Impact of improved phosphite hydrolytic stability on the processing stabilization of polypropylene (original) (raw)
Related papers
A new phosphite offers an excellent balance of properties
Journal of Vinyl & Additive Technology, 1997
Phosphites are a critical component of stabilizer formulations and provide molecular weight and color protection to the polymer. This paper profiles a new phosphite antioxidant whose structure provides a n excellent balance of high activity, hydrocarbon solubility, and excellent handling characteristics. A wide range of performance data is illustrated in polypropylene.
Polymer Degradation and Stability, 1997
The behaviour of mixtures of hindered amine light stabilizers (HALS), their nitroxyl radical, and alkylamine analogues, with aromatic and aliphatic phosphites during photoxidation of polypropylene (PP) has been examined. The photostabilizing performance of the above mixtures of stabilizers was compared with that of the individual antioxidants and with the performance of a number of synthesized bifunctional stabilizers containing aromatic phosphite or phosphonite and either of the above HALS or related functions in the same molecule (referred to as 'HALS-Phosphites' or 'HALS-Phosphonite'). Combinations of the hindered aryl phosphite Irgafos 168, with the hindered amine Tinuvin 770, the tertiary amine Tinuvin 292 and the bis-nitroxyl-analogue of Tinuvin 770, gave antagonistic effects at most molar ratios examined. Furthermore, in all cases, the extent of antagonism was reduced with increasing the amount of Irgafos 168 in the mixtures. Combination of the aliphatic phosphite, trilaurylphosphite, TLP, with Tinuvin 770 in PP, on the other hand, has shown synergistic effect under photoxidative conditions. The HALS-Phosphites and HALS-Phosphonite examined have shown better stabilizing efficiency than the corresponding mixtures of the individual stabilizers.
Polyesters of phosphoric acid: Synthesis and kinetics of hydrolysis
Macromolecular Symposia, 1998
Three major methods have been elaborated in our laboratory for preparation of polymers with poly(alky1ene phosphates) backbones: ring-opening polymerization, poly-condensation and transesterification, and polyaddition. The second method is based on the reaction of the commercially available compounds, namely dialkyl (or diaryl)-H-phosphonates and glycols. Reaction of the aliphatic H-phosphonates with aliphatic glycols is a reversible process, whereas polycondensation of diphenyl H-phosphonates with aliphatic and cycloaliphatic diols is practidy irreversible. This latter method has recently been developed and is described in this paper. Poly H-phosphonates with up to 40103 were prepared. Polymers are easily oxidized and quantitatively converted into the relatively stable poly(a1kylene phosphates). Some physical properties of these polymers and kinetics of their hydrolysis is discussed.
Journal of Thermal Analysis and Calorimetry
A new phosphine-type potential secondary stabilizer was synthesized successfully with large natural raw material content. The stabilizer is a waxy white powder with a relatively low melting temperature. Both the thermal and the storage stability of the stabilizer are sufficient for practical use. The new stabilizer was introduced into a Phillips-type high-density polyethylene, and its stabilizing efficiency was determined by multiple extrusions. Commercial phosphite and phosphonite stabilizers were used as references. The additive packages contained a primary antioxidant and a phosphorus compound, both added at 1000 ppm. The chemical structure of the polymer, viscosity, color, and residual stability were determined after each extrusion. The comparison of the stabilizing efficiency of the three secondary antioxidants showed that the phosphine stabilizer is at least as efficient as the phosphorous secondary stabilizers available in the market. The new stabilizer proved to be the most ...
Macromolecules, 2018
Currently, hindered phenol (HP) antioxidants mixed in PP products provide thermal-oxidative protection during PP melt processing (homogeneous mixing). However, there are concerns about their effectiveness during applications. This paper presents computer simulation and experimental results to demonstrate a facile phase separation of HP molecules in the PP matrix and investigates a new approach that can dramatically improve PP thermal-oxidative stability under elevated temperatures. This technology is centered on a new PP−HP copolymer containing a few comonomer units with HP moieties, homogeneously distributed along the polymer chain. Because of the cocrystallization between the PP and PP−HP copolymer, all HP antioxidant groups are homogeneously distributed in the PP matrix (amorphous domains). The resulting PP/PP−HP blends demonstrate a thermal-oxidative stability nearly proportional to the HP content. While commercial PP products (containing regular antioxidants and stabilizers) degrade within a few minutes at 210°C in air, the PP/PP−HP blend, with the same concentration of HP groups, demonstrates nearly no detectable weight loss after 1000 h. In an ASTM endurance test under a targeted application temperature (140°C in air), the commercial PP shows 1% weight loss within 10 days. On the other hand, the new PP/PP−HP (5/1) blend with the same HP content lasts for about 2 years under the same constant heating condition. Overall, the experiment results of the PP−HP antioxidant present the potential of expanding PP applications into a far higher temperature range (>140°C) under thermal-oxidative environments.
A series of poly(ethy1ene terephthalate) (PET) samples was prepared from dimethyl terephthalate and ethylene glycol. In each sample a phosphorous compound was added as heat stabilizer after the transesterification and before the polycondensation. These compounds were: phosphoric acid, tributyl phosphate, triphenyl phosphate, phenylphosphonic acid, phenylphosphinic acid, and sodium phenylphosphinate. Firstly, their interference with the transesterification catalyst was examined. Their stabilization effect was estimated by DSC analysis in nitrogen and air. Various thermal criteria have been used, such as stabilization coefficient and induction period of oxidation. Under the conditions used for polymerization, the more efficient stabilizers were tributyl phosphate, phenylphosphonic and phenylphosphinic acid.
Natural antioxidants for polypropylene stabilization
Polymer Degradation and Stability, 2011
A study on the efficiency of bio-based compounds as stabilizers for polypropylene (PP) is reported. A water extract from French maritime pine bark (Pycnogenol Ò ), a by-product containing polyphenols obtained from wine production, and a carotenoid-containing oleoresin from processing of tomatoes were used. Their stabilizing activity was compared with that of a commercial phenolic antioxidant. Thermogravimetric analysis and Oxidative Induction Time measurements performed on unaged samples, as well as infrared spectroscopy on samples aged at 70 C, provided evidence for the effectiveness of the natural stabilizers. Mechanical characterization was carried out on aged films and injection moulded samples. Experimental results indicated that particularly grape extract could provide long-term stabilization to PP under conditions of oxidative degradation. Therefore, it could be used as efficient and high value-added additive for polypropylene. Pycnogenol Ò also showed antioxidant activity, however the achievement of a more homogeneous dispersion in the polymer matrix could improve the mechanical performance of aged samples.
Journal of Vinyl and Additive Technology, 2001
The influence of zinc stearate (ZnSt) on the thermal and photochemical stabilities of phenolic antioxidant/phosphite combinations has been determined in HDPE by using FTIR analysis. The results show that while under thermal aging the effects are generally antagonistic, under photooxidation the effects are synergistic. The interactions appear to be dominated by the role of complex formation between the phosphites and ZnSt. Such interactions would remove the hydroperoxide effectiveness of the phosphite in thermal oxidation, while under light they could cause stabilization. Derivative UV and FTIR analysis on pre‐melt blends of the additives in solution shows evidence for strong complexation for the phosphite antioxidants. Other acid scavengers such as hydrotalcite and calcium stearate also appear to influence the behavior of phenolic antioxidants in thermal oxidation. The antagonistic effect of zinc stearate was also confirmed following a single pass in an extruder, where for all formu...