Photostabilising action of ortho-hydroxy aromatic compounds: A critical review

Radiation-induced grafting of binary monomers containing HALS onto polypropylene

Many attempts have been made to obtain polymer-bound stabilisers. Such permanent antioxidants and light stabilisers are non-migratory and hence resistant to extraction and volatilisation. Two routes to obtain polyolefin-bound stabilisers are described in this chapter, both involving polyolefin grafting. In the first method, polyolefins are grafted with reactive stabilisers—bifunctional compounds containing a polymerisable group and an antioxidant or UV-absorbing functionality. Bulk or surface stabilisation of the polyolefin may also be achieved depending on the grafting method employed so that the stabilising groups may be located either in the entire mass of the polyolefin or only at the surface of the finished article. The second route involves the functional- isation of polyolefins by grafting with monomers which contain functional groups which are subsequently able to react with non- polymerisable but chemically reactive stabilisers. The stabilisation of polyolefins by grafting is compared with other approaches to polyolefinbound stabilisers.

Polyolefin Stabilisation by Grafting

A study has been made on the effect of the presence of grafted acrylic layers on the autoadhesion of polyethylene. Methyl methacrylate (MMA), ethyl methacrylate (EMA), methyl acrylate (MA), ethyl acrylate (EA), and butyl methacrylate (BMA) were grafted onto high density polyethylene (HDPE). The grafting reaction was faster at higher temperature and methacrylates graft more easily than acrylates. For methacrylates and acrylates, the grafted amount increases with increasing length of the pendant alkyl chain. The grafting temperature is a crucial factor affecting the adhesion of grafted PE samples. For the samples grafted at lower temperature (in a room temperature water bath), the adhesion is very low (less than 50 N/m), even for very thick grafted layers. But for the samples grafted at higher temperature, much higher adhesion can be obtained. The presence of homopolymer was another factor affecting the adhesion of PE samples. When homopolymer is removed from the surface of the grafted sample, higher adhesi...

Autoadhesion of high density polyethylene (HDPE) to HDPE by ultraviolet grafting of methacrylates and acrylates

The γ-radiation-induced graft copolymerization of 2,2,6,6-tetramethyl-4-piperidinyl methacrylate (TMPM) onto polypropylene (PP) was investigated using a simultaneous-irradiation technique The effects of solvents, atmospheres, dose, and monomer concentration on the percent of grafting were studied The grafted TMPM showed better thermal stability, solvent extraction resistance, and compatibility with PP than monomeric TMPM or polymeric PTMPM The stabilizing effectiveness of grafted TMPM on the radiation resistance of PP was found to be better than that of monomeric TMPM The combination of grafted TMPM and low molecular weight hindered amine light stabilizers showed higher stabilizing effectiveness

P.J. Burchill

Papers

Photo-stabilisation of polyethylene by graft co-polymerisation