Jeff Dickerhoof; Zeon Europe GmbH, Germany and Samuel C. Harber*, Brian J. Cail, Charles Smith, Zeon Chemicals, USA
In early 2003 a new class of high performance thermoplastic vulcanizates (TPV) was commercially introduced. These materials have improved heat (150
An overview of rubber lattices
Dr Prachaya Jumpasut, International Rubber Study Group, UK
This paper draws on the strengths of the International Rubber Study Group (IRSG) as the leading provider of economic and statistical information on the world rubber industry. The presentation, essentially non-technical in nature, provides a concise overview of the broad trends in production, consumption, trade and prices in the natural rubber latex (NRL) segment of the rubber industry at the national, regional (particularly with respect to Europe) and global level. Furthermore, in order to put NRL into context, its position relative to other types of NR is considered. While the main thrust of the paper is concentrated around NRL, the presentation will briefly touch on synthetic rubber lattices (SRL), particularly with respect to end uses and perceived material competition. One important conclusion drawn from the paper is that consumption of both NRL and SRL is greatest in producing countries, reflecting the existence of policies aimed at providing value-addition and high transportation costs.
Chemical modification of a new thermoplastic polyolefin elastomer
Nikhil K. Singha and Sandip Biswas, Indian Institute of Technology, India
Development of new single site constraint geometry metallocene catalysts enabled to prepare copolymers of ethylene with higher α-olefins which have improved properties and better processibility compared to conventional polyolefin elastomers like EPDM, IIR etc. The copolymers can be elastomers or thermoplastic elastomers (TPE) depending on the comonomer content. These new polyolefin elastomers (commercially named as Engage) have poor compatibility towards polar polymers. Chemical modification via grafting is an interesting method of compatibilizing immiscible polymer blends as well as improving interfacial adhesion and technological properties in polymeric composites. In this investigation Engage has been modified by grafting with various materials like different (meth)acrylates, thioglycolic acid, maleic anhydride etc.. This kind of modification not only improves its interfacial properties but also other important properties. For example, grafting with hydroxyl ethyl methacrylate improves the biocompatibility of the elastomers. The grafting has been carried out by different methods. The different mechanical properties have been carried out and are compared with the unmodified polymer. The modified elastomers have been characterized by FT-IR, NMR, TGA, DSC, SEM, Zwick tensile machine.
Compounding latices to meet performance and cost requirements
David Hill, SSL International plc, UK
This paper will address the factors to be taken into account when formulating rubber latices for dipping. Many products made from latices must comply with stringent regulations dictating performance and residual chemical content, and satisfying these requirements whilst meeting cost and environmental constraints provide the compounder with a multi-faceted challenge. This paper will describe the general principles, both practical and scientific, which underlie the compounding of natural and synthetic latices, including the selection and preparation of stabilizers, accelerators and antioxidants. Other aspects of formulation, such as blending different latices, incorporating fillers, pigments and plasticizers will be explored. The influence the formulation can have on dipping, film-forming, drying and other manufacturing operations will be discussed, and ways in which the latex compound can be made more environmentally friendly through reduction in materials, energy usage and effluent will be presented.
Effect of morphology on the elastic properties of segmented block copolymers
Reinoud J. Gaymans and Martijn van der Schuur, University of Twente, The Netherlands
The elastic properties of cross linked polyurethanes are excellent, however poor for linear PU
EPDM-based thermoplastic vulcanisates: crosslinking chemistry and dynamic vulcanisation along the extruder axis
Martin van Duin, DSM Research, The Netherlands
This paper will consist of two parts: 1) A general overview on TPVs will be given, dealing with positioning of TPVs as thermoplastic elastomers, commercial production and suppliers, composition, morphology, properties and applications. The relationships between composition/morphology/properties/applications will be explained. 2) Results of recent experimental studies will be presented. The chemical mechanism of resol crosslinking of EPDM has been elucidated using low-molecular-weight model studies and via 13C NMR of resol-crosslinked 13C-labeled EPDM. The proposed cationic mechanism explains the reactivity of different EPDM grades. Increasing the number of substituents on the residual EPDM unsaturation results in enhanced reactivtiy for resol crosslinking. The dynamic vulcanisation process of EPDM/HDPE blends has been studied by taking samples along the extruder axis and determining the morphology and degree of crosslinking. Crosslinking of the elastomer phase already starts before melting of the thermoplastic phase. Upon melting the morphology is more or less immediately established, while crosslinking of the elastomer phase continues. For a 50/50 blend phase inversion from an EPDM matrix via a co-continuous EPDM phase to an EPDM dispersion is observed. Finally, the melt and solid state properties of the resulting TPVs will be correlated with the morphology and composition.
Masterbatches: a cost effective delivery system for latex compounding raw materials
James Finn, Akron Dispersions, USA
Latex formulations are typically designed using a wide variety of chemical ingredients, i.e. accelerators, activators, antioxidants and modifiers. These materials are added to the latex, during compounding, as separate waterbased dispersions. Masterbatches or a dispersion representing the combination of all the individual chemical dispersions, in the correct proportions, offers some significant advantages to the latex compounder. These advantages, namely, reduced stock keeping units (SKU
New highly-crosslinked TPES based on VNB-EPDM with improved compression set
Maria D. Ellul, Advanced Elastomer Systems, L.P., USA and P.S. Ravishankar, ExxonMobil Chemical Co., USA
5-vinyl-2-norbornene EPDM, (VNB-EPDM) is more efficient than 5-ethylidene-2-norbornene, (ENB-EPDM) in peroxide crosslinking, producing high cure state at low concentrations of VNB and peroxide. Recently a process for incorporating 5-vinyl-2-norbornene, (VNB), diene termonomer in the EPDM backbone was developed, resulting in a polymer with a high degree of long chain branching by Ziegler polymerization of the VNB pendent double bond and yet free of gel. For TPVs made by dynamic vulcanization of EPDM-polypropylene, it is advantageous to use lower peroxide levels to produce highly-crosslinked TPVs, in order to mitigate the undesirable degradation of the polypropylene. Through the use of these new VNB-EPDMs only a low level of VNB termonomer is necessary (<3 wt%) to produce TPVs with lower levels of peroxide and a high degree of cure. The resulting materials have improved elasticity resulting in up to 50% lower compression and tension set values than conventional phenolic resin cured TPVs. These new peroxide-cured TPVs based on VNB-EPDM have other useful attributes that include, lighter color, low moisture uptake and improved chemical resistance.
New thermplastic vulcanizates (TPVs) with improved processability for injection molding applications
Harry Lardinoye, Jan Tom Fernhout, Yundong Wang, Hua Cai, and Ryszard Brzoskowski, DSM Thermoplastic Elastomers BV , The Netherlands
A new line of thermoplastic vulcanizates (TPVs) has been introduced by DSM Thermoplastic Elastomers for injection molding applications where UV resistance is critical. This new line of products, consisting of several grades with hardness ranging from 50 to 85 shore A in black color, shows superior flow characteristics and balanced properties meeting existing automotive material specifications. In this paper, we will discuss some of the features associated with this new line of products. After a short introduction on injection molding, specifically for TPVs, some basic properties of these new products are discussed, like crystallization behavior and cycle time. Most of these grades are formulated with the intention to increase their rate of crystallization over other commercially available TPVs. This ensures a faster solidification of the melt upon cooling, leading to a reduction in cycle time. A processing guideline gives information on the processing window of these new materials. Also some examples of typical applications in the automotive industry as glazing and sealing systems are included. As a conclusion: These high flow products are formulated to have low viscosity for ease of flow and better surface appearance. Through composition and process optimization, this product line is designed to offer excellent UV resistance, good fogging properties, and good mechanical and elastic properties with superior processability and consistency.
Novel accelerators for synthetic polyisoprene and carboxylated nitrile latices
K B Chakraborty and R Couchman, Robinson Brothers Limited, UK
Unlike Natural Rubber latices Synthetic Polyisoprene and Carboxylated Nitrile latices are free from natural proteins and do not exhibit TypeI allergic reactions. However they are usually vulcanised with traditional Dithicarbamate and Thhiuram based accelerators. These are the precursors to Type IV skin allergy, potentially carcinogenic nitrosamines and contact discoloration.
Peroxide cured ethylene-propylene-diene/polypropylene (PP/EPDM) Thermoplastic vulcanizates: effects of methacrylate co-agents on properties
F.R. de Risi and J.W.M Noordermeer, Dutch Polymer Institute and University of Twente, The Netherlands
The development of thermoplastic vulcanizates (TPVs) as a type of thermoplastic elastomers, has gained large technical and economic importance. TPVs are typically characterized by a chemically crosslinked rubber phase, embedded in a thermoplastic matrix, produced by dynamic vulcanization during mixing the rubber with the thermoplastic in the molten state. In the present work, the effects of different methacrylate-type co-agents as co-curing agents for peroxide vulcanization of PP/EPDM TPVs are reported, whereby the weight fraction of the EPDM vs. the PP is varied from 30, 50 to 70%. The methacrylates tested were: Ethylene glycol dimethacrylate (EDMA), Trimethylol propane trimethacrylate (TMPTMA, often referred to as TRIM) and Zinc dimethacrylate (ZDMA). Crosslinking was carried out at a fixed content of dicumyl peroxide with the amounts of co-agents varied. The purpose of the co-agents was to boost EPDM-crosslinking and at the same time prevent degradation of the PP by β-scission. Significant differences are reported: although all three methacrylates have the same ethylenic moieties as the reactive groups, the observed differences in mechanical properties point to diverse structures of the crosslink networks of the PP/EPDM TPVs. Out of the three co-agents, TMPTMA gives the best overall balance of properties, in EPDM crosslinking and preventing PP-degradation. This is explained by the positioning of the solubility parameter of this co-agent just in between those of EPDM and PP. The solubility parameter for EDMA is far away from either one. ZDMA, although giving very good room temperature properties like Tensile Strength, shows signs of thermo-reversion of the crosslinks in the Compression Set measured at 70 C.
Recovery and fatique properties of NRTPV
S. Cook, J. Patel and A. J. Tinker, Tun Abdul Razak Research Centre, UK
The recovery and fatigue properties are compared for a range of different
The 21st century value chain: solutions in action
U. Nilsson , Advanced Elastomer Systems NV/SA, Belgium
Market leaders get more from every step of the value chain. That includes traditional steps such as manufacturing, purchasing and distribution but also information technology, commercial operations, customer service and chief executive involvement. The foundation of that leadership is a customer-focused culture that permeates all levels of the organization. Through strategic and skillful coordination of every aspect of the value chain and a commitment to making customers more profitable, organizations can make themselves more profitable in the process. They add more value for their customers, suppliers and shareholders and add more job security for employees. This presentation will provide examples of the solution-oriented value chain in action, including a description of how the Santoprene(TM) product line of ExxonMobil Chemical has excelled by adding value for customers.
Towards higher mixer line productivity by optimising fingerprints
Gerard Nijman, Vredestein Banden BV, The Netherlands
The paper deals with a study of fingerprints of several mixer lines for various compounds and situations. It will be shown that - arbitrary mixing process variations (like charging time of fillers) could lead to a mixing time variation of 10
Vita Talalay latex - the best foam for mattresses
Anna Teeuwen, Radium Foam BV, The Netherlands
Joseph Talalay invented