PVDC-modified

Table 4.2 Strength of PVDC-Modified Mortar as a Function of Latex Particle Size.

In general, the coefficient of thermal expansion of latex-modified mortar and concrete is directly influenced by that of the aggregates used, as in ordinary cement mortar and concrete. Latex-modified mortar and concrete usually have coefficients of thermal expansion equal to or slightly larger than that of ordinary mortar and concrete. Table 4.6l gives the coefficient of linear thermal expansion of SBR- and PVDC-modified mortars with variation of polymer-cement ratio. 

Chemicals ( fcl Un- SBR- EVA- PAE- PVDC- Un- SBR- EVA- PAE- PVDC-Modified Modified Modified Modified Modified Modified Modified Modified Modified Modified ... 

In the early 1980s, the corrosion of structural steel supports due to chloride ions liberated from PVDC-modified mortar which had been used to repair an old brick building, led to a civil suit in the United States l l therefore, PVDC latex is not currently used as a cement modifier in the United States and other countries. In a laboratory study, the liberation of chloride ions is observed in such a chloride-containing polymer, and a possibility of the conosion of the reinforcing bars which is induced by the chloride ions in reinforced concrete structures is suggested.l H The use of PVDC-modified mortars with polymer-cement ratios of 5% or more causes the liberation of sufficient chloride ions to exceed flie tolerable corrosion limits for the reinforcing bars in reinforced concrete structure. 

The properties of PVDC (Table 3) ate usually modified by copolymerization. Copolymers of high VDC content have lower melting temperatures than PVDC. Copolymers containing mote than mol % acrylate or methacrylate ate amorphous. Substantially mote acrylonitrile (25%) or vinyl chloride (45%) is required to destroy crystallinity completely. 

The crystal structure of PVDC is fairly well established. Several unit cells have been proposed. The unit cell contains four monomer units with two monomer units per repeat distance. The calculated density, 1.96 g/cm3, is higher than the experimental values, which are 1.80-1.94 g/cm3 at 25°C, depending on the sample. The melting temperature, T , of PVDC is independent of molecular weight above DP = 100. The properties of PVDC (Table 2) are usually modified by copolymerization,... 

Polyvinylidenechloride, PVDC, was discovered in 1838 by Regnault but commercialized 100 years later as Saran . The commercial PVDC is modified by the incorporation of either 15-20 wt% vinyl chloride, or 13 wt% vinyl chloride and 2 wt% acrylonitrile. PVDC blends are summarized in Table 1.32. 

To prepare the graft copolymer, a PO (MW = 50 to 1,000 kg/mol) was either dissolved or swollen in an inert hydrocarbon, monomers (>80 wt% of a methacrylic ester, CH2=C(CH3)COOR) and an initiator was added to the heated mixture while stirring. As a result, acrylic branches of a relatively high molecular weight (MW = 20 to 200 kg/mol) were grafted onto the PO macromolecules. The graft copolymer could be used as a compatibilizer-cwm-impact modifier in a variety of polymers selected from between PO, acrylic polymers, SAN, EVAc, PA, PEST, PC, POM, PAr, PVC, ABS, PVDC, cellulosics, polyester-polyether block copolymers, PEA, PEEK, PEI, PES, CPVC, PVDF, PPE, PPS, PSF, TPU, PAI, PCL, polyglutarimide, blends of PEST with PC or PVC [Ilendra et al., 1992, 1993]. 

The halide-containing (co)polymers, such as PVC or PVDC, recovered from commingled polymer scrap were contaminated by low melting point PA S [e.g., PA-6, PA-1212 or PARA]. The recyclate was compatibilized and impact modified by addition of an acrylic copolymer of ethylene, alkyl(meth)acrylate, vinylacetate, (meth)acrylic acid, CO and MA. To prevent degradation, the blends were processed at T < 220°C, then formed by extrusion or injection molding into a variety of articles [Hofmann, 1994]. 

Uses Associative thickener, rheology modifier for industrial latex paints, adhesives, waterborne architectural coatings, printing inks, suitable for acrylics, PVC/PVdC, PU Features Maximizes high sheer vise. 

Polyvinyl dichloride (PVDC) - not recommended for use with reinforced concrete because of the danger of chloride release. Styrene butadiene rubber (SBR) - suitable for most circumstances. Acrylics and modified acrylics - suitable for most circumstances. 

Sato et al. [52] demonstrated the potential of FUV-DUV spectroscopy in the 120-300 nm region in the nondestructive classification of commercial food wrap films (polyethylene (PE) films from three sources, two polyvinylidene chloride (PVDC) films with different additives, and one polyvinyl chloride (PVC) film each film was about 10 Im in thickness). More recently, Tanabe et al. [63, 64] measured absorption spectra (150-300 nm) of Ti02 and Ti02 modified with metal (Pt, Pd, and Au) nanoparticles using the ATR-FUV spectrometer. The deposition of metal nanoparticles altered the spectral shape and intensity, indicating changes in the electronic states and photocatalytic activities of Ti02. 

Polyamide, Nylon 6, Modified 7 Polyvinylidene Chloride (PVDC) 7-8 ABS 4-9... 

---