Polypropylene colour

The seats of bus shelters can be made out of polypropylene, HDPE, PVC or polyamide. The structures of play areas (ladders, stationary motorbikes, labyrinths, huts. ..) can be in highly coloured HDPE or polypropylene. 

The addition of MAPP at around 1-2% ensures perfect coverage of the wood fibres by polypropylene or polyethylene. The micrographs in Figure 5.25 clearly show the lack of adhesion between the fibres (in dark colour) and the PP matrix (in light colour). The mechanical properties are increased by at least 30% when a coupling agent is used. 

AG (now Datacolor International) software. Finally, the Colour Measurement Committee (CMC) of the Society of Dyers and Colourists in the United Kingdom made some compromises and published a formula based on the J P Coates work but incorporating the CIELAB coordinates [53], This was made a British standard (BS 6923) and soon was adopted by textile associations around the world. The usefulness of such an equation has been demonstrated many times in the textile industry and in some papers from manufacturers of textured, molded polypropylene as well. 

Products composed of one type of plastic only. Examples are monolayer foils used, e.g., in packaging for bakery or in the form of bags for household application. It is worth noting that a mono-material film, consisting, e.g., of polypropylene, may contain more than one component. If the film is coloured, this is obtained by mixing a polypropylene matrix with a colourant carried by another polypropylene, normally of lower molecular weight. 

Figure 16.14 Change of gloss of UV-stabilized, white-coloured ASA and polypropylene during outdoor weathering in Germany...

Method. Portions of red and yellow coloured HDPE, polypropylene, PET and clear PMMA plastic materials are comminuted into sizes approximately 4x4 mm using a diamond edge cutter. 

The cis-trans isomerisation process in the photofading of azo dyes has been found to be a first-order process in polypropylene and independent of polymer crystallinity l. oye lightfastness on leather has however been found to depend upon the colour of the dye lS while alkyl and peroxy radicals have been observed in the photofading of Rhodamine and azo dyes in solution . More specifically basic triphenylmethane dyes have been found to give benzophenone products on photofading 20 structure of a series... 

Plastics can have a layer of metallic aluminium deposited on the surface by vacuum. Although aluminium is basically a bright silver, it may be lacquer tinted to give a wide range of metallic colours. Polyester, polystyrene, urea and phenol formaldehyde, and polypropylene are readily metallised. Other plastics need a pretreatment. 

If colour is very strong, litho in thin layers is not so rub-resistant as letterpress because of low varnish level. Note that rub resistance and brightness can usually be improved by the addition of over-lacquers or varnishes (based on shellac (spirit), nitrocellulose, Saran, vinyl, epoxy, water varnishes, etc.) or lamination (cellulose acetate, polypropylene, PVC, etc.). Coatings or laminations may also provide heat sealability. 

Appearance is only a guide to the type of plastic present because various fillers and colouring materials can change the appearance of a polymer considerably. However, Bakelite (phenol-formaldehyde) is always brown, black or red, while urea- and melamine-formaldehydes may have pastel shades. Polyethylene and polypropylene always appear slightly cloudy as thin films, while most other colourless plastics, particularly polyesters and polycarbonate, are crystal clear. 

Visit a beach and collect plastic articles that have been there for a couple of years. Apart from foam and hollow air-filled products, there will be polyethylene (PE) or polypropylene (PP) products, which are less dense than water. Note how colours have faded, the surface has become opaque, and the product has started to crack. 

Two-component membranes were synthesized by volume grafting of acrylic acid on polypropylene in the form of thin films. Distribution of acrylic acid across the membranes was determined by microphotometration of the coloured thin cross-section of the membranes cut perpen-diculary to the surface. It was found that grafted polyacid produces a concentration gradient inside the membranes, Applying the multilayer electrochemical model and conductivity data the volumes of both components, i.e., PP and swollen gel of g-PAA in the gradient membranes, were calculated. 

Structure of Polypropylene Fibres Coloured with Organic Pigments... 

The K value observed in fibres coloured with quinacridone pagment is comparable to the value obtained during crystallization of polypropylene melt in quiescent conditions in the presence of very effective p nucleating agents. 

Influence of processing on the structure of polypropylene fibres coloured with quinacridone pigment... 

---