A study of chemical and physical changes during biaxially oriented polypropylene film production

Polypropylene films obtained during the biaxial orientation process were characterized by energy dispersive X-ray analysis (EDX), scanning electron microscopy. X-ray diffraction, differential scanning calorimetry, infrared spectroscopy. Inorganic particles with Al, Si, Na, Mg, Ti, K,O elements were present in biaxially oriented films. Polypropylene had molecules with both isotactic configuration and it was crystallized only in isotactic α phase. The films drawn in one and two directions had unit cells with b axis parallel to surface of the films. The antioxidants present in the films were consumed during processing, preventing polypropylene oxidation in air at high processing temperatures. One surface of the films contained less polypropylene and had functional groups rich in oxygen such as C=O and COO

Organotin compounds as PVC stabilizers

When poly(vinyl chloride) is fabricated, it passes between rollers (calendars) at about 200 ◦C, which causes elimination of some HCl at allylic defects in the polymer, as shown below (Figure 3.3.1). Furthermore, the released HCl induces further elimination, giving a polyolefin structure with a yellow coloration, which turns red, and then black, after which the polymer becomes brittle. This degeneration can be inhibited by organotin stabilizers, often organotin mercaptides that appear to have two principal functions. Firstly, they react with the HCl to give organotin chlorides, which do not catalyze the elimination process. Secondly, they substitute the chloride at the reactive sites, introducing other groups, such as mercaptide groups, which are not easily eliminated. Organotin maleates may also remove diene units by the Diels–Alder reaction

Thermal stabilisation of poly(vinyl chloride) by organotin compounds

The effect of LSN 117 (dioctyl tin bis isooctyl thioglycollate, an organotin compound) on the heat stability of plasticised PVC was investigated in this study. The organotin stabiliser had carbonyl and carboxylate groups and PVC contained traces of Fe, Zn, Ca, Cu and Sn. The heat stability of the films were tested at 140 °C and 160 °C or 180 °C by heating in an air circulation oven up to 2 h and by measuring HCl evolved using a Metrohm 763 PVC thermomat and by thermogravimetric analysis. The onset of HCl evolution was at 14.3 and 2.5 h at 140 °C and 160 °C, respectively, for PVC film without LSN117. On the other hand, the film with LSN117 did not evolve HCl in 30.3 h at 140 °C. HCl started to evolve from the films with LSN 117 in 14.3 h at 160 °C. The TGA curve also indicated PVC film with LSN 117 degraded at higher temperatures than control films. LSN 117 was found to be a good heat stabiliser for plasticised PVC and it did not have any detrimental effect on mechanical properties.Ege University Research Fund: No. 98/MÜH/1

Tin soaps in emulsion PVC heat stabilization

In this study, the effect of a liquid stabilizer based on organotins on PVC heat stability is investigated. Control and films with tin soap heat stabilizer Sn500K were prepared by solvent casting and they were heated at 160 and 180°C for different time periods. X-ray fluorescence spectroscopy analysis showed that tin was present in Sn500K and it was lead-free. DSC analysis showed that glass-transition temperature of films with Sn500K increased from 67 to 75-85°C by heating for 15 min at 180°C. IR spectroscopy indicated that concentration of carboxylate groups of Sn500K decreased with heating. Films with Sn500K did not degrade for short heating periods; however, degradation occurred in long heating times. Low concentration of Sn500K was recommended, since at high levels incompatibility with PVC and acceleration of degradation was observed. In the high temperature range, control and stabilized samples degraded in the same manner in two step

Synergistic effect of natural zeolites on flame retardant additives

The thermal degradation and flammability of intumescent fire-retardant polypropylene matrix composites consisting of ammonium polyphosphate (APP) as an acid source and blowing agent, pentaerythritol (PER) as a carbonisation agent and natural zeolite (clinoptilolite rich, Gördes II) as a synergistic agent were examined. APP and PER combinations were examined at different ratios (0.25, 0.33, 0.5, 1, 2, 3, and 4) for optimisation of the formulation for flame retardancy. The zeolite was incorporated into flame retardant formulation at four different concentrations (1, 2, 5, and 10 wt%) to investigate the synergism between the flame retardant materials. The thermal degradation and flammability of composites were characterized by thermogravimetric analysis (TGA) and by limiting oxygen index (LOI) measurement and horizontal burning (HB) tests. A synergistic effect in flame retardancy was observed when natural zeolites were used in combination with APP and PER.Izmir Institute of Technology (IYTE-34- 2002

Morphology, order, light transmittance, and water vapor permeability of aluminum-coated polypropylene zeolite composite films

In this study, the polypropylene-zeolite composite films having 2-6 wt % natural zeolite were coated with a thin film of aluminum (Al) by magnetron sputtering, and the contribution of the Al coating on film properties was investigated. The samples were characterized by EDX, X-ray diffraction, SEM, AFM, UV-visible spectroscopy, and water vapor permeation analyses. The surface of the films coated with a smooth Al film having 98-131 nm thickness. EDX revealed that Al percentage on the surface appeared to be as 8-10 wt % indicating contribution of polymer surface under Al film to analysis. XRD analysis showed that the grain size of Al at the surface was 22-29 nm. The surface roughness increased after Al-coating process. The transmission of coated films was very low for both UV and visible regions of the light spectrum. Permeation analysis indicated that water vapor permeation was lower for Al-coated material.State Planning Organization (2002K 120390