Crosslinking monomer

The influence of styrene concentration in UPR on the miscibility with unsaturated polyester and the mechanical properties was investigated [24]. A commercial UPR containing 38 wt % styrene was used to prepare samples with 6-58 wt % styrene by partial evaporation of styrene in vacuo or dilution with fresh styrene. Sets of curves presenting the effect of styrene content on the glass transition temperature and the mechanical properties of the cured UPR vs. temperature were presented. Phase separation in the crosslinked UPR with increase in styrene concentration was observed. 

Properties Styrene Vinyltoluene 2-Hydroxyethyl methacrylate Glycerol a-allyl ether 

A - the resins synthesized in two-step procedure, B - the resins obtained in one-step synthesis - Two exotherm signals were recorded 

Vinyltoluene, 2-hydroxyethyl methacrylate and glycerol monoallyl ether (Table 12) were tested as the crosslinking monomers for the curing of unsaturated polyesterimide resins [28]. The monomers were chosen taking into account their lower volatiUty and toxicity in comparison to styrene. 

The enthalpy (Aff) and activation energy (Ea), pre-exponential coefficient [In(Ko)], and order of reaction (n) for each monomer were determined using the DSC method (Table 13). 

---

This is also known as Bulk Moulding Compound (BMC). It is blended through a mix of unsaturated polyester resin, crosslinking monomer, catalyst, mineral fillers and short-length fibrous reinforcement materials such as chopped glass fibre, usually in lengths of 6-25 mm. They are all mixed in different proportions to obtain the required electromechanical properties. The mix is processed and cured for a specific time, under a prescribed pressure and temperature, to obtain the DMC. 

Reaction between crosslinking monomers already incorporated in the backbone. 

The polymers were prepared using MAA as functional monomer and EDMA as crosslinking monomer if not otherwise noted. VPY= 2- or 4-vinylpyridine TRIM = trimethylolpropane trimethacrylate DPGE = (R)-N,0-dimethacryloylphenylglycinol PYAA = 3-(4-pyridinyl)acrylic acid. 

At the downstream of the extrusion process a suitable reaction catalyst, reactive diluent, e.g., crosslinking monomer, is fed into the molten polymer mix. 

John, G. and Pillai, C.K.S. (1992) Self-crosslinkable monomer from cardanol crosslinked beads of poly(cardanyl acrylate) by suspension polymerization. Makromolekulare Chemie Rapid Communications, 13, 255—259. 

Fig. 1. Preparation of configurational biomimetic imprinted networks for molecular recognition of biological substrates. A Solution mixture of template, functional monomer(s) (triangles and circles), crosslinking monomer, solvent, and initiator (I). B The prepolymerization complex is formed via covalent or noncovalent chemistry. C The formation of the network. D Wash step where original template is removed. E Rebinding of template. F In less crosslinked systems, movement of the macromolecular chains will produce areas of differing affinity and specificity (filled molecule is isomer of template).

In polymer science and technology, linear, branched and crosslinked structures are usually distinguished. For crosslinked polymers, insolubility and lack of fusibility are considered as characteristic properties. However, insoluble polymers are not necessarily covalently crosslinked because insolubility and infusibility may be also caused by extremely high molecular masses, strong inter-molecular interaction via secondary valency forces or by the lack of suitable solvents. For a long time, insolubility was the major obstacle for characterization of crosslinked polymers because it excluded analytical methods applicable to linear and branched macromolecules. In particular, the most important structural characteristic of crosslinked polymers, the crosslink density, could mostly be determined by indirect metho ds only [ 1 ], or was expressed relatively by the fraction of crosslinking monomers used in the synthesis. 

In the early days of polymer science, when polystyrene became a commercial product, insolubility was sometimes observed which was not expected from the functionality of this monomer. Staudinger and Heuer [2] could show that this insolubility was due to small amounts of tetrafunctional divinylbenzene present in styrene as an impurity from its synthesis. As little as 0.02 mass % is sufficient to make polystyrene of a molecular mass of 2001000 insoluble [3]. This knowledge and the limitations of the technical processing of insoluble and non-fusible polymers as compared with linear or branched polymers explains why, over many years, research on the polymerization of crosslinking monomers alone or the copolymerization of bifunctional monomers with large fractions of crosslinking monomers was scarcely studied. 

The intrinsic viscosity of microgels described in [9] decreased with increasing fractions of the crosslinking monomer to about 8 ml/g which was still above the theoretical value for hard spheres of about 2.36 ml/g according to the Einstein equation and assuming a density of 1.1 g/ml. Obviously, due to the relatively low fraction of the crosslinking monomer, these microgels did not behave like hard spheres and were still swellable to some extent. 

For the formation of microgels the presence of a crosslinking monomer is not always necessary. Thus, microgels have also been detected in polymers prepared with bifunctional monomers, e.g. poly(acrylonitrile-co-vinylacetate) [39], polyethylene [40],poly(vinylchloride) [41] andpoly(vinylidenefluoride) [42].Obviously, the reason for the intramolecular crosslinking with the formation of microgels are side reactions. 

Fig. 21. Molecular imprinting of (R)-propranolol using methacrylic acid (MAA) as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the crosslinking monomer. (Reprinted with permission from [126], Copyright 1998 Elsevier). The enantiose-lectivity of a given polymer is predetermined by the configuration of the ligand, R-propranolol present during its preparation. Since the imprinted enantiomer possesses a higher affinity for the polymer, the separation is obtained with a predictable elution order of the enantiomers...

The morphology of the monoliths is closely related to their porous properties, and is also a direct consequence of the quality of the porogenic solvent as well as the percentage of crosslinking monomer and the ratio between the monomer and porogen phases. The presence of synergistic effects of these reaction conditions was verified using multivariate analysis [65]. 

Note When the content of the crosslinking monomer is high, the macromolecule is treated as a copolymer molecule. 

The name of a crosslinking monomer molecule having two or more different types of polymerizable groups, each serving as a monomeric unit for one of two or more different linear chains, is cited with the name of each of the chains with the symbol v. 

Note When the proportion of the crosslinking monomer having two or more different polymerizable groups is a significant fraction of the total, the constituent chains are treated as copolymer chains. 

Crosslinkable monomers including 1,2-ethanediol di(meth)acrylate, 1,12-dode-canediol di(meth)acrylate, and 1,4 butanediol di(meth)acrylate were reacted with step 2 monomers of the current application by Moore et al. (3) to create biological amine-reactive materials useful in medical diagnostics. Additional crosslinked amine-reactive materials were prepared by Leir et al. (4) and are discussed. 

VI), were prepared in a mixture containing a crosslinkable monomer having liquid crystalline group side chains. 

Formulation and method of polyesterification impart considerable changes in properties whereas variation of crosslinking monomers and fillers impart only minor changes. 

Polymeric binders based upon a vinyl acetate and ethylene backbone incorporating a self crosslinking monomer have been widely used in the nonwoven industry (3). 

Ethylene in the polymer provides softness to the product and is low cost. However, the softness in the product often comes at the expense of its wet tensile strength. Increasing the level of self crosslinkable monomer in the polymer often is not a viable option to increase the wet tensile strength. 

Crosslinking monomers include N-methylol acrylamide, acrylamide, further, acrylamidobutyraldehyde, dimethyl acetal, diethyl... 

---