ast
J
e
0. R. SWEENEY, L. K. ARNOLD, AND J. T.LONG1 Iowa Engineering Experiment Station, Iowa S t a t e College, Ames, Za.
iX R E C E N T years, attention has been drawn to the fact that the supply of chemical raw materials in the forms of coal and petroleum is subject to eventual exhaustion, and interest is developing in those chemicals which are obtainable from annually renewable sources. Of these, probably none is more interesting than 2-furaldehyde. The resinification of 2-furaldehyde in the presence of mineral acids was reported in 1840 ( 1 7 ) ,but because chemists in the nineteenth century were unaware of the utility of resinous materials, this reaction received little attention for nearly a century. The advent of commercial plastics in the forms of celluloid and phenolformaldehyde materials aroused interest in other resin-forming substances, including 2-furaldehyde. The production of 2-furaldehyde on a commercial scale beginning in 1922 and the subsequent reductions in price aroused increasing interest in this chemical. 2-Furaldehyde is capable of condensation in two ways : through the reactions of the aldehyde group, which form resins analogous to those formed by formaldehyde, and through the unsaturation of the furan nucleus. The ehydeald resins have been investigated extensively, and will not be considered here. When 2-furaldehyde is condensed by means of acids, the product is a weak, porous substance resembling charcoal in texture. Bruins ( 1), while searching for rubber vulcanization accelerators, discovered that the addition of about 20% by weight of furfurin to 2-furaldehyde changed the nature of the product to a strong, glossy material resembling black glass in appearance. The product was resistant to chemicals and heat, and could be molded by casting without t h e need for elevated temperatures and pressures. -4resin made from furfuryl alcohol has been investigated a t some length, and its use for chemically resistant surfaces has been reported (9). 2-Furaldehyde has the advantage over furfuryl alcohol of lower cost, being obtained directly from certain vegetable sources, while the furfuryl alcohol is obtained by reduction of 2-furaldehyde. Studies of the furfurin-modified 2-furaldehyde plastic have been carried out in these laboratories for some time (18). Several references are to be found in the literature concerning the acid-catalyzed polymerization of 2-furaldehyde with and without other materials which might be considered as additives. Patents have been issued covering the polymerization of 2-furaldehyde with acids (7, 16) and with metallic salts (19). The resinification of furfurin upon the application of heat has been mentioned (10, 21). The partial condensation of 2-furaldehyde with acetone, followed by polymerization of this mixture with hydrochloric acid, has been described in a patent issued to Richardson (16). Phillips (14) prepared a plastic by mixing 2-furaldehyde and lignin and condensing the mixture with hydrochloric acid. Other substances condensed with 2-furaldehyde in such a manner as might make them useful as additives were urea (3, I S ) , thiourea ( 5 ) , aniline, 1- and 2-naphthylamine, rn- and p-phenylenediamine (6),acetone (2, I I ) , other aldehydes (4, 8), furfuryl alcohol (do), and p-toluenesulfonamide (12). EXPERIMENTAL WORK
Since no systematic study of t h e influence of additives other than furfurin t o 2-furaldehyde has been made, i t seemed desir1 Present address, Chemical Engineering Department, Alabama Polytechnic Institute, Auburn, Ala.
able to determine the effects of various compounds or classes of compounds on the 2-furaldehyde polymerization product. The additives used fell into five clawes. Class 1 consisted for the most part of organic amines. Class 2 consisted of derivatives of 2-furaldehyde prepared by an aldol or Claisen condensation in situ. Class 3 consisted of other furan derivatives. Claes 4 consisted of Indulin -4,a form of pine lignin manufactured by the West Virginia Pulp and Paper Co. Class 5 consisted of a conibination of lignin (class 4) n i t h one of the additives of the first three classes. The 2-furaldehyde, hydrochloric acid, sulfuric acid, and most of the additives were commercial or technical grade. The p-toluenesulfonic acid was a product of higher purity. Evaluation of the various additives was done by making flexural strength on pieces of the finished plastic containing them and by observation of the amount of shrinking and cracking which resulted during the curing of these pieces. In some cases, Charpy impact tests (SRTM D 256-47) were also made. Specimens for the strength tests were cylindrical in shape, approximately 6 inches in length and inch in diameter. The supports on the flexural strength testing machine were 4 inches apart. Because the test specimens were not of the standard shape, the experimental values obtained mag not be strictly comparable with values reported for other materials, but are comparative among themselves. The shrinkage was measured by determining the decrease in diameter of a specimen approximately hemispherical in shape, obtained by molding 10 ml. of the casting mixture in a Coors crucible KO. 3A, such as is used for coal analysis. The crucible had a top diameter of 43 mm., a height of 23 mm., and a capacity of 23 ml. ORGA-IC AMINE 4DDITIVES
Each of the amine additives (67, by weight, based on the weight of 2-furaldehyde) was dissolved in 2-furaldehyde a t room temperature. To 3 volumes of this mixture was added 1 volume of concentrated (18" Be.) aqueous hydrochloric acid. The mixture was swirled in a flask for 15 or 20 seconds to enwre complete mixing, and then was poured into the molds. After a period of time, the solution set to a gel, which hardened upon further standing. All samples were cured in the molds for 7 days before testing, in order to permit complete hardening. (The 7-day curing time was adopted after preliminary studies using diphenylamine as an additive and gave the following strength data: 6 days, 2700; 7 days, 3300; 37 days, 3100; 56 days, 2900; and 111 days, 2900 pounds per square inch.) The length of time required for gelation to occur was different for each additive, but no correlation between time required for gelation and strength of product was found. The data in Table I show that in general the secondary aromatic amines are more helpful than the other classes of compounds tested. These compounds are also useful as rubber antioxidants, and in one instance a commercial rubber antioxidant was successfully employed as an additive for 2-furaldehyde polymerization. Ten of the additives which showed the most promise were subjected to further study to determine the effect of varying concentration. The results (Table 11) indicated that the optimum concentration occurred at about 3 mole %. Furfurin was tested a t concentrations up t o 207, by weight, and the strongest product was obtained with a concentration of 14%, based on t h e weight of 2-furaldehyde. At this concentration, the flexural
1582
July 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY TABLEI. EFFECTON Surface Appearance
Additivea Primary AliDhatic Amines Ethylenediamine Propylenediamine Triethylenetetramine Tetraethylenepentamine Monoisopropylamine %-Butylamine Ethanolamine Cyanoguanidinea m-Nitrobenehydrazide Phenylthiourea Melamineb Guanidine carbonate* Ureas
*
Primarv Aromatic Bmines Anilhe o-Toluidine m-Toluidine
- ...-...
2-Amino-4-nitrophenol 4-Chloro-2-aminoanisole Cresidine Phenylthiourea 0- Aminophenol-v-sulfonic acid 4-Aminoazobenrene-4sulfonic acid 2-Amino-8-naphthol-6sulfonic acid 4-Nitro-2-aminoanisole m- Aminophenol ~Anisidine I-Aminoanthroquinone 2-Aminoanthroquinone m-Nitroaniline 2-Naphthylamine o-Dianisidine Secondary .4liphatic Amines TX-isonrooviamine Mo;;pioliG Cyanoguanidinea Di-n-butylamine 1,3-Diphenylguanidine Guanidine carbonetea
%FURALDEHYDE
Linear Shrinkage
Flexural Strength, Lb./Sq. I n .
%
Very dull Very dull Very dull Very dull Dull Dull Dull Smooth. cracked Smooth Glossy, cracked Smooth, cracked Smooth Glossy, cracked
14 17 11 16 9 20 0 2
..
0 0 0 0 0 0 0 0 3400 3800 1400 300 Exploded
Smooth Smooth Glossy, cracked Very dull Very dull Glossy Glossy Glossy, cracked
17 20 16 19 16 4 5 9
500 1500 1500 1200 1500 2700 3200 3800
Very dull
9
1700
Very dull
2
0
Drill Smooth Glossy Dull. cracked Smooth, cracked Very dull Dull Dull Dull
14 6 2
700
.. ..
0 0 0
Smooth Very dull Smooth, cracked Glossy. cracked Smooth Smooth
1 15 2 12 18
900 1400 1800 2600 1500 300
10 9 16 11
100
11
ADDITIVES
Linear Flexural Surface Shrinkage, Strength Additive" Appearance Lb./Sq. Ih. % Secondary Aromatic Amines PDA-lob, 0 Glossy 20 3800 p-Hydroxydiphenylamine Glossy, cracked 15 1700 Diphenyl-p-phenylenediamine Smooth, cracked 18 2900 Di-2-naphthyl-p-phenylenediamine Glossv 19 3200 Di henylamine Glossy, cracked 12 3300 p-&opropoxydiphenylamine Glossy, cracked 17 3400 Triphenylguanidine Glossy, cracked .. 200. Phenyl-1-naphthylamine Glossy, cracked 12 Exploded 3300 Phenyl-2-naphthylamine Glossy, cracked 20 Phenylthioureab Glossy, cracked 3800 9 I ,3-Diphenylguanidine Smooth 18 1500 Furfurin Glossy, cracked 16 3600 Tertiary Amines Triethanolamine Very dull 16 1500 Melamine Smooth, cracked 16 1400 Triphenylguanidine Dull 200 Diphenylpiperazine Dull, cracked 14 1800 N-nitroso-diphenylamine Smooth, cracked 16 700 Nitriles Hydracrylonitrile Smooth 23 2700 a-Hydroxyisobutyronitrile Glossy, cracked 16 3500 Acrylonitrile Smooth 19 1000 Cyanoguanidine Smooth, cracked 2 1800 Unclassified Additives Methylamine hydrochloride Very dull .. 950 Cyanuric acid Very dull 33 2200 Anisaldehyde Dull, cracked 15 1600 Paraformaldehyde Glossy, cracked 21 3100 Acetone 12 Glossy 1850 Phenol Glossy 13 1600 Hydroquinone Dull 1000 %Naphthol Smooth '3 1700 Ammonium persulfate Very dull 12 700 Ammonium chloride Smooth 1500 Smooth Ferrous ammonium sulfate .. 700 Sodium silicate Dull .. 700 Amount of additive 6% by weight. Compounda not pkoperly under this classification but included for comparison, bein considered similar to amines. 0 A commercia? rubber antioxidant.
..
0 950 0 0
.. .. .. ..
PLASTIC O F VARIOUS
1583
strength was 3900 pounds per square inch, and the Charpy impact strength was 14.6 inch-pounds. Some cracking was encountered.
..
*
results comparable with those obtained by the use of the better additives in the organic amine class.
2-FURALDEHYDE DERIVATIVES A S ADDITIVES
Additives of this class were prepared by refluxingurea, acetone, or thiourea with an excess of 2-furaldehyde in the presence of pyridine, which was used as a catalyst. For condensation with acetone, variables studied were acetone concentration and pyridine concentration. The data indicate (Tables I11 and IV) that the best results were obtained when 1mole of acetone and 1/6 mole of pyridine were refluxed with 5 moles of 2-furaldehyde for 12 hours. This mixture, when cooled and condensed with hydrochloric acid in the ratio of 3 volumes of mixture to 1 volume of acid, had a flexural strength of 2600 pounds per square inch. Thus, although acetone was beneficial, its use did not lead to
ON FLEXURAL STRENGTH OF TABLE 11. EFFECT CONCENTRATION OF ADDITIVES
Additive Furfurin Diphenyl-p-phenylenediamine Di-2-naphthyl-pphenylenediamine Phenyl-%naphthylamine Diphenylamine p-Isopropoxydiphenvlamine
VARYING
----1
..
Flexural Strength, Lb./Sq. In. Additive Concn., % by Weight---2 3 4 5 6 7 2500 2300 2900 3800 3300
..
8 3600
1900 2500
2300
2600
2600
2900
3700
3600
1700 2000
2000
3000
2600
3200
..
3200
1200 1800 1600 2000 1400 1500 2000 2200
2600 2200
3300 3300
3400 2700
3000 2700
1200
1900 3100
..
2600
1600
1800 2300
TABLE111. EFFECTOF VARYINGACETONE CONCENTRATION WHENPREPARINQ FURFURAL ACETONE^ Acetone Flexural Conen Strength, Linear Lb./Sq. In. Mole" Shrinkage, % 0.33 1900 7 0.20 2600 3 0.10 12 1900 0.05 11 2200 a One mole of 2-furaldehyde and 0.01 mole of pyridine were refluxed for 12 hours with the amount of acetone shown: the cooled mixture was then oondensed with hydrochloric acid.
TABLEIV. EFFECTOF VARYINGPYRIDINE CONCENTRATION WHENPREPARING FURFURAL ACETONE^ Flexural Amount of Pyridine Strength, Linear M1. Mole % ' Lb./Sq. In. Shrinkape, yo 0.05 0.04 1700 11 0.20 0.16 2400 17 0.60 0.48 1700 18 5.0 4.00 1700 16 The molar ratio of 2-furaldehyde to acetone was 5 t o 1. Of this mixture, 146 ml. were refluxed with the amount of pyridine shown for 12 hours; the cooled solution was then condensed with hydrochloric acid.
Urea was refluxed with 2-furaldehyde in the same manner aa acetone, and studies were made of the effects of varying urea concentration, pyridine concentration, and length of reflux time. It was found that the use of more than 1 mole of urea to 20 moles of 2-furaldehyde resulted in resin formation during the refluxing period, before the acid was added. The use of 1 mole of urea to 40 moles of 2-furaldehyde resulted in a plastic which was substantially equal in strength to that obtained when the urea con-
1584
Vol. 44, No. 7
INDUSTRIAL AND ENGINEERING CHEMISTRY
centration was twice as great. The effect of varying pyridine concentration is shown in Table V, and the effect of varying reflux time is shown in Table VI. The same optimum pyridine concentration was found for urea as had been found earlier for acetone. While the use of urea is desirable from the standpoint of cost of materials, this advantage is offset, partially a t least, by the long reflux time which is necessary.
obtainable from any additive alone, particularly from the standpoint of shrinkage. The results of some tests on combinations of additives are shown in Tables IX and S. CONDENSING AGENTS OTHER THAT HYDROCHLORIC ACID
Throughout the work on the evaluation of additives, hydrochloric acid was used as the condensing agent. After the question of additive agents was explored rather extensively, it was TABLEV. EFFECTOF VARYISG PYRIDINE COSCENTRATIOX decided to make a study of possible condensing agents, to discover one that was more suitable than hydrochloric acid. The FURFURAL UREA" WHENPREPARING difficulty encountered in the use of hydrochloric and sulfuric Flexural Amount of Pyridine Strength acids was that the acid diffusedto the surface of the finished prodLb./Sq. Ih. 1'11. Mole % uct and attacked suscept,ible materials, such as metal, paper, and Molar Ratio of 2-Furaldehyde to Urea, 20:1 varnished surfaces. This effect' was not short lived, but contin0.05 0.04 3300 ued over a considerable time. 3200 0.20 0.16 3200 0.60 0.48 Hydrobromic acid produced a plastic which was substantially 2500 5.0 4.00 the same in physical properties as that produced with hydroMolar Ratio of 2-Furaldehyde to Urea, 40:l chloric acid but which !Vas more costly. The plastic obtained by 2800 0.0 0 using hydrofluoric acid ?vas inferior in strength. Phosphoric 3100 0.05 0.04 0.16 0.20 3400 acid and phosphorus pentoxide required several days to effect 2500 0.60 0.48 2300 5.00 4.00 condensation and produced a weak product. Bromine and iodine were both found effective in carrying out, a Mixtures containing 144 grams of 2-furaldehyde a n d 4.5 grains of urea (20:l) or 2.2 grams of urea (40:l) were refluxed for 12 hours with the amount the condensation; bromine was preferable because it was in the of pyridine shown, cooled, a n d condensed with hydrochloric acid. liquid st.ate and dissolved readily in the 2-furaldehyde. Solid crystals of iodine apparently became coated with the polymer, TABLEVI. EFFECTOF REFLUXTIME IS PREPARATIOX OF thus preventing solution of the crystal. Bromine was extremely F U R F U R A L U R E a ADDITIVEa reactive with 2-furaldehyde and cautious addition accomTime of Flexural Refluxing, Strength, Linear panied by cooling to near 0" C. and vigorous stirring were necesHours Lh./Sq. I n . Shrinkage, % sary t o prevent an overly violent reaction. 8 0 11 1 The use of halogens or other nonacidic condensing agents was a 12 2 solution to the problem of acid diffusion encountered with hy13 4 16 8 drochloric acid, since if no acid were used in the reaction none .. 12 18 3000 .. could come out. With this thought in mind, several inorganic salts which are Lewis acids were tested to see if the plastics a Mixtures having t h e proportions of 100 moles of !Z-furaldehyde, 5 inoles of urea, a n d 1 mole of pyridine were refluxed for the times shown, cooled, and produced would have acceptable physical properties. The condensed with hydrochloric acid. salts tested, in decreasing order of their reactivity, were aluminum chloride, ferric chloride, stannic chloride, and zinc chloride. I t was necessary to heat the mixture of salt and 2-furaldehyde, A series of tests was made in which thiourea was substituted and with the exception of aluminum chloride it was necessary also for urea in the ratio of 1mole of thiourea to 5, 10, 15, and 20 moles to add a small amount of an acid to completely harden the plastic. of 2-furaldehyde. I n all of these tests, the mixture hardened Another condensing agent which was tested was p-tolueneduring the refluxing period to a brittle solid which could not be sulfonic acid. Although this compound is an acid, it does not softened by heat. present the diffusion problem that sulfuric or hydrochloric acid does, and it gives a strong product. A comparison of the properFURAN DERIVATIVES Several furan derivatives in the amount of 3 mole % were tested as additives. An inspection of the data (Table VII) shows that furfurin and methylfuran are substantially equal in effect, with furfural acetone and 2,5-dimethylfuran slightly inferior and the other compounds definitely inferior to either furfurin or methylfuran. However, all of these compounds show considerable improvement over the material made without additives, in which case the flexural strength was only 1300 pounds per square inch. LIGNIN ADDITIVES
Because of the cheapness and abundance of lignin, its use as an additive would be highly desirable. Lignin is soluble in 2-furaldehyde to the extent of about 33y0 but prolonged stirring is necessary to effect solution. When the mixture was heated to increase the rate of solution, it hardened prematurely. The effect of lignin in varying amounts is shown in Table VIII. Cracking was eliminated with 10 or 15% lignin, but reappeared when greater amounts were used. LIGNIN COMBINED WITH OTHER ADDITIVES
I t was found t h a t by combining lignin with one of the other additives. a product was obtained which was superior to that
TABLE VII.
EFFECT OF CERTAIN FURAN DERIVATIVES as ADDITIVES (Additive concentration, 3 mole %)
Additive Furfurin Methvlfuran F u r f j r a l acetone 2,d-Dimethylfuran Furfural acetophenone Fury1 acrolein Furfuryl alcohol Furfuryl acetate
TABLE VIII. Amount of Lignin, % b y Wt. 0 5 10 16 20 25
Flexural Strength, Lb./Sq. In. 3600 3400 3000
2800 2300 2200 2200 2300
Charpy Impact 8trength, In.-Lb. 6.2
9.4 4.4 2.5 3.2 2.8 2.4 2.0
EFFECT OF VARYIKG CONCENTRATION OF LIGNIN (ISDULINA) AS ADDITIVE Flexural Strength, Lb./Sq. In. 1300 3400 3200 3700 3700 3800
Charpy I m p a c t Strength, In.-Lb. 2.3 2.6 . I .
8.9 4.8
...
Linear Shrinkage, % 42 20 17 12 12
..
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1952
OF EFFECTS OF LIGNINUSED ALONE TABLE I X . COMPARISON AND WITH
Amount of Lignin, % by Wt.
Flexural Strength, Lb./Sq. In.
COADDITIVES Charpy Impact Strength, In.-Lb.
Linear Shrinkage,
Yo
1585
additives from the class of secondary aromatic amines decreased the gelling time according t o a logarithmic function depending upon their concentration. While the relation between gelling time and strength or the products containing certain individual additives could be determined, no general relation applicable
Lignin 2.3 5.3 4.8
0 10 20
1300 3200 3700
0 10 20
Lignin plus 3 % Urea 2900 ... 5.4 3600 6.5 3600
0 10 20
Lignin plus 6 % Diphenylamine 3000 3.7 5.2 3300 6.0 3600
0 10 20
Lignin plus 6% Furfurin 3300 ... 4.1 3200 4.3 3600
42 17 12
..
14 7 12 9 5 16 15
8
TABLEX. EFFECTS OF LIGNIN AND 15% FURFURIN AS COADDITIVES
Amount of Lignin, yo by Wt. 0 5 10 15 20
TABLE XI.
Flexural Strength, Lb./Sq. In. Lignin plus Lignin furfurin 1300 3600 3000 3400 3200 3300 3700 3600 3700 3800
Charpy Impact Strength, In.-Lb. Lignin plus Lignin furfurin 2.3 . . 2.6 . . ... 3 9 ... 8.9 4.8 8.4
Linear Shrinkage, % Lignin plus Lignin furfurin 42 10 20 9 17 7 12 6 12 2
PHYSICAL PROPERTIES OF PLASTICS PREPARED WITH VARIOUSCONDENSING AGENTS
(Casting sirup contained 15% lignin and 15% furfurin by weight) Charpy Flexural Impact Strength, Strength, Linear Condensing Agent 'Lb./Sq. In. In.-Lb. Shrinkage, % 6 Hydrochloric acid 3600 9:2 1 3600 Sulfuric acid Sulfuric acid diluted with 7.5 2 1700 equal vol. of water Sulfuric acid diluted with 3800 0.3 12.9 equal vol. of acetone 4 p-Toluenesulfonic acid 3600 14.8 1 Bromine 8.4 2500
F i g u r e 1. Effect of G e l a t i o n T i m e of V a r i o u s Additives to all additives between gelling times and strength of product could be found. Such a relation, had i t been available, would have materially reduced the work of selecting the best additive. I t was also found that below about 19" C. (varying for different additives) no polymerization occurs. Above this the gelling time decreases almost logarithmically with the increase in temperature (Figure 2).
80
P
-t5 a
K a W
ties of plastics prepared by some of these condensing agents acting on a 2-furaldehyde solution containing 15y0 furfurin and 15% lignin is given in Table XI. All the condensing agents were used in the amount of 0.24 equivalent per mole of 2-furaldehyde. Of these p-toluenesulfonic acid was the most desirable. With its use, no diffusion of the acid was encountered; and the product was equally strong in flexure and stronger in impact than that obtained by the use of the other condensing agents. It is postulated that acid diffusion is not encountered with p-toluenesulfonic acid because of the affinity of the 2-furaldehyde for the benzene ring of the acid. Bromine was the only other eompound that did not cause diffusion difficulties, but it produced a product t h a t was considerably weaker in flexure. Experiments are now under way t o improve this product.
70
w' 6 0
I IW
5 0 40 30
20 8
F i g u r e 2.
10
20 30 40 60 80 100 GELLING TIME, M I N U T E S
150
Effect of Temperature on Time R e q u i r e d for Gelation
Since the gelling reaction may, under certain conditions, proceed with explosive violence, attention to proper mixing technique and temperature control is also important from the standpoint of safety. This would be particularly important in t h e commercial production of these products.
FACTORS INFLUENCING GELATION TIME
CHARACTERISTICS OF THE RESULTING PLASTIC
The time required for gelation of the various compositions was determined as the difference between the time when the casting sirup and condensing agent were mixed and the time when the product had gelled t o the point where a crucible containing it could be tipped through 90 degrees without spilling any of the plastic. The influence of various factors on the time required for gelation was studied in the hope of finding some correlation between strength or other properties and the gelation time. From the results of these studies (Figure I) i t can be seen that various
The product of 2-furaldehyde-containing additives previously described is a hard, glossy black, opaque material which can be readily cast without expensive molding equipment, making it especially suited t o small production runs. It has excellent heat resistance, not igniting when held in a Bunsen flame. The specific gravity of the molded product is 1.4. It is not greatly affected by chemical reagents (Table XII) and thus has a possible application t o chemically resistant tanks and surfaces. The cost of raw material for the casting sirup is estimated at from 10
INDUSTRIAL AND ENGINEERING CHEMISTRY
1586 TABLE
XII.
RESISTANCE O F %FURALDEHYDE REAGENTS
Reagent Distilled mater 2-Furaldehyde E t h y l acetate 3 % sulfuric acid 30% sulfuric acid I % sodium hydroxide 10% sodium hydroxide
Amount Absorbed,
Amount Soluble,
6.84 0.42
0.64 0.0 0.0 0.21
%
0.80
5,98
2.98 6.30 2.22
'
70
0.0 1.02 0.80
50% ethyl alcohol
0.82 2.07 Acetone 0.62 0.0 a Rubbed off on towel when wiped dry. b Did not r u b off on towel.
PLASTIC TO
Color of Solution Colorless Amber Colorless Colorless Colorless Light yellow Faint yellow Colorless Faint yellow
CHEMICAL
Appearance of Surface of Sample Glossy Glossy Glossy Glossy Glossy Srnootha Glossy, b u t rough a n d blisteredb Glossy Glossy
to 14 cents per pound of finished product. Thus the materials cost of the finished articles using bromine as a condensing agent would be 12 to 16 cents per pound. If p-toluenesulfonic acid is used the cost will he about 25 cents per pound. SUBIU4RY
The effect of various additives on the strength propelties oi a plastic based on the polymerizing tendencies of 2-furaldehyde has been studied. It has been found that among suitable additives are secondary aromatic amines; certain furan derivatives such as furfurin, methylfuran, furfural acetone, 2,5-dimethylfuran, furfural acetophenone, fury1 acrolein, furfuryl alcohol, and furfuryl acetate; and ligninsulfonic acid or preferably mixtures of ligninsulfonic acid with one of the other additives. p-Toluenesulfonic acid has been found to be an excellent condensing agent, resulting in a product having good strength but free from acid-diffusion difficulties encountered with other acidic reagents. Bromine also has advantages as a condensing agent.
Vol. 44, No. 3
The resulting product is a hard, shiny, black material which is readily cast and which shows excellent resistance to chemicals., Products having flexural strengths up to 3800 pounds per square inch have been produced. Raw material costs are estimated betrveen 12 and 25 cents a pound depending upon the condensing agent used. LII'ERATURE CITED
(1) Bruins, P. F., Ph.D. thesis, Iowa State College,
1934. (2) Harvey, 11. T., C. S. Patent 2,481,510(1949). (3) Kappeler, Hans, Brit. Patent 293,872 (1927). (4) Kappeler, Hans, French Patent 697,169 (1930). (5) Kappeler, Hans, Swiss Patent 133,387 (1927). Ibid., 133,707-12 (1927). Ibid., 146,561 (1929). Kappeler, Hans, C . S.Patent 1,873,599 (1932). Kline, G. M., IND. ENG.CHEX, 41,2132-7 (1949). Mains, G. H., and Phillips, bIax, C'hem. & M e t . Eng., 24, 661-3 (1921). Mevnier, G., French Patent 472,384 (1916). Moss, W. H., and White, B., Can. Patent 303,697 (1930). Novotny, Emil, C. S.Patent 1,827,824 (1932). Phillips, Max, Ibid., 1,750,903 (1930). Richardson. L. T., I h i d . , 1,584,144 (1926). Ibid., 1,682,934 (1928). Stenhouse, J., Ann., 35, 301 (1840); Phil. Muo., 18, Ser. 3, 1224. (1841). Sweeney, 0. R., and Arnold, L. IC, Iowa Eng. Esp. Sta., Bull. 169 (1950). Trickey, J. P., and RIiner, C. S., U. S.Patent 1,665,233 (1928). Ihid., 1,665,235 (1928). Trickey, J. P., Miner, C. S., and Brownlee. H. J,,IND.Ex
