Stabilizer for polypropylene

The catalytic degradation of polypropylene was carried out over ferrierite catalyst using a thermogravimetric analyzer as well as a fixed bed batch reactor. The activation of reaction was lowered by adding ferrierite catalyst, which was similar with that from ZSM-5. Ferrierite produced less gaseous products than HZSM-5, where the yields of i-butene and olefin over ferrierite were higher than that over HZSM-5. In the case of liquid product, main product over ferrierite is C5 hydrocarbon, while products were distributed over mainly C7-C9 over HZSM-5. Ferrierite showed excellent catalytic stability for polypropylene degradation. 

Substituted tetramethylpiperidines and their oxidation products appear to act as UV stabilizers for polypropylene by weakly scavenging PP, PPO2 and possibly other radicals involved in the photo-oxidation. Their weak scavenging ability is off-set by the... 

Gijsman, P. Gitton, M. Hindered amine stabilizers as long-term heat stabilizers for polypropylene. Polym. Degrad. Stab. 1999, 66, 365— 371. 

A number of ortho hindered alkyl-substituted phenyl phosphites and phosphonites were found to be effective process stabilizers for polypropylene and high density polyethylene combining more effective stabilization activity at high temperatures with good storage stability at relatively elevated humidity and ambient temperature, as well as resistance to discoloration. 

By using very thin samples, the oven aging of polypropylene can be appreciably accelerated. Specimens of definite and reproducible shape and thickness were made by using a microtome. The first phase of the work evaluated the influence of sample thickness from 0.2 to 12 mils on oven life at different temperatures. In the second phase, this modified technique was used to study the effectiveness of three anti-oxidant/DLTDP systems as thermal stabilizers for polypropylene. The results obtained over a wide spectrum of antioxidant/DLTDP combinations are shown in three-dimensional graphs. 

Phosphite processing stabilizer for polypropylene, polyethylene, and adhesives. 

The second part of this study [92] considered this peculiar point that has considerable consequences in terms of fundamental aspects of both the photooxidation of nanocomposites and the durability of these materials. A special attention was given to the interactions between the antioxidant, the clay (montmorillonite), and the compatibilizing agent (maleic anhydride), in terms of influence of each component on the rate of oxidation of the polymeric matrix. Two kinds of stabilizers were tested a phenolic antioxidant (Scheme 15.14) generally used to process polypropylene and a redox antioxidant of the hindered amine light stabilizer (HALS) class (Scheme 15.15) that is used as long-term stabilizer for polypropylene. 

Typical processing stabilizers for polypropylene and butylated hydroxy-toluene (BHT) as the primary antioxidant and phosphates and phosphonates as secondary antioxidants. Examples of the latter that are commonly used are tetrakis-(2,4-di-terr-butyl-phenyl)-4-4 -bisphenylylenediphosphonite, distearyl-pentaerythrityl-diphosphonite, tris-(nonylphenyl)-phosphite, tris-(2,4-di-teft-butyl-phenyl)-phosphite and bis(2,4-di-ferr-butyl-phenyl)- pentaerythrityl-diphosphite. In commercial polypropylenes, phosphorous compounds are always used together with a sterically hindered phenol. The compounds are commonly added in concentrations between 0.05 and 0.25%. 

The most important long-term heat stabilizers for polypropylene are phenols of medium (300-600) and especially high (600-1,200) molecular weight, which are frequently used together with thioethers as synergists, e.g., dilauryl thiodipropionate (DLTDP), or distearyl thiodipropionate (DSTDP), or dioctadecyl disulfide. 

An alkyl phosphite which functions as a secondary stabilizer for PVC. As a lubricant additive, Weston DOPI phosphite iaq>roves antifriction and antiwear characteristics. It can also be used as a color and molecular weight stabilizer for polypropylene when regulatory approval for food contact is not required. 

Novel pyperidine-triazine co-oligomers are useful as light and heat stabilizers for organic materials, in particular as light stabilizers for polypropylene fibers [27]. 

Brit. Patent, 858, 889 (1961), Stabilized polypropylene (Ferro Corp.) — Brit. Patent, 945,050 (1963), Improvements in or relating to complex salts of nickel as light stabilizers for polypropylene (Hercules Powder Comp.). 

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