The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Anthony J. Ryan - One of the best experts on this subject based on the ideXlab platform.
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Application of thermal methods in the characterisation of poly(urethane-urea)s formed by Reaction Injection Moulding†
British Polymer Journal, 2007Co-Authors: Anthony J. Ryan, John L. Stanford, Richard H. StillAbstract:Compose forme par Reaction du diisocyanate de diphenylmethane avec des melanges de polyethertriol avec differentes diamines aromatiques
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Copolyureas formed by Reaction Injection Moulding: correlations between chemical structure, thermal properties and microphase separation
Polymer, 2003Co-Authors: Anthony J. Ryan, John L. Stanford, Adrian J. BirchAbstract:Abstract Segmented copolyureas comprising soft segments based on a polyoxypropylene polyamine and hard segments based on 4,4′-diphenylmethane diisocyanate (MDI) reacting with either 3,5-diethyltoluenediamine (DETDA) or methylene-bis-2,6-diisopropylaniline (MDIPA) have been formed by Reaction Injection Moulding (RIM). Novel RIM materials with MDI/DETDA hard segments and poly(dimethylsiloxane) soft segments have also been studied. RIM materials were characterized by d.s.c. and d.m.t.a. to obtain soft- and hard-segment glass transition temperatures, Tsg and THg, and the degree of microphase separation. Correlations between the chemical structure, thermal properties and microphase separation have been established using interaction parameters, χ, estimated from solubility parameters, and critical values of χ estimated from block copolymer theory. Hard-segment sequence length increases with hard-segment content, and values of THg are shown to increase according to the Flory-Fox relation. The effects of process and thermal histories on microphase separation are interpreted with reference to a phase diagram.
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Morphology and properties of novel copoly(isocyanurate-urea)s formed by Reaction Injection Moulding
Polymer, 2003Co-Authors: Anthony J. Ryan, John L. Stanford, Xiao Qiu TaoAbstract:Abstract Novel copoly(isocyanurate-urea)s have been produced by Reaction Injection Moulding (RIM). The materials were formed from ∼2:1 weight ratio of polyisocyanate to polyoxypropylene polyamine in the presence of an organic trimerization catalyst. In some cases an aromatic diamine chain extender was also used. The effects of the polyether polyamine functionality and the incorporation of aromatic diamine chain extenders on the morphology and properties of the copoly(isocyanurate-urea)s were studied using the SAXS, TEM, d.m.t.a. and tensile stress-strain techniques. The RIM materials were stiff plastics with room-temperature Young's moduli between 1.5 and 0.7 GPa, depending on the morphology. Development of morphology is a result of competition between polymerization kinetics, chemical gelation and (micro)phase separation. Materials with an isotropic, co-continuous morphology with a size-scale of ∼100 A had higher moduli than materials containing isolated glassy particles of ∼1 μm in size. Correlations between morphology and dynamic mechanical-thermal and tensile stress-strain properties of a systematic series of copoly(isocyanurate-urea)s have been established.
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Reactive processing of acrylic–polyurea interpenetrating networks: Reaction kinetic studies
Polymer International, 2001Co-Authors: John L. Stanford, Anthony J. Ryan, Ying YangAbstract:Interpenetrating networks (IPNs), comprising a crosslinked acrylic polymer as one component and either a polyurea, a segmented copolyurea or a copoly(urea–isocyanurate) as the other component, have been formed by Reaction Injection Moulding (RIM). The effects on the processability and the formation of the IPNs of (i) the crosslinker concentration in the acrylic component, (ii) the functionality of the amine-functionalized polyether used for the polyurea, and (iii) the weight fractions of acrylic components are evaluated. Reaction kinetics during RIM processing of the IPNs are studied using adiabatic temperature rise (ATR) measurements. The macroscopic structures of RIM materials, determined via optical microscopy, are used to assess the mixing characteristics operative during reactive processing of the various IPNs. The results are interpreted in terms of differences in the rates of polymerization and in the solubilities of the acrylic- and polyurea-forming components. © 2001 Society of Chemical Industry
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The formation and properties of acrylic-polyurea interpenetrating networks formed by Reaction Injection Moulding (RIM)
Macromolecular Symposia, 2001Co-Authors: John L. Stanford, Anthony J. Ryan, Ying YangAbstract:Interpenetrating networks (IPNs), comprising a crosslinked acrylic as one component and either a rubbery copoly(ether-urea) or a glassy copoly(urea-isocyanurate) as the other component, have been formed by Reaction Injection Moulding (RIM). Reaction kinetics during RIM processing of the IPNs were studied using adiabatic temperature rise (ATR) measurements. The effects of (i) crosslinker concentration in the acrylic component and (ii) the weight fraction of acrylic, on the formation of the IPNs during RIM and on the dynamic mechanical properties of finally-formed IPNS, were evaluated. The results are interpreted in terms of differences in the rates of polymerisation and in the solubilities of the acrylic- and polyurea-forming components, and of the phase-separated structures of the IPNs.
John L. Stanford - One of the best experts on this subject based on the ideXlab platform.
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STRUCTURAL COMPOSITES FORMED BY Reaction Injection Moulding
FRC 2000–Composites for the Millennium, 2014Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:ABSTRACT Structure development during the reactive processing of micro-composites comprising glass fibres and a copoly(urethane-urea) (PUUr) matrix was monitored, between 60 and 120 °C, by simultaneous SAXS/WAXS. Ordering in the PUUr matrix occurred by a two-stage, phase-separation process which, up to 100 °C, was retarded by the presence of fibres: above 100 °C, ordering in the micro-composites was accelerated and occurred by a single-stage process. Macro-composites containing up to 40% by volume of random continuous glass-fibres in a copoly(urea-isocyanurate) (PUrI) matrix were also formed by Reaction Injection Moulding. Microphase separation in the PUrI, between 70 and 135 °C, was monitored using time-resolved SAXS. The interlaminar fracture properties of the PUrI SRIM-composites were measured using Mode I and Mode II test geometries to determine fracture energy values GIc and GIIc, respectively.
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Application of thermal methods in the characterisation of poly(urethane-urea)s formed by Reaction Injection Moulding†
British Polymer Journal, 2007Co-Authors: Anthony J. Ryan, John L. Stanford, Richard H. StillAbstract:Compose forme par Reaction du diisocyanate de diphenylmethane avec des melanges de polyethertriol avec differentes diamines aromatiques
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Effects of soft-segment prepolymer functionality on structure–property relations in RIM copolyurethanes
Polymer, 2003Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyurethanes comprising 40–60% by weight of polyurethane hard segments (HS) and polyether soft-segment (SS) with different functionalities (SS-fn), have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4′ diphenylmethane diisocyanate (MDI) reacted with ethane diol (ED). The three SS-prepolymers used were all hydroxyl-functionalised poly(oxypropylene-b-oxyethylene)s with different nominal functionalities (fn) of 2, 3 and 4 but with a constant molar mass per functional group of ∼2000 g mol−1. RIM materials were characterised using differential scanning calorimetry, dynamic mechanical thermal analysis, tensile stress–strain and single-edge notch fracture studies. Predictions using a statistical model of the RIM-copolymerisation showed that increasing SS-fn lead to more rapid development of copolymer molar mass with isocyanate conversion. Experimentally, the RIM-PU exhibited a wide range of mechanical behaviour resulting from differences in molecular and morphological structures. Increasing SS-fn produced materials with improved mould release behaviour and fracture resistance. However, increasing SS-fn also reduced the degree of phase separation developed in the copolyurethanes, resulting in increased modulus–temperature dependence and poorer tensile properties.
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Structural composites formed by Reaction Injection Moulding - Interlaminar fracture properties of glass fibre mat-copoly(urea/isocyanurate) resin composites
Plastics Rubber and Composites, 2003Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:Structural (SRIM) composites, comprising up to 40% by volume of random continuous glass fibres in a specially developed copoly (urea/isocyanurate) (PUrI) matrix, have been formed via Reaction Injection Moulding (RIM). The two stage polymerisation process of the PUrI matrix provided low initial viscosity during mould filling followed by a snap Cure' to give tough composite materials in
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structural composites formed by Reaction Injection Moulding interlaminar fracture properties of glass fibre mat copoly urea isocyanurate resin composites
Plastics Rubber and Composites, 2003Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:Structural (SRIM) composites, comprising up to 40% by volume of random continuous glass fibres in a specially developed copoly (urea/isocyanurate) (PUrI) matrix, have been formed via Reaction Injection Moulding (RIM). The two stage polymerisation process of the PUrI matrix provided low initial viscosity during mould filling followed by a snap Cure' to give tough composite materials in <30s. Characterisation by DMTA confirmed the two phase morphology of the rubber toughened glassy matrix. Mode I and mode II interlaminar fracture tests, carried out in accordance with the ESIS protocol, gave values of G(Ic) and G(IIc) in the ranges 1.4-2.8 kJ m(-2) and 3.3-5.0 kJ m (-2), respectively, and were an order of magnitude greater than those determined for unidirectional carbon fibre-epoxy composites. The G(Ic) values for the SRIM composites are a factor of 2-3 greater than that (0.8 kJ m (-2)) for the unreinforced PUrI matrix and show significant variation due to extensive fibre bridging during crack propagation.
Arthur Wilkinson - One of the best experts on this subject based on the ideXlab platform.
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STRUCTURAL COMPOSITES FORMED BY Reaction Injection Moulding
FRC 2000–Composites for the Millennium, 2014Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:ABSTRACT Structure development during the reactive processing of micro-composites comprising glass fibres and a copoly(urethane-urea) (PUUr) matrix was monitored, between 60 and 120 °C, by simultaneous SAXS/WAXS. Ordering in the PUUr matrix occurred by a two-stage, phase-separation process which, up to 100 °C, was retarded by the presence of fibres: above 100 °C, ordering in the micro-composites was accelerated and occurred by a single-stage process. Macro-composites containing up to 40% by volume of random continuous glass-fibres in a copoly(urea-isocyanurate) (PUrI) matrix were also formed by Reaction Injection Moulding. Microphase separation in the PUrI, between 70 and 135 °C, was monitored using time-resolved SAXS. The interlaminar fracture properties of the PUrI SRIM-composites were measured using Mode I and Mode II test geometries to determine fracture energy values GIc and GIIc, respectively.
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Effects of soft-segment prepolymer functionality on structure–property relations in RIM copolyurethanes
Polymer, 2003Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyurethanes comprising 40–60% by weight of polyurethane hard segments (HS) and polyether soft-segment (SS) with different functionalities (SS-fn), have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4′ diphenylmethane diisocyanate (MDI) reacted with ethane diol (ED). The three SS-prepolymers used were all hydroxyl-functionalised poly(oxypropylene-b-oxyethylene)s with different nominal functionalities (fn) of 2, 3 and 4 but with a constant molar mass per functional group of ∼2000 g mol−1. RIM materials were characterised using differential scanning calorimetry, dynamic mechanical thermal analysis, tensile stress–strain and single-edge notch fracture studies. Predictions using a statistical model of the RIM-copolymerisation showed that increasing SS-fn lead to more rapid development of copolymer molar mass with isocyanate conversion. Experimentally, the RIM-PU exhibited a wide range of mechanical behaviour resulting from differences in molecular and morphological structures. Increasing SS-fn produced materials with improved mould release behaviour and fracture resistance. However, increasing SS-fn also reduced the degree of phase separation developed in the copolyurethanes, resulting in increased modulus–temperature dependence and poorer tensile properties.
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Structural composites formed by Reaction Injection Moulding - Interlaminar fracture properties of glass fibre mat-copoly(urea/isocyanurate) resin composites
Plastics Rubber and Composites, 2003Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:Structural (SRIM) composites, comprising up to 40% by volume of random continuous glass fibres in a specially developed copoly (urea/isocyanurate) (PUrI) matrix, have been formed via Reaction Injection Moulding (RIM). The two stage polymerisation process of the PUrI matrix provided low initial viscosity during mould filling followed by a snap Cure' to give tough composite materials in
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structural composites formed by Reaction Injection Moulding interlaminar fracture properties of glass fibre mat copoly urea isocyanurate resin composites
Plastics Rubber and Composites, 2003Co-Authors: John L. Stanford, Jonathan Powell, Arthur WilkinsonAbstract:Structural (SRIM) composites, comprising up to 40% by volume of random continuous glass fibres in a specially developed copoly (urea/isocyanurate) (PUrI) matrix, have been formed via Reaction Injection Moulding (RIM). The two stage polymerisation process of the PUrI matrix provided low initial viscosity during mould filling followed by a snap Cure' to give tough composite materials in <30s. Characterisation by DMTA confirmed the two phase morphology of the rubber toughened glassy matrix. Mode I and mode II interlaminar fracture tests, carried out in accordance with the ESIS protocol, gave values of G(Ic) and G(IIc) in the ranges 1.4-2.8 kJ m(-2) and 3.3-5.0 kJ m (-2), respectively, and were an order of magnitude greater than those determined for unidirectional carbon fibre-epoxy composites. The G(Ic) values for the SRIM composites are a factor of 2-3 greater than that (0.8 kJ m (-2)) for the unreinforced PUrI matrix and show significant variation due to extensive fibre bridging during crack propagation.
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Effects of soft segment prepolymer functionality on structure development in RIM copolymers
Polymer, 2000Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyureas and copoly(urethane-urea)s comprising 50 % by weight of polyurea hard segments (HS) and polyether soft segments (SS) with different functionalities, have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4'-diphenylmethane diisocyanate reacted with mixed isomers of 3,5-diethyltoluene diamine. The nominal functionality of the SS prepolymers used (either amino- or hydroxyl-functionalized polyoxypropylenes with a constant molar mass per functional group of similar to 2000 g mol(-1)) was systematically increased from 2 to 4. RIM materials were characterized using a simple demould toughness test, and d.s.c. and d.m.t.a. were used to obtain SS and HS glass transition temperatures, T-g(S) and T-g(H), and the degree of phase separation. Variations in the development of copolymer molar mass and HS sequence length, resulting from reactivity differences between the monomers and increasing functionality of the SS prepolymer, have been modelled using a statistical analysis of the RIM copolymerization. Schematic phase diagrams are presented, to aid interpretation of the complex effects of SS structure on the kinetic competition between polymerization and phase separation processes during the formation of RIM copolymers.
A. F. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Control of Reinforced Reaction Injection Moulding Machinery
IFAC Proceedings Volumes, 2017Co-Authors: Philip D. Coates, A. I. Sivakumar, A. F. JohnsonAbstract:Reinforced Reaction Injection Moulding (RRIM) has aroused considerable interest as a reactive processing method because of its low energy requirements and the design flexibility which is possible in the final polymer article. This area of reactive processing technology has been reviewed.1 The basis of the technology is that two reactive low viscosity fluids are delivered quantitative via a mixhead to a mould where rapid polymerization occurs with the formation of a solid article. The total cycle time can be very short e.g. < one minute. In our laboratories we have recently completed the construction of a laboratory-scale research machine for studying the dynamic interactions of the processing technology and the chemistry for very fact reacting urethane systems. The demands made by the urethane chemistry on the processing machinery are very considerable in that the two-component Reaction system has to be quantitatively mixed and delivered to the mould in a controlled manner and in a matter of just a few seconds (< five seconds). The dynamic characteristics of the machinery and the control strategies are of paramount importance. The system we have developed is fully computerized and not only incorporates the feedback loops and time sequencing of events, but also allows for the full monitoring of the behaviour of the polymerization Reaction in the mould. In this short communication we wish to describe the fundamental principles of the technology we have used, the control procedures which have been adopted and the influence of the processing technology in general on the final product quality.
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Thermal behaviour of nylon 6-poly (ether-esteramide) block copolymers
Journal of Materials Science, 1995Co-Authors: S. -w. Tsui, A. F. JohnsonAbstract:Block copolymers have been produced by anionic polymerization of caprolactam with end-functionalized soft-block components derived from polymeric polyols. This method of synthesis gives rise to linear segmented block copolymers with alternating polyether soft blocks and polyamide hard blocks. Copolymers with 10–50% w/w of polyether polyol prepolymer have been the particular focus of attention in this work because of their better physical integrity than copolymers of other compositions. Their phase inversion and morphology/property relationships have been examined by means of differential thermal calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). In this work, the polymers have been hand-cast, but the materials do find application in the Reaction Injection Moulding field.
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Structural Reaction Injection Moulding of polyethylene fibre reinforced epoxy composites
Plastics Rubber and Composites Processing and Applications, 1995Co-Authors: S. D. Long, P. J. Hine, Philip D. Coates, A. F. Johnson, R. A. Duckett, I. M. WardAbstract:This paper describes the manufacture and properties of polyethylene fibre reinforced epoxy composites made by structural Reaction Injection Moulding (SRIM). A two stream fast reacting epoxy formulation was reinforced with mats woven from two different high modulus polyethylene fibres : melt spun TENFOR fibre and gel spun DYNEEMA fibres. The fibres were used in both the untreated and plasma treated states to assess the effects of surface treatment on fibre/matrix adhesion. The high speed impact properties of the various composite systems were obtained from falling dart and high speed three point bend tests, and are discussed in comparison with properties of epoxy-polyethylene fibre composites made by a traditional prepreg compression Moulding route.
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Influence of Reaction Injection Moulding (RIM) processing variables on the mechanical properties of a commercial linear segmented polyamide
Plastics Rubber and Composites Processing and Applications, 1995Co-Authors: S. D. Long, I. Dawood, P. D. Coates, A. F. JohnsonAbstract:The influence of reactant Injection time and mould resistance time on the properties of a commercial polyamide Reaction Injection Moulding (RIM) formulation has been investigated, using a centre-gated disk mould. The machine performance during Injection and the stoichiometry of each Injection has been analysed. A range of tests has been carried out on the Mouldings including mechanical, instrumented falling weight impact and differential scanning calorimetry. The Mouldings are found to contain voids, resulting from gaseous entrainment at the reactant flow front during mould filling and the absorption of nitrogen gas by the reactants, which are found to have a critical effect on the mechanical properties, particularly the extension at the maximum tensile stress. In the case of void-free material, small changes in Injection time can lead to significant changes in mechanical properties, whereas changes in mould residence time are less significant
Richard H. Still - One of the best experts on this subject based on the ideXlab platform.
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Application of thermal methods in the characterisation of poly(urethane-urea)s formed by Reaction Injection Moulding†
British Polymer Journal, 2007Co-Authors: Anthony J. Ryan, John L. Stanford, Richard H. StillAbstract:Compose forme par Reaction du diisocyanate de diphenylmethane avec des melanges de polyethertriol avec differentes diamines aromatiques
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Effects of soft-segment prepolymer functionality on structure–property relations in RIM copolyurethanes
Polymer, 2003Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyurethanes comprising 40–60% by weight of polyurethane hard segments (HS) and polyether soft-segment (SS) with different functionalities (SS-fn), have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4′ diphenylmethane diisocyanate (MDI) reacted with ethane diol (ED). The three SS-prepolymers used were all hydroxyl-functionalised poly(oxypropylene-b-oxyethylene)s with different nominal functionalities (fn) of 2, 3 and 4 but with a constant molar mass per functional group of ∼2000 g mol−1. RIM materials were characterised using differential scanning calorimetry, dynamic mechanical thermal analysis, tensile stress–strain and single-edge notch fracture studies. Predictions using a statistical model of the RIM-copolymerisation showed that increasing SS-fn lead to more rapid development of copolymer molar mass with isocyanate conversion. Experimentally, the RIM-PU exhibited a wide range of mechanical behaviour resulting from differences in molecular and morphological structures. Increasing SS-fn produced materials with improved mould release behaviour and fracture resistance. However, increasing SS-fn also reduced the degree of phase separation developed in the copolyurethanes, resulting in increased modulus–temperature dependence and poorer tensile properties.
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Effects of soft segment prepolymer functionality on structure development in RIM copolymers
Polymer, 2000Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyureas and copoly(urethane-urea)s comprising 50 % by weight of polyurea hard segments (HS) and polyether soft segments (SS) with different functionalities, have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4'-diphenylmethane diisocyanate reacted with mixed isomers of 3,5-diethyltoluene diamine. The nominal functionality of the SS prepolymers used (either amino- or hydroxyl-functionalized polyoxypropylenes with a constant molar mass per functional group of similar to 2000 g mol(-1)) was systematically increased from 2 to 4. RIM materials were characterized using a simple demould toughness test, and d.s.c. and d.m.t.a. were used to obtain SS and HS glass transition temperatures, T-g(S) and T-g(H), and the degree of phase separation. Variations in the development of copolymer molar mass and HS sequence length, resulting from reactivity differences between the monomers and increasing functionality of the SS prepolymer, have been modelled using a statistical analysis of the RIM copolymerization. Schematic phase diagrams are presented, to aid interpretation of the complex effects of SS structure on the kinetic competition between polymerization and phase separation processes during the formation of RIM copolymers.
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Effects of soft-segment prepolymer functionality on the thermal and mechanical properties of RIM copolymers
Polymer International, 1996Co-Authors: John L. Stanford, Richard H. Still, Arthur WilkinsonAbstract:Segmented copolyureas (PUr) and copoly(urethane-urea)s (PUU) comprising 50% by weight of polyurea hard segments (HS) and polyether soft segment (SS) with different functionalities, have been formed by Reaction Injection Moulding (RIM). The HS were formed from 4,4'-diphenylmethane diisocyanate reacted with mixed isomers of 3,5-diethyltoluene diamine. The nominal functionality of the SS prepolymers used (either amino- or hydroxyl-functionalised polyoxypropylenes with a constant molar mass per functional group of ∼2000 g mol -1 ) was systematically increased from 2 to 4. RIM materials were characterised using dynamic mechanical thermal analysis, differential scanning calorimetry, tensile stress-strain and fracture mechanics studies. Generally, the PUr exhibited far superior thermal-mechanical properties than equivalent PUU materials but inferior fracture resistance, owing to morphological variations resulting from differences in copolymerisation behaviour. For both systems, tensile behaviour was shown to be dominated by the degree of phase separation, whereas fracture properties showed a degree of dependence on SS functionality.
