Plastic low-profile

Low profile plastics are added to reduce shrinkage during cure. They are normally thermoplastics that include polyvinyl acetates, polymethyl methacrylate, and copolymers with other acrylate, vinyl chloride-vinyl acetate copolymers, polyurethane, polystyrene, polycaprolactone, cellulose acetate butyrate, saturated polyester, and styrene butadiene copolymers. More details about the low profile additive (LPA) mechanism are published in the literature. ... 

DMTA is a very interesting tool for characterizing heterogeneous materials in which domains of distinct Tg values coexist. The most interesting cases involve modified thermosets of different types (see Chapter 8). Examples are the use of rubbers (e.g., liquid polybutadiene and random copolymers), or thermoplastics (e.g., polyethersulphone or polyetherimide in epoxy matrices or poly(vinyl acetate) in unsaturated polyesters), as impact modifier (epoxies), or low-profile additives (polyesters). The modifier-rich phase may be characterized by the presence of a new a peak (Fig. 11.10). But on occasions there may be superposition of peaks and the presence of the modifier cannot be easily detected by these techniques. If part of the added polymer is soluble in the thermoset matrix, its eventual plasticizing effect can be determined from the corresponding matrix Tg depletion, and the... 

This moldable material primarily consists of TS polyester resin, glass fiber reinforcement, and filler. Additional ingredients, such as low-profile additives, cure initiators, thickeners, and mold-release agents are used to enhance the performance or processing of the material. As with any material, such as metallics and plastics, SMC can be formulated in-house or by compounders to meet performance requirements of a particular application such as tensile properties or Class A surface finish. Varying the type and percentage of the composition will result in variations in mechanical properties and processability. 

The photooxidation of polymers on the other hand continues to remain at a low profile. Bio- and photodegradable plastics continue to be useful for agricultural usage, although interest here is again minimal. The same applies to polymer photostabilization, where commercial applications dominate very much, with emphasis on the practical use of stabilizers. For dyes and pigments stability continues to be a major issue in so far as this section is concerned. 

Rigid laminate substrate (with or without soldermask), wire bonds, over-molded Small outline, low profile (1.0 mm), enhanced electrical performance over 2.4 GHz, JEDEC moisture sensitivity level (MSL) 3 Plastic thin fine pitch quad flat no lead package (P-TFQFN), plastic thin shrink small outline no lead package (P-TSSON), and fine-pitch BGA, FBGA (National) Portable applications, flash memory... 

Major suppliers of low-profile thermoplastic additives include Discas Inc. and Union Carbide Chemicals Plastics Co. Major suppliers of low-profile elastomeric additives include Dexco Polymers, Shell Chemical Co., and Union Carbide Chenucals Plastics Co. 

Description Most widely used filler for plastics forms vary according to geographical source. Surface treatments greatly improve properties and controlled particle size makes functional fillers possible improved flow properties, low-profile anti-shrinkage, anti-blocking additives treatment with aluminium trihydroxide (ATH) gives some flame retardancy ... 

I hope, therefore, that readers who are unfamiliar with additives for plastics will take a few moments to read on, while those who are involved professionally every day with optical brighteners, or hindered amine light stabilizers, or low profile additives, or nucleating agents, will forgive the use of some rather elementary examples to illustrate the central theme additives are essential. 

Atkins, K.E. and Rex, G.C. (1994) Internal Pigmentation of Low Profile Composites, Part III, Proceedings of the Society of Plastics Industry Composites Institute 49th Annual Conference, Section 13-D. 

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