certain conditions. The obstacle to implementing these models lies not only on the potential results of the new relationships created, but also on the consistent blend of customs and social structures which generate a culture, being the symbolic meaning of the –public and private– identity which provides a purpose to the adaptation and assimilatory process of those migrants. Due to the bipolar effect of the migration, on the one hand it favors the promotion of an institutional flexibility which fosters a more politically plural system on the States’ side, and on the other hand it has boosted the notion of the existence of collective identities alien to nation-wide matters, which compromise the social consistency within a nation-state.