78 research outputs found
Process control in injection moulding machine
Get PDFInjection moulding is a method used to convert a polymer feedstock into the a final product. The process require process control technology to provide a workable process process at economic cost and to provide a consistent product within specification. This paper presents an overview of process control in the injection moulding machine
Synthesis and characterization of polymer hydrogel composites based on poly acrylic acid grafted cotton microfiber
No full textThe optimum content of initiator (APS), cross linker (MBA), sodium hydroxide (NaOH) and oil palm empty fruit bunch micro-fiber (OPEFB), were optimized using central composite design method (CCD). Polymer hydrogel composite (PHGC) and plain polymer hydrogel (PHG) were characterized using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The influence of OPEFB on biodegradation of PHG was studied
Drop mixing in suspension polymerisation
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Swelling behaviors and characterization of oil palm empty fruit bunch-graft-poly (Acrylamide) superabsorbent polymer composites
Get PDFThe development on a class of technologically advanced materials like superabsorbent polymer composites (SAPC) involved multidisciplinary research started when its potential is recognized. Oil palm empty fruit bunch-graft-poly (acrylamide) (OPEFB-g-PAAm) SAPC was synthesized via simultaneous crosslinking and graft copolymerization of acrylamide (AAm) monomer onto OPEFB backbone with N,N’-methylenebisacrylamide (MBA) and ammonium persulphate (APS) acts as crosslinker and initiator, respectively, along with neutralization using solution polymerization method. Systematically, variables that affect the swelling behaviors of OPEFB-g-PAAm SAPC were optimized. The effects of initiator, crosslinker and filler concentration as well as solvent quantity and the degree of neutralization on water absorbency of OPEFB-g-PAAm SAPC were studied. Maximum absorbency of OPEFB-g-PAAm SAPC was achieved at 589.06 g/g when the amount of APS and MBA were 1.5 wt.% and 0.15 wt.%, respectively, and the OPEFB loading was at 10 wt.%. The optimum amount of solvent used was 15 mL and the degree of neutralization was 20%. The chemical structure of the OPEFB-g-PAAm SAPC was characterized by means of Fourier transform infrared (FTIR) spectroscopy. A mechanism pathway in synthesizing OPEFB-g-PAAm SAPC was suggeste
Drop mixing in suspension polymerisation
No full textSuspension polymerisation is one of the major processes used to produce
polymers. In this process, monomer is suspended as liquid droplets in a continuous
water phase by mean of strong agitation and the presence of a suspending agent. As
the suspension polymerisation proceeds, the viscosity of a monomer–polymer droplet
increases with conversion. Hence, the physical behaviour of the droplet changes
during the process. When new dispersible material is added to the existing suspension
drops, the new material and existing drops can remain segregated for significant
amounts of time. This will affect the properties of polymer products.
The aim of this project was to study the behaviour of drop mixing when new material
is added to the existing suspension polymerisation. This study concentrated on the
effect of the dispersed phase viscosity on the drop mixing, but agitation intensity and
surface stabilities were also important. [Continues.
Effect of Different Monomers on Water Retention Properties of Slow Release Fertilizer Hydrogel
No full textAbstractThe combination of hydrogel and fertilizer as slow release fertilizer hydrogel (SRFH) has become one of the promising materials to overcome the shortcomings of conventional fertilizer by decreasing fertilizer loss rate, supplying nutrients sustainably, and lowering frequency of irrigation. A comparative study on water retention and plant growth performances of SRFH made from three hydrophilic monomers; acrylic acid (AA), acrylamide (AAm) and AA-co-AAm was executed. PAA SRFH has smaller swelling rate constant, k as it required only 166.67minutes to absorb 0.63 of its equilibrium capacity of swelling, followed by P(AA-co-AAm) SRFH and PAAm SRFH. Although PAAm SRFH has the lowest swelling rate constant, it has the most excellent water retention ability in soil followed by P(AA-co-AAm) SRFH. Additionally, the presence of PAA SRFH in soil has enhanced the plant growth performances of model plant (capsicum annum) in term of its average leaf width and plant height. The synergistic effects of acrylic acid and acrylamide in P(AA-co-AAm) SRFH could be utilized to produce hydrogel used in agriculture
Asessing the effect of emulsion viscosity on the adesive properties of model waterbone acrylic pressure sensitive adhesives
Get PDFIn recent years, increasing social and political awareness, coupled with the tightening of worldwide environmental legislation, has forced coating industries to decrease levels of pollutant substances released to the atmosphere. Solvents from the coatings industry are considered to be volatile organic substances. For this reason there is an increasing tendency to move away from conventional solvent-borne coatings to those that use water as the fluid vehicle [1]. One of the more important film-forming pigment binders used in water borne coatings is that class of resins known as acrylics. Acrylic polymers are widely used as pressure-sensitive adhesives (PSAs). An emulsion is a mixture of two immiscible liquids, one the dispersed phase, existing as discrete droplets dispersed throughout the other, the continuous phase. In the case of emulsion polymerization the continuous phase is comprised mainly of water and is therefore termed the aqueous phase. Emulsion polymer is actually a dispersion of solids, or semi-solids, polymer particles in a continuous aqueous phase. Acrylic polymer emulsions give excellent weather resistance, water and alkali resistant films due to the main polymer chain’s carbon-carbon bonds. However, the elasticity and abrasion resistance of acrylic polymer emulsions are inferior [2]. It has long been recognized that the reaction pathway in emulsion. Polymerization plays a decisive role in determining the particle morphology and consequently the emulsion polymers properties. Zhao and his co workers carried out a study of structured polymer latex particles which were prepared by a swelling emulsion polymerization process, in which the initial particles are first swollen by ethylenically unsaturated monomers and the polymerization of the latter is then carried out [3]. Latex particle size distribution (PSD) is probably the most important variable in designing low viscosity, concentrated aqueous polymer dispersions. Asua and colleagues prepared the adhesive and rheological properties of model acrylic pressuresensitive adhesives (PSA) films prepared from high solid emulsions with different particles sizes and distributions have been investigated with a customized probe tack apparatus. The results showed that a broad PSD is favored over a narrow a PSD and that the present of large particles is recommended [4]. The molecular weight directly influences the final viscosity of the resins. The viscosity of the polymer is further strongly influenced by the rigidity of the sequences. At identical molecular weights and at equal concentrations, a solution of polymethyl methacrylate for example will be much more viscous than a solution of polybutyl acrylate. Another factor strongly influencing viscosity is the formation of associations. In non-polar solvents, the carboxyl groups have a strong tendency to form associations between one another via hydrogen bonding. These hydrogen bonds markedly increase the viscosity. The degree of polymerization is proportional to the concentration of monomers and inversely proportional to the initiator concentration. As a general rule, the lower the concentration of monomer, the lower the molecular weight of the polymer. The higher concentration of initiator, the lower the final molecular weight obtained [5]
Quality enhancement of plastics recycled by incorporating lubricant additives.
Get PDFThis paper discusses the method to enhance the quality of recycled plastics. The material used is High Density Polyethlylene (HDPE) by incorporating Calcium Stearate as an additive. Results obtained suggested that the lubricant additive has improved the physical property of the recycled plastics. Detailed discussion of the study is available in the attached article
Synthesis, optimization, characterization, and potential agricultural application of polymer hydrogel composites based on cotton microfiber
No full textThe optimum content of cotton microfiber, initiator, cross-linker, and sodium hydroxide were determined using the central composite design method. Polymer hydrogels (PHGs) were characterized using Fourier-transform infrared (FT-IR), scanning electron microscopy, and thermal gravimetric analysis. A comparison between plain PHG and the polymer hydrogel composite (PHGC) in terms of biodegradation, swelling rate, and re-swelling capacity was carried out. The effect of PHGC on the sandy soil holding capacity, urea leaching loss rate (ULLR), and okra plant growth were evaluated. The highest water absorption capacity was obtained at 1.30 mass %, 0.15 mass %, 13.00 mass %, and 13.50 mass % of the initiator, cross-linker, sodium hydroxide, and cotton microfiber, respectively. Cotton microfiber has a prominent effect on the swelling rate, re-swelling capacity, and biodegradability of PHG. Okra plant growth and ULLR were positively affected by PHGC and the best leaching loss rate of 33.3 mass % was observed for the lowest urea loaded sample
The influence of plant natural fibers on swelling behavior of polymer hydrogels
No full textCentral composite design method was used to design and optimize the best content of initiator, cross-linker, neutralizer and plant natural fibers of cotton and oil empty fruit bunch. The effect of buffer and saline solution on plant natural fiber based polymer hydrogel composites was investigated. The influences of plant natural fiber content and swelling behavior of polymer hydrogels were studied. Natural fibers had positive effect on polymer hydrogels in terms of absorption capacity and swelling rate. Polymer hydrogel composite of natural fiber with higher cellulose content had better swelling properties than that of less cellulose content and plain hydrogels. Polymer hydrogel composite base of high cellulose fiber content is less affected by the pH and ion concentration of the external solutions
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