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In this paper, the properties of some polymeric materials used as consolidating and protective products in the restoration field of stone manufactured objects of artistic interest are discussed. The penetration of polymeric consolidating products is very small because of their macromolecular nature, and in situ polymerization of the monomers is suggested as an alternative technique to the use of macromolecular solutions. The effects of plasticizer agents in the reaction system have been investigated, in order to decrease T g and make the products more elastic.

An ethylene—propylene (EPR) copolymer functionalized with (1,2-dicarboethoxy)ethyl groups has been blended with a vinylidene fluoride—hexafluropropene elastomer (NML). The existence of intermolecular interactions involving mainly the carbonyl groups of the side chains of the functionalized copolymer and the methylene hydrogens of the fluoroelastomer through hydrogen bonding was shown by means of FT—IR spectroscopy. The structure and composition of some microdomains in the mixture was examined by means of FT—IR microspectroscopy.

Peroxide initiated vinylidene fluoride (VDF) telomerization was investigated in the presence of bromine terminated perfluoropolyethers CF 3 (OCF 2 CF 2 ) m (OCF 2 ) p Br, (R f -Br). R f -Br act as telogen agents producing the above reaction compounds of general formula R f -(VDF) n Br. Data on telomer microstructure by fluorine NMR, glass transition temperature and crystallinity of (VDF) n moiety are also reported and discussed. The products show properties of di-block copolymers.

Copolymers of 1,1-difluoroethene with tetrafluoroethene, chlorotrifluoroethene, and bromotrifluoroethene have been prepared by emulsion polymerization, and their crystallinity has been investigated by means of x-ray diffraction. The results are discussed in relation to copolymer composition and structure.

19F nuclear matnetic resonance spectra of vinylidene fluoride-hexafluoropropene copolymers and vinylidene fluoride-hexafluoropropene-tetrafluoroethylene terpolymers are reported and discussed. Their interpretation allows average composition and sequence distribution to be determined. Sequence distribution is shown to be relevant in determining the trend of glass transition temperatures and in the study of the mechanism of vulcanization.

The Fox, Gordon-Taylor-Wood, Johnston and Barton equations have been applied to predict the glass transition temperatures, Tg of vinylidene fluoride-hexafluoropropene (VDF-HFP) copolymers and VDF-HFP-tetrafluoroethene (TFE) terpolymers. The Fox equation fails to describe the co- and terpolymer systems. The experimental data for VDF-HFP copolymers are well interpreted by the Gordon-Taylor-Wood equation. The Johnston and Barton equations, based on sequence distribution, yield good results for VDF-HFP and VDF-HFP-TFE. The assumptions made about kinetic constants of propagation and the Tg contributions of alternating monomer dyads and polyTFE are also discussed.

Copolymers of tetrafluoroethene (TFE) with hexafluoropropene (HFP) have been prepared in the 0-14mol% HFP composition range. Their melting temperatures (Tm), enthalpies (ΔHf) and entropies (ΔSf) of first and second fusion, and crystallinities (X) according to x-ray diffraction(x.r.d.) and differential scanning calorimetry (d.s.c.) have been determined. The results indicate that ΔHf/Xx.r.d of the polymer crystals decreases with higher HFP content.

Copolymers of vinylidene fluoride (VDF) with fluoroolefins of the series CF2CFX (X = F, Cl, Br, CF3 and C5F11) have been synthesized in the 0–16 mole % CF2CFX range. Results of physico-chemical characterisation by means of DSC techniques (Tg, TM, ΔHf) and X-ray diffraction are examined and related to the nature of the substituent of the fluoroolefin. The Tg/TM ratio varies from 0.5 for the VDF homopolymer to higher values at increased CF2CFX content, although to a different extent for the various series of copolymers. The results show that the Beaman-Boyer empirical rule (Tg/TM=2/3), developed for homopolymers, also applies to some copolymeric systems.

Tetrafluoroethene (TFE)–chlorotrifluoroethene (CTFE) and TFE–bromotrifluoroethene (BTFE) copolymers have been synthesized by solution copolymerization over the entire range of comonomer composition. Crystallinity data are reported and first- and second-order transitions have been investigated by DSC. Glass transition temperatures of TFE-CTFE copolymers vary in a nonlinear fashion in the range defined by the homopolymers conforming best to the Johnston equation; the behavior in the TFE-BTFE system is more linear. Whereas TFE-BTFE copolymers show a steep decrease of melting temperature at higher BTFE content, due to the amorphous character of the polymers, more regular behavior was found for TFE-CTFE copolymers. Enthalpies of fusion are also reported. The results are discussed in relation to copolymer composition and structure and are compared with data on tetrafluoroethene–hexafluoropropene (FEP) fluorocarbon resins.

Hexafluoropropene (HFP) — 1,1-difluoroethene (VDF) copolymers have been synthesized in the 0–16 mole % HFP range and the results of a physico-chemical characterization by means of XRD (cristallinity index) and DSC techniques are related to the microstructure of the polymers, as determined by 19F NMR. The addition of a small percentage of the HFP comonomer does not affect the polymorphism of poly(vinyl-idenefluoride).

Reactions occurring in the first steps of crosslinking of vinylidene fluoride (VDF)-hexafluoropropene (HFP) elastomer copolymers (molar ratio 4/1) are investigated operating in homogeneous solution, phase transfer catalysis conditions and bulk. Two kinds of principal unsaturation, monitored by FT-IR and 1H-NMR spectrometry, -CH=CF- and (CF3)C=CH-, have been detected. The former seems to be the curing site in the nucleophilic crosslinking of the fluoroelastomer. Polymer chain scission is also observed and has to be related to the HFP units as well as to the base content in the system.

Films of blends of Paraloid(R) B72 (copolymer of ethyl methacrylate and methyl acrylate) and Tecnoflon NM(R) (copolymer of vinylidene fluoride and hexafluoropropene) with different compositions were investigated by means of FT-IR spectroscopy and FT-IR microspectroscopy before and after UV and thermal treatments. Preliminary results of DSC measurements are also reported. Paraloid B72 has been extensively applied as a protective agent for stone since the 1950s. More recently considerable research has also been carried out on the application of fluorinated polymers in the field of stone conservation, eg, the fluoroelastomer Tecnoflon(R). A high content of Tecnoflon with respect to Paraloid increases the stability of the blends when they are submitted to UV radiation and thermal treatments. A THF solution of a blend of this kind was successfully applied to a marble surface of the Saint Maria Cathedral in Lucca, Tuscany, Italy. The changes in the properties of such mixtures with different compositions can offer new possibilities in developing suitable protective materials. (C) 2000 Society of Chemical Industry.

The alkaline dehydrofluorination of Vinylidene Fluoride (VDF) -Hexafluoropropene (HFP) copolymers in dimethylacetamide has been reported by Schmiegel [1]. Basing on the reduction of 19F NMR signals related to HFP-VDF-HFP sequences and the apprearance of small low-field resonances attributed to allilic CF3, he suggested that the reaction takes place at HFP-VDF-HFP sequences, to give conjugated dienes and α, β unsaturated ketones deriving from OH− addition to dienes. This communication presents a study of the dehydrofluorination of VDF-HFP copolymers in THF, by alcoholic KOH. The reaction has been followed by analysis of the fluoride ion in solution. The intrisinc viscosity of the polymer did not change after elimination of up to 7.9 x 10−4 moles F− per g polymer. Higher reaction extents resulted in a decrease of intrinsic viscosity, suggesting polymer chain degradation. The reation products exhibit IR absorptions at 1720, 1684 and 1638 cm−1, that can be attributed to isolated double bonds and/or carbonil groups. No IR bands indicate conjugation that is also not evidenced by UV spectra. 19F NMR spectra are similar to those reported by Schmiegel, but show a larger variety of new CF3 signals, both in the low-field and the usual CF3 regions. The Tg of the unsaturated polymers and the reation of these products with phenate anions have also been studied.

Copolymers of Bromotrifluoroethene (BTFE) with Tetrafluoroethene (TFE) and with 1,1-Difluoroethene (VDF) have been synthesized in the whole composition range by solution polymerization in 1,2,2-Trichloro-1,1,2-Trifluoroethane (FC 113), free radical initiator bis(4-terg.butylcyclohexyl)percarbonate, reaction temperature 40°C, monomer conversion < 10%. Monomer composition was adjusted in order to yield the desired copolymer. Polymer composition was determined by elementary chemical analysis. The reactivity radios for BTFE-TFE copolymerization have been computed: rBTFETFE = 0.24, rTFEBTFE = 0.82 19F NMR spectra of BTFETFE and BTFEVDF copolymers are also reported and discussed. The latter show patterns similar to those of VDF-Chlorotrifluoroethene copolymers.