All cast acrylic products in PMMA technical properties

Transcription

1 All cast acrylic products in PMMA technical properties Index Preface 1 Technical properties 1.1 Mechanical properties 1.2 Thermic and electric properties 1.3 Chemical properties 1.4 Optical qualities 1.5 Technical properties: synthetic table 1.6 Cast tubes under pressure: synthetic table 2 Processing 2.1 Cutting 2.2 Boring 2.3 Turning and milling 2.4 Lapping and polishing 2.5 Thermo-formature 2.6 Glueing

2 Preface All cast acrylic tubes, rods and bars in PMMA are produced with an unsaturated ester called methyl- methacrylate. Its polymerisation is got through light and heat and accelerated through catalytic agents. The process of solidification of the products is got by regulating the temperatures of the pre-polymerised resin in the mould. Cast acrylic tubes, bars and rods in PMMA have the same thermo-plastic features of cast acrylic sheets and blocks 1. That is to say: - clearness: a transparency of 98%; - brightness of the walls: very good transmittance of the light (92,3%); - very good resistance to weather conditions and corrosion; - good chemical resistance 2 ; - good resistance to break.. Cast acrylic products in PMMA have to be distinguished from extruded acrylic products as they have different physical and chemical properties. We suggest you to use cast acrylic products in PMMA in the following cases: - when perfect transparency and brightness are necessary for your end-product; - when manufacturing requires sticking; - for high-tech processing; - when the products have to bear a high service pressure; - in any case above Ø 250 mm. as there are no extruded tubes above this diameter. 1 Technical properties The most important technical characteristics which are analytical described in the following chapters are to find also in the table 2 of Mechanical properties The cast acrylic glass is a light stuff: its specific weight is 1,19 g/cm³. Thanks to its molecular structure it is a hard but elastic material, it has a high tensile resistance to the traction and to break and at the same time is easy to be manufactured on mechanical tools. Cast acrylic glass is according to the Rockwell s scale the hardest within the thermo-plastic materials. 1 Cast acrylic glass is normally called PLEXIGLAS as a trademark of Röhm GmbH, the German firm that invented it 2 As indicated in the table 1 2

3 1.2 Thermic and electric properties The service temperature of all acrylic products is max. 80 C. As the transformation from solid into liquid takes easily place as for the other thermo-plastic materials, mould and form them does not require a lot of energy. The acrylic glass remains in the solid state until 110 C. The forming temperature is between 150 and 180 C. 3 Cast acrylic glass is besides a more isolating stuff as glass or rubber; it does not conduct energy. Like all kind of plastics it is an electrostatic material. 1.3 Chemical properties Cast acrylic glass resists to the most common chemical products. It does not resist to alcohol and spirits with more than 30 vol., some solvents and some acids. The table 1 shows the chemical resistance of cast acrylic tubes, rods and bars in PMMA. TABLE 1: Chemical resistance of cast acrylic tubes, rods and bars in PMMA R= resistant; N= non resistant; M= medium resistance INORGANIC ACIDS boric acid R chlorine-sulphuric R nitric acid 30% M sulphuric acid M acid 80% hydrochloric acid R hydrofluoric acid M concentrated nitric N sulphurous acid R 40% 40% acid 1% chromic acid 40% R phosphoric acid R sulphuric acid R battery acid R 30% 40% ORGANIC ACIDS concentr. acetic N formic acid N oxalic acid R tartaric acid 20% R acid acetic acid 10% R formic acid 2% R picric acid 1% R thioglycolic acid M 10% butyric acid 5% R lactic acid 10% R stearic acid R trichloroacetic acid N ALKALI ammonia R saturated M concentr. caustic M lime R potassium carbon. potash saturated barium R saturated sodium M concentr. caustic M soap solution R hydrate carbon. soda INORGANIC SUBSTANCES chlorine water R barium sulphide R bichromic R sudium chlorate R potassium hydrogen peroxide R calcium chloride R potassium R sodium chlorate R 40V carbonate hydrogen peroxide N calcium M potassium cyanide R sodium fluoride R 120V hypochlorite aluminium chloride R liquid chlorine N potassium chloride R sodium phosphate M aluminium fluoride M sulphuryl chloride N potas. ferricyanide R sodium ipochloride M aluminium oxalate R chloride iron R potas. ferrocyanide R sodium nitrate R aluminium sulphate R chlorinated iron R potassium nitrate R sodium sulphate R rock alum R sulphated iron R potassium permanganate R sodium sulphur R 3 See 2.5 3

4 ammonium R magnesium R potassium sulphide R chloride tin R carbonate chloride Ammonium R magnesium R potassium sulphate R chlorated tin R chloride sulphate Ammonium R manganese R copper chloride R sulphate tin R phosphat sulphate Ammonium nitrate R mercury chloride M copper sulphate R sulphate zinc R Ammonium R sulphate nickel R silicon N chloride zinc R sulphate tetrachloride Silver nitrate R chloride nickel R sodium bisolphite R sulphur R Barium chloride R potassium R sodium cyanide R bicarbon. SOLVENTS AND ORGANIC SUBSTANCES Banana oil N aniline N diethyl phtalate M monobromic R naphtalate Ethyl acetate N petrol M heptane R naphtalate R Acetone N benzol N esalin R pyridine N Allylic alcohol N ethyl bromide N hexan R propylene N Amylic alcohol N ethyl butyrate N ethylchloroether N carbonate sulphur N Butyl alcohol N chlorophenol N oil ether R tetrachloroethan N Ethyl alcohol 20% R chloroform N ethyl ether N tetrachlorethylene N Ethyl alcohol N amyl chloride N phenol N tetrachlor.carbonat N anhydr. e Isopropylic alcohol N ethyl chloride N phtalate diamilic M tetrahydrofuran N Methylic alcohol N aircraft fuel M phtalate dibuthylic N tetrahydrophtalene N Propylic alcohol N cresol N glycerine N toluolo N Acetic aldehyde N decaline R glycol diethylene R turpentine R Benzoic aldehyde N diacetonalcohol N glycol ethylene R trichlorethyl. N Formic aldehyde R dioxan N buthyle lactate N trietilammin R Acetic anhydride N ethylene bromide N methylethylketone N xylol N FOOD-STUFFS Vinegar R coffee R bay leaf R pepper R Water R cinnamon R cloves N fruit juices R Mineral water R chocolate R milk R wine R Anise R onion R liqueurs N Beer R camomile R nutmeg R OILS;WAXES Refining acid R diesel oil R oils, minerals fats R Polishing wax M oils, vegetable oils R transformer oils R DETERGENTS Alcohol 20% R pure petrol N dry cleaner N Alcohol anhydrous N bleach R ammonia water R solution DISINFECTANTS Hydrog. peroxide R formalin R chloride paste/lime R chlor.calcium sul. R 100V. 2% Phenic acid N chloramine paste N denatured alcohol N corrosive sublim. R GASES Ammonia R sulphide anhydride R sulph. hydrogen R oxygen R Carbon dioxide R nitrogen dioxide R methane R ozone R Sulphuric anhydride R illuminating gas R carbonate oxid R chloride vapour M R= resist; N = does not resist; M = medium resistance 4

5 1.4 Optical qualities All cast acrylic products are characterised by a high purity and brightness. Transparent tubes, rods and bars are the plastic materials with the highest light transmittance: 92,3%. This property remains unalterable over years. Light is reflected without any absorption or dispersion: a ray of light that strikes the surface of a tube is completely reflected over the whole surface; for this reason cast PMMA is also very good as light conductor. The tubes absorb ultra-violet rays Technical properties: synthetic table TABLE 2: Technical properties PROPERTY NORM 5 UNIT VALUES MECHANICAL PROPERTIES specific weight DIN gr/cm³ 1,19 water absorption DIN % 0,21 flexural strength D790 Kg/cm 1200 tensile strength at break D638 Kg/cm 700 modulus of elasticity D790 Kg/cm² elongation at break DIN % 3 notch impact strength DIN kj/m² 2.2 impact strength ( Charpy ) DIN kj/m² 25 ball identation hardness (Rockwell) DIN MPa 100 THERMIC ELECTRIC PROPERTIES service temperature (without mech. stress) - C -40; +80 softening temperature (Vicat) DIN C 107 coefficient of linear thermic expansion DIN mm/m. C 0,8 thermic conductivity at 20 C DIN W/(m*K) 0,19 inflammability (propagation speed) D 635 cm/min 3 dielectric constant at 1 MHz DIN ,9 dielectric loss factor at 1 MHz DIN ,035 dielectric strength DIN Kv/mm 35 CHEMICAL PROPERTIES see table 1 in OPTICAL PROPERTIES index of refraction D 542-1,49 light transmittance D 1003 % 92,3 average spectral transmittance: -ultraviolet mµ -visible mµ -infra-red mµ 5 D 307 D 307 D 307 turbidity (Haze) D1003 % 0,3 light absorbtion - % < 0,05 limit angle D It is also possible to produce tubes which allows the transmittance of UV rays 5 The norms indicated in this table are taken from: a) DIN (Das Ist Norm): German Society for Standardisation; b) D (or ASTM): American Society for Testing Materials % % %

6 1.6 Cast tubes under pressure: synthetic table TABLE 3: Cast tubes under pressure CAST ACRYLIC TUBES IN PMMA: service pressure at 18 C Spec. thickn. External Diameter Thickness Thickness Thickness Thickness Thickness Thickness Thickness Thickness mm. 3 mm 4 mm 5 mm 6 mm 7 mm 8 mm 10 mm mm 25 26,00 *** *** *** *** *** *** *** 44 14,77 19,70 24,62 *** *** *** *** *** 50 13,00 17,33 21,67 26,00 *** *** *** *** 60 10,83 14,44 18,06 21,67 25,28 28,89 36,11 *** 64 10,16 13,54 16,93 20,31 23,70 27,08 33,85 *** 70 9,29 12,38 15,48 18,57 21,67 24,76 30,95 37, ,55 11,40 14,25 17,11 19,96 22,81 28,51 34, ,13 10,83 13,54 16,25 18,96 21,67 27,08 32, ,22 9,63 12,04 14,44 16,85 19,26 24,07 28, ,50 8,67 10,83 13,00 15,17 17,33 21,67 26, ,91 7,88 9,85 11,82 13,79 15,76 19,70 23, ,65 7,54 9,42 11,30 13,19 15,07 18,84 22, ,42 7,22 9,03 10,83 12,64 14,44 18,06 21, ,42 7,22 9,03 10,83 12,64 14,44 18,06 21, ,20 6,93 8,67 10,40 12,13 13,87 17,33 20, ,85 6,47 8,08 9,70 11,32 12,94 16,17 19, ,68 6,24 7,79 9,35 10,91 12,47 15,59 18, ,33 5,78 7,22 8,67 10,11 11,56 14,44 17, ,33 5,78 7,22 8,67 10,11 11,56 14,44 17, ,06 5,42 6,77 8,13 9,48 10,83 13,54 16, ,96 5,28 6,61 7,93 9,25 10,57 13,21 15, ,82 5,10 6,37 7,65 8,92 10,20 12,75 15, ,51 4,68 5,86 7,03 8,20 9,37 11,71 14, ,25 4,33 5,42 6,50 7,58 8,67 10,83 13, ,25 4,33 5,42 6,50 7,58 8,67 10,83 13, ,95 3,94 4,92 5,91 6,89 7,88 9,85 11, ,71 3,61 4,51 5,42 6,32 7,22 9,03 10, ,60 3,47 4,33 5,20 6,07 6,93 8,67 10, ,50 3,33 4,17 5,00 5,83 6,67 8,33 10, *** 2,89 3,61 4,33 5,06 5,78 7,22 8, *** 2,89 3,61 4,33 *** *** *** *** 400 *** 2,17 2,71 3,25 3,79 4,33 5,42 *** 500 *** *** 2,17 2,60 3,03 3,47 4,33 *** 6

7 For higher temperature moltiplicate the above indicated values to following coefficients coefficient temperature C The data above are typical values supplied in accordance with the normally commercial acceptable standards. Gevacril supplies them for your information but do not assume any responsibility for the a.m. data 2 Processing Cast acrylic tubes, rods and bars in PMMA can be manufactured like other thermo-plastic materials or light metals. The service temperature must not exceed 80 C and overheating must be absolutely avoided using, if necessary, local air, water or emulsifying oil cooling systems. 2.1 Cutting You can cut with all kind of industrial saws band, circular or portable ones which toothing is not too big. As the material tends to soften while processing it and sticks to the toothings of the saw reducing the cutting efficiency it is very important to cool the blades in their free stroke way. Band saws are usually used to cut big tubes, rods and bars and for diagonal cuttings. It is suggested to use 25 or 31 mm. guideway-band blades with a toothing-angle inferior than and superior than 2-5. The properties of the blades corresponding to the thickness of the tube are: BREADTH OF THE BLADE mm. THICKNESS OF THE TUBE mm. 7 TOOTHING/ 1" n. PERIPHERIC SPEED mt/ Circular saws are used to cut small tubes, rods and bars diagonal or straight. They are also used for straight cuttings of big tubes, rods and bars. In order to avoid chipping the slide must not stretch out more than 10 mm. above the internal wall of the tube. We suggest to use steel circular blades with hard metal toothing, (widia). The best properties for processing are indicated in the following table:

8 DIAMETER mm. LAPS N/1 THICKNESS mm. STEEL TOOTH. (N.) , , , , , , WIDIA TOOTHING 2.2 Boring After having marked out the tube with a normal marker mark the centre of the bore with a sharp graver so that the drill does not slip out at the contact with the tube. In order to avoid vibrations or chipping hold the tube firmly. Push down the drill slowly and with a light pressure so that its advancement becomes constant and regular. We suggest to bore with helicoidal drills which have the following properties: INFERIOR RAKE ANGLE 3 8 SUPERIOR RAKE ANGLE 0 3 COIL ANGLE DRILL ANGLE CUTTING-ANGLE negat.: -1-6 The rotation speed varies from turns/min. for Ø 1 mm. points to turns/min. for points until Ø 20 mm. 2.3 Turning and milling It is made with normal machines used to manufacture metals, with steel or widia tools, sharpened with the same rake angle used for turning brass, but the angle of cutting must be absolutely negative. Here are the properties of the tools: SUPERIOR CUTTING ANGLE from 0 to 4 INFERIOR CUTTING ANGLE from 5 to 10 LATERAL RAKE ANGLE about 15 RADIUS OF THE EDGE ON THE TOP about 5 mm. The cutting speed must be as high as possible comparable to the turning-lathe and the piece to work with values of 250 mt./min. The best conditions take place when shavings are regular. 8

9 2.4 Lapping and polishing The surfaces worked with well-sharpened tools and successfully cooled appear perfectly ground and bright. On the contrary, if the result is not satisfying you can rub down the surface with a fine grained abrasive paper or cloth - per hand, with water or with a lapping machine. Final polishing and buffing can be done with polishing-machines equipped with cloth-wheels on which is distributed abrasive paste (of various grains) or polishing waxes. Peripheric speed of the wheels must be of mt./sec.; the basic conditions of this kind of polishing system is to carry out the work with a light pressure of the tube on the cloth-wheels in order to avoid overheating. 2.5 Thermo-formature Thermo-formature is got by heating the tube with warm air at a temperature within 150 and 180 C, forming it in the right mould and letting it cool in the same one. You can bend the tube using a decomposable mould with the exact form of the finished piece. In order to prevent an ovalisation of the tube 6 we suggest to put inside it a rubber tube with a smooth surface which external diameter is 2 mm. littler than the internal one of the acrylic tube. Tubes with a bigger diameter than 60 mm. are blown in the following way: - heat the tube to a temperature of 180 C and put it into the mould; - apply two airtight caps equipped with loading/unloading valves for compressed air on the tops of the tube; fix the caps up while closing the mould; - put compressed air so that thanks to the pressure the piece adhere completely to the mould; - let the formed tube cool in the mould; - cut both of the tops of the tube where the caps where applied. Moulds can be made of wood, metal or resin. 2.6 Glueing You can join the tubes in various ways: - through connection, i.e., by widening a top of the tube the suggested widening length is 2 x diameter length so that the external diameter of the tube inserted corresponds to the internal diameter of the other tube; - through threading; this kind of joining is used for acrylic tubes with a big diameter; - through flange-joining, i.e, sticking methacrylate flange or sliding flange in other materials; - through glueing it with ACRIFIX von Röhm GmbH The data contained in this document represent mean values and are based on our experience. Gevacril is pleased to put them at your disposal but does not assume any responsibility for their use. 6 This is valid for tubes with a small diameter 9