Relationships between micromorphology and impact properties of injection moulded isotactic polypropylene

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The micromorphology and properties of injection moulded semi-crystalline polymers can be significantly modified by changes in the injection moulding parameters and the design of mould. Further modifications to the microstructure and properties occur following the incorporation of additives into a thermoplastic compound, such as stabilisers, pigments, nucleants, etc. Many published papers refer to these changes in microstructure, but very little attention has been devoted to the detailed characterisation of the outer surfaces of injection mouldings, which play an important part in determining impact properties. The main objective of this research project was to carry out a systematic examination of the micromorphology of a range of isotactic polypropylene injection mouldings, paying particular attention to the outer layers which are difficult to characterise and to then relate the micromorphology revealed to the impact properties. Models which relate the mechanism of impact failure to microstructure and processing route have been developed as a result. Particular attention was given to the careful production of injection mouldings to ensure reproducible micromorphologies and mechanical properties for set processing conditions. This was carried out prior to very comprehensive characterisation of micromorphology using a range of analytical techniques including, straightforward microtomy and optical microscopy, x-ray diffraction, Differential Scanning Calorimetry and the application of a new etching and replication method for transmission electron microscopy studies. The impact properties of mouldings were determined by instrumented falling-weight and instrumented Izod impact test methods. Injection mouldings revealed a complex skin-core morphology, the width, degree of orientation, crystal form (α or β) and spherulite size of the various layers were found to be strongly dependent on the moulding parameters and additives incorporated. The role of such factors in determining the impact properties was identified providing valuable information to commercial moulders of polypropylene.National Physical Laboratory and Science and Engineering Research Counci

State estimators in soft sensing and sensor fusion for sustainable manufacturing

State estimators, including observers and Bayesian filters, are a class of model-based algorithms for estimating variables in a dynamical system given sensor measurements of related system states. They can be used to derive fast and accurate estimates of system variables which cannot be measured directly (’soft sensing’) or for which only noisy, intermittent, delayed, indirect or unreliable measurements are available, perhaps from multiple sources (’sensor fusion’). In this paper we introduce the concepts and main methods of state estimation and review recent applications in improving the sustainability of manufacturing processes. It is shown that state estimation algorithms can play a key role in manufacturing systems to accurately monitor and control processes to improve efficiencies, lower environmental impact, enhance product quality, improve the feasibility of processing more sustainable raw materials, and ensure safer working environments for humans. We discuss current and emerging trends in using state estimation as a framework for combining physical knowledge with other sources of data for monitoring and control of distributed manufacturing systems

Rheological Properties of Polymers: Structure and Morphology of Molten Polymer Blends

The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compounds and blends are discussed. The importance of the rheological properties of polymer mixtures in the development of the phase structure is discussed. And the importance of considering the stress and/or strain history of a material sample in a rheological investigation is discussed. Finally, the outlook on the past, present and future developments in the field of polymer rheology are given. The review concludes with a brief discussion on the opportunities and challenges in the field of polymer blends and blend rheology

Various Aspects of Silicon Polymer Chemistry

This special issue of Molecules is dedicated to Professor Julian Chojnowski on the occasion of his 85th birthday for his outstanding achievements in the field of organosilicon chemistry. This issue contains one review and eleven original articles written by eminent experts on various aspects of silicon polymer chemistry, which reflect the tireless passion of Professor Chojnowski to the development of organosilicon chemistry

Novel biopolymer constructs: physical properties and antimicrobial efficacy

Antimicrobial resistance (AMR) is a life-threatening issue and the situation is deteriorating each year resulting in an increasing number of deaths. The resistance of drugs developed by microbes is a natural process but this can be sped up easily due to unhygienic environments, lack of appropriate guidelines for the use of drugs in certain countries as well as the unclear direction of scientific research into AMR. Some pessimistic experts even believe this problem will never be tackled as it is the result of a long-term human intervention that has affected other biological organisms which inhabit the same ecosystem. Fortunately, such negative comments and predictions have actually accelerated momentum and encouraged and inspired more research activity in this area. In this project, the main idea involved producing a selection of biopolymer constructs with the specific aim of translating the intrinsic antimicrobial properties of naturally occurring materials (e.g. chitin, lignin, banana leaf) to a biodegradable polymer (PLA) for possible biomedical applications (e.g. would healing). All chitin, lignin and natural products (e.g. banana leaves) have one thing in common which is that they all exhibit intrinsic antimicrobial properties and have great potential for use as non-toxic antimicrobial materials. Versatile engineering tools such as electrospinning, melt-extrusion and injection moulding also allow us to produce additional materials and visualise the possibility of producing the products on an industrial scale. The first interest in this project lied on using ionic liquids (ILs), electrospinning and film casting to produce novel biomaterials. In the later stage of the project, poly(L-lactic acid) as a base polymer matrix, tungsten disulphide and triacetin as a plasticizer were introduced that can be subjected to melt-extrusion and injection moulding along with chitin and lignin. In this report, the history of antibiotic discovery and key features of antimicrobial resistance are introduced. Previous research conducted is also described in a detailed literature review with supporting evidence focused on chitin, lignin, banana leaves, poly(L-lactic acid), tungsten disulphide as well as techniques used in this project such as electrospinning and melt-extrusion. The detail of the initial scoping experiments electrospinning of biopolymer/ionic liquid solutions is then described as is the introduction of co-solvents and other polymers to assist the electrospinning process. The characteristics of the composites produced using melt-extrusion and injection moulding are also fully discussed. More importantly, bioassays of the composites will be shown which to provide crucial ideas for the key elements required for biomedical applications

Rheological Properties of Polymers: Structure and Morphology of Molten Polymer Blends

The article reviews a brief literature on the rheological properties of polymer melts and blends. Experimental results on polymer blends are summarized. Technically, vital types of multi-phase polymers such as compounds and blends are discussed. The importance of the rheological properties of polymer mixtures in the development of the phase structure is discussed. And the importance of considering the stress and/or strain history of a material sample in a rheological investigation is discussed. Finally, the outlook on the past, present and future developments in the field of polymer rheology are given. The review concludes with a brief discussion on the opportunities and challenges in the field of polymer blends and blend rheology

ALIPHATIC SILICA‐EPOXY SYSTEMS CONTAINING DOPO‐BASED FLAME RETARDANTS, BIO‐WASTES, AND OTHER SYNERGISTS

Most industrial applications require polymer‐based materials showing excellent fire performances to satisfy stringent requirements. No‐dripping and self‐extinguishing hybrid silica‐epoxy composites can be prepared by combining tailored sol‐gel synthesis strategies with DOPO‐based flame retardants, bio‐wastes, and other synergists. This approach allows for achieving V‐0 rating in UL‐94 vertical flame spread tests, even using a sustainable route, aliphatic amine as hardener, and low P loadings