responsibility. As teenagers looking for summer work, we did a lot of lawn-mowing. We

Transcription

1 Introduction Everything is going green. We wanted to contribute something to environmental responsibility. As teenagers looking for summer work, we did a lot of lawn-mowing. We noticed bags and bags of grass clippings at the curb for trash pick-up or piles and piles of grass clippings accumulating in remote areas of backyards. Even households that composted couldn t absorb all of the grass-clippings. Furthermore, even though we can recycle newspapers in our town, they are not accepted if they have become damp or wet. We reviewed the literature for relevant research. We found plenty of information about the ancient history of paper. We learned that fibers can be recycled as many as six times before they get too short to be used again. We learned that newspaper make up about 28% of municipal solid waste and that grass clippings make up about 14% of municipal solid waste. There was information about utilizing trees, leaves, and other plants as fiber sources. However, there was very limited information available about using normal lawn grass. We knew from our visits to a flax-processing demonstration that processing would likely be required to use grass as a paper-making fiber. However, the literature search we conducted referred only to chemical processing (stewing in soda ash) to release the fibers and even that literature was subjective and anecdotal, not empirical. We found nothing about mechanical processing. We wanted to see if we could combine grass clippings and recycled newspaper to make new sheets of paper. We knew that we could make new sheets of paper using 100% recycled newspaper, so we used that as our control for measuring tensile strength, fatigue strength, and flexibility and for evaluating write-ability, appearance, and smell. It was our hypothesis that paper using as much as 50% grass clippings would still function as paper in an economicallyand environmentally productive manner. 1

2 Materials: We used water, recycled newspaper, and grass clippings. Equipment: The items of equipment used in our project were as follows: Preparation of the recycled newspaper: 100-cm ruler, scissors, electric paper shredder, cardboard for template, pen for tracing template, and containers for paper after shredding and cross-cutting. Preparation of the grass clippings: lawnmower with grass-catcher and a trash bag (to line the grass-catcher). Preparation of the paper pulp: both liquid and dry measures, KitchenAid blender, scraper (to scrape the pulp out of the blender), and a stopwatch to time blending. Preparation of the paper: roasting pan (to hold the deckle during drying), deckle (consisting of support grid, a screen, a wooden frame to contain the pulp, and a cover screen), sponge, rolling pin, plastic fork, an absorbent dish towel, two cotton handkerchiefs, an electric iron, an ironing board, sections of newspaper to hold paper after ironing for final drying, a clipboard, one 2# weight, one 3# weight, and two 5# weights. Testing: cardboard for template, scissors for cutting out samples, paper and pen for tracing templates, recording results, and evaluating write-ability, digital hanging scale, a hole punch, adhesive hole reinforcement stickers, plastic bag closing clip, and binder clips for flexibility testing. Acknowledgements We want to acknowledge our parents, who provided the equipment (and the materials, for that matter) and purchased the deckle for our use. We also want to acknowledge Mrs. Kendrick, our Honors Chemistry teacher, who served as our mentor. Methodology Content material recycled newspaper: The first part of our project was to prepare the content material which, mixed with water, would become the pulp. For our recycled newspaper content, we went through recent (within the previous week) copies of the Observer- 2

3 Reporter. With a 10-cm ruler, we located 10cm x 10cm squares with relatively uniform ink density on both sides, i.e. no photos, advertisements, or bold titles. We marked the squares with a cardboard template and a pen, cut out the squares, and grouped them by tens. We fed each group of ten squares through a shredder, captured the strips, and cross-cut them into squares with scissors. We placed the shreds from each group of ten squares into separate containers. Content material grass clippings: For the grass clippings, one of us lined the mower s grass-catcher with a trash bag, mowed a green section of the lawn, and captured the clippings. Because we couldn t control the weather/humidity/grass type variables, it was important that all of the grass used as content material be captured at the same time and under identical conditions. Pulp preparation: The second part of our project was to produce the paper. We started with two cups of content material, measured by dropping into the measuring cup without compressing, then tapping the measuring cup against the counter three times. We measured four cups of moderately warm water, assuming that, avoiding extremes, the temperature of the water was not significant to the outcome. We added half the water to the KitchenAid blender container, then the content material, then the remainder of the water. Using a stop watch, we turned on the blender with the liquefy setting for fifteen seconds, scraped down the container, and liquefied five seconds more. Paper preparation: We took turns pouring the pulp into the 20 cm x 25 cm deckle using an even-flowing S-pattern. We used a plastic fork to spread pulp evenly, our greatest challenge. After carefully lifting off the deckle frame, we laid the cover screen over our sheet of paper. We pressed a brand-new sponge down in an even pattern across the cover screen, wringing it frequently, working over the entire deckle screen three time. We peeled off the cover 3

4 screen, our second-most-significant challenge. We smoothed a cotton handkerchief over the sheet. Using the same sponge, we pressed across the handkerchief-covered sheet one time. We flipped over the handkerchief-sheet stack, removed the deckle screen, and put another handkerchief and an absorbent dishtowel on top. We rolled across the stack three times with a rolling pin. We ironed the stack on the high (cotton) setting to remove the last bit of free water. Then we placed each damp sheet of paper in the center of a section of newspaper, marking the newspaper section to identify the % of grass content. We topped the stack of newspaper sections with a clipboard to distribute the weights to be applied. On top of the clipboard, we placed one 5-pound weight along each 20-cm end and stacked one 2-pound weight and one 3-pound weight along the centerline of the paper. We left the stack to dry for three weeks. Modifications to the original experiment design: The first time we attempted the production of paper, we experimented with different tools to spread the pulp evenly in the deckle. The pulp adhered to both a non-stick silicon scraper and a metal spoon. We found that patting and dragging with the back of a plastic fork resulted in the most even distribution of pulp. We planned to also conduct our tests on a sample of paper produced using 100% grass clippings. However, the pulp which contained 100% grass clippings failed to form a sheet of paper on which to conduct testing. In conducting our tensile strength testing, we planned to suspend the sample from a binder clip, to attach a plastic bag-closing clip to the bottom of the sample, and to suspend increasing amounts of weight from the bottom of the sample. However, the papers greatly exceeded our expectations of their strength and the accumulated weights caused the bag-closing clip to slide off the bottom of the sample before the paper failed. As a result, we had to modify our tensile strength testing. 4

5 Testing General: The third part of our project was the testing of our paper products. As the paper we produced dried, there was some shrinkage, and some gaps and thin spots became apparent. We placed our product against a window to clearly reveal thin spots/gaps. Using an 8cm x 8cm cardboard template and a pen, we traced out the three most-uniform samples on each sheet and cut them out with scissors. This resulted in three samples of each product produced under identical conditions. Just for comparison purposes, we also tested a sheet of typical printer paper. We understand that the printer paper has longer fibers, has been chemically processed, is much thinner (and more flexible), and has been produced with machines to achieve a uniform thickness. We were merely interested in getting an idea of the relative strength. Testing Tensile strength: We used the hole punch to penetrate the samples and applied two adhesive hole reinforcement stickers on the front of each hole and two more adhesive hole reinforcement stickers on the back of each hole. We mounted the digital hanging scale on a fixed door knob. We hung each sample on the hanging hook. We attached the plastic bag-closing clip to the bottom of the sample to apply uniform gripping pressure across the bottom of the sample. We then exerted slowing-increasing downward pressure on the clip until failure, noting the scale reading at failure and any observations about the nature of the failure. Testing Fatigue strength: We used the remaining portions of the tensile strength testing samples to test and compare fatigue strength. We folded each sample in half and creased the sample, then folded it in half the other way and creased the sample, and repeated until the sample failed, counting the number of folds until the sample failed. Testing Flexibility: Based upon the material remaining from each product, we determined that the largest samples we could cut were 2cm x 15cm. We cut three such samples 5

6 from each sheet, and attached a binder clip to the top and bottom of each sample. We suspended the top binder clip from a fixed door knob. We stabilized top and bottom with our hands. Careful not to put any weight on the bottom binder clip, we twisted each sample counterclockwise until it failed, measuring the degrees of rotation in 45 increments and noting any observations about the nature of the failure. Testing Writing: To evaluate the write-ability of our paper sample, we used both a ballpoint pen and a fine-tipped Sharpie. Using a normal writing posture and position, we drew lines across each sample along the vertical dimension, along the horizontal dimension, and along the diagonal. We based our evaluation upon the ease of moving the pen and the degree to which our pen strokes disturbed the fibers of the paper. Testing Smell: We had made no attempt to sterilize, dry, or otherwise heat the grass clippings before using them in the paper pulp, so we recognized that there was a possibility that our paper products would have an unacceptable smell. Three weeks after preparing our paper, we evaluated the smell of the samples. We put each sample in a bowl and each of us waved the air toward us with a closed hand to evaluate the odor. 6

7 Results Testing Tensile strength In testing tensile strength, we measured the amount of downward-pulling weight required to cause an 8cm x 8cm sample of the paper to fail. The weight reading was displayed on a digital scale. We also made observations about the nature of the failure. This test was designed to learn the overall ability of the product sample to carry tensile loads. Material Sample 1 Sample 2 Sample 3 grams to failure grams to failure grams to failure Control - 100% recycled newspaper % recycled newspaper/ 25% grass clippings % recycled newspaper/ 50% grass clippings % recycled newspaper/ 75% grass clippings 520* Compare w/ typical printer paper failed at weak spot * 7

8 Testing Fatigue strength In testing fatigue strength, we measured the number of back-and-forth creased folds required to cause the sample to fail. This test was designed to assess the ability of the material to achieve and maintain crisp corners in manufacturing/molding. Material Sample 1 Sample 2 Sample 3 # of creased folds # of creased folds # of creased folds Control - 100% recycled newspaper % recycled newspaper/ 25% grass clippings % recycled newspaper/ 50% grass clippings % recycled newspaper/ 75% grass clippings

9 Testing Flexibility In testing flexibility, we measure the degrees of rotation of a 2cm x 15 cm sample which could be achieved before the paper failed. We also made observations about the nature of the failure. Material Sample 1 Sample 2 Sample 3 degrees of rotation degrees of rotation degrees of rotation Control - 100% recycled newspaper ! 540* 75% recycled newspaper/25% grass clippings 360# 630* 180# 50% recycled newspaper/50% grass clippings % recycled newspaper/75% grass clippings Compare w/ typical printer paper Gradual rip + failed at weak spot (not included in graph)! creased, then ripped * sudden rip (not included in graph) # 9

10 Testing Writing In evaluating the write-ability of our paper samples, we drew lines across each sample vertically, horizontally, and diagonally, evaluating the ease of moving the pen and the degree to which our pen strokes disturbed the fibers of the paper. We had the same results from each of the three samples of each kind of paper. Material w/ ballpoint pen w/ Sharpie Control - 100% recycled newspaper 75% recycled newspaper/ 25% grass clippings 50% recycled newspaper/ 50% grass clippings 25% recycled newspaper/ 75% grass clippings worked in all 3 directions with no fiber disturbance worked in all 3 directions with no fiber disturbance worked in all 3 directions with very slight fiber disturbance Worked in all 3 directions with slight fiber disturbance worked in all 3 directions with no fiber disturbance worked in all 3 directions with very slight fiber disturbance worked in all 3 directions with moderate fiber disturbance worked in all 3 directions with major fiber disturbance Testing Smell In evaluating smell, we compared the odor emitted by each sample. Obviously, having no grass content, the 100% newspaper sample had no particular smell. The 25% grass sample also had no discernable odor. The 50% grass sample had a slight herbal odor. The 75% grass sample had a mild herbal odor. No sample had a rotting or fermenting smell such as we experience in our yards. 10

11 Discussion Our background research found no investigation of paper products incorporating lawn grass clippings. Additionally, while we found some anecdotal evidence of paper production incorporating decorative grasses, all such anecdotes involved significant chemical processing and none involved lawn grass. We found no information about large-scale manufacturing of products incorporating grass of any sort and found no available commercial paper products containing lawn grass. Our experiments, on the other hand, used various combinations of common lawn grass clippings and 100% recycled newspaper. We used minimally-processed ingredients and only a basic deckle and common kitchen tools to produce the sample products. Through our investigations we have been able to determine that it is economically possible to produce paper which incorporates some proportion of grass clippings. Any incorporation of grass clippings into paper products would directly reduce use of landfill volume and directly reduce destruction of trees for paper production. Based upon the performance of our paper products in the various tests, we have concluded that grass clippings can effectively be incorporated into recycled paper products. The performance deviations associated with the various percentages of grass content suggest different applications. We concluded that applications for our grass-containing paper would include craft/construction paper, exotic writing papers, and, in dry conditions, packaging products. We initially also considered the possibility of using grass-containing paper for disposable takeout containers, but then realized that this paper would either not hold up under wet/greasy scenarios or could transfer grass color or flavor to the contents. Only to obtain an industrial reference, we compared the performance of our products to typical printer paper. We drew no conclusions on the basis of the performance of the printer 11

12 paper because of our inability to generate identical or even similar production circumstances. However, our investigation gave us a perspective on the relative performance of our products. Knowing that paper products are currently produced using 100% recycled newspaper, we produced samples using 100% recycled newspaper to serve as our control. We treated this formulation as our control because we knew that the market had already determined that 100% recycled newspaper was cost-effective and environmentally-beneficial. At the other end of the spectrum, we also attempted to produce samples using 100% grass clippings. However, attempts to use only grass clippings to create paper did not result in a finished product with sufficient cohesion to be tested. (See illustration 4.) While it might be possible to produce 100% grass paper with substantial additional mechanical processing or chemical processing or both, without that additional processing, it appeared that the grass fibers were not sufficiently separated to form a useable product. We see no possible utility for a 100% grass product. The costs, both environmental and financial, of additional processing of the grass outweigh the benefits and would defeat our intent of increasing utilization of otherwise-landfillbound recycled materials without increasing environmental or financial burdens. The mean tensile strength showed that the 75% paper/25% grass sample performed at 75% of the mean tensile strength of the 100% paper, while the 50/50 sample performed at 58% and the 25% paper/75% grass sample performed at 31%. These results mean that the loss of tensile performance was less than the loss of newspaper content, with optimal performance from the 50/50 sample. We considered this the most important test for the use of the paper in molded packaging because the packaging product needs to resist deformation in order to successfully protect the package contents. 12

13 The results of the fatigue testing were the most dramatic and the most interesting to us. The flexing capacity of the 50/50 sample was double that of both the 75% paper/25% grass sample and the 100% newspaper sample. The 25% paper/75% grass sample, unsurprisingly, came in as the least durable, but was not significantly weaker than the 75% paper/25% grass sample and 100% newspaper. The 75% paper/25% grass sample and the control samples failed by fracturing, but the 25% paper/75% grass failed when the sample simply disintegrated under the handling. We concluded that the 50/50 paper was the most successful in the fatigue testing because this proportion of the grass fibers and paper fibers yielded a very durable and cohesive product. We believe that the fatigue test is especially relevant to applications involving folding or other manipulation, such a craft/construction paper, folded packaging, or stationary. We obtained erratic results from our flexibility test. We had two sudden failures which appeared to be inconsistent with the data we were attempting to collect. As a result, we did not include those failures in our graphic display or in our calculation of mean performance. Our flexibility test results showed that the 75% paper/25% grass sample actually out-performed the 100% newspaper sample, while the samples of the other proportions performed identically and significantly underperformed the 100% newspaper sample. It was no surprise that the printer paper showed nearly double the flexibility of our hand-made samples. The ratio of thickness (.07cm) to sample width for our hand-made samples was.035, while the printer paper had an industry-standard thickness of.01 cm, for a ratio of thickness to sample width of 0.005; it was to be expected that the thinner sample would outperform the thicker sample in terms of flexibility. We see flexibility as advantageous for applications such as construction/craft paper, where folding and other manipulation could be important. Flexibility would also be valuable for applications involving both molded and folded packaging, where the ability to maintain a crisp 13

14 edge without failure could be important. Flexibility would be of minimal significance for stationary applications. Write-ability was of interest primarily in application as stationary. We anticipated that any printing required for packaging would with be ink-stamped or silk screened onto the packaging component, or relief-stamped into the mold for the packaging component. Since the application we were considering was stationary, write-ability had to be optimized with appearance. Between the two factors, we concluded that the most attractive product in our purely subjective evaluation was the 50/50 sample and, although the write-ability of the 75% newspaper/25% grass sample was slightly better than the 50/50, the appearance of the 50/50 sample made that proportion the most appropriate for an application as stationary. In light of the malodorous piles of glass clippings in one of our backyards which smokes, smolders, and occasionally ignites, we believed that the products needed to be monitored for smell as an indicator of potential bacterial activity. We did not observe a significant change in the level of odor from week to week. After three weeks, none of the product had developed any sour smell or any odor such as we would associate with fermentation or decay. Only the 50/50 sample and the 25% newspaper/75% grass sample had any discernable odor, an herbal scent which was not unpleasant. Analyzing product by product, 100% grass did not result in a viable sheet that we could test. While the 25% newspaper/75% grass sample did result in a viable sheet, since it produced the worst results in every test. It proved to be extremely weak in tensile strength, moderately weak in the fatigue test, and weak and fragile in the flexibility test. Additionally, while we could write on it with a ballpoint pen and an ultrafine tip Sharpie, the fibers were significantly disturbed by the Sharpie and noticeably loosened by the ballpoint. Furthermore, we suspect 14

15 that the odor, however mild, suggests potential bacterial activity which may eventually result in fermentation, rotting, and the attraction of rodents and insects. Our conclusion is that a product of these proportions presently has no economically-useful purpose. The 50% newspaper/50% grass sample proved to be the optimal product for commercial production and use as it was the most durable, least brittle sample. It performed the best in the fatigue strength test, which is a positive asset for applications as construction/craft paper, as it can be folded and manipulated into shapes if used in that fashion, and as folded packaging. This sample also performed optimally in the tensile strength test, which recommends it for both molded and folded packaging. We also anticipate an application of this product being used as stationary due to its write-ability and attractive appearance. While the fibers were slightly disturbed by the ballpoint pen and the more disturbed by the Sharpie, the paper remained useable. This sample had the best overall value as it had the most environmental benefits while maintaining functionality. Additionally, the odor after three weeks did not seem strong enough to suggest rotting and fermentation later on. The 75% newspaper/25% grass paper performed the best in the tensile strength test, the flexibility test, and the writing test. Due to these results, we have concluded that this paper would be best used for molded packaging purposes. Flexibility and sturdiness are both important for packaging as the pulp must be molded and set in order to maintain the desired shape. Lastly, there was no discernable odor when the grass was in this proportion. 15